Degree, duration, and causes of visual impairment in eyes affected with ocular tuberculosis

Background: Ocular tuberculosis (TB) can affect nearly every ocular tissue, leading to a variety of vision-threatening clinical manifestations. The goal of this study is to estimate the degree, duration, and causes of visual impairment in eyes affected by ocular TB. Results: This was a retrospective study of patients diagnosed as ocular TB based on polymerase chain reaction (PCR) for Mycobacterium tuberculosis complex. We applied the World Health Organization definition of visual impairment (VI) to affected eye(s), instead of better-seeing eye. Best-corrected visual acuity (BCVA) of < 6/18 and >= 6/60 in the affected eye was classified as moderate VI and < 6/60 and >= 3/60 as severe VI. Data collected included presenting and final BCVA of affected eyes and the worst BCVA during the study period. Sixty-one eyes of 40 patients were analyzed. Twenty-five patients (52.1%) had bilateral disease. The mean worst BCVA and mean final BCVA (logMAR) were 1.26 +/- 0.87 and 0.61 +/- 0.85, respectively, and their difference was highly significant (p < 0.0001, Friedman test). The median worst and final BCVA results were 1.30 (range 0.0 to 3.0) and 0.20 (range 0.0 to 3.0), respectively. The mean duration of follow-up was 98.34 +/- 81.81 weeks. Moderate and severe VIs were seen in 14 (22.9%) and 12 (19.7%) eyes, respectively, during the course of follow up. Twenty eyes (32.8%) had BCVA of < 3/60. Moderate VI or worse was most commonly seen in eyes with multifocal serpiginoid choroiditis (n = 6; 100%), retinal vasculitis (n = 25; 80.6%), and panuveitis (n = 12; 80%). The mean duration of visual loss was 25.2 +/- 42.37 weeks (median 6.43 weeks, range 0 to 206.42 weeks). Vitreous hemorrhage, complicated cataract, and macular scarring were the common causes of VI. Conclusion: Ocular TB can result in prolonged visual impairment, more commonly in patients with posterior uveitis or panuveitis.