Post operative-corneal-edema

POST-OPERATIVE-CORNEAL EDEMAa complication of cataract surgery

PRECEPTOR: Dr (MRS) UZZI I.A OKHUOSAMI F.S Pharm.D

OUTLINE Cataract (Pathophysiology, surgery, complications of surgery) Corneal edema Corneal edema as a complication of cataract

surgery( pathophysiology, epidemiology) Management of post-operative corneal edema Conclusion Acknowledgements and References

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FIG 1.0The Human eye

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WHAT IS CATARACT??? A cataract is a clouding of the natural intraocular crystalline

lens that focuses the light entering the eye onto the retina. This cloudiness can cause a decrease in vision and may lead to eventual blindness if left untreated.1.

Cataract can also be defined as complete or partial opacity of the ocular lens.

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PATHOPHYSIOLOGY OF CATARACT

The clear lens of the eye transmits light rays entering the eye and focuses them on the

retina

With aging, lens proteins progressively denature causing

increase in density and yellowish-brown coloration of

the lens2

Other factors such as blunt-force trauma can cause

thickening and irreversible whitening of the lens

The resultant cloudy lens lacks the ability to transmit and focus

light rays on the retina

This manifests as blurry vision or loss of vision in advanced

cases

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FIG 1.2Unilateral cataract in the right eye

FIG 1.1A healthy human eye

Jagat. R(2012) MEAJO. Pediatric Cataract surgery. Vol. 19:1

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CATARACT SURGERY

Eye drops(containing an anesthetic) that dilate the pupils will be administered

A tiny cut is made in the cornea through which a

probe is inserted

Probe breaks up cloudy lens into small pieces which are sucked out3

The artificial lens is inserted through the cut

and sits in the lens capsule. It unfolds when in

position.

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FIG 1.3Removal and replacement of an infected lens with an artificial lens during cataract surgery

COMPLICATIONS OF SURGERY Modern cataract surgery is safe in more than 95% of patients.

In a small number of cases, an intra-operative posterior capsular rupture can lead to vitreous loss or a dropped nucleus and can increase the risk of post-operative complications4.

CORNEAL EDEMA and CYSTOID MACULAR EDEMA are common post-surgical complications that occur due to persistent swelling in the cornea as seen in corneal edema or in the retina as in cystoid macular edema. In both cases, patients may notice blurred, foggy vision. The risk of either occurring is around 1 in 100.

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POST-SURGICAL-CORNEAL-EDEMA???

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FIG 1.4Anatomy of the cornea showing it’s five membranes

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CORNEAL EDEMA Corneal edema is the hydration(swelling) of the corneal

stroma due to damage of the corneal endothelium causing decreased visual acuity.

It may occur naturally as in the genetic condition; Fuch’s dystrophy or as a complication of cataract surgery.

The endothelium continuously pumps fluid from the cornea keeping it dry and clear as corneal clarity is essential for clear vision.

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CORNEAL EDEMA AS A COMPLICATION OF CATARACT SURGERY

Corneal edema often resolves within a few days or weeks post-surgery.

If the cornea was not healthy prior to surgery, high intraocular pressure(IOP) can cause the cornea to fail, and severe edema can result.

Edema may persist for months after surgery. This may be the case in Fuch’s dystrophy or extremely dense/difficult to remove cataracts.

Some early designs of lenses implanted during surgery caused injury to the endothelium. However, these implant designs are no longer manufactured.5

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PATHOPHYSIOLOGYCorneal tissue must remain

thin and transparent for clear vision

The corneal endothelium is a hydrophobic barrier made up of a single layer of non-

regenerative cells6

Cataract surgery with or without pre-existing Fuch’s

dystrophy can injure the corneal endothelium

Upon injury, surviving cells change shape and grow

larger to fill the spaces left by the destroyed cells7

When a lot of cells are damaged, the cornea

stroma will be flooded by fluids causing the swelling

(edema)

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FIG 1.5 The hydrated corneal stroma reduces causes reduced visual performance and blurred vision as seen in the image above

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PATHOPHYSIOLOGY cont’d If the number of destroyed cells exceeds the threshold

necessary to maintain normal functioning of the cornea, fluids seep through and hydrate the corneal stroma.

