Follow–up of cataract operations in national blindness control program is done by –
25 sentinel surveillance units have been established in departments 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.
Active surveillance
Passive surveillance
Sentinel surveillance
Routine check-up