Background Exodeviation is a horizontal form of strabismus characterized by visual axes that form a divergent angle. The different types of acquired exotropia are intermittent exotropia, sensory exotropia, exotropia with neurologic causes and field defects, and consecutive exotropia. Certain conditions, such as third nerve palsy , thyroid ophthalmopathy , and iatrogenic trauma following retinal detachment surgery or endoscopic sinus surgery, could cause acquired exotropia; however, these conditions are not discussed in this article. Pathophysiology The deviation usually begins as an exophoria. Exophoria is a condition in which the alignment of the eye is straight when both eyes are open, but either eye drifts outward when covered. During this phase, the patient has bifoveal fixation. This deviation may later progress to intermittent exotropia, during which the deviation may be manifest (exotropia) or latent (exophoria). When intermittent exotropia develops in a child whose visual system is still immature, bitemporal suppression develops, and the child does not perceive 2 separate images (diplopia ). As suppression increases, intermittent exotropia may finally progress to constant exotropia. If acquired exotropia develops in adults, the patient experiences periods of diplopia during the tropic (manifest) phase. See the images below. Patient with intermittent exotropia at distance only. Patient is fixing with the left eye. Note the outward deviation of the right eye. Patient with intermittent exotropia at distance only. Patient is now fixing with the right eye, showing that he can alternate well. Patient with intermittent exotropia at both distance and near. Patient is fixing with the left eye. Note the outward deviation of the right eye.
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BackgroundExodeviation is a horizontal form of strabismus characterized by visual axes that form a divergent angle. The different types of acquired exotropia are intermittent exotropia, sensory exotropia, exotropia with neurologic causes and field defects, and consecutive exotropia.
Certain conditions, such as third nerve palsy, thyroid ophthalmopathy, and iatrogenic trauma following retinal detachment surgery or endoscopic sinus surgery, could cause acquired exotropia; however, these conditions are not discussed in this article.
PathophysiologyThe deviation usually begins as an exophoria. Exophoria is a condition in which the alignment of the eye is straight when both eyes are open, but either eye drifts outward when covered. During this phase, the patient has bifoveal fixation. This deviation may later progress to intermittent exotropia, during which the deviation may be manifest (exotropia) or latent (exophoria).
When intermittent exotropia develops in a child whose visual system is still immature, bitemporal suppression develops, and the child does not perceive 2 separate images (diplopia). As suppression increases, intermittent exotropia may finally progress to constant exotropia. If acquired exotropia develops in adults, the patient experiences periods of diplopia during the tropic (manifest) phase. See the images below.
Patient with intermittent exotropia at distance only. Patient is fixing with the left eye. Note the outward deviation of the right eye.
Patient with intermittent exotropia at distance only. Patient is now fixing with the right eye, showing that he can alternate well.
Patient with intermittent exotropia at both distance and near. Patient is fixing with the left eye. Note the outward deviation of the right eye.
Patient with intermittent exotropia at both distance and near. Patient is now fixing with the right eye, showing that she can alternate well.
EpidemiologyFrequency
InternationalEsodeviations are more frequent than exodeviations, with a ratio of 3:1.
Acquired exotropia is more common in the Middle East, Africa, and Asia and
in those latitudes with higher levels of sunlight. It is less common in the United States and Europe.
Mortality/Morbidity
Diplopia and eyestrain associated with acquired exotropia can affect daily activities, such as driving and reading.
Race
No racial predilection exists.
Sex
Acquired exotropia is more common in females than in males, with a female preponderance of 63-70%.
Age
Contrary to a previous belief, intermittent exotropia can have an early onset, with 25-40% of cases occurring before the second year of life.
Proceed to Clinical Presentation
HistoryClinical presentation
Patients may experience asthenopia (eyestrain) during visual tasks, especially after prolonged near work. A common complaint is that a patient loses his or her place on a line while reading and repeatedly restarts on the same line.
Diplopia that is horizontal and crossed (ie, the right eye sees the image on the left, and the left eye sees the image on the right) may develop in some patients.
Some patients are subjectively aware of when the divergence of their eyes occurs, and they are able to volitionally restore binocularity.
Some patients may complain that objects appear smaller and closer because they use accommodative convergence to control the exodeviation.
Children characteristically close one eye in bright light. This action may precede the actual divergence of the eyes, or the parents may notice this phenomenon, which becomes the presenting complaint. Although various theories have been proposed to explain this phenomenon (eg, glare hinders fusion and causes its disruption), it remains incompletely understood.
Some attentive patients may notice an increase in the temporal visual field of the affected eye, called panoramic viewing.
Duane classificationIf the deviation is greater at distance than at near, it is called the
divergence excess type of exotropia.If the deviation is greater at near than at distance, it is called the
convergence insufficiency type of exotropia.If little (< 10 prism diopters [PD]) or no difference exists between distance
and near deviation, it is called the basic type of exotropia.Burian classificationThe divergence excess type of exotropia occurs when the deviation is
greater at distance than at near (same as Duane classification). Burian divided it into 2 types: simulated divergence excess and true divergence excess. The simulated divergence excess type of intermittent exotropia demonstrates an increase in the near deviation after monocular occlusion or with +3.00 diopter (D) lenses placed in front of the habitual (if any) spectacle or contact lens prescription. If no increase occurs in the near deviation with either test, a true divergence excess type of intermittent exotropia is present.
The basic type of exotropia occurs when little or no difference exists between distance and near deviation (same as Duane classification).
The convergence insufficiency type of exotropia occurs if the deviation is greater at near than at distance (same as Duane classification).
Kushner classificationThis classification system takes into account the effect of monocular
occlusion, the use of either -2.00 D lenses or +3.00 D lenses, and the accommodation convergence-accommodation (AC/A) ratio.
The Kushner classification of intermittent exotropia is depicted in the image below.Kushner classification of intermittent exotropia.
PhysicalA complete ophthalmic examination and an ocular motility examination should be performed in each patient.
Specific parts of the examination are outlined below, followed by physical findings of the different types of acquired exotropia.
Measurement of the deviationDistance deviation is measured at 6 meters with an accommodative target;
target size is 20/70 or smaller.
Far distance deviation is measured when the patient looks out of a window or at any target 50-100 feet away. This method may help obtain the full exotropic angle, which may increase from 10 PD to 30 PD when compared to the distance deviation measured at 6 meters.
Near deviation is measured at 33 centimeters with an accommodative target.
Deviation is measured after monocular occlusion to disrupt fusional convergence. Distance and near measurements are taken after patching either eye for at least 30-45 minutes.
Deviation is measured after using either +3.00 D lenses (near deviation) or –2.00 D lenses (distance deviation) to disrupt the accommodative convergence. The deviation with +3.00 D lenses should always be measured after the monocular occlusion test to avoid an erroneous measurement of a high AC/A ratio.
