Rapid glycemic correction before cataract surgery should be avoided in patients with moderate to severe diabetic retinopathy because it might increase the risk of retinopathy or maculopathy progression.
Blood glucose levels that are quickly corrected in the 3 months before surgery might actually contribute to macular damage, wrote Dr. Chikako Suto of the department of ophthalmology at Tokyo Women's Medical University, and associates (Arch. Ophthalmol. 2006; 124:38–45).
“Early [postoperative] worsening might be due to irreversible invasive damage to the macula resulting from vascular hyperpermeability in patients with rapid correction of glycemic control who have maculopathy before surgery. On the basis of these findings, rapid reduction of blood glucose levels should not be advocated” for these patients, they said.
The researchers examined disease progression 1 year after cataract phacoemulsification and lens replacement surgery in 87 patients with type 2 diabetes (mean age 63 years). The same surgeon performed all of the operations.
The patients were divided into three groups. The rapid control group consisted of 27 patients with elevated (9% or higher) glycosylated hemoglobin (HbA1c) levels, which were reduced by at least 3% at 3 months before surgery. The poor control group consisted of 30 patients with consistently elevated HbA1c levels that remained high (8.5% or higher) until surgery. The good control group consisted of 30 patients with normalized HbA1c levels (mean 7%).
Postoperative progression of retinopathy occurred in 30% of the rapid control group, 17% of the poor control group, and 13% of the good control group; there were no significant differences between groups. In a multivariate analysis of risk factors, only the presence of preoperative maculopathy was significantly associated with progression (odds ratio 4).
“[This] indicates that the postoperative rate of retinopathy progression is the same regardless of whether rapid correction is attempted,” the authors wrote.
Postoperative progression of maculopathy occurred in 33% of the rapid control group, 13% of the poor control group, and 3% of the good control group. In the multivariate analysis, rapid preoperative glycemic correction increased the risk of progression by more than 8 times; preexisting maculopathy increased the risk by more than 11 times. “To achieve a good visual outcome, it may be important to perform surgery in cooperation with physicians who are advised to avoid [rapid glycemic correction] in patients with moderate to severe [nonproliferative diabetic retinopathy] or maculopathy,” the researchers concluded.