Studies have consistently reported that women require reading glasses or bifocal lenses earlier than men. According to a recent Investigative Ophthalmology & Visual Science paper, the gender difference is caused by factors other than focusing ability, such as arm length or preferred reading distance, which should be considered when prescribing readers or bifocals.

The new evidence was found by a team of researchers who performed a meta-analysis using nine cross-sectional studies to compare the prevalence and magnitude of presbyopia -- commonly described as the loss of near vision that occurs with age -- among men and women. The researchers further subdivided the analysis to determine what differences in presbyopia might exist between men and women.

The new evidence was found by a team of researchers who performed a meta-analysis using nine cross-sectional studies to compare the prevalence and magnitude of presbyopia -- commonly described as the loss of near vision that occurs with age -- among men and women. The researchers further subdivided the analysis to determine what differences in presbyopia might exist between men and women.

While the results of a subgroup of studies showed that there was no significant gender-related difference in the eye's ability to focus clearly on objects at near distances, the overall analysis provided evidence that women have a need for higher power reading glasses or bifocals than men of an equivalent age. According to the researchers, this discrepancy is likely due to differences in preferred reading distances or arm length as women tend to hold reading materials closer than men do.

"These findings could impact global vision care in multiple ways," said Hickenbotham. "The findings reinforce the need for presbyopia correction programs for women -- a group that often has greater unmet vision needs in developing countries. It also points out that presbyopia is a multi-factorial problem and requires solutions that are tailored to each individual."

While the researchers urge clinicians to do more than measure the eye's ability to focus when diagnosing presbyopia, they also suggest more carefully performed studies be conducted that better isolate and measure the various factors that contribute to its development. In particular, the paper states longitudinal studies that consider the interaction between the preferred reading distance and the change in accommodative amplitude across time for males and females could help determine to what extent biological factors or environmental factors plays a role in the loss of focusing ability with increasing age.