Ocular surface effects of repeated application of povidone iodine in patients receiving frequent intravitreal injections

Background: The aim of this study was to investigate the patient reported symptoms and objective signs of tear film and ocular surface abnormalities experienced by patients undergoing repeated exposure to povidone iodine as a consequence of requiring frequent intravitreal injections for wet macular degeneration. Methods: This was a prospective study of consecutive patients who had received recent povidone 5% solution for sterile preparation of intravitreal injection less than 3 months prior to inclusion with a total of at least 3 intravitreal injections for macular degeneration. Each patient had one study eye which was undergoing regular intravitreal injection and a fellow eye which was not undergoing any injections. Each patient underwent evaluations of various tear film parameters on a single occasion for both eyes. The primary outcome was severity of dry eye symptoms as measured by the Schein dry eye questionnaire. The secondary outcomes were tear film osmolarity and corneal punctate staining using the Oxford Grading Scale. Results: A total of 90 patients were included in the study. 43.3% n = 39, were using ocular lubricating medication on a regular basis. A significantly greater proportion of study eyes had a Schein dry eye questionnaire score of 7 or higher; 12.2%, n = 11 amongst study eyes vs 4.4%, n = 4 amongst control, fellow eyes (p>0.05). In terms of secondary outcomes, the study eyes had a slightly higher mean tear film osmolality compared to control, fellow eyes: 305.5 +/- 1.7 in study eyes vs 302 +/- 1.6 in control eyes although this difference was not statistically significant (p = 0.087). The study eyes had statistically significantly worse corneal staining as determined by the Oxford grading scale; 0.69 in study eyes vs 0.58 in control, fellow eyes (p = 0.02). Conclusion: Our results confirm the detrimental impact of repeated application of povidone iodine for intravitreal injection procedures on symptoms of dry eyes as experienced and reported by patients.