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A summary of an essay about

Corneal oedema in cataract surgery

Presented by

Malek Mohammad Al-Kott M.B. B.Ch.

Faculty of medicine Al-Azhar University, Cairo

Supervised by

Prof. Dr. Hassan El-Sayed El-Baz

Professor of Ophthalmology Faculty of medicine

Al-Azhar University, Cairo

Dr.Mahmoud Abdel-Badie Mohamed

Assist. Professor of Ophthalmology

Faculty of medicine Al-Azhar University, Assiut

Dr. Mohamed abdel-Monem Mahdy Assist. Professor of Ophthalmology

Faculty of medicine Al-Azhar University, Cairo

Dr. Ashraf Mohamed Gad Elkareim Lecturer of Ophthalmology

Faculty of medicine Al-Azhar University,Assiut

Al-azhar University

Assiut, Egypt 2013

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The cornea is the transparent dome shaped layer of the

anterior portion of the outer fibrous coat of the eyeball. The cornea

serves a refractive function accounting for approximately two thirds

of eye’s total optical power while maintaining mechanically tough

and chemically impermeable barrier between the eye and

environment. The cornea must remain clear to have a good vision.(1)

The endothelium plays an important role in regulating stromal

hydration by constantly removing the fluid out of the corneal

stroma. This function is executed by active metabolic pumps in

corneal endothelium so corneal endothelial cell function is the

most important factor for corneal hydration control.(2)

Cataract surgery affect the cornea, and aqueous humor diffuses into

the corneal stroma and produces corneal edema which may be

stromal and/or epithelial, immediate or late onset , reversible or

irreversible (3) .

The incidence of corneal edema following cataract surgery is 5-15%

with intracapsular cataract extraction, 12% with extracapsular

cataract extraction and less than 10% after the use of Viscoelastics

and more than 30%with phacoemulsification(4).

The principal causes of corneal edema in cataract surgery are:-

1-Surgical trauma by:-

A-Instruments. B-IOL. C-Irrigating solutions.

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D-Ultrasonic vibrations. E-Temperature. F-Nuclear fragments. G- Air bubbles

2-Primary corneal endothelial disease:-

A-Fuchs dystrophy. B-Low endothelial cell density without guttae.

3-Chemical injury :-

Many agents used in cataract extraction surgery have been reported to be toxic to the corneal endothelium which may lead to corneal oedema , including:

A-Antiseptic solutions used preoperatively.

B- Topical and intracameral anesthetics.

C- Sterilization detergents.

D- Intraocular stains .

E-Preservations in solutions.

F- Free radicals.

G-Residual toxic chemicals on instruments (e.g.,

detergents, dried solutions).

H-Improper concentrations of solutions

(e.g.,antibiotics):-

I-Mistakenly used toxic chemicals, expired

agents, or incorrect solutions (e.g., normal saline

instead of balanced salt solution).

4-IOL syndromes:-

A-Direct endothelial touch. B-Long-term toxicity(?inflammatory).

5-Contact with other ocular tissues:-

A-Flat chamber. B-Iris bombe. C-Suprachoroidal effusion or hemorrhage.

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D-Vitrous touch or adherence. 6-Detachment of descemet's membrane. 7-Trauma from retained foreign material:-

A-Nuclear chips.

B-Particulate matter. 8-Postoperative glaucoma. 9-Inflammation. 10-Membranous downgrowth or ingrowth.

11-Brown-McLean syndrome.(5)

Evaluating corneal oedema depends on corneal endothelial cell

density and corneal thickness . Optical slit lamp and ultrasonic

pachymetry are used routinely to measure corneal thickness.

However several new instruments have been recently

developed to determine corneal thickness; these include

Optical coherence tomography, confocal microscopy,

Ultrasonic biomicroscopy, the Scheimpflug camera and

specular microscopes (contact and non contact) which provides

magnified view of a small area of corneal endothelial cells to

measure and record endothelial cell counts.(6)

The aims of treatment is to restore vision and decrease pain ,

this can be achieved with conservative medical measures during

the early phases of corneal edema for up to three months to

elicit a compensated cornea. The treatment often requires

surgical intervention and the most commonly procedure is

penetrating keratoplasty. Also posterior lamellar endothelial

transplantation can be done. (5)

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References

1-Stephen DK, Roger WB: Structure and function of the cornea. In

Kaufman HE, Barron BA, McDonald MB (eds): The cornea, 2nd ed.

Butter-Heinemann, Washington, 1998; 3-50

2- Ruberti JW and Klyce SD. Nacl osmotic pertubation can modulate

hydration control in rabbit cornea. Exp Eye Res 2003; 76-349

3- Stephen DK: Corneal physiology.In Foster CS, Azar DT, Dolhman CH

(eds): The cornea scientific foundations and clinical practice, 2nd ed.

Lippincott Williams and Wilkins, Philadelphia, 2005,37-58

4-Elisabeth JC, Christopher JR: (1998), ''Corneal changes from ocular

surgery''.In ''The cornea'' ,page 673-696 ; by Kaufman HE, Barron BA,

McDonald MB (eds) , 2nd ed. Butter-Heinemann, Washington.

5- Steinert RF. Corneal edema after cataract surgery. In cataract surgery,

3rd ed. Saunders, Duxbury 2010, 595-602

6- Rockville MD. ''Cataract management guideline panel''. Cataract in

Adults: Management of Functional Impairment, AHCPR publication no

1993, 93-0542.