Assessment of the control of the deviationThis testing is important to obtain a baseline assessment and to monitor
deterioration and progression of the intermittent exotropia.Subjective methodsIn home control, parents assess the deviation. The assessment of deviation
is categorized as follows: excellent control, where deviation occurs rarely or only at distance when tired, fatigued, or inattentive; good control, where deviation occurs less than 5 times a day and only at distance; fair control, where deviation occurs more than 5 times a day and only at distance; or poor control, where deviation occurs frequently at distance and near.
In office control, ophthalmologists assess the deviation in a clinical setting. The assessment of deviation is categorized as follows: good control, where the patient breaks down only after cover testing and resumes fixation without a blink; fair control, where the patient breaks down after cover testing and blinks to refixate; or poor control, where the patient breaks down without any form of fusion disruption.
Objective methodsDistance stereoacuity provides an objective measure of the control of the
deviation and the deterioration of fusion.Near stereoacuity does not correlate well with the degree of control of the
distance deviation.
AmblyopiaAmblyopia does not occur as frequently in patients with intermittent
exotropia as in patients with esotropia. This type of amblyopia is usually nonstrabismic and frequently anisometropic.
Assessment of refractive error is an important part of the examination because unequal visual clarity could hinder binocular fusion and lead to the progressive loss of control of the exotropia. Cases of exotropia resolving after the optical correction of a high hyperopic refractive error have been reported.
Sensory changesSuppression may be noted. Alternate suppression with temporal scotomas
(which tend to split fixation) has been demonstrated in 52% of patients with intermittent exotropia.
Retinal correspondence is determined.Distance and near stereoacuity is assessed.
Lateral incomitancesThe size of the deviation differs in the primary position and in the lateral
gaze positions.Horizontal incomitance has been reported in 5-60% of patients with
exotropia.Recognizing lateral incomitance is important since an alteration of the
surgical strategy to avoid diplopia in side gaze postoperatively may be required.
Vertical incomitancesThe incidence of A- and V-pattern strabismus and oblique muscle
dysfunction is lower in exotropia than in other types of strabismus.
The most common pattern associated with exotropia is V-pattern strabismus.
X-pattern exotropia can occur secondary to the overaction of the inferior and superior oblique muscles.
Convergence: When the deviation is greater at near than at distance, convergence insufficiency is possible.
Sensory exotropia is a condition of unilateral divergence as a sequela to loss of vision or long-standing poor vision in one eye.
Sensory exotropia can occur because of visual loss at any age. In younger children, the incidence of esotropia or exotropia occurring in the nonseeing eye is about equal. In adults, the tendency is toward exotropia.
Sensory exotropia accounts for 20-25% of all causes of acquired exotropias.The deviation angles are characteristically large. An eye with long-standing
sensory exotropia often develops any of the several mechanical and innervational abnormalities, especially if the angle is large. These abnormalities include tight lateral rectus muscle
syndrome with limited adduction, secondary pseudo–oblique muscle overaction, and shortening and tightening of the Tenon capsule and the conjunctiva over the lateral rectus muscle.
Superior oblique overreactions with A-pattern strabismus are more common than V-pattern strabismus.
On examination, the deviation needs to be measured with the Krimsky test or the light reflex-prism test if the visual acuity in the exotropic eye is poor.
Exotropia can develop if both eyes have a significant visual field loss. Exotropia may occur with either bilateral homonymous field defects or heteronymous defects (eg, bitemporal field defects). This condition is uncommon.
Exotropia with bilateral homonymous visual field defectsAcquired neurologic disorders may produce bilateral homonymous field
defects. Some patients may develop exodeviations, mostly exophorias or small intermittent exotropias.
Characteristically, these patients have normal retinal correspondence and good fusional ability. They do not have significant visual difficulties. Patients rarely complain of diplopia.
Whether the exotropia that develops is a true compensatory phenomenon or a coincidental finding is unclear. The exotropia may be helpful by allowing enlargement of the total visual field.
Exotropia with bitemporal visual field defectsBitemporal hemianopia, which may occur with lesions (eg, pituitary tumors,
aneurysms near the optic chiasma), is rarely associated with exotropia.
Unlike a homonymous field defect, a bitemporal defect always interferes with fusion, and, in cases where strabismus develops, a significant field loss, including central vision, occurs in both eyes.
These patients are usually disturbed by the symptoms of disordered binocular vision. Because of retinal sliding, the patients have a subjective sensation of an elongated target or a duplication of some features of a target. Loss of fixation beyond the fixation target may occur. All of these phenomena make routine visuomotor tasks difficult.
Consecutive exotropia, also called secondary exotropia, is the type of exodeviation that occurs after surgical overcorrection of an esodeviation.
CausesHereditary does play a role, but the genetics of this disorder are multifactorial. Exodeviations tend to occur earlier and to be larger in
Laboratory StudiesLaboratory tests are not usually required, except for those routinely performed prior to surgery.
Imaging StudiesImaging studies are not routinely required, although they may be beneficial for patients with certain conditions (eg, craniosynostosis, suspected abnormalities of the pulley systems).
Proceed to Treatment & Management
Medical CareNonsurgical treatment is indicated in patients with excellent or good control of the deviation as measured by normal distance stereoacuity and in young children where the risk of surgical overcorrection is undesirable.
Nonsurgical treatment modalitiesCorrection of refractive error: All kinds of refractive errors, particularly
astigmatism and anisometropia, must be corrected. The associated improvement in visual acuity could be associated with increased fusional ability and better control of intermittent exotropia.
Minus lenses: The lenses stimulate convergence through the accommodative convergence synkinesis and help control divergence. The efficacy largely depends on the patient's AC/A ratio. The larger the AC/A ratio, the larger the effect (ie, patients can compensate for larger deviations). Various studies have reported not only an improvement in quality of fusion but also a quantitative decrease in the angle of deviation. Minus lenses range from –2 D to –4 D; they may be most helpful in younger children with exodeviations of 5-15 PD. A study showed that the overcorrecting minus lenses worked well in children aged 2-17 years and that the average reduction in the exodeviation was approximately 10 PD.[1]
Occlusion: Patching the dominant eye or alternate patching of either eye is suggested to interrupt the process of suppression and to reduce the progression of the exotropia.
Prisms: Base-in prisms may aid control and relieve asthenopic symptoms in small comitant exodeviations of up to approximately 20 PD.
Orthoptics: Convergence exercises improve convergence fusional amplitudes and the near point of convergence. Convergence exercises are indicated for patients with symptoms of the convergence insufficiency type of intermittent exotropia. Near point exercises, prism convergence exercises, and red glass convergence exercises are recommended.
Role of botulinum toxin (BOTOX®) injections in the extraocular muscles to treat secondary exotropia: A study showed good results in 383 subjects with exotropia who were treated with BOTOX®.[2] Multiple injections may be required, but they were well tolerated with no permanent adverse effects.
Sensory exotropia: The most important aspect of the management is to find and/or eliminate and/or reverse a treatable cause of the exotropia. Prisms and botulinum toxin injections do not play a significant role in the treatment of sensory deviation.
