Seasonal variation in the incidence of malignant glaucoma after cataract surgery

Purpose: To investigate a potential link between the incidence of malignant glaucoma after cataract surgery and seasonal variations in daylight. Methods: In total, 18,374 uncomplicated cataract surgeries were performed between June 2008 and June 2013 at an ambulatory surgery center in Toronto. Toronto's average monthly daylight over that time period - in hours per day for each month - was determined. The number of malignant glaucoma cases that developed after cataract surgery performed in months with above average daylight was compared to the number of cases that developed after cataract surgery performed in months with below average daylight. Fisher's exact test was used to analyze the relationship between the development of malignant glaucoma and variation in daylight during the month of cataract surgery. Results: Malignant glaucoma developed in 16 eyes. Thirteen cases of malignant glaucoma developed in months with above average daylight and three cases developed in months with below average daylight (P = 0.01). Eyes that developed malignant glaucoma in months with more daylight were slightly longer (21.95 ± 1.23 mm) than those that developed malignant glaucoma in months with less daylight (21.55 ± 0.88 mm). Conclusion: Light-induced choroidal expansion may play a major role in the development of malignant glaucoma following cataract surgery.