Influência do diabetes mellitus no diâmetro pupilar em pacientes submetidos à cirurgia de catarata

Abstract

A cirurgia de catarata está associada a alterações no diâmetro pupilar no período pós-operatório, fenômeno relevante para o planejamento cirúrgico e a escolha de lentes intraoculares. O diabetes mellitus, por sua associação com disfunções autonômicas, pode influenciar o comportamento pupilar, porém ainda não está claramente estabelecido se essa condição modifica a resposta pupilar à facoemulsificação. Este estudo teve como objetivo comparar a variação do diâmetro pupilar antes e após a cirurgia de catarata em participantes diabéticos e não diabéticos. Trata-se de um estudo prospectivo observacional longitudinal que incluiu 354 olhos de 251 participantes submetidos à cirurgia de catarata por facoemulsificação. O diâmetro pupilar horizontal foi mensurado em condição escotópica no período pré-operatório e entre 30 e 40 dias após a cirurgia. A presença de diabetes mellitus foi definida por valores de hemoglobina glicada iguais ou superiores a 6,5%. Para considerar a correlação intraindividual decorrente de cirurgias bilaterais, foi utilizado modelo linear de efeitos mistos, com intercepto aleatório por participante, incluindo o tempo cirúrgico, a presença de diabetes mellitus e a interação entre essas variáveis como efeitos fixos. Os resultados demonstraram que o diâmetro pupilar pré-operatório foi significativamente menor nos olhos de participantes diabéticos em comparação aos não diabéticos. Após a cirurgia, observou-se redução significativa do diâmetro pupilar na amostra global. Entretanto, a magnitude da redução pupilar foi semelhante entre participantes diabéticos e não diabéticos, não sendo identificada interação significativa entre diabetes mellitus e tempo cirúrgico. Conclui-se que o diabetes mellitus associa-se ao menor diâmetro pupilar basal, mas não modifica a variação do diâmetro pupilar após a cirurgia de catarata. A miose pós-operatória observada parece decorrer predominantemente do próprio procedimento cirúrgico, independentemente da presença de diabetes. É recomendável a individualização do planejamento cirúrgico na avaliação das condições pupilares e escolha da lente intraocular.

Abstract: Introduction Cataract is the leading reversible cause of blindness worldwide and is treated by phacoemulsification with intraocular lens implantation. Previous studies have shown that cataract surgery leads to a reduction in postoperative pupil diameter, a phenomenon attributed to anatomical changes in the anterior chamber and alterations in iris dynamics. Diabetes mellitus, in turn, is associated with autonomic dysfunction that may affect the pupillary response, resulting in smaller pupils. However, the influence of diabetes on the magnitude of pupil diameter change after cataract surgery remains uncertain, with relevant clinical implications, particularly for the selection of pupil-dependent intraocular lenses. Objective To compare changes in pupil diameter before and after cataract surgery in diabetic and non-diabetic individuals, and to evaluate the association between demographic characteristics, glycemic control, and pupillary behavior. Methods This prospective, observational, longitudinal study was conducted between October and December 2024 and included 354 eyes from 251 participants who underwent cataract surgery by phacoemulsification. Horizontal pupil diameter was measured under scotopic conditions preoperatively and between 30 and 40 days after surgery. Diabetes mellitus was defined based on glycated hemoglobin levels (HbA1c = 6.5%). To account for intraindividual correlation due to bilateral surgeries, a linear mixed-effects model with a random intercept for each participant was used. Surgical time, diabetes status, and their interaction were included as fixed effects, with adjustment for age, sex, and laterality. A secondary analysis evaluated the association between HbA1c levels and pupil diameter exclusively in the diabetic group. Results Preoperative pupil diameter was significantly smaller in eyes of diabetic participants compared with non-diabetic individuals. After surgery, a significant reduction in pupil diameter was observed in the overall sample, with a mean decrease of 9.4%. The linear mixed-effects model confirmed a significant effect of the surgical procedure on pupil diameter, resulting in a reduction independent of age, sex, or laterality. No significant interaction was identified between diabetes mellitus and the surgical procedure regarding changes in pupil diameter, indicating that the magnitude of postoperative pupil reduction after phacoemulsification was similar in diabetic and non-diabetic patients. Changes in pupil diameter (?PD) also did not differ between groups. Within the diabetic group, HbA1c levels were not significantly associated with either pupil diameter or postoperative changes in pupil diameter. Discussion The present findings indicate that diabetes mellitus is associated with a reduced baseline pupil diameter, corroborating previous evidence of autonomic dysfunction affecting pupillary behavior in diabetic individuals. However, the absence of a significant interaction between diabetes status and surgical time demonstrates that the pupillary response to cataract surgery follows a similar pattern in diabetic and non-diabetic participants. This suggests that the postoperative miosis observed after phacoemulsification is predominantly related to mechanical and anatomical changes induced by the procedure itself, such as increased anterior chamber depth and altered iris?lens dynamics, rather than to metabolic or autonomic factors associated with diabetes. These results align with prior studies reporting a consistent reduction in pupil diameter after cataract surgery, regardless of systemic conditions, and provide further evidence that the effect of phacoemulsification on pupil size is largely uniform across different metabolic profiles. Final Considerations In summary, although diabetes mellitus influences baseline pupil diameter, it does not appear to modify the magnitude of postoperative pupil diameter reduction following cataract surgery. From a clinical perspective, these findings suggest that postoperative pupillary behavior can be anticipated similarly in diabetic and non-diabetic patients. Therefore, the planning of cataract surgery and the selection of pupil-dependent intraocular lenses should be individualized and account for the expected postoperative miosis in general, without the need for diabetes-specific correction factors when predicting final pupil diameter variation in diabetic individuals.