Cataract Surgery Outcomes in Patients with Type 2 Diabetes

Study characterises risk factors for posterior capsule rupture in higher risk patients. Cheryl Guttman Krader reports.

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Previous studies show patients with type 2 diabetes mellitus undergoing cataract surgery are at increased risk for posterior capsule rupture (PCR). However, according to a study investigating this issue on a more granular level, the risk for these patients depends on diabetic retinopathy status and history of intravitreal injection (IVI). “According to our study, the main driver of increased rates of PCR in eyes with diabetic retinopathy is a history of intravitreal injection,” reported Valerie J Dawson MD, at ARVO 2021. She presented findings from a single institution retrospective study including 10,893 eyes of 6,636 patients. Eyes of patients without type 2 diabetes mellitus accounted for 76.8% of the cohort, while 17.8% had diabetes without retinopathy, and 5.5% had diabetes with retinopathy. The rate of PCR was 0.4% in eyes of patients without diabetes and significantly higher in those with diabetes and retinopathy (1.8%). This was not the case in eyes with type 2 diabetes who did not have retinopathy. Results of a multivariate analysis adjusting for a host of confounders and with eyes categorised into six groups based on presence/absence of type 2 diabetes, diabetic retinopathy, and intravitreal injection showed that a history of intravitreal injections, regardless of diabetes status, was an independent risk factor for PCR. Relative to eyes without T2DM/DR and IVI, eyes with T2DM and neither DR nor IVI were not at increased risk of PCR while the risk was increased more than twofold in eyes with T2DM and DR but no IVI. Eyes of patients with type 2 diabetes but no retinopathy or history of injections did not appear to be at increased risk of PCR. However, the risk was increased more than twofold in eyes with diabetic retinopathy with no history of injections. The p-value for the latter comparison achieved only borderline significance, which was felt to be due to the relatively small sample size, said Dr Dawson, ophthalmology resident, University of Colorado, Denver, Colorado, USA. Her team is planning to incorporate another year of data from the University of Colorado Cataract Database and expects to see this group reach statistical significance on re-analysis. “Advancements in technology and knowledge have led to a decrease in posterior capsule complications during phacoemulsification, but it is prudent to understand the risk factors and identify subgroups of susceptible patients,” she said. “We feel that patients who have undergone IVI and those with DR should be offered preoperative counselling, and surgeons operating on these patients should use caution to avoid surgical manoeuvres that may place unnecessary stress on the lens capsule.” Dr Dawson suggested that the association between DR and PCR risk is likely explained by pathological changes in the lens capsule induced by prolonged exposure to elevated glucose levels that may predispose to capsule rupture by reducing tensile strength. She noted evidence that bevacizumab injections decrease lens epithelial cell viability and proliferation that leads to mechanical changes from decreased cell density and capsular bag confluence. Valerie J Dawson MD valerie.dawson@cuanschutz.edu Image caption: Valerie J Dawson MD
Tags: cataract and refractive