Exotropia with neurologic causes and field defectsExotropia with bilateral homonymous visual field defects: Nonsurgical
methods of treatment, such as patching, prisms, or botulinum toxin injections, should be tried before surgical realignment.
Exotropia with bitemporal visual field defects: Nonsurgical treatment includes the use of prisms to increase the separation of images and to avoid diplopia without sacrificing the total visual field.
Surgical CareOpinions vary widely with regard to the appropriate timing of surgical intervention for patients with intermittent exotropia. Surgery is indicated in the following:
Poor control of the deviation: When the tropic (manifest) phase is present at least 50% of the time, poor control of the intermittent exotropia is indicated, and surgery should be considered.
Deterioration of control of intermittent exotropia: Serial observations of an increase in the size of the deviation, a progressive deterioration in distance and/or near stereoacuity, a loss of control, and a progressive inability to re-fuse after manifestation of the deviation all indicate deterioration of control, and surgery should be considered.
Bothersome diplopia: Surgery is indicated for patients with this condition.Severe asthenopia: Orthoptic exercises may be tried. If unsuccessful, then
surgery should be considered.
Surgical procedures that can be used are lateral rectus muscle
recession, recess-resect procedure (ie, lateral rectus muscle recession and ipsilateral medial rectus muscle resection), and bilateral medial rectus muscle resection. Indications for each surgical procedure are outlined in the image below.
Management options for various types of intermittent exotropia. A unilateral recess-resect procedure can also be performed in children with exotropia of the convergence insufficiency type where the exodeviation is more at near and less or absent at distance.[3] Comparison of treatment options for intermittent exotropia have shown that surgery with preoperative orthoptic/occlusion therapy have the highest success rates compared to treatment with prisms alone or horizontal muscle surgery alone.[4] Since undercorrection is a frequent sequela to surgery for intermittent exotropia, it is recommended that the largest angle ever measured be taken as the target angle for surgery and that the surgical dose be based on this angle.[5] Sensory exotropia: If possible, surgery should be confined to the eye with the visual defect. The recess-resect procedure (lateral rectus muscle recession combined with ipsilateral medial rectus muscle resection) is recommended. When indicated, the recess-resect procedure should be combined with recession of the conjunctiva in a long-standing deviation. Exotropia with bitemporal visual field defects: Surgical correction is difficult because of the varying nature of this alignment. Adjustable sutures may be used, but results tend to be unstable because of the absence of fusion. Consecutive exotropia
Management depends on the amount of exodeviation and the type of previous surgical procedure.
If the deviation is small, it can be treated with minus lenses, which can be started immediately after surgery. Base-in prisms can be tried for small angle comitant deviations. If the deviation is large, a reoperation is the procedure of choice.
The choice of a reoperation procedure depends on the type of previous surgery, the amount of exodeviation present at distance and near, and any limitation of ocular rotations as a result of the previous surgery.
If the previous procedure was a bilateral medial rectus recession for esotropia, a limitation of adduction may indicate a slipped medial rectus muscle. In such cases, medial rectus advancement must be performed to correct the secondary exotropia.
In situations where adduction is full and the exodeviation is greater at distance than at near, lateral rectus recessions may be considered.
A repeat recess-resect procedure on the same eye or the contralateral eye can be performed when the deviation is the same at distance and near.
ConsultationsPatients with exotropia associated with a neurologic disorder should be referred for a neurologic consultation.
Proceed to Follow-up
Further Outpatient CareStrabismus surgery is performed as an outpatient procedure.Although regimens vary among surgeons, regular follow-up visits are necessary to assess eye alignment and to examine fusional abilities.
ComplicationsIf left untreated, intermittent deviations could progress to constant exodeviations, with subsequent development of amblyopia and loss of fusional abilities in young children. No specific complications are related to surgery for this condition; however, complications of eye muscle surgery in general apply. Postoperative complications include overcorrection, undercorrection, residual A- or V-pattern strabismus, and diplopia in side gazes due to lateral incomitances.
PrognosisSome factors that affect the prognosis are as follows:
Some authors believe that surgical alignment before age 4 years yields better results with lower risks for amblyopia. On the other hand, even a slight overcorrection increases the risk of loss of bifoveal fixation at this young age.
Patients with better fusional control preoperatively do better postoperatively.
Correction of refractive error should be continued postoperatively.Tenacious proximal fusion may predict better postoperative results.
Both motor alignment and sensory functional improvement should be included in the postoperative assessment of response to surgery.
BackgroundPseudoexotropia is a condition in which the alignment of the eyes is straight (also known as orthotropic); however, they appear to be turned outward.[1]
See related CME at Highlights of the American Association for Pediatric Ophthalmology and Strabismus Annual Meeting.
PathophysiologyPseudoexotropia occurs with a wide interpupillary distance or a positive angle kappa. Angle kappa is the angle formed between 2 imaginary lines: the visual axis and the pupillary axis. To construct the visual axis, extend a straight line from the viewing object through the nodal point. A straight line going through the center of the pupil and perpendicular to the corneal plane constructs the pupillary axis. Since fovea is displaced temporally, a small angle kappa (up to 5°) manifests as a nasally displaced corneal light reflex. Children may falsely appear to have an exotropia when they look to the side.
EpidemiologyFrequency
United StatesThe incidence of pseudoexotropia is higher in children with a temporally dragged macula from retinopathy of prematurity.
Sex
No known sexual predilection exists.
Age
The appearance of pseudoexotropia is seen at any age.
Proceed to Clinical Presentation
HistoryParents bring their child to their physician, reporting that the child's eyes appear to be turned out.
PhysicalPatients appear to have a large angle kappa or nasally deviated corneal light reflex. By performing the cover-uncover test, no movement can be demonstrated. In the case of a dragged macula, an ophthalmoscope examination reveals an ectopic macula displaced temporally.
CausesA common cause of pseudoexotropia is a dragged or temporally displaced macula associated with retinopathy of prematurity.
Retinal scarring in the temporal periphery caused by Toxocara canis is another cause of a temporally displaced macula resulting in pseudoexotropia.
Proceed to Differential Diagnoses
Further Outpatient CareA patient with pseudoexotropia should be observed on a regular basis to ensure no subsequent development of true strabismus.[2]
Patient EducationParents of a child with pseudostrabismus should be reassured that the alignment of their child's eyes is straight (orthotropic). However, follow-up care should be continued because pseudoexotropia can hide a true strabismus.[2]
Kelumpuhan otot dapat mengenai satu otot, biasanya m.rektus lateralis, m.obliqus superior atau
salah satu otot yang diurus oleh N.III. Dapat juga mengenai beberapa otot yang diurus oleh
N.III13.
