Cystoid macular edema can permanently alter vision, so it is highly crucial to utilize best practices for treating the cataract surgery complication.
Take-home message: Cystoid macular edema can permanently alter vision, so it is highly crucial to utilize best practices for treating the cataract surgery complication.
By Fred Gebhart; Reviewed by Keith Warren, MD
CME affects about 1% of patients, 10 to 25 times the incidence of postoperative infections.
“One percent is high for an adverse event following cataract surgery,” said Keith Warren, MD, founder of Warren Retina Associates, Overland Park, KS, and clinical professor of ophthalmology, University of Kansas. “That’s 10,000 patients per million cataract surgeries in the United States every year. And if you get CME, your vision is usually permanently altered. That makes it an important event to assess, to treat, and to prevent.”
Dr. Warren presented the latest developments in the prevention and treatment of CME. Prompt treatment and prophylaxis are key steps in the preservation of vision.
The typical CME patient shows normal healing and visual improvement initially following surgery. The first obvious problem is a sudden blurring of vision in the 4 to 6 weeks postoperative period.
Treatment begins with a careful evaluation of the patient, Dr. Warren said. In some cases, there are obvious causes for inflammation and blurring. Common problems include:
Every patient should have ocular coherence tomography and color photography of the retina. Any retinal thickening is significant, Dr. Warren noted. Patients with a history of diabetes or some other condition that could affect the retinal vasculature may also benefit from evaluation with fluorescein angiography.
“OCT is highly sensitive and allows us to measure even small changes in the retina,” Dr. Warren said. “More importantly, it allows us to monitor how well the patient is responding to treatment. I can watch the swelling go from worse to better with treatment or from worse to no change. OCT is the best way to image patients to tell whether treatment is working or not.”
Corticosteroids have long been the treatment of choice for ocular inflammatory disease, including CME. In vascular disease such as diabetes and CRVO, corticosteroids block vascular endothelial growth factors. In primary inflammatory disease and surgical trauma, they inhibit inflammatory cells and their mediators. The net effect is to reduce inflammation and macular edema.
Prednisolone is the most familiar agent, but topical difluprednate offers better penetration and may spare patients from the need for periocular and intraocular injections.
Nonsteroidal anti-inflammatory agents have traditionally been viewed as second-line agents. However, there is growing clinical evidence that these agents may play a role in the prophylaxis of CME.
Nepafenac and bromfenac appear to be most effective, although ketorolac and diclofenac are also used. None of these agents are approved for use in CME, Dr. Warren noted, though all four are indicated for postoperative pain and inflammation.
These four NSAIDs inhibit cyclooxygenase-2 (COX-2) and prostaglandin production. There is growing evidence that corticosteroids and NSAIDs may have a synergistic effect because each blocks different steps