This excessive hydration interferes with normal spacing of the proteins (Type I collagen fibrils) of the cornea.

As corneal edema progresses and worsens, first stromal and then intercellular epithelial edema develops.

Epithelial edema is associated with the development of bullae; hence, the term bullous keratopathy

Bullae + IOL= PBKBullae without IOL= ABK

IOL= Intra-ocular-lensABK=Aphakic bullous keratopathyPBK=Pseudophakic bullous keratopathy

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FIG1.6 Pseudophakic bullous keratopathy (PBK). Large multiple bullae, such as depicted here, are associated with moderate to severe pain and discomfort.

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EPIDEMIOLOGY The exact incidence rate for corneal edema is unknown. It is

however, estimated that 0.1% of patients undergoing cataract surgery will develop this problem.

CORNEAL OEDEMA

AGE SEX RACE FIG1.7

Older patients(>50years) are more prone

No known association

No known association

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EPIDEMIOLOGY cont’d Despite an increase in the overall number of cataract

surgeries performed, cases of ABK and PBK have decreased. The overall drop in the incidence of post-operative corneal

edema reflects the rapid development and improvement of both intraocular lens design and cataract surgical technique7.

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TREATMENT/MANAGEMENT Treatment of corneal edema is based on the exact cause. There

is no treatment to promote the healing of the destroyed endothelial cells though, the extent of the edema can be controlled.

A. HYPERTONIC DROPS AND OINTMENTS: Patients with early/mild corneal edema may benefit from the use of hypertonic/concentrated saline agents to reduce corneal thickness.

Examples: 2% and 5% Hypertonic saline solution and ointment. Mode of action: These agents work by creating an osmotic

gradient via a tear film outside the cornea that pulls fluid from the cornea.

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Cont’d As evaporation from the tear film is minimal at night with the

eyes closed (therefore, the tears are less hypertonic), corneal edema tends to be worse in the morning. Use of hypertonic Nacl 5% ointment at night and/or a hypertonic solution early in the morning limits this build-up of edema.

A typical regimen is Hypertonic Nacl (Muro128®) 2% drops used hourly in the affected eye until noon (4-5 times). As the day progresses, evaporation from the tear film begins to create relative hyper-tonicity of the tears, drawing fluid from the cornea. This accounts for the typical history of improved vision towards the end of the day.

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Cont’d Side effects: Nil or minor (e.g mild burning or irritation). Rare

severe side effects include; severe allergic reactions, eye pain and changes in vision8.

B. ANTI-INFLAMMATORY AND IOP-LOWERING AGENTS: Treatment of edema in eyes with borderline endothelial function should be focused on ocular inflammation and elevated intraocular pressure if present.

The IOP inside the eye may become elevated due to inflammation in the eye following surgery causing the drainage angle inside the eye to be blocked. If the pressure is 25mmHg - 35mmHg, the patient should begin IOP-lowering drops.

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Cont’d Examples of anti-inflammatory agents: Ketorolac 0.4% qid,

Diclofenac 0.1% (Voltaren®) t.i.d and Corticosteroids such as Prednisolone acetate 1% solution 2-4 times daily used for not more than 10 days.

Mode of action: NSAIDs act by blocking the cyclo-oxygenase enzymes, COX-1 and COX-2(mediates production of prostaglandins that contribute to the inflammatory response and ocular disease). Inhibition of COX-2 determines the clinical efficacy of an ophthalmic NSAID.

Side effects: Mild effects include; Burning and stinging, itchy eyes, dizziness, headache. Serious effects include; Eye pain, eye discharge and blurred vision9.

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Cont’d Examples of IOP-lowering drugs: Selective alpha 2-adrenergic

agonists such as Brimonidine 0.2% (Alphagan®) t.d.s or beta-adrenergic blockers such as Timolol 0.25% and 0.5% b.d ophthalmic preparations.

Mode of action: These drugs lower IOP by reducing the production of aqueous humor and facilitating it’s outflow.

Side effects: Timolol may cause eye irritation, double vision, drowsiness and in severe cases, fainting, breathing difficulties and sudden weight gain10. Brimonidine may cause blurred vision, red/swollen eyelids, sore throat and in sever cases, blind spots, dizziness and rash11.