H. Penatalaksanaan
d..1. Tujuan :7
a. mengembalikan penglihatan binokular yang normal
b. alasan kosmetik
d..2. Dapat dilakukan dengan tindakan:4,5
a. Ortoptik
d..2.a.1) Oklusi
Jika anak menderita strabismus dengan ambliopia, dokter akan merekomendasikan untuk
melatih mata yang lemah dengan cara menutup mata yang normal dengan plester mata
khusus (eye patch).
d..2.a.2) Pleotik
d..2.a.3) Obat-obatan
b. Memanipulasi akomodasi
1) Lensa plus / dengan miotik
Menurunkan beban akomodasi dan konvergensi yang menyertai
2) Lensa minus dan tetes siklopegik
Merangsang akomodasi pada anak-anak
c. Operatif
Prinsip operasinya :
- reseksi dari otot yang terlalu lemah
- resesi dari otot yang terlalu kuat
Tindakan operatip dilakukan apabila terpi lain telah gagal untuk memperbaiki posisi bola
mata. Preoperatif yang sudah cukup lama dilakukan, kira-kira 1 tahun, tetapi tak berhasil,
maka dilakukan operasi. Dan juga pada strabismus dengan deviasi bola mata yang lebih dari
45º.
3. Tahapan:7
a. Memperbaiki visus kedua mata dengan terapi oksklusi
a.i.1.a.Pada anak berumur dibawah 5 tahun dapat diteteskan sulfas atropin 1 tetes satu
bulan, sehingga mata ini tak dipakai kira-kira 2 minggu. Ada pula yang menetesinya
setiap hari dengan homatropin sehingga mata ini beberapa jam sehari tak dipakai.
a.i.1.b. Pada anak yang lebih besar, mata yang normal ditutup dilakukan penutupan
matanya 2-4 jam sehari. Dengan demikian penderita dipaksa untuk memakai matanya
yang berdeviasi. Biasanya ketajaman penglihatannya menunjukkan perbaikan dalam 4-
10 minggu. Penutupan ini mempunyai pengaruh baik pada pola sensorisnya retina, tetapi
tidak mempengaruhi deviasi. Sebaiknya terapi penutupan sudah dimulai sejak usia 6
bulan, untuk hindarkan timbulnya ambliopia. Penetesan atau penutupan jangan
dilakukan terlalu lama, karena takut menyebabkan ambliopia pada mata yang sehat.
a.i.1.c.Pada strabismus yang sudah berlangsung lama dan anak berumur 6 tahun atau lebih
pada waktu diperiksa pertama, maka hasil pengobatannya hanya kosmetis saja. Sedapat
mungkin ambliopia pada mata yang berdeviasi harus dihilangkan dengan cara
penutupan, pada anak yang sudah mengerti (3 tahun), harus dikombinasikan dengan
latihan ortoptik untuk mendapatkan penglihatan binokuler yang baik. Kalau pengobatan
preoperatif sudah cukup lama dilakukan, kira-kira 1 tahun, tetapi tak berhasil, maka
dilakukan operasi.
b. Memperbaiki posisi kedua bola mata agar menjadi ortoforia.
Hal ini dapat dicapai dengan pemberian lensa, melaukan operasi atau kombinasi keduanya.
Tindakan operasi sebaiknya dilakukan bila telah tercapai perbaikan visus dengan terapi
okslusi. Tindakan operatif sebaiknya dilakukan pada umur 4-5 tahun, supaya bila masih ada
strabismusnya yang belum terkoreksi dapat dibantu dengan latihan.
c. Melatih fusi kedua bayangan dari retina kedua mata agar mendapatkan penglihatan
binokuler sebagai tujuan akhir yang hasilnya tergantung dari hasil operasi, pemberian lensa
koreksi dan latihan ortoptik.
Uji Juling
Terdapat bermacam-macam uji atau pemeriksaan untuk membuat
diagnosiskeseimbangan otot geak mata seperti :
Uji Hirschberg, refleks kornea
Pada uji coba ini mata disinari dengan sentolop dan akan terlihat refleks sinar pada
permukaan kornea. Refleks sinar pada mata normal terletak pada kedua mata sama-sama di
tengah pupil. Bila satu refleks di tengah pupil sedangkan pada mata yang satunya di nasal,
berarti pasien juling keluar atau eksotropia.
Uji Krimsky, (untuk menilai derajat deviasi mata)
Mengukur sudut deviasi pada juling dengan meletakkan ditengah cahaya refleks kornea
dengan prisma. Refleks cahaya diobservasi agar dipusatkan pada pupil mata yang nirfiksasi.
Sudut deviasi dan arah di baca langsung dari prisma.
Uji tutup mata berganti
Bila satu mata ditutup dan kemudian mata yang lain maka bila kedua mata berfiksasi
normal maka mata yang dibuka tidak bergerak. Bila terjadi pergerakan pada mata yang baru
dibuka berarti terdapat foria atau tropia.
Uji tutup buka mata
Uji ini sama dengan uji tutup mata, dimana yang dilihat adalah mata yang ditutupp dan
dingganggu fusinya sehingga mata yang tidak normal atau juling akan menggulir. Bila mata
tersebut ditutup dan dibuka akan terlihat pergerakan mata tersebut. Pada keadaan ini berarti
mata ini mengalami foria atau juling atau berubah kedudukan bila mata ditutup.
BAB III
RINGKASAN
Gangguan lapang pandang
Jalur penglihatan merupakan saluran saraf dari retina ke pusat penglihatan pada daerah
oksipital otak. Gangguan pada jalur penglihatan akan mengakibatkan gangguan fungsinya.
Terdapatbeberapa dasar jalur penglihatan dan lapang pandang mata, seperti :
5. Retina bagian nasal dari makula diproyeksikan ke arah temporal llapang pandangan.
6. Serabut saraf bagian nasal retina menyilang kiasma optik.
7. Serabut saraf bagian temporal berjalan tidak bersilang pada kiasma optik.
8. Lapang pandangan normal pada suatu mata terletak 90 derajat temporal, 60 derajat
medial, 60 derajat atas, dan 75 derajat bawah.
FUNDUSKOPI
Tujuan :Tes untuk melihat dan menilai kelainan dan keadaan pada fundus okuli
Dasar :Cahaya yang dimasukkan kedalam fundus akan memberikan refleks fundus.Gambaran fundus mata akan terlihat bila fundus diberi sinar.
