You are here



Lecture available on:
Definition of Blindness: WHO 2011
“Visual acuity of less than 3/60 (Snellen’s chart) or its equivalent”
Equivalent of < 3/60: Inability to count fingers in daylight at a distance of 3 meters
(3/60 is practically equivalent to counting fingers in daylight at a distance of 3 meters)
(Similarly, 1/60 is practically equivalent to counting fingers in daylight at a distance of 1 meters)
Leads to:

National Programme for Control of Blindness

Lecture available here:
• launched in the year 1976 as a 100% Centrally Sponsored scheme
• Goal: reduce the prevalence:
– From 1.4% ->0.3%
– (As per 2006-7 survey, the prevalence was 1.0%)
• Various activities/initiatives undertaken during the Five Year Plans under NPCB are targeted towards achieving the goal of reducing the prevalence of blindness to 0.3% by the year 2020.

Epidemiology: Tests of Significance

Commonly used tests of significance are

For qualitative data: (comparing two proportions)

  • Standard error of difference between two proportions
  • Chi – square test

For quantitative data: (comparing two means)

  • Unpaired – t test (the t – test)
  • ‘Z’ – test
  • Paired t – test

Chi – square test
• Applied on qualitative data
• Equally applicable on small and large samples
• Can be applied if there are more than 2 categories

Epidemiology: Basic Concepts

Definition of ‘Epidemiology’

The study of distribution and determinants of health related states in specified populations and the application of this study to control the health problems.

Aims of Epidemiology

1. Describing disease and health related events in specified populations
2. Understanding causation of disease and
3. To provide data for planning of health services

Types of data:

I. Qualitative-


Subscribe to RSS - blogs