Bifocal adds and environmental temperature.

Area of Science:

• Ophthalmology
• Optometry
• Vision Science

Background:

• Presbyopia, the age-related loss of accommodation, necessitates bifocal correction.
• Previous research suggested a correlation between environmental temperature and the required bifocal addition (add).
• The influence of geographical temperature variations on presbyopia correction remains an area of investigation.

Purpose of the Study:

• To investigate the relationship between mean annual community temperature and prescribed bifocal addition in different age groups.
• To analyze differences in bifocal add between males and females across various age levels.
• To re-evaluate previously reported correlations between temperature and bifocal add, considering potential biases.

Main Methods:

• Survey of 888 optometrists in North and Central America regarding typical bifocal additions for males and females aged 45, 50, 55, and 60.
• Analysis of 577 returned responses, correlating bifocal add data with mean annual community temperatures.
• Statistical analysis to determine the significance of temperature and sex on bifocal add.

Main Results:

• No statistically significant difference in mean bifocal addition was found across varying mean annual temperatures for any age group.
• Mean annual temperatures surveyed ranged from -7°C (Alaska) to 26°C (Puerto Rico).
• Females exhibited slightly higher mean adds (0.05–0.06 D) than males across all age levels.

Conclusions:

• Environmental temperature does not appear to significantly influence the required bifocal addition for presbyopia correction.
• Observed inverse correlations in prior studies may be attributed to patient self-selection bias based on age of onset criteria.
• Slightly higher bifocal adds in females may be linked to differences in physical stature rather than presbyopia onset or progression.