Alat : 1. Oftalmoskop 2. Obat melebarkan pupil - tropicamide 0.5%-1% (mydriacyl) - fenilefrin hidroklorida 2.5% (kerja lebih cepat)
Perhatian :Sebaiknya sebelum melebarkan pupil diukur tekanan bola mata terlebih dahulu.Sebaiknya melakukan pemeriksaan dengan pupil dilebarkan, kecuali bila :- Bilik mata yang dangkal - Trauma kepala - Implan fiksasi pada iris- Pasien pulang mengendarai kendaraan sendiri - Pasien glaukoma sudut sempit
TehnikOftalmoskopi direk
F. Mata kanan pasien dengan mata kanan pemeriksa, mata kiri pasien dengan mata kiri pemeriksa kecuali bila pasien dalam keadaan tidur dapat dilakukan dari atas.3. Mula-mula diputar roda lensa oftalmoskop sehingga menunjukkan angka +12 D4. Oftalmoskop diletakkan 10 cm dari mata pasien. Pada saat ini fokus terletak pada kornea atau pada lensa mata.5. Bila ada kekeruhan pada kornea atau lensa mata akan terlihat bayangan yang hitam pada dasar yang jingga.( oftalmoskop jarak jauh)6. Selanjutnya oftalmoskop lebih didekatkan pada mata pasien dan roda lensa oftalmoskop diputar, sehingga roda lensa menunjukkan angka mendekati nol.7. Sinar difokuskan pada papil saraf optik.8. Diperhatikan warna, tepi, dan pembuluh darah yang keluar dari papil saraf optik.9. Mata pasien diminta melihat sumber cahaya oftalmoskop yang dipegang pemeriksa, dan pemeriksa dapat melihat keadaan makula lutea pasien10. Dilakukan pemeriksaan pada seluruh bagian retina.
Oftalmoskopi indirekc. Pemeriksa menggunakan kedua matad. Alat diletakkan tepat didepan kedua mata dengan bantuan pengikat di sekeliling kepalae. Pada celah oftalmoskop dipasang lensa konveks +4D yang menghasilkan bayangan jernih bila akomodasi diistirahatkanf. Jarak dengan penderita kurang lebih 40cmg. Pemeriksaan juga membutuhkan suatu lensa tambahan , disebut lensa objektif yang berkekuatan S +13 D, ditempatkan 7-10 cm didepan mata penderita
h. Bila belum memproleh bayangan yang baik, lensa objektif ini digeser mendekat dan menjauh.
Direk IndirekSifat bayangan tegak TerbalikPembesaran 15x 4-5xLapang pandang kecil Lebih besarHal-hal khusus Refleks macula dan detail
retina lebih jelasNon stereoskopikTidak berfungsi pada kekeruhan media
General view
Stereoskopik, penting pada ablatio retinaMasih dapet memperlihatkan gambaran fudus meskipun media keruh
NilaiDapat dilihat keadaan normal dan patologik pada fundus mata kelainan yang dapat dilihat
g. Pada papil saraf optik4. Papiledema (normal C/D ratio 0,3-0,5) 5. Hilangnya pulsasi vena saraf optik6. Ekskavasi papil saraf optik pada glaukoma7. Atrofi saraf optik
3.Pembuluh darah retinac. Perbandingan atau rasio arteri vena (normal=2:3)d. Perdarahan dari arteri atau venae. Adanya mikroaneurisma dari vena
TONOMETRI
DASARTonometer schiotz merupakan tonometer indentasi atau menekan permukaan kornea dengan bebat yang dapat bergerak bebas pada sumbunya.Benda yang ditaruh pada bola mata (kornea) akan menekan bola mata kedalam dan mendapat perlawanan tekanan dari dalam melalui kornea. Keseimbangan tekanan tergantung pada beban tonometer.Tonometer schiotz merupakan tonometer indentasi lebih dalam bila tekanan mata lebih rendah di banding mata dengan tekanan tinggi.Pada tonometer schiotz bila tekanan rendah atau bola mata empuk maka beban akan dapat mengindentasi lebih dalam dibanding bila tekanan bola mata tinggi atau bola mata keras.
TUJUANMelakukan pemeriksaan tekanan bola mata dengan tonometer.
ALAT e. Obat tetes anestesi lokal (tetrakain)f. Tonometer schiotz
TEKNIKc. Pasien diminta melonggarkan pakaian termasuk dasi yang dipakai.d. Pasien tidur terlentang di tempat tidur tanpa bantale. Mata ditetes tetrakainf. Ditunggu sampai pasien tidak merasa pedasg. Kelopak mata pasien dibuka dengan telunjuk dan ibu jari (jangan tertekan bola mata pasien)h. Pasien diminta meletakkan ibu jari tangannya didepan matanya atau pasien melihat ke langit-langit ruang pemeriksaani. Telapak tonometer schiotz diletakkan pada permukaan korneaj. Setelah telapak tonometer menunjukkan angka yang tetap di baca nilai tekanan pada skala busur schiotz yang berantara 0 – 15.k. Bila skalanya <3 maka bebannya diganti (beban yg tersedia 5,5gr; 7,5gr; 10gr; dan 15 gr.
NILAI Pembacaan skala dikonversi pada tabel untuk mengetahui tekanan bola mata dalam milimeter air raksa
• Pada tekanan lebih tinggi 20 mmhg di curigai adanya glaukoma • Bila tekanan lebih dari 25 mmhg pasien menderita glaucoma
Pemeriksaan tekanan bola mata secara palpatoirPenderita harus melihat ke bawah tanpa menutup mata. Dengan jari telunjuk kita menekan bola mata, kemudian jari telunjuk tangan lainnya merasakan tahanan yang didapatkan. Harus dibandingkan dengan mata sebelahnya dan tekanan pada mata normal.HasilN bila tekanan normalN+ bila tekanan tinggi (glaukoma)N- bila tekanan rendah (hipotoni)
Funduskopi merupakan tes untuk melihat dan menilai kelainan dan keadaan pada fundus okuli. Cahaya yang dimasukkan kedalam fundus akan memberikan refleks fundus dan gambaran fundus mata akan terlihat bila fundus diberi sinar.
Alat yang diperlukan adalah oftalmoskop dan obat melebarkan pupil (tropicamide 0.5%-1% (mydriacyl) / fenilefrin hidroklorida 2.5% (kerja lebih cepat))
Tehnik Oftalmoskopi direk
G. Mata kanan pasien dengan mata kanan pemeriksa, mata kiri pasien dengan mata kiri pemeriksa kecuali bila pasien dalam keadaan tidur dapat dilakukan dari atas.
H. Mula-mula diputar roda lensa oftalmoskop sehingga menunjukkan angka +12 DI. Oftalmoskop diletakkan 10 cm dari mata pasien. Pada saat ini fokus terletak pada kornea atau pada
lensa mata.J. Bila ada kekeruhan pada kornea atau lensa mata akan terlihat bayangan yang hitam pada dasar yang
jingga.( oftalmoskop jarak jauh)K. Selanjutnya oftalmoskop lebih didekatkan pada mata pasien dan roda lensa oftalmoskop diputar,
sehingga roda lensa menunjukkan angka mendekati nol.L. Sinar difokuskan pada papil saraf optik.M. Diperhatikan warna, tepi, dan pembuluh darah yang keluar dari papil saraf optik.N. Mata pasien diminta melihat sumber cahaya oftalmoskop yang dipegang
pemeriksa, dan pemeriksa dapat melihat keadaan makula lutea pasienO. Dilakukan pemeriksaan pada seluruh bagian retina
Oftalmoskopi indirek P. Pemeriksa menggunakan kedua mataQ. Alat diletakkan tepat didepan kedua mata dengan bantuan pengikat di sekeliling kepalaR. Pada celah oftalmoskop dipasang lensa konveks +4D yang menghasilkan bayangan jernih bila
akomodasi diistirahatkanS. Jarak dengan penderita kurang lebih 40cmT. Pemeriksaan juga membutuhkan suatu lensa tambahan , disebut lensa objektif yang berkekuatan S
+13 D, ditempatkan 7-10 cm didepan mata penderitaU. Bila belum memproleh bayangan yang baik, lensa objektif ini digeser mendekat dan menjauh.
