Purpose: To estimate the incidence and predisposing factors for cataract extraction (CE) after Deep Sclerectomy (DS) with Mitomycin-C (MMC) and its effect on intraocular pressure (IOP) control. Methods:: Retrospective study of phakic eyes which had DS with MMC performed over a 5-year period. 179 eyes of 179 patients were included. Results: Mean age at time of DS was 68.6 ± 9.7 years and mean follow-up was 89.4 ± 29.4 months. 63 eyes had CE and the probability of CE following DS was 0% at 1, 11.6% at 3, 21.0% at 5 and 33.2% at 7 years, with a 50% probability (median survival time) of 10 years. Age was association with increased risk for CE (Hazard ratio 1.05, 95% CI: 1.03–1.08, p < 0.0001). Mean IOP had increased from 11 mmHg to 15 mmHg in the first 3 months and remained higher up to a year (p < 0.001). There was no difference in the probability of maintaining an IOP < 16 mmHg without additional medications or needle revision (p = 0.05,Log-rank test). 20/47 eyes that failed were from the CE group, of which 14 (22.2%) failed prior to CE. Number of eyes on glaucoma medications before CE was 6 (mean edications 0.2 ± 0.5 m) and by last follow-up, 9 eyes were on medications (mean medications 0.2 ± 0.7). Post-CE needle revision was performed on 4 eyes. Conclusions: The probability of CE after DS is low, with a gradual increase with time. Increasing age was found to be a statistically significant risk factor. There was a modest increase in IOP after CE and increase use of glaucoma medications.