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Cataract surgery requires extra care in diabetic patients
Diabetes is a chronic disease with disordered metabolism characterized by a high blood glucose level. The rate of diabetes has markedly increased over the last decade. As of 2014, an estimated 387 million people have diabetes worldwide. In our country, more than 10% of the population is diabetic, and the number is increasing sharply.
Diabetic patients are two to four times more at risk for cataract formation and develop cataracts at a much earlier age. Paralleling with the increasing rates of diabetes, the number of diabetic patient with cataract is rising. Although the safety and success of cataract surgery have improved dramatically in recent years with a smaller and smaller phacoemulsification wound, cataract surgery in diabetic patients still poses a 30% higher risk of perioperative and postoperative complications than in non-diabetic patients. Therefore, meticulous preoperative assessment, careful intraoperative maneuvers and close postoperative monitoring are of utmost importance in order to achieve favorable cataract surgery outcomes in diabetic patients.
Preoperative care
Because diabetes is a systemic disorder, collaboration with physicians for good glycemic control is mandatory. Control of other concomitant conditions such as hypertension and hypercholesterolemia also needs to be optimized.
Ocular assessment needs to be comprehensive and multidisciplinary. In anterior segment examinations, special attention needs to be paid to the status of the cornea, iris and cataract. In diabetic patients, the corneal endothelium may be damaged. Some studies have shown increased corneal thickness in diabetic patients and persistent corneal edema after cataract extraction and vitrectomy. Pupil dilatation may be suboptimal in diabetic patients due to autonomic neuropathy, iris atrophy and/or iris damage by previous laser treatment. Careful slit lamp inspection, which may include the use of gonioscopy, is required before rubeosis iridis can be detected. The density of the cataract is also an important preoperative factor and may govern the choice of surgical approach and the need for intraoperative precautions.
In posterior segment examinations, the main focus should be on the presence and severity of diabetic retinopathy and diabetic macular edema. If significant diabetic retinopathy is present, preoperative panretinal photocoagulation should be considered when the retinal view is clear enough. If the retinal view is so poor that preoperative fundus exam is not satisfactory, postoperative monitoring has to be vigilant, with PRP performed in the early postoperative stage if needed. Besides clinical examinations, more advanced investigations such as OCT and fluorescein angiography are of great value in eliciting the presence of preoperative DME. When DME is present, pretreatment with intravitreal steroid and/or anti-VEGF, or simultaneous cataract surgery and intravitreal injection, should be considered.
Intraoperative care
In view of the many structural deficits in the eyes of diabetic patients, careful intraoperative maneuvers are highly desirable. Special care needs to be exercised as to not damage the already small or constricting pupil. Generous use of viscoelastic agent helps protect the cornea and maintain pupil size. Minimize phaco energy, and avoid damaging the posterior capsule. Use of subconjunctival steroid injection at the end of the surgery may help reduce postoperative inflammation and DME. If DME is pre-existing, intravitreal injection of steroid and/or anti-VEGF should be considered.
Postoperative care
The severity of postoperative inflammation and the chance of postoperative infection may be higher in diabetic patients. Therefore, a more vigilant follow-up plan is needed, especially when alarming signs such as a drop in vision and pain occur. Postoperative macular edema in diabetic patients may be due to pseudophakic cystoid macular edema or postoperative DME. It may be difficult in differentiating these conditions, but prompt treatment is required for both of them. In patients without pre-existing DME, a topical NSAID can be tried for 8 to 12 weeks. On the other hand, in patients with pre-existing DME, more aggressive treatments such as intravitreal injection of steroid and/or anti-VEGF may be added.
In conclusion, favorable cataract surgery outcomes in diabetic patients are achievable when meticulous preoperative assessment, careful intraoperative maneuvers and close postoperative monitoring are undertaken.
Disclosure: The authors report no relevant financial disclosures.