Gambar 1. a. Oftalmoskopi direk dan b. Oftalmoskopi indirek
Gambar 2. Prosedur Oftalmoskopi
Gambar 3. Fundus Normal. Pembuluh darah retina tidak menyebrangi fovea.
Dapat dilihat keadaan normal dan patologik pada fundus mata kelainan yang dapatdilihat1. Pada papil saraf optik
2. Pada retinah. Perdarahan subhialoidi. Perdarahan intra retina, lidah api, dots, blotsj. Edema retinak. Edema makula
3. Pembuluh darah retina8. Perbandingan atau rasio arteri vena (normal=2:3)9. Perdarahan dari arteri atau vena10. Adanya mikroaneurisma dari vena
Tonometri
Tonometri schiotz merupakan salah satu pemeriksaan yang ditujukan untuk menghitung tekanan intraocular. Pemeriksaan ini menghitung sejauh mana kornea dapat diindentasi pada pasien yang sedang terletang. Semakin rendah tekanan intraocular, semakin dalam tenggelam pin tonometer dan semakin besar jarak pergerakan jarum. Bila tekanan bola mata lebih rendah maka beban akan mengindentasi lebih dalam permukaan kornea dibanding tekanan bola mata lebih tinggi. Tekanan bola mata normal adalah 10-20 mmHg.
Namun, indentrasi tonometry sering memberikan hasil yang tidak pasti. Misalnya kekakuan sclera yang berkurang pada mata rabun, menyebabkan pin tonometry tenggelam lebih dalam karena hal tersebut. Karena itu, tonometry ini sering digantikan dengan tonometry aplanasi.
Gambar 4. Tonometri Schiotz
Loupe dengan sentolop dan lampu celah (sitlamp)
Loupe merupakan alat untu melihat benda menjadi lebih besar disbanding ukuran normalnya. Loupe mempunyai kekuatan 4-6 dioptri. Untuk melihat benda dengan Loupe yang berkekuatan 5.0 dioptri maka benda yang dilihat harus terletak 20 cm (100/5) atau pada titik api lensa Loupe. Dengan jarak ini mata tanpa akomodasi akan melihat benda yang dilihat akan lebih tegas. Hal ini dipergunakan sebagai pengganti sitlamp, karena cara kerjanya hamper sama.
Pemeriksaan dengan Loupe atau sitlamp (lampu celah) akan lebih sempurna di dalam kamar yang gelap.
Shadow Testing atau Retinoskopi
Retinoskopi atau yang dikenal juga dengan skiaskopi atau Shadow Test, merupakan suatu cara untuk menemukan kesalahan refraksi dengan metode netralisasi. Retinoskopi memungkinkan pemeriksa secara objektif menentukan kesalahan refraktif spherosilindris, dan juga menentukan apakah astigmatisma regular dan irregular, untuk menilai kekeruhan dan ketidakteraturan.
Prinsip retinoskopi adalah berdasarkan fakta bahwa pada saat cahaya dipantulkan dari cermin ke mata, maka arah dari bayangan tersebut akan berjalan melintasi pupil bergantung pada keadaan refraktif mata.
Alat yang digunakan untuk pemeriksaan ini adalah lampu sentolop dan loupe. Tekhnik pemeriksaan adalah sebagai berikut:• Sentolop disinarkan pada pupil dengan sudut 45 derajat dengan dataran iris
• Dengan loupe lihat bayangan iris pada lensa yang keruh
Jika bayangan iris pada lensa terlihat besar dan letaknya jauh terhadap pupil berarti lensa belum keruh seluruhnya, ini terjadi pada katarak imatur, dan keadaan ini disebut shadow test positif. Jika bayangan iris pada lensa kecil dan dekat dengan pupil berarti lensa sudah keruh seluruhnya (sampai pad akapsul anterior), terdapat pada katarak matur, dan keadaan ini disebut shadow test negatif. Dan bila katarak hipermatur, lensa sudah keruh seluruhnya, mengecil serta terletak jauh di belakang pupil, sehingga bayangan iris pada lensa besar dan keadaan ini disebut dengan pseudopositif.
Shadow test juga sering disebut dengan uji bayangan iris, diketahui bahwa semakin sedikit lensa keruh semakin besar bayangan iris pada lensa yang keruh. Sentolop disinarkan pada pupil dengan membuat sudut 45 derajat dengan dataran iris, dan dilihat bayangan iris pada lensa keruh. Bila letak bayangan jauh dan besar berarti katarak imatur, sedang bila bayang kecil dan dekat pupil berarti lensa katarak matur
Gambar 5. Shadow Test
Pada gambar ini retina diterangi melalui pupil. Pemeriksaan ini mengamati fenomena optic pupil pasien saat sumber cahaya bergerak.
Mikrobiologi
Seperti membrane mukosa lainnya, kojungtiva dapapt dikultur dengan swab untuk identifikasi bakteri. Specimen untuk pemeriksaan sitology diperoleh dengan mengorek palpebral konjungtiva secara ringan dengan spatula platinum kecil setelah anastesi topical. Untuk evaluasi sitology konjungtivitis, Giemsa
merupakan pewarnaan yang digunakan untuk mengidentifikasi jenis sel inflamasi, sementara pewarnaan gram menunjukan tipe bakteri.
Gambar 6. Pengambilan specimen dari konjungtiva
Kornea biasanya steril. Seseorang yang diduga mengidap infeksi ulkus korea basisnya harus dikerok dengan spatula platinum untuk kultur dan pewarnaan gram. Spatula harus digunakan untuk menempatkan specimen langsung pada plat kultur tanpa intervensi media transport.
Kultur dari cairan intraocular adalah metode yang hanya dapat diandalkan untuk mendiagnosa atau mengesampingkan endophtalmitis menular. Aquos dapat disadap dengan memasukan jarum pendek 25-gauge pada spiut tuberculin melewati limbus secara parallel ke iris. Hasil diagnostic lebih baik jika vitreous yang dikultur. Specimen vitreous dapat diperoleh menggunakan jarum tekan melewati pars plana atau dengan operasi vitrectomy . Untuk mengevaluasi inflamasi intraocular non-infeksius, specimen sitology kadang diperiksa menggunakan tehnik tertentu.
