Relationship Between Intraocular Pressure and Age: A Population-Based Study in Nepal

Abstract

Prcis: Intraocular pressure (IOP) decreased with age in a population-based study in Nepal, from a mean of 14.1 mm Hg among those 60-64 years old to 13.0 mm Hg among those 80 years old or older.

Purpose: Few studies have assessed the distribution of IOP from the Indian subcontinent, despite its large population and high burden of glaucoma. The objective of this study was to assess the distribution of IOP measurements from adults living in a lowland region of Nepal.

Methods: In a population-based cross-sectional study, all individuals aged 60 years and older from an area of lowland Nepal were invited for an IOP assessment with a rebound tonometer.

Results: Of 160 communities (28,672 people aged ≥60 y) enrolled, 79 (13,808 people aged ≥60 y) were randomly selected for IOP testing. Of those eligible, 10,017 (72.5%) individuals underwent tonometry. Mean IOP decreased monotonically over 5-year age groups, from 14.1 mm Hg (SD: 3.6) among those aged 60-64 years to 13.0 mm Hg (SD: 4.2) among those 80 years or older. The 97.5th percentile IOP measurement was 21.0 mm Hg for all age groups. In adjusted analyses, younger age, self-reported diabetes, and higher population density were each associated with higher IOP, and self-reported cataract surgery was associated with lower IOP.

Conclusions: Mean IOP was lower among older individuals in Nepal, consistent with many studies from East Asia and in contrast to many studies from western populations. These results suggest that ethnic background might be a consideration when diagnosing ocular hypertension.

Figure 1.. Participant flow.

Participants were drawn from 41 wards in Nepal.

Figure 2.. The relationship between non-participation and estimates of intraocular pressure, stratified by age.

Each dot represents an age stratum in one of the 79 study communities. The proportion of eligible participants in the age stratum participating in tonometry is plotted against the mean intraocular pressure in the age stratum. Generalized additive models were used to fit smoothed lines and 95% confidence bars, and to provide approximate P-values for the relationship between non-participation and mean IOP for each age stratum.

Figure 3.. Mean intraocular pressure across age strata in cross-sectional population-based studies.

Age strata starting from 50 years are depicted, with lines connecting the mean IOP of successive age strata. The present study is depicted as a dashed line. The present study is depicted as a dashed line. Studies were found from the United States of America (USA), the Caribbean, Europe, Africa, the Middle East, South Asia, East Asia, and Australia (references provided in the online supplement). The relationship between IOP and age was significantly different for the Asian versus non-Asian studies (interaction P<0.001 in mixed effects linear regression), with a mean reduction in IOP of 0.4mmHg (95%CI −0.5 to −0.3) per decade of age among the Asian studies and a mean increase in IOP of 0.1mmHg (95%CI −0.05 to 0.2) per decade of age among the non-Asian studies.