Pupil Size Reduced More in Men Than Women After Cataract Surgery

Age, sex impact changes to pupil size following cataract extraction.

The impact of cataract surgery on pupil size is likely more dependent on the patient’s sex and age than previously thought, according to a study published in the Journal of Optometry. These differences could affect how clinicians monitor patients postoperatively, including watching for dysphotopsia or checking on adaptation to multifocal intraocular lenses (IOL) with apodized design. 

Previous research has been directed to the influences that age and anterior chamber depth (ACD) have on pupil characteristics post-cataract. Investigators of the current study note they have observed from clinical experience that postoperative pupil diameter is related to the patient’s sex, prompting a deeper look at this variable. In the prospective single-center investigation, 109 patients — 71 women and 38 men — underwent bilateral cataract surgery at Clínica Oftalmológica TACIR, Barcelona, Spain. The study selected 1 eye per participant at random for analysis.

Participants were divided into 2 groups — men and women. Both displayed a statistically significant reduction in photopic and mesopic pupil diameter. For men, the photopic pupil decreased by -0.11 mm and for women by -0.04 mm, with a statistically significant intergroup difference (P =.048). In men, the mesopic pupil was reduced by -0.56 mm and for women -0.38 mm, with well-defined significance between groups (P =.025).

Interestingly, a slight negative correlation occurred between photopic pupil change and increased age for females (P =.041), with an opposite trend in men’s photopic pupils (P =.497). On the other hand, for males there was a weak correlation between mesopic pupil change and increased age (P =.039); however, for women, the trend differed (P =.662). Thus, the older a male subject, the less change occurred postoperatively.

“Although the nervous system (regulator of pupillary size) is independent of the endocrine, they often work together to help the body function properly,” according to the research. They suggest that hormonal changes, such as menopause or andropause may provide some of the reasons for differing pupillary responses between men and women.

In both groups, the average photopic pupil had a small reduction, -0.07 mm (-2.4%), and mesopic pupil a larger decrease of -0.44 mm (-9.6%) — the mesopic data indicate a “substantial clinical change.” Previous studies have not agreed on the amount of pupil reduction, which may be due to various measuring instruments. Alternately, this new data representing pupillary changes relating to age and ACD may show that results depend on sex and age sample ratio.

A limitation of this analysis was a lack of age and sex control groups. However, the pupillary changes detected based on sex and age proved meaningful. “Changes in the diameter of the men pupils are up to three times as much as that of the women pupils,” the study says. “And these differences are not only statistically significant but have moderate clinical relevance.”


Ordiñaga-Monreal E, Castanera-Gratacós D, Castanera F, et al. Pupil size differences between female and male patients after cataract surgery, J Optom. Published online February 3, 2021. doi:10.1016/j.optom.2020.09.005