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Nathan Pezda, Sherif Metwally, Tamer H. Mahmoud, Jayne S. Weiss; Risks of Corneal Epithelial Scraping During Vitreoretinal Surgery and Effect on Outcomes. Invest. Ophthalmol. Vis. Sci. 2012;53(14):2624.
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Scraping of the corneal epithelium may be required for visualization during vitreoretinal procedures. This may lead to permanent damage to the corneal epithelium/basement membrane adhesion complex and therefore affect prognosis. This study aims to characterize the incidence of scraping of the corneal epithelium, the risk factors predisposing a patient to corneal epithelial removal, and the longer term results.
Retrospective operative report and EMR chart review of patients operated on by a single surgeon undergoing a vitreoretinal procedure between 2005 and 2011. Each dictated operative report included specific documentation regarding corneal epithelial status at the end of the case (scraped vs unscraped). Patients were divided into two groups depending on whether the epithelium was scraped. Preoperative, intraoperative and 3 and 6 months postoperative visual parameters and complications were assessed.
Detailed information was available on 800 patients. Operative corneal coating for visualization and procedure of scraping was consistent among all patients. The corneal epithelium was scraped intraoperatively in 24 out of 61 (39%) hypertensive patients compared to 4 out of 40 (10%) normotensive patients (p-value 0.0003) and in 4 out of 39 (10%) type 1 diabetics vs. 24 out of 62 (39%) non-diabetics (p-value 0.004). Gender, race and re-operation were not found to be statistically significant predisposing factors to scraping (p-values 0.85, 0.69 and >0.99 respectively). Diabetes mellitus type 2 and hyperlipidemia also were not statistically significant predisposing factors to scraping (p-values 0.59 and 0.66 respectively). Sample at this time is not large enough to assess previous corneal pathology as a factor in long term prognosis (one patient with keratitis, one with keratoconus, one s/p LASIK and one s/p PKP [none with long term complications]). In those patients who had the corneal epithelium removed, the mean length of procedure was 130 min. versus 70.14 min. in the control (p-value 0.0001). Mean Snellen BCVA at 3 months: 20/800 for scraped, 20/40 for unscraped. Mean Snellen BCVA at 6 months: 20/800 for scraped, 20/200 for unscraped. Twenty out of 28 scraped patients had severe retinal pathology (13 PDR with TMD, 7 RRD with PVR) versus 14/73 unscraped. Average number of postop visits over first six monthswas 4.91 for scraped, 5.20 for unscraped. No corneal complications were documented over 6 months follow up period.
Scraping of the corneal epithelium is unlikely to negatively affect long term post-operative outcomes following vitreoretinal procedures. Duration of the vitreoretinal surgery is more correlated with incidence of scraping rather than the indication.
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