Population-based study of presbyopia in Shahroud, Iran

Background: There is limited information regarding the prevalence of presbyopia in different parts of the world. The add power and the prevalence of presbyopia by age and gender in general population of Shahroud, north of Iran, were studied.

Design: Population-based cross-sectional study.

Participants: Using random cluster sampling, 6311 people from the 40- to 64-year-old population of Shahroud were invited. Of the invited population, 5190 individuals (82.2%) participated in the study.

Methods: Presbyopia was defined as the correction of near vision to logMAR 1 (N8 point) with at least 1 D of add power.

Main outcome measures: Near visual acuity of participants was evaluated with a logMAR chart at a distance of 40 cm.

Results: Mean add power in the age groups of 40-44, 45-49, 50-54, 55-59 and 60-64 years was 0.65, 1.30, 1.70, 1.87 and 2.08 D, respectively. For each 5-year increase in age, a 0.35 D increase in add power was noted. The prevalence of presbyopia was 58.15% (95% confidence interval: 56.46-59.84). Presbyopia was more prevalent in women (P < 0.001) and increased with ageing more in women than in men (P < 0.001). Furthermore, in the 60-64-year-old age group, 11% of men and 23% of women were not presbyopic.

Conclusions: Compared with other reports, the add power in different age groups was 0.5 D less, and presbyopia was less prevalent. More than 50% of the over 45-year-old individuals were presbyopic and 17% of the over 60 individuals were free of this condition.