Justin Cooper , 2025-05-19 18:44:00
Key takeaways:
- Patients with diabetes and HbA1c above 7% had thickening of central macular thickness and increased cystoid macular edema after cataract surgery.
- Blood glucose management could improve recovery.
Blood glucose levels in patients with diabetes are strongly correlated with the risk for cystoid macular edema and thickening of the central macula after cataract surgery, according to data published in Clinical Ophthalmology.
“Macular edema after cataract surgery can impair vision, especially in the elderly with [diabetes],” Rui Ding and colleagues at Lanzhou Bright Eyesight Hospital, China, wrote. “There is substantial evidence that maintaining blood glucose levels between 80 and 180 mg/dL during the postoperative period is associated with improved surgical outcomes. … Despite the high prevalence of [diabetes] in patients, few studies have focused on the relationship between postoperative blood glucose control and complications.”
In a retrospective analysis, Ding and colleagues compared the occurrence of cystoid macular edema (CME) and thickening of central macular thickness (CMT) in 80 patients with diabetes with varying levels of blood glucose control who underwent cataract surgery and IOL implantation between December 2018 and December 2023.
Fifty-six patients were in an “intensive” treatment group with HbA1c at 7% or below, receiving both insulin and oral hypoglycemic drugs, and 24 patients were in a “standard” treatment group with HbA1c above 7%, receiving only oral hypoglycemic drugs.
In the standard treatment group, CMT was significantly thickened at 3 months and 6 months after surgery vs. the day before surgery (P < .05). In the intensive treatment group, thickening was “mildly higher” after surgery but was not significant through 6 months.
Both groups had no CME at baseline. In the standard treatment group, CME was significantly reduced at 3 months and 6 months compared with 1 week postop (P < .05). In the intensive treatment group, CME was mildly elevated through 6 months, but the difference was not significant.
Ding and colleagues found that HbA1c predicted CMT thickening and CME in a receiver operating curve analysis. At an HbA1c cutoff value of 6.125 mmol/L and above, it had a sensitivity of 43.24% and a specificity of 88.37%.
“The results suggest that HbA1c has a predictive validity for CMT thickening and CME in patients after surgery,” they wrote.
The researchers offered some potential mechanisms behind this relationship.
“We speculate that when the level of HbA1c is elevated, the combination with oxygen is reduced, aggravating tissue ischemia and hypoxia, causing further dilation of capillaries and increased release of inflammatory factors, coupled with a greater post-surgical stress response, accompanied by a large amount of inflammatory factors released into the eye, exacerbating the changes in capillary permeability, resulting in CMT thickening,” they wrote.
“Combined with the results with the intensive treatment group, we believe that if HbA1c is controlled below 7% in the postoperative period, it may be able to effectively improve the recovery after cataract surgery and reduce the occurrence of complications.”
Perspective
This study emphasizes the importance of glycemic control in patients with diabetes undergoing cataract surgery. The main takeaway for clinicians is that HbA1c levels are strongly prognostic of postoperative CME and CMT changes. This is particularly applicable to practitioners, as it highlights the need to optimize HbA1c levels in patients with diabetes both before and after surgery to achieve the best visual outcomes. These results also reinforce the need for proactive coordination with primary care and endocrinology providers to manage systemic health around the time of surgery. Additionally, these findings suggest that high-risk patients may benefit from closer retinal surveillance to allow timely detection and management of retinal complications.
However, the study has some limitations. The small sample size and short 6-month follow-up period inhibit our understanding of long-term predictive value. Furthermore, excluding patients with any diabetic retinopathy limits real-world applicability, as it is common for cataract patients with diabetes to have some degree of retinal disease. Nonetheless, the evidence supports that tight glycemic control should be emphasized during perioperative care in cataract patients with diabetes.
Alek Karthikeyan, OD, FAAO
Disclosures: Karthikeyan reports no relevant financial disclosures.
