Paracentral Acute Middle Maculopathy following Vitrectomy for Proliferative Diabetic Retinopathy: Incidence, Risk Factors, and Clinical Characteristics.

PURPOSE: To report the incidence of, risk factors for, and characteristics of paracentral acute middle maculopathy (PAMM) after 25-gauge pars plana vitrectomy for proliferative diabetic retinopathy (PDR). DESIGN: Retrospective, consecutive, interventional case series. PARTICIPANTS: Five hundred thirty eyes of 427 patients who underwent primary vitrectomy for PDR from 2013 through 2016. METHODS: The patients underwent measurement of best-corrected visual acuity (BCVA), fundus photography, and OCT before and within 2 weeks after vitrectomy. A generalized linear mixed-effects model was used to evaluate risk factors for development of PAMM. MAIN OUTCOME MEASURES: The incidence, associated risk factors, and clinical characteristics of PAMM following vitrectomy, including the change in BCVA in eyes with PAMM and the distribution of PAMM as determined by en face OCT. RESULTS: Four hundred ninety-six eyes of 395 patients who met the eligibility criteria were evaluated. The incidence of PAMM was 3.8% (15/395) for patients and 3.6% (18/496) for eyes. Multivariate analysis showed the significant risk factors for PAMM development to be younger age (mean age, 49 years in patients and 59 years in control participants; odds ratio [OR] 0.94; 95% confidence interval [CI], 0.89-0.99; P = 0.021) and female gender (66.7% of patients and 31.3% of control participants; OR, 4.48; 95% CI, 1.57-12.6; P = 0.005). The PAMM was distributed on either side of the causative arterioles. In 14 of the 18 eyes (78%), PAMM was located within a 3-mm diameter of the fovea. In 10 eyes (56%), PAMM measured 1 disc diameter or more, and in 5 eyes (28%), PAMM measured one third disc diameter or less. No emboli were found in any eyes; however, multiple segmental arterial constrictions were confirmed during vitrectomy in 1 eye. The BCVA decreased more than 2 lines in 2 eyes (5%). CONCLUSIONS: Paracentral acute middle maculopathy can develop after pars plana vitrectomy for PDR, especially in patients who are younger and female. Impaired blood flow in arterioles, which leads to tissue hypoxia, was associated with development of PAMM.