Assessment of the Pupil Size in Emmetropic and Myopic Eyes

Introduction: This study aimed to determine the influence of age and gender on pupil size under different illuminance conditions in emmetropic and myopic healthy eyes using Keratograph 4 topography. Methods: This study investigated 221 eyes of 221 subjects. After complete ocular examination, the undilated pupil diameters were measured using a pupilometer and Keratograph 4 software (OCULUS, Wetzlar, Germany) with a sequence of 9.8 seconds of the scotopic stimulus (0.1 lux) and 0.2 seconds of the photopic stimulus (150 lux) repeated 5 times automatically. At the end of the procedure, the software provided maximum and minimum values (scotopic and photopic) of the pupil diameter. The age, gender, and refraction related changes of the pupil size were evaluated in different illuminance conditions. Results: Out of 221 participants in this study, 122 (85 female) and 99 (66 female) cases were myopes (MSE: -2.18±1.69 D, age: 26.03±6.98 years) and emmetropes (MSE: -0.11±0.27 D, age: 28.05±10.17 years), respectively. Considering refractive groups, pupil size was larger in myopes, compared to the emmetropes in both illuminance conditions (P<0.001). Moreover, the pupil size was found to be independent of gender in both photopic and scotopic conditions (P=0.71 and P=0.55, respectively). Additionally, a significant decrease was observed in pupil size with increasing age (P<0.001). Conclusion: This study showed that pupil size is influenced by age, illumination levels, and refractive status. These findings are important in both the optical industry and clinical decision-making process regarding treatment management.