Tear function following photorefractive keratoplasty with solid state laser

Purpose: Determine tear function (TF) parameters and correlate results with corneal haze following PRK. Methods: We measured tear flow, tear volume, osmolarity, evaporation rate, Schirmer's test, and meibomian gland drop-out in the operated and unoperated eyes of 10 patients at 2 months following PRK with the Novatec laser. Eyes were classified as Normal Tear Function if no more than one parameter was outside one standard deviation of the mean value of normals grouped by decile. Eyes were classified as Abnormal Tear Function if two or more parameters including osmolarity were outside that range. Eyes were classified as Abnormal Tear Function with Compensation if they were abnormal but the tear osmolarity was within one standard deviation of the normal, age-grouped mean. Results were correlated with occurence of haze. Results: 8 of 10 patients had abnormal tear function with or without compensation in at least one eye. 6 of 20 eyes had normal TF, 7 had abnormal TF and 7 had abnormal TF with compensation. 4 of 6 normal eyes were laser-treated and 2 were the unoperated eye. 2 of 7 abnormal TF and 4 of 7 abnormal TF with compensation were laser treated. All contact lens wearing eyes showed abnormal TF (lens off) with 2 showing compensation. 4 of 10 lasered eyes had 0.5 haze (scale 0 to 4). 2 of 4 had normal TF and one each had abnormal and abnormal with compensation TF. Conclusion: We found no evidence that solid state laser ablation altered tear function relative to the unoperated eye. Haze was not correlated with abnormal tear function in this small series. Patients may self-select for laser surgery because of poor tear dysfunction even when using contact lenses successfully.