The role of ascorbic acid in corneal endothelial protection during small incision cataract surgery.

Sruthi, S (2012) The role of ascorbic acid in corneal endothelial protection during small incision cataract surgery. Masters thesis, Madras Medical College, Chennai.


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INTRODUCTION: Modern cataract surgery aims to achieve an unaided visual acuity with rapid post surgical recovery and minimal surgical complications. This has been made possible with a smaller incision size, appropriate use of ophthalmic viscosurgical devices (OVD) and irrigating solutions, better instrumentation and technology. The advantages associated with phacoemulsification have made it the ideal technique for cataract surgery and the preferred one where resources are available. However, this technique cannot be employed as the standard procedure in developing countries due to certain reasons. Manual small incision cataract surgery offers similar advantages with the merit of wider applicability, better safety, a shorter learning curve and lower cost. AIM OF STUDY: To determine the role of ascorbic acid in corneal endothelial protection during manual small incision cataract surgery (SICS). Primary objective: To compare the corneal endothelial cell loss after manual SICS with and without ascorbic acid Secondary objectives: To compare the morphology of corneal endothelial cells before and after manual SICS, with and without ascorbic acid To compare the central corneal thickness before and after manual SICS, with and without ascorbic acid. MATERIALS & METHODS: 1. Information sheet 2. Consent form 3. Slit lamp biomicroscopy for anterior segment examination and grading of cataract 4. Schiotz tonometer for intra ocular pressure measurement 5. Non-contact specular microscope (Topcon SP – 2000P) for corneal endothelial analysis and central corneal thickness measurement. 6. Biochemistry department of the Institute for blood glucose estimation 7. Parentral ascorbic acid (1 ampoule containing 100mg in 5 ml) 8. Ringer‟s lactate solution as sterile intraocular irrigating solution RESULTS: 150 patients were enrolled in the study, of which 75 were enlisted to receive lactated ringer’s solution without ascorbic acid (control group) and the remaining 75 to lactated ringer’s solution with ascorbic acid (interventional group) as the intraocular irrigating solution during manual SICS. All patients were reviewed on the first post operative day and 1 week after surgery. DISCUSSION: L-Ascorbic acid, an antioxidant present abundantly in aqueous humor is thought to confer protection against the harmful effects of photochemical and oxidation reactions involving oxygen and its radicals. During manual SICS, this antioxidant is lost with aqueous humor and is replaced with irrigating solution which doesnot contain ascorbic acid thereby rendering the postoperative endothelium to greater oxidative stress and damage. The damage is increased further by the release of inflammatory mediators and exposure to sunlight following cataract surgery. CONCLUSION: Ascorbic acid has a protective effect over the human corneal endothelial cells during manual SICS. The protective effect is due to its free radical scavenging properties thus protecting the endothelium from oxidative damage. Ascorbic acid was used in a constant concentration of 0.2mg/ml throughout the study. Further studies are warranted to find out the optimal and most effective concentration of ascorbic acid that could be combined with the intraocular irrigating solution. The follow up period of this study was short. Further studies with long term follow up can establish the reversal of post operative corneal swelling and factors influencing it, in addition to the long term effects of oxidative damage on the corneal endothelium.

Item Type: Thesis (Masters)
Uncontrolled Keywords: ascorbic acid; corneal endothelial protection; small incision cataract surgery
Subjects: MEDICAL > Ophthalmology
Depositing User: Devi S
Date Deposited: 08 Sep 2017 10:20
Last Modified: 08 Sep 2017 10:20

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