Transcript
REFRECTIVE ERROR AND CATARACTNg Boon Keat, Mohd Hanafi, Anand Kumar
PART 1: REFRECTIVE ERROR
EMMETROPIA
• The state of refraction of the eye in which parallel rays, when the eye is at rest, are focused exactly on the retina.
» Stedman’s Medical Dictionary, 2005
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EMMETROPIA
• Eye with no refractive error• Parellel light = light from
infinity (light from far far away)
• Images are focused with relaxed lens and cornea
• Without the need for accommodation
» ABC of Eyes, 2004
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MYOPIA
• That optic condition in which parallel light rays are brought by the ocular media to focus in front of the retina.
• Synonym: – Shortsightedness– nearsightedness.
» Stedman’s Medical Dictionary, 2005
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Pathophysiology• globe too long relative to refractive
mechanisms, or refractive mechanisms too strong
• light rays from distant object focus in front of retina blurring of distant vision
» Toronto notes: Ophthalmology, 2006
MYOPIA
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MYOPIA
Clinical features:• usually presents in 1st or 2nd decade, stabilizes in
2nd and 3rd decade; rarely begins after 25 years except in diabetes or cataracts
• blurring of distance vision; near vision usually unaffected
Complications:• retinal tear/detachment, macular hole, open
angle glaucoma. » Toronto notes: Ophthalmology, 2006
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CORRECTIONS
» ABC of Eyes, 20048/59
HYPERMETROPIA
• An ocular condition in which only convergent rays can be brought to focus on the retina.
• Synonym:– Hyperopia– Farsightedness
» Stedman’s Medical Dictionary, 2005
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HYPERMETROPIA
Pathophysiology:• globe too short relative to refractive
mechanisms, or refractive mechanisms too weak
• light rays from distant object focus behind retina blurring of near +/-distant vision
» Toronto notes: Ophthalmology, 2006
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HYPERMETROPIA
Clinical features: • youth: usually do not require glasses (still have sufficient
accommodative ability to focus image on retina)• 30s-40s: blurring of near vision due to decreased
accommodation, may need reading glasses• >50s: blurring of distance vision due to severely decreased
accommodation Complications:• angle-closure glaucoma, particularly later in life as lens
enlarges » Toronto notes: Ophthalmology, 2006
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CORRECTIONS:
» ABC of Eyes, 200412/59
PRESBYOPIA
• The physiologic loss of accommodation in the eyes in advancing age.
» Stedman’s Medical Dictionary, 2005
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PRESBYOPIA
Pathophysiology • hardening/reduced deformability of the
lens results in decreased accommodative ability
• near images cannot be focused onto retina (focus is behind retina as in hyperopia)
• Normal aging process (especially over 40 years)
» Toronto notes: Ophthalmology, 2006 14/59
PRESBYOPIA
Clinical Features: • if initially emmetropic, person begins to hold reading
material further away, but distance vision remains unaffected
• if initially myopic, person begins removing distance glasses to read
• if initially hyperopic, symptoms of presbyopia occur earlier
Corrections:• Usually as same as treatment of hypermetropia
» Toronto notes: Ophthalmology, 2006
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APHAKIA
• Absence of the lens of the eye.» Stedman’s Medical Dictionary, 2005
• A state of having no lens (eg removed because of cataract surgery)
» Oxford Handbook of Clinical Specialties, 2009
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APHAKIA
Clinical features:• Removal of lens will result hypermetropic
refractory error
Corrections:• Glasses• Contact lens• Secondary intraocular lens implant
» ABC of Eyes, 2004
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INTRAOCULAR LENS IMPLANTS
» ABC of Eyes, 200418/59
CATARACT GLASSES
» ABC of Eyes, 200419/59
ACCOMMODATION
» ABC of Eyes, 2004
Component of accommodation:
1. Pupil Constriction2. Ciliary muscle
contraction and globular changes of the lens
3. Convergence of the eyes
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PART 2: CATARACT
Anatomical site Cortical NuclearSubcapsular
Anterior SubcapsularPosterior Subcapsular
CATARACT: DEFINITION
Any opacity of the crystalline lensA cataract is clouding of the lens of the eye, which impedes the passage of light. Most cataracts are
