OSDI score deterioration in patients treated with prostaglandins versus SLT as initial treatment. María Alejandra Carrasco, MD Mendoza. Argentina Email: glaucoma.mendoza@gmail.com Financial disclosure: none Introduction: Ocular Surface Disease is a common problem in glaucoma patients treated with topical glaucoma medications. It is associated with a poor quality of vision, a poor quality of life1 and failure of glaucoma surgery.2 SLT is effective as a first-line therapy to lower IOP avoiding the issues of adverse effects of medications and poor compliance.3 Purpose: To compare the outcomes of IOP and Ocular Surface Disease Index (OSDI) in patients receiving selective laser trabeculoplasty (SLT) or prostaglandin analogs as an initial treatment for open angle glaucoma. Methods: In this prospective, comparative study, 77 patients with open angle glaucoma were analyzed. Forty patients received latanoprost, travoprost or bimatoprost preserved with benzalkonium chloride once daily and 37 patients received 360-degree SLT as an initial treatment. IOP and OSDI were recorded at baseline and after 12 months following each treatment. A score of 13 or greater was considered as a marker for ocular surface disease. Results: In the prostaglandin analogs group (24 female, 16 male), the IOP decreased 28% at the 12-month follow-up. The mean OSDI score at baseline was 14.55 with 47.5% of patients classified as normal. At twelve months the OSDI score increased to 22.37 (P < 0.01) with 17.5% of patients classified as normal. Fig. 1 In the SLT group (20 female, 17 male), the IOP decreased 29% at the 12-month follow-up. The mean OSDI score at baseline was 15.29 with 37.8% of patients classified as normal. At twelve months, the OSDI score increased to 16.22 but it was not statistically significant (P = 0.35), with 32.4% of patients classified as normal. Fig. 2 Fig.1. Percentage of patients with OSDI score classified as normal, mild, moderate or severe ocular surface disease before and after 12-month treatment with prostaglandin analogs. Fig. 2. Percentage of patients with OSDI score classified as normal, mild, moderate or severe ocular surface disease before and after 12-month treatment with SLT. PG analogs SLT P value Age 58.82 ± 14.08 57.49 ±16.34 0.86 Baseline IOP 23.15 ± 1.29 23.46 ± 1.54 0.35 12-month IOP 16.65 ± 2.24 16.62 ± 1.04 0.66 Baseline OSDI 14.55 ± 4.57 15.29 ± 5.34 0.62 12-month OSDI 22.37 ± 6.98 16.22 ± 5.28 0.00022  Age, baseline IOP. baseline OSDI, IOP after treatment were not found to be statistically significant between both groups. However, OSDI at 12 months was statistically significant between both groups. Table 1 Table 1. Comparative results between Pg Analogs and SLT at 12 months. Conclusion: IOP reduction was similar in both groups after a follow-up of 12 months. A marked increased in the OSDI score was noted in patients treated with prostaglandins. The benzalkonium chloride or the drug itself may be responsible for the deterioration of the ocular surface in this group2;4. SLT as initial treatment achieved a 29% of IOP reduction with preservation of OSDI scores. References: 1.Skalicky SE, Goldberg I, McCluskey P. Ocular surface disease and quality of life in patients with glaucoma. Am J Ophthalmol 2012;153:1-9. 2. Baudouin C. Detrimental effect of preservatives in eyedrops: implications for the treatment of glaucoma. Acta Ophthalmol 2008;86:716-726. 3. Waisbourd M, Katz LJ. Selective laser trabeculoplasty as a first-line therapy: a review. Can J Ophthalmol 2014;49:519-522. 4. Tomic M, Kastelan S, Soldo KM, Salopek-Rabatic J. Influence of BAK-preserved prostaglandin analog treatment on the ocular surface health in patients with newly diagnosed primary open-angle glaucoma. Biomed Res Int 2013;2013:603782.