Predictors of visual impairment in primary and secondary glaucoma in a tertiary institute in North India

To find out and compare various predictors of glaucoma-related visual impairments in primary and secondary glaucoma.

A prospective observational study of patients, who were above 30 years of age. They were diagnosed as primary/secondary glaucoma with visual acuity <20/200 Snellen's/visual field showing less than 20° isopter in at least one eye, with a minimum follow-up of one year at a tertiary center. Patients were classified into advanced and end-stage glaucoma and outcome was assessed according to visual acuity and visual fields to see predictors of visual impairments.

There were 169 (99 primary/70 secondary) glaucoma patients with mean age of 62.67 ± 11.9 and 54.65 ± 15.26 years, respectively. Trauma (21.4%), complicated cataract surgery (15.7%), and silicon oil tamponade (14.3%) were common causes of secondary glaucoma. There was significant delay in diagnosis in primary compared to secondary glaucoma (57.57% vs 32.85%) and non-compliance was significantly higher in primary glaucoma (34.3% vs 17.1%, p = 0.01). In univariate analysis, literacy, income status, locality, and delayed or missed diagnosis were found to be significant (p < 0.05) according to visual acuity criteria. Out of the 33 patients who had undergone glaucoma filtration surgery, 18 (54.5%) were in the end-stage group. While 105 (77.2%) of 136 patients who were not subjected to any glaucoma filtration surgery reached end-stage glaucoma as per visual fields criteria (p = 0.011).

Lack of awareness, delayed diagnosis, low literacy, and income were associated with poor visual outcome. Patients who underwent glaucoma filtration surgery had significantly better visual outcome in comparison to patients managed medically.