related to ageing, although occasionally children may be born with the condition, or cataract may develop
after an injury, inflammation or disease.-WHO-
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CATARACT: TYPESCataract
DevelopmentalCoronary Lens Opacity
Blue dot Lens Opacity
Dilacerated Lens Opacity
CongenitalNuclear cataract
Lamellar (Zonular) cataract
Anterior and Posterior Polar Cataract
SenileNuclear Sclerosis
Cortical (Cuneiform) Cataract
Subscapsular (Cupuliform) Cataract
2ndary to OcularInflamation, Injury, Glaucoma
With Systemic DiseaseDiabetes Mellitus
Hypoparathyroidism
Galactosemia
Dystropia Myotonica
Down’s Syndrome
Steroid 23/59
CATARACT: DEVELOPMENTAL
Developmental
Coronary Lens Opacity Blue dot Lens Opacity Dilacerated Lens Opacity
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CATARACT: CONGENITALCongenital
Nuclear cataract Lamellar (Zonular) cataract Anterior and Posterior Polar Cataract
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CATARACT: SENILENuclear Sclerosis (Progression)
• Exaggeration of normal nuclear ageing change• Causes increasing myopia
• Increasing nuclear opacification• Initially yellow then brown26/59
CATARACT: SENILE
Senile
Cortical (Cuneiform) Cataract
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CATARACT: SENILESubcapsular (Cupuliform)
Anterior PosteriorMK
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CATARACT: SENILESubcapsular (Cupuliform)
PosteriorMK
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CATARACT: SENILE
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CATARACT: TYPES
Cataract
2ndary to OcularInflamation, Injury, Glaucoma
Prolonged Iritis
Injury: Penetrating and Non-penetratingRetinitis pigmentosa
Phtisis bulbi 31/59
CATARACT: TYPES
Systemic Disease
Diabetes Mellitus Hypoparathyroidism Galactosemia
Systemic Disease
Dystropia Myotonica Down’s Syndrome Steroid
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• White punctate or snowflake posterior or anterior opacities
• May mature within few days
•Cortical and subcapsular opacities• May progress more quickly than in non-diabetics
DIABETES MELLITUS
AdultJuvenile
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Atopic dermatitis
• 90% of patients after age 20 years
• Stellate posterior subcapsular opacity
• No visual problem until age 40 years
• Anterior subcapsular plaque (shield cataract)
Myotonic dystrophy
• Other type – posterior subcapsular
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Causes of traumatic cataract Penetration
Concussion
‘Vossius’ ring from imprinting of iris pigment Flower-shaped
• Ionizing radiation
• Electric shock
• Lightning
Other causes
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CATARACT: AETIOLOGY
Cataract
Acquired
Systemic- Age Related- Drugs- Others
Local (Ocular)
- Trauma- High myopia
- Chronic anterior uveitis
- Topical medical- Intraocular
tumour- Radiation
Congenital
InheritedCongenital infectionSystemic syndromes36/59
CATARACT: SYMPTOMS
Congenital Cataract
• Leukocoria• Squint• Nystagmus• Amblyopia (failure of normal visual development)
Senile / Acquired Cataract
• ↓ visual acuity• Glare• Monocular diplopia and Distortion of lines• Altered colours• Not associated with pain, discharge or redness 37/59
CATARACT: SIGNS
• ↓visual acuity• Diminished red reflex • Change in lens appearance• Normal perception of light• Pupillary reflexes normal• Slit lamp examination allows the cataract to be
examined in detail
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TEMPORARY MANAGEMENT
• Not the definitive management• Cannot slow the progression• May in the end have to go for surgery
anyway
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TEMPORARY MANAGEMENT
• UV blocking sunglasses• Change of spectacles correction• Instilling dilating drops• Anti-oxidant vitamin intake• Avoiding smoking - smoking
accelerates cataract development
• Increase lighting especially when reading - illumination from above & behind
• Routine eye examination - esp. when having certain diseases and taking drugs (eg.steroids, chlorpromazine )
(Only preventive, does not treat cataract)
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DEFINITIVE MANAGEMENT
• Extracapsular Cataract Extraction (ECCE)• Phacoemulsification• Intracapsular Cataract Extraction (ICCE)
(All these are followed by intraocular lens implantation)
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INDICATION FOR SURGERY
1) Visual impairment• varies from person to person-depends on the location of
the opacity.
