Cataract surgery in patients with diabetes mellitus : clinical studies

Abstract

The aim was to evaluate phacoemulsification cataract extraction with small incision and implantation of heparin-coated intraocular lens (IOL) in the capsular bag in patients with diabetes mellitus (DM).

The aqueous flare intensity, which reflects the protein concentration in the aqueous humor, was used to evaluate blood-aqueous function in patients with DM type I and type II. The highest aqueous flare values were obtained in eyes more impaired by diabetes: those with clinically significant macular edema (CSME) in mild to moderate diabetic retinopathy (DR), advanced stages of DR, advanced forms of diabetic iridopathy, such as iris rubeosis, and a long duration of diabetes mellitus. The pharmacological response to cholinergic stimulation on pupil size and flare intensity after instillation of 4% pilocarpine was weaker in eyes with advanced stages of DR than in control eyes.

All diabetic patients and controls received the same phacoemulsification procedure with implantation of a heparin-coated IOL into the capsular bag. The phacoemulsification procedure and the entire operation lasted longer in patients with diabetes than in nondiabetic subjects. Both phacoemulsification and the entire operation produced significantly more pronounced miosis in diabetic eyes than in controls. Significantly higher postoperative laser flare values were found in eyes with advanced stages of DR, particularly those with CSME. The postoperative inflammation ran parallel with the preoperative laser flare values and was thus related to a high leakage from diabetic blood vessels. The duration of surgery also seemed to influence the postoperative laser flare values.

No complications were recorded during cataract surgery. Postoperative laser photocoagulation was performed in the majority of diabetic eyes. The visual acuity (VA) was improved in 88% of the patients 1 year after phacoemulsification. A best corrected visual acuity of 0.5 or better was achieved in 79% of the patients. Significantly lower final corrected visual acuity was found I year after surgery in eyes with advanced DR as compared to controls. Eyes with clinically significant macular edema (CSME) had also a lower visual acuity than those eyes without CSME. Stability or improvement of the retinal status was found in 79% of the diabetic eyes 1 year after cataract surgery. Progression was found in 21% of the eyes, only in eyes with DR. Eyes with an indication for laser photocoagulation at baseline (1 week postoperatively) showed a significantly higher rate of progression of DR after surgery than those without indication for laser treatment. Also, less posterior capsule opacification was found 2 years after surgery in diabetic eyes as compared to controls.

We conclude that diabetic eyes with advanced and severe stages of DR are significantly different from nondiabetic eyes concerning the blood-aqueous barrier (BAB), aqueous humor dynamics, and pupillary function. In spite of these diabetic changes, a satisfactory postoperative result was achieved after phacoemulsification with heparin-coated IOL implantation and postoperative laser photocoagulation treatment. Eyes with active stages of diabetic retinopathy or with CSME at the time of surgery had the worst postoperative prognosis. However, visual acuity was improved in the majority of the diabetic patients 1 year after phacoemulsification. The low formation of secondary cataract, found in diabetic eyes, seems to have no relation to postoperative inflammation. Based on these results, phacoemulsification surgery itself seems to be a safe and efficient surgical procedure in diabetic patients.