Pressure restoration and visual recovery time in hypotony after trabeculectomy

Objectives To asses the course of intraocular pressure (IOP) restoration and visual acuity (VA) recovery in eyes with hypotony after trabeculectomy. Methods Medical charts of patients undergoing trabeculectomy between January 2017 and June 2019 were reviewed. Cases with hypotony (IOP < 5 mmHg) due to over-filtration in the early postoperative period were assessed retrospectively. Primary outcome measures included change in IOP and VA in the postoperative period and percentage of eyes with hypotony on each follow-up. Results Thirty-five eyes of 31 patients (23 male, 8 female) were included. The mean follow-up was 18.3 ± 6.9 months. The mean IOP was 3.0 ± 3.2, 9.2 ± 6.2, 9.4 ± 5.6, 9.4 ± 4.0, 10.9 ± 3.6 and 10.2 ± 3.3 mmHg at week 1, months 1, 3, 6, 12 and last follow-up, respectively. Out of 35 hypotonic eyes, 8 (22.8%) had prolonged hypotony at month 1, 4 (11.4%) at month 3, 1 (2.9%) at month 6. The decrease in VA continued to be significant at months 1 and 3 ( p = 0.015, p = 0.036, respectively) and returned to baseline after the sixth month ( p > 0.524). Conclusions In eyes with early hypotony after trabeculectomy while low IOP recovers at first month, it takes longer for the visual restoration. The postoperative month 1 appears to be decisive for recovery of hypotony.