Measuring IOP and Hypotony Incidence

The IOP was measured using Goldmann applanation tonometry (Haag-Streit, Köniz, Switzerland). The device had been calibrated according to manufacturer’s recommendations. The number of IOP-lowering medications was calculated by adding the number of different categories of medication. The categories were: beta-blockers, prostaglandin-analogues, carbonic anhydrase inhibitors, alfa2-agonists, and oral acetazolamide. Fixed combinations of eye drops were calculated as two separate drugs. Hypotony was defined as an IOP ≤ 4 mmHg at two or more consecutive visits (excluding one-day postoperative) during the first year of follow-up [8 (link)].