<prompt> Follow-up ofcataract operations in national blindness control program is done by -Active surveillancePassive surveillanceSentinel surveillanceRoutine check-up  <response>: Ans. is c i.e., Sentinel surveillance o 25 sentinel surveillance units have been established in depaments of ophthalmology and PSM in medical collages in India for assessment of - Beneficiary profiles. Visual outcomes based on cataract surgery records. Follow-up of operated cases. Ocular morbity data. 