Prevalence and causes of functional low vision and implications for services: the Pakistan National Blindness and Visual Impairment Survey.
OBJECTIVE
To determine the prevalence and causes of functional low vision (FLV) and total blindness and to estimate the assessment needs for low-vision services in Pakistan.


METHODS
Multistage, cluster random sampling was used to select a nationally representative sample of adults (age, > or =30 years). Participants underwent visual acuity measurement and detailed ophthalmic examination. Functional low vision was defined as a corrected visual acuity in the better eye of less than 6/18 to more than no perception of light (NPL) in individuals with untreatable causes of visual loss. Total blindness was defined as NPL in both eyes. Needs assessments were categorized into three groups: optical services, nonoptical/environmental interventions, and rehabilitation.


RESULTS
A sample of 16,507 adults (95.3% response rate) was examined. The standardized prevalence of FLV and total blindness were 1.7% (95% CI: 1.5%-1.9%) and 0.2% (95% CI: 0.1%-0.2%), respectively. More than 90% of those with FLV were illiterate and 35.3% were of working age (i.e., <60 years). An estimated 727,000 (586,000-891,000) adults in Pakistan had FLV. Retinal conditions were the commonest cause in urban populations (39.8% vs. 26.5% rural) compared with corneal opacity in rural areas (38.0% vs. 25.5% urban). It was estimated that 565,000 adults require assessment for optical services, 735,000 for nonoptical interventions, and 424,000 for rehabilitation.


CONCLUSIONS
As VISION 2020 enters its second 5-year phase, the provision of low-vision services and their integration into national eyecare programs is a priority. In Pakistan, planning must take account of the magnitude along with the demographic and educational characteristics of those affected.
Shah
Shaheen P
SP
International Centre for Eye Health, London School of Hygiene and Tropical Medicine, London, United Kingdom. shaheen.shah@lshtm.ac.uk
Minto
Hasan
H
Jadoon
Mohammad Z
MZ
Bourne
Rupert R A
RR
Dineen
Brendan
B
Gilbert
Clare E
CE
Khan
Mohammad D
MD
D000328:Adult; D017677:Age Distribution; D000368:Aged; D000550:Amblyopia / Q000150:complications; D001766:Blindness / Q000453:epidemiology* / Q000209:etiology*; D003318:Corneal Opacity / Q000150:complications; D005260:Female; D006301:Health Services Needs and Demand / Q000706:statistics & numerical data*; D006306:Health Surveys; D006801:Humans; D008297:Male; D008875:Middle Aged; D010154:Pakistan / Q000453:epidemiology; D015995:Prevalence; D012164:Retinal Diseases / Q000150:complications; D012307:Risk Factors; D012424:Rural Population / Q000706:statistics & numerical data; D017678:Sex Distribution; D014505:Urban Population / Q000706:statistics & numerical data; D015354:Vision, Low / Q000453:epidemiology* / Q000209:etiology*; D014792:Visual Acuity; D019987:Persons with Visual Disabilities / Q000706:statistics & numerical data*