Are There Differences Between Male and Female Eyes?

Male and female eyes have important differences in biometrical parameters that need further study to better understand the surgery and treatment outcomes. An expert panel debated this topic during a TOGA Session held during the 2025 ESCRS Winter Meeting in Athens chaired by Marie-José Tassignon MD, PhD.

“There are already differences between male and female eyes in babies, and they continue in adults. Now, whether that is important, I do not know because nobody ever studied it,” she commented.

While there is data about gender differences in the lenses and axial length of baby eyes, she said what is missing is an extensive study on adult eyes.

Professor Tassignon reported that the Project Gullstrand Study Group, named for Nobel Prize winner Allvar Gullstrand, measured the eyes of a large sample of all ages and found some differences between female and male eyes in refractive errors, with different parameters such as axial length, lens thickness and shape, and anterior chamber volume.

In recent years, various fields of medicine have focused more on gender differences to better address patients’ needs. But this has not always been the case.

“Most do not know that until 1993, most women were not allowed to participate in clinical trials,” said Sotiria Palioura MD, PhD. “And that means a lot of the data we have now in medicine is based on only half the population.”

An example of these significant differences lies in cardiac marker troponin levels, as the actual cut-off is much lower in women than men. The discrepancy led to many missed heart attacks, and research has only expanded in the last three or four years. Moreover, gender differences also appear in drug dosages that are sometimes calculated for adult males, resulting in women complaining more often about side effects.

In a surgical specialisation such as ophthalmology, differences in biometrical parameters of the eye are particularly impactful, as Víctor Lázaro-Rodríguez MD suggested. “Women have steeper corneas, shallower anterior chambers, shorter axial length, and greater diameter, and these differences have been significant in surgical outcomes,” he said.

Some IOL calculation formulas consider gender, such as the Kane formula, Nic Reus MD, PhD pointed out, which has proven to improve surgical outcomes. “In ophthalmology, especially in cataract surgery, most operated patients are women because they live longer and have higher chances of getting cataract than men. So, is there a bias towards women having better outcomes than men in ophthalmology?” he asked.

From the audience, Anders Behndig MD, PhD commented that the Swedish Cataract Register showed the biometry prediction error in women was higher than in men. “It was annoying and shocking, and it turned out the SRK/T formula we used did not really account for the steeper corneas or shorter eyes of women,” he recalled. “When we switched to more modern formulas, like the Haigis formula, this difference disappeared.”

Differences between female and male eyes do not just stop at biometric parameters or anatomical issues, but continue with systemic factors. Few studies have been done on gender differences in arterial hypertension risks, cholesterol, or systemic medical treatments, Prof Tassignon emphasised.

Age could make a significant difference between female eyes as well. Menopause is crucial, Dr Palioura observed, as other fields of medicine have found it creates huge changes in women’s bodies, where the oestrogen drops to one-third of its original level. Therefore, young women’s eyes probably behave differently from those of women in menopause.

This, Prof Tassignon concluded, really demonstrates how more studies are needed on the issue. “There are quite a lot of variables and there is already a good attempt to get good and solid results, but we are not completely there.”

Marie-José Tassignon MD, PhD, FEBO is emeritus professor and head of the department of ophthalmology, University Hospital, Antwerp, Belgium. marie-jose.tassignon@uza.be

Víctor Lázaro-Rodríguez MD, FEBO, FICO is ophthalmologist at the Hospital de la Santa Creu i Sant Pau and the Institut Català de Retina, both in Barcelona, Spain.

Nic Reus MD, PhD is an ophthalmologist at Amphia Hospital, Breda, Netherlands. nreus@amphia.nl

Sotiria Palioura MD, MSc, PhD is US-trained eye surgeon working in Athens, Greece. info@sotiriapalioura.gr

Anders Behndig MD, PhD is the co-chair at EUREQUO, former president of the Swedish National Cataract Register and Swedish Ophthalmological Society, and professor at Umeå University Hospital, Sweden. anders.behndig@umu.se