2) Medical indications• presence of cataract adversely affecting health of eye (eg.
phacolytic glaucoma, secondary angle closure by an intumescent lens & diabetic retinopathy)
3) Cosmetic indication• mature cataract in a blind eye removed to restore a black
pupil. 42/59
PREOPERATIVE ASSESSMENT
• CardiovascularHypertension (orbital haemorrhage, suprachoroidal
expulsive haemorrhage)Heart rate (suprachoroidal expulsive haemorrhage)
• Anticoagulant• Posture
difficult if orthopnoea or kyphoscoliosis• Ocular of eye
cornea focusing powerlength
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EXTRACAPSULAR CATARACT EXTRACTION (ECCE)
• Incision is made in the eye• Anterior capsule is open• Nucleus is expressed and soft lens fibres
aspirated• Non-folding lens is inserted into the lens bag• Incision closed with fine sutures
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ECCE
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PHACOEMULSIFICATION
• Make a small tunnel incision is made(3 mm) in the eye
• Circular hole is made in anterior capsule of lens.
• Ultrasonice probe-liquefy the hard nucleus• Remaining soft lens fibre was aspirated• A folded replacement lens inserted .
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PHACOEMULSIFICATION
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INTRACAPSULAR CATARACT EXTRACTION (ICCE)
• Removal of entire lens together within its capsule with a cryoprobe,
• suspensory ligaments of the lens have been dissolved ( -chymotrypsin ).
• bigger incision and slow to heal (around 6 weeks)• Higher incident of retinal detachment (vitreous
prolapse)and cystoid macular oedema• used when facilities for extracapsular surgery are not
available.48/59
INTRAOCULAR IMPLANTS
• Consists of central the lens in position biconvex optic & two legs/haptic to maintain
• Types of IOL:1) Polymethylmethacrylate
(PMMA)2) Silicone
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INTRAOCULAR IMPLANTS (CONT.)
• Posterior chamber lens - placed in the empty lens bag.
• Anterior chamber lens - fixed in the angle of the anterior chamber of the eye.
• “Pupil clip” lens - clipped to the margin of the iris.
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COMPLICATIONS OF CATARACT SURGERY
1. Operative complications• Vitreous prolapse-may cause retinal detachment• Suprachoroidal (expulsive) haemorrhage2. Early postoperative complications• Iris prolapse• Striate keratopathy• Acute bacterial endophthalmitis-emergency.• Uveitis-prone in pt with DM and previous ocular
inflammtry dx.
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3. Late postoperative complications• Capsular opacification• Implant displacement• Corneal decompensation• Retinal detachment• Chronic bacterial endophthalmitis
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ACUTE BACTERIAL ENDOPHTHALMITIS
incidence - about 1:1,000• common causative organism : Staph. epidermidis,Staph
aureus, Pseudomonas sp.• Source of infection :
- patient’s own external bacterial flora is the most frequent culprit- contaminated solutions and instruments- environmental flora including that of the surgeon and operating room personel
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• Signs of mild endophthalmitis- mild pain and visual loss- hypopyon in anterior chamber - fundus visible with indirect ophthalmoscope
• signs of severe endophthalmitis - pain & marked visual loss
- corneal haze, fibrinous exudate and hypopyon- absent or poor red reflex- inability to visualize fundus with indirect opthalmoscope
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DIFFERENTIAL DIAGNOSIS
1) Uveitis associated with retained lens material - no hypopyon present 2) Sterile fibrinous exudate- no pain and few if any anterior cells- posterior synechiae may develop
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1. Preparation of intravitreal injections
2. Identification of causative organisms• Aqueous samples• Vitreous samples
3. Intravitreal injections of antibiotics
4. Vitrectomy – only if VA is PL
5. Subsequent treatment
MANAGEMENT OF ACUTE ENDOPHTHALMITIS
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1. Periocular injections• Vancomycin 25 mg with ceftazidime 100 mg or gentamicin 20 mg with cefuroxime 125 mg
• Betamethasone 4 mg (1 ml)
2. Topical therapy
• Fortified gentamicin 15 mg/ml and vancomycin 50 mg/ml drops
• Dexamethasone 0.1%
3. Systemic therapy
• Antibiotics are not beneficial
• Steroids only in very severe cases
SUBSEQUENT TREATMENT
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CHRONIC BACTERIAL ENDOPHTHALMITIS
• signs:- late onset, persistent, low-grade uveitis- may be granulomatous- commonly caused by P. acnes or Staph. epidermidis- low virulence organisms trapped in capsular bag
• Rx:- initially good response to topical steroids- recurrence after cessation of treatment- inject intravitreal vancomycin- remove IOL and capsular bag if unresponsive
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THANK YOU
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