EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.
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50 EW CATARACT November 2012 Complicated cataract cases Cataract surgery and diabetes by Thomas A. Oetting, M.D. O D iabetes mellitus is one of the most common medical conditions in the western world. A Saturday Night Live skit on the iPhone 5 jokingly suggested that diabetes is the United States' number one export (www.nbc.com/Saturday-night- live/video/tech-talk-iphone-5/1420759). Primary concerns with patients who have diabetes mellitus include the develop- ment of post-op cystoid macular edema, worsening diabetic macular edema, progres- sion to proliferative diabetic retinopathy, and the development of rubeosis iridis. Patients with well-controlled type 2 diabetes mellitus can often be treated as normal individuals. Those with retinopathy and macular edema require a thoughtful approach. When- ever possible, the retinopathy and macular edema should be treated before cataract sur- gery. This is not always possible, however. Poor vision may lead to poor diabetic control because patients cannot read their glucose monitors or measure out the correct amount of insulin for injection. In such patients, it may be necessary to remove visually significant cataracts before their blood sugars can be brought under control. There are occasional patients who have such dense cataracts that the extent of their diabetic retinopathy cannot be ascertained pre-op. The cataract surgeon must be pre- pared to inject a VEGF inhibitor or perform panretinal laser photocoagulation through an indirect ophthalmoscope on the operating table or shortly thereafter. Surgeons, anesthesiologists, and hospital or ambulatory surgery centers often have varying recommendations for diabetic patients on the morning of surgery. At the Jules Stein Eye Institute we instruct diabetics to withhold their oral hypoglycemics and insulin after midnight. We do not want their blood sugars to bottom out in the morning hours. We check them on arrival to the pre-op suite and administer short-acting insulin if needed. In this month's column, Thomas A. Oetting, M.D., discusses his approach to patients with diabetes mellitus. He reviews the use of nonsteroidal anti-inflammatory agents, intraocular lens selection, and pre-op consultation with a retina specialist. Diabetes mellitus is a common medical condition, and all ophthalmologists should be comfortable managing diabetic patients pre-op, intraoper- atively, and through the post-op recovery period. Kevin Miller, M.D., Complicated cataract cases editor cular coherence tomogra- phy (OCT) and vascular endothelial growth factor (VEGF) inhibition have changed the management of cataract surgery in our patients with diabetes mellitus (DM). Patients with DM cannot be ignored. The National Eye Institute estimates that over 26% of our patients over 65 have DM.1 Most of these patients with DM are treated like all of our other cataract patients; however, some patients with poor control or retinopathy will need extra attention before, during, and after surgery.2 Prevention of cystoid macula edema (CME) and limiting the accel- eration of diabetic macular edema (DME) following cataract surgery are the most important issues. While the use of nonsteroidal anti-inflam- matory drugs (NSAIDs) in routine patients is controversial, most agree that NSAIDs are important in high risk patients, such as those with DM. I typically use a nonsteroidal for a week prior to surgery. I usually stop the NSAIDs for a week following sur- gery while the epithelium heals and then start them back up. Guidance for the duration of treatment is not clear. I usually use NSAIDs for a month for lower risk patients (e.g., DM with no retinopathy) and for 2-3 months for higher risk patients (e.g., DM with pre-op macular edema). Patients with pre-op retinal edema should be considered for consultation with a retina specialist for possible injection of VEGF inhibitors or intravitreal or sub- Tenon's corticosteroid injection.3-8 OCT is critical to the perioperative management of patients with DM as a sensitive test for the development of CME and progression of DME. IOL selection is also an impor- tant issue for patients with DM.2 Patients with macular edema or those at high risk for macular edema are not good candidates for multifo- cal IOLs, which can limit contrast sensitivity. I think that multifocal IOLs are reasonable in type 2 DM patients with great control of their blood sugars and no existing retinopathy. However, I personally avoid multifocal IOLs in type 2 DM patients with poor control or all pa- tients with type 1 DM even if they have no retinopathy as they are at increased risk for retinopathy in the Figure 1. Patient with early cataract following vitrectomy with lens following at the start of phacoemulsification through pre-existing tear in the posterior capsule future. Vitreous surgeons can be bothered by silicone IOLs. Silicone IOLs can cloud with air fluid exchange and really cloud with silicone oil, which adheres to the silicone IOL. In deference to our retinal surgeons, I tend to use acrylic IOLs in patients with DM who are at risk for vitrectomy in the future. While I typically will use a single- piece acrylic lens (SPA) for DM patients, I often use a large optic three-piece monofocal acrylic IOL for patients at very high risk for vit- rectomy (e.g., neovascular disease). Patients with type 2 DM with excellent control and no pre-op retinopathy are not likely to need vitrectomy in the future. In these patients, it seems reasonable to use a silicone IOL, however I still typically use an acrylic IOL just in case they progress in the future. I think that multifocal IOLs are also reasonable in this set of patients. Even this set of patients with type 2 DM and ex- cellent control of their blood sugars are at increased risk for cystoid macular edema post-op and should be treated with pre- and post-op NSAIDs (Table 1). Patients with type 1 DM with good control and no retinopathy are similar in many ways to the type 2 DM. However, one might assume that over time they would be more likely to develop retinopathy, so I would most likely avoid multifocal IOLs and would not use a silicone IOL in these patients (Table 1). Patients with poor control of their blood sugars, whether type 1 or type 2, present some difficult issues. One strategy would be to withhold the surgery until they had developed a strategy with their endocrinologist for better control. However, some- times this is not possible as better vision is necessary for the manage- ment of their diabetes. In these pa- tients, I would consider a monofocal acrylic IOL as their poor control makes macular edema and future vitrectomy more likely (Table 1). In patients with poor control who have background diabetic retinopathy, I am more concerned about the possibility of worsening retinopathy following the surgery and, specifically, of diabetic macular edema. Typically for these patients, pre-op I will do an OCT to rule out subtle diabetic macular edema and if this is present, will refer them to a retina colleague for possible treat- ment. I will also use a monofocal acrylic lens in these patients, as macular function will be an issue in the future and they are at risk for pars plana vitrectomy. I use the usual regimen with a nonsteroidal pre-op with a break around the time of surgery for a week and then for 1-2 months following surgery. In patients with poor control who have existing diabetic macular edema, it is important to consult with your retina colleagues for pre- treatment in these patients. The use of OCT and possibly fluorescein angiography is indicated in these patients to assess the level of diabetic macular edema. Focal laser and more recently VEGF inhibitors in this set of patients prior to surgery can limit the possibility of worsening macular edema. I use my usual NSAID regimen starting 1