Perkin s tonometer

The data collection included information on patient demography, diagnosis of glaucoma, prior ocular surgeries, measurement of visual acuity, IOP, number of antiglaucoma medications at pre-AGV and every post-AGV follow-up visit, duration between placement of episcleral encircling element and AGV, and complications, if any. Visual acuity was measured using Snellen visual acuity chart. We measured IOP either by applanation tonometer, namely, Goldmann tonometer (Haag-Streit, Switzerland), a hand-held Perkin's tonometer (Haag-Streit, Essex, UK), or by Tonopen XL (Reichert ophthalmic instruments, Walden ave. Depew, NY, USA). The cause (s) for low vision and postoperative reduction in visual acuity, if any, were also recorded. Surgical success was defined as a final IOP between 5 and 22 mmHg without (complete success) or with topical antiglaucoma medication (s) (qualified success) and without any vision threatening complication. Descriptive statistics were calculated. Paired t-test was used to compare measurements of IOP and number of antiglaucoma medications at the preoperative and the final visits. Data analysis was done using SPSS software version 15.0 for Windows (SPSS Inc., Chicago, IL, USA).