Terhadap spesimen dilakukan :f. Pemeriksaan direct smear dengan pewarnaan metode gram g. Segera di kultur pada media : blood agar, chocolate agar, Loeffler media (untuk
Corynebactyerium) h. Dikultur dalam candle jar untuk bakteri tersangka Neisseriae dan Corynebacterium i. Dikultur dalam anaerobic jar untuk tersangka bakteri anaerob
j. Semua kultur harus dalam 48 jam.
Uji Ultrasonografi
Ultrasonografi dipakai untuk melihat struktur abnormal pada mata dengan kecepatan kekeruhan media dimana tidak memunginkan melihat jaringan dalam mata secara langsung.
Sinar ultrasonic direkam yang akan memberikan kesan keadaan jaringan yang memantulkan getaran yang berbeda-bea.
Scan B Ultrasonografi
Gambar 7. USG
USG merupakan tindakan melihat dan memotret alat atau jaringan dalam mata dengan menggunakan gelombang tidak terdengar. Alat ini sangat penting untuk melihat susunan jaringan intraocular.
Bila USG normal dan terdapat defek aferen pupil maka operasi walaupun mudah, tetap akan memberikan tajam pengelihatan yang kurang. Kelainan USG dapat disertai kelainan macula.
USG juga merupakan pemeriksaan khusus untuk katarak terutama monocular dimana akan terlihat kelainan badan kaca seperti perdarahan, peradangan, ablasi retina dan kelainan kongenital ataupun adanya tumor intraocular.
X-Ray dan CT-Scan
Foto polos dan CT Scan berguna dalam mengevaluasi kondisi orbital dan intracranial. CT scan khususnya telah menjadi metode yang paling banyak digunakan untuk lokalisasi dan karakterisasi penyakit struktural dalam jalur visual yang luar mata. Kelainan orbital umumnya ditunjukan oleh CT scan meliputi neoplasma, massa inflamasi, patah tulang, dan pembesaran otot luar mata terkait Grave’s disease.
Aplikasi radiologi intraocular terutama dalam mendeteksi benda asing berikut trauma dan tumor seperti retinoblastoma. CT scan berguna untuk lokalisasi benda asing karena kemampuan dan kemampuannya untuk menghasilkan gambar dinding okular.
MRI (Magnetic Resonance Imaging)
Teknik pencitraan resonansi magnetik (MRI) memiliki banyak aplikasi dalam diagnosis orbital dan intrakranial. Tidak seperti CT, teknik MRI tidak mengekspos pasien untuk terkena radiasi pengion. Pandangan multidimensi (aksial, koronal, dan sagital) dapat terjadi tanpa harus mereposisi pasien. Karena MRI lebih baik dalam membedakan jaringan dan kadar air yang berbeda, MRI lebih unggul
dari CT scan pada kemampuannya untuk melihat edema, bidang demielinasi, dan lesi vaskular. Karena MRI menangkap sinyal tulang lebih rendah, memungkinkan resolusi lebih baik dari penyakit intraosseous dan pandangan yang lebih jelas dari fossa posterior intrakranial.
Daftar Pustaka
g. Riordan, Paul. Whitcher, John P. Vaughan & Asbury's General Ophthalmology. 16th Ed. USA: The McGraw-Hill Companies, 2007.
h. K Lang, Gerhard. Opthamology. New York: Thieme, 2000.
i. Retinoskopi. Diunduh dari http://repository.usu.ac.id/bitstream/123456789/3440/1/09E01856.pdf pada tanggal 23 Februari 2012 pukul 20.35
BackgroundConvergence insufficiency is a common condition that is characterized by a patient 's inability to maintain proper binocular eye alignment on objects as they approach from distance to near.[1] There is typically an exophoria or intermittent exotropia at near, a receded near point of convergence, reduced positive fusional convergence amplitudes, and a low accommodation convergence/accommodation (AC/A) ratio. The symptoms associated with convergence insufficiency vary from mild to severe, but they are often extremely troublesome for patients with this condition, especially when associated with a small angle exotropia at the near working distance causing binocular diplopia.[2]
PathophysiologyThe underlying etiology for convergence insufficiency is probably innervational.[1] The dramatic reduction of symptoms demonstrated by patients after undergoing appropriate therapy, which is accompanied by objective clinical findings of improved near point of convergence and fusional convergence amplitudes, strongly supports this hypothesis.
Some cases of convergence insufficiency also appear to have an etiologic connection to accommodative dysfunction.[3]
Convergence insufficiency is associated most commonly with an exophoric binocular posture at near, but patients with this disorder may demonstrate orthophoria or even mild esophoria at the time of their examination. The reasons for this variability are described within this article.
In the past, many ophthalmologists considered convergence insufficiency and its associated symptoms to be a neurotic manifestation of nonrelated psychological problems best dealt with by a psychiatrist.[4] However, it is
now clear that convergence insufficiency is a legitimate, problematic binocular dysfunction. The clinician must consider whether the behavioral manifestations displayed by patients really result from the frustration caused by their inability to perform desired near vision tasks.
EpidemiologyFrequency
United StatesThe prevalence of convergence insufficiency has been reported to be approximately 3-5% of the population. Incidence increases with additional near work demand. The disorder is reported to be rare in children younger than 10 years of age. However, the increased visual demands of schoolwork and prolonged periods of reading exacerbate symptoms in older children. Indeed, many patients with this disorder have vocational and/or avocational visual demands that require prolonged close work. The most common presentation encountered by the clinician is that of a high school or college student who develops symptoms when excessive demands are placed on the visual system during extended periods of studying. Lack of sleep, illness, and anxiety are known to aggravate the problem.
InternationalThe prevalence of this condition is the same in all industrial societies.
Mortality/Morbidity
The morbidity of convergence insufficiency relates to the near point visual demands of the patient's activities. Headaches, fatigue, frequent loss of place when reading, as well as frank binocular diplopia associated with near point tasks are among the symptoms associated with this condition.
Race
No racial predilection exists for convergence insufficiency.
Sex
No sexual predilection exists.
Age
The frequency of symptoms may increase with age as patients' ability to compensate for their relative divergent binocular alignment decreases with time.
Proceed to Clinical PresentationHistoryPatients typically present as teenagers or in early adulthood, complaining of gradually worsening eyestrain, periocular headache, blurred vision after
brief periods of reading, and, sometimes, crossed diplopia with near work. It is not unusual for the patient to squint one eye while reading to relieve blurring or diplopia. Few, if any, symptoms are present at distance fixation. Symptoms are aggravated by illness, lack of sleep, anxiety, and prolonged near work. Left untreated, the exophoria at near may break down to a poorly controlled intermittent exotropia. Fortunately, in most cases, convergence insufficiency is very amenable to orthoptics and vision therapy.
The symptoms of convergence insufficiency are directly associated with reading or other close work visual demands. Many patients with objectively measured convergence insufficiency may not complain of symptoms. This usually occurs because of suppression of the nonfixating eye or avoidance of near vision tasks. The clinician should inquire about any such avoidance behavior in patients who are not experiencing any symptoms but who have clinical objective findings consistent with convergence insufficiency. The most common symptoms associated with convergence insufficiency include asthenopia (eyestrain) and headache, diplopia, blurred vision, and perceived moving of print when reading.