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Cont’dC. SURGICAL PROCEDURES: These include; Anterior

Stromal Puncture, Bandage contact lenses and Corneal Transplant.

1) Anterior Stromal Puncture: Patients who have poor visual potential and severe pain can benefit from this safe, simple cost-effective procedure12.

Small superficial punctures are placed in the affected area of the cornea with depths just at the Bowman’s layer.

A bandage contact lens is the applied as an adjunct and left for 7-14 days to hold the healing epithelium in place as it grows back over the cornea13.

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Cont’d2) Bandage contact lenses: These are soft lenses useful for the

temporary relief of pain and discomfort due to bullous keratopathy.

They must not be too tight as this may worsen the edema especially when used at night.

They can increase the risk of infections. Therefore, antibiotics are prescribed for corneal edema patients using Bandage lenses.

A broad-spectrum antibiotic such as Polymyxin-B ophthalmic drop/ointment used 2-4 times a day for 7-10 days is recommended.

Bandage contact lens

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Cont’d3) Corneal Transplant: Ultimately, if vision is substantially impaired,

the surgeon can transplant the entire cornea. Corneal transplant, when paired with glasses or contact lenses,

often restores vision to a significant degree. Only the endothelial layer of cells may be replaced in cases of

advanced edema resulting in fewer side effects than a full transplant.

The procedures used are called Deep Lamellar Endothelial Keratoplasty or Descemet’s Stripping Endothelial Keratoplasty14.

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ACKNOWLEDGEMENTS Dr(Mrs.) Uzzi I.A Pharm Faransa C. Pharm Ogie R.U.

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REFERENCES Alpa S. Patel MD(2014). Cataract. American Academy Of Ophthalmology.

Available from eyewiki.aao.org/Cataract Ocampo J, etal(2014). Senile Cataract. eMedicine [MedScape]. Available from

emedicine.medscape.com/article/1210914-overview Christian Nordqvist(2014). What are Cataracts? What causes Cataracts?

Medical News Today. Available from medicalnewstoday.com/articles/157510.php Elsie C, Omar A(2010). Complications of Cataract Surgery. Clinical and

Experimental Optometry. DOI: 10.1111/j.1444-0938.2010.00516.x University of Washington Medical Center(2015). Corneal Edema. Available from

uwmedicine.org/health-library/Pages/corneal-edema.aspx Brunton L, Chabner B, Knollman B(2010). Corneal endothelium. Goodman &

Gilman’s The Pharmacological Basis of THERAPEUTICS (12th ed). Mc Graw Hill Medical, California: pp1774-1775

Taravella M, etal(2014). Post-Operative-Corneal-Edema. eMedicine [Medscape]. Available from emedicine.medscape.com/article/1193218-overview

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Drugs.com [ Micromedex® , Cerner Multum™ , etal(2015) ]. Sodium chloride drops: Indications, Side Effects, Warnings. Available from drugs.com/cdi/sodium-chloride-drops.html

The American Society of Health-System Pharmacists(2011). Diclofenac Ophthalmic. US. National Library of Medicine[MedlinePlus]. Available from nlm.nih.gov/medlineplus/druginfo/meds/a606003.html

The American Society of Health-System Pharmacists(2010). Timolol Ophthalmic. US. National Library of Medicine[MedlinePlus]. Available from nlm.nih.gov/medlineplus/druginfo/meds/a682043.html

The American Society of Health-System Pharmacists(2011). Brimonidine Ophthalmic. US. National Library of Medicine[MedlinePlus]. Available from nlm.nih.gov/medlineplus/druginfo/meds/a601232.html

Zauberman N, etal(2014). Anterior Stromal Puncture for the Treatment of Recurrent Corneal Erosion Syndrome: Patient Clinical Features and Outcomes. American Journal of Ophthalmology Vol. 157, Issue 2: pp273-279

Fan M, etal(2014). Anterior Stromal Puncture. American Academy of Ophthalmologists. Available from eyewiki.aao.org/Anterior_Stromal_Puncture

Taravella M, etal(2014). Post-Operative-Corneal-Edema. eMedicine [Medscape]. Available from emedicine.medscape.com/article/1193218-treatment

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THIS HAS BEEN FUN!!

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Starships were meant to fly…hands up and touch the sky