Asthenopia (eyestrain) and headacheThese symptoms were clearly described by von Graefe as early as 1855.
Classically, such symptoms occur after short periods of reading or other close work. This most frequently occurs due to the sustained increased effort required to increase fusional convergence.
Accommodative insufficiency is often associated with convergence insufficiency and symptoms of asthenopia and headache. This occurs as the patient tries to eliminate near vision diplopia by increasing accommodative effort. The increased accommodative effort results in increased convergence, which may be more than what is required for the near vision task, thereby resulting in an esophoria (as mentioned above). This also explains the frequent accompaniment of blurry vision and diplopia that occur with asthenopia and headache symptoms.
DiplopiaThe diplopia that manifests in some patients with convergence insufficiency
may subjectively present as two distinct images or just an overlap of two images (a "ghost" image.) This distinction may be difficult for the patient to decipher. Many patients describe their symptoms as "blurry" vision rather than "double" vision. Proper testing can distinguish the two entities fairly easily by testing for "blurry" vision during monocular visual acuity testing.
Patients with uncorrected hyperopia in excess of +5.00 diopters (D) may
generate little or no accommodative effort at near.Patients with mild-to-moderate myopia do not need to stimulate
accommodation to see clearly at the near working distance in their uncorrected state. This lack of accommodative effort results in decreased accommodative convergence.
Patients with early treated presbyopia frequently demonstrate convergence insufficiency. The relief provided by plus lenses at near is thought to translate to an inappropriate abandonment of appropriate accommodative effort. This results in decreased accommodative convergence and the manifestation of an exophoria that previously was partially compensated by using accommodative convergence.
Some patients with convergence insufficiency do not have symptoms of diplopia despite an obvious exodeviation at near. This probably occurs because of suppression of the nonfixating eye.
Blurred visionPatients with uncorrected hyperopia in excess of +5.00 D may produce little
or no accommodative effort at near. This lack of accommodative effort results in blurry near images.
Efforts to increase convergence through stimulation of accommodative convergence to eliminate diplopia can sometimes cause blurry vision by simultaneously producing blurred near vision via over-accommodation.
Moving of print: This occurs because of unstable binocular alignment relative to the near vision convergence demand. This usually occurs when the patient tries to engage and maintain sufficient fusional convergence to establish and maintain binocular vision.
PhysicalThe physical diagnosis of convergence insufficiency is based on the findings of a reduced convergence near-point along with decreased positive fusional convergence amplitudes at near.
Remote near point of convergence: Patients should be able to maintain binocular fixation on a fusional target as it is brought up to at least 5 inches from the tip of the nose.
Significant exophoria or intermittent exotropia at near: Rarely, patients are orthophoric or even exhibit a small degree of esophoria at near, but all have a remote near point of convergence.
Patients may demonstrate small-to-nonexistent exophoria at distance.Patients may demonstrate reduced stereoacuity at near.Normal near point of accommodation may be present in many patients.
CausesThe underlying cause(s) of convergence insufficiency are not clearly established. A significant exophoria at near with inadequate fusional convergence appears to be the primary underlying problem. Von Graefe, who first described the condition in 1855, believed that this condition was myogenic in etiology, but subsequent electromyographic work has failed to demonstrate support for this theory. A connection has been made between accommodative insufficiency and convergence insufficiency. Closed head trauma and lesions in the pretectal area of the brain have been associated with acquired convergence insufficiency. Lesions in the midbrain dorsal to the third cranial nerve nuclei may also cause convergence insufficiency with normal third nerve function.
Laboratory StudiesUsually, no laboratory studies are indicated.Tensilon testing, acetylcholine receptor antibody titers, and single fiber electromyography (EMG) testing can be performed to differentiate convergence insufficiency from ocular myasthenia.
Other TestsCover testing and accommodation testing are the basic tests used to help diagnose this condition.Measurement of fusional convergence amplitudes at near is also helpful.
Proceed to Treatment & Manag
Medical CareConvergence exercises (ie, orthoptics, vision therapy) and/or base-in prisms are the mainstays of treatment of convergence insufficiency.
Orthoptics and vision therapy
Near point of convergence exercises: An accommodative target, such as a column of telephone numbers taped to a tongue depressor or piece of cardboard, is placed remote to the patient's near point of convergence and gradually brought toward the tip of the nose with the patient converging to
avoid diplopia. Just before there is a break in fusion, the patient holds fixation on the target for 10 seconds. This so-called push-up is repeated 10 times, 2-4 times a day, until the patient is able to hold fixation to approximately 6-8 cm from the nose. The exercises can be tapered and then used on an as-needed basis when the patient notices a recurrence of symptoms.
Other forms of convergence training: Base-out prism reading and stereogram cards may be used by an orthoptist or a vision therapist to improve fusional convergence. New, affordable computerized fusional vergence training programs (eg, Computer Orthoptics) are also available. These self-paced programs can be used on a personal computer in the patient's home.
Base-in prisms for near only: These prisms can be ground into a separate pair of reading glasses, or Fresnel membrane prisms can be fitted over the reading segment of the patient's bifocals.
A paper by Scheiman et al[5] in a review of 3 multicenter randomized clinical trials, while recognizing some limitations of the summarized studies, reported that office-based vision therapy provides superior results as a treatment modality versus specific home-based therapies (pencil push-up and some computer-based therapy) or placebo.
Surgical CareThe decision to proceed with surgery should be made with caution and only after all orthoptic efforts have failed.[6]
Bilateral medial rectus resection is usually the most effective operation for convergence insufficiency.[7] However, the patient should be warned about the possibility of uncrossed diplopia at distance fixation after surgery. This typically resolves within 1-3 months postoperatively. The exophoria at near often recurs after several years, although most patients remain asymptomatic.
ActivityPatient activities are not restricted.
Proceed to Medication
Further Outpatient CareA combination of in-office and at-home orthoptics and vision therapy probably represents the best therapeutic approach for convergence insufficiency.[5]
Since the underlying etiology of convergence insufficiency is unclear, no specific recommendations can be given to prevent it. Avoidance of near work is often both undesirable and impractical.
ComplicationsUntreated convergence insufficiency often can make both work and recreational near vision tasks difficult.
PrognosisIn most cases, if the patient is motivated, the prognosis for successful treatment of convergence insufficiency is excellent.Orthoptics and vision therapy exercises are extremely effective, but compliance with the treatment program is critical.Symptoms can also be relieved with the use of the appropriate amount of prism glasses (with the appropriate amount of base-in prism) or occluding one eye. While these interventions treat the symptoms of the problem but not the underlying problem itself, they may be the most appropriate treatments to meet an individual patient's specific needs.
Patient EducationPatients should be made aware that convergence insufficiency is a fairly common condition and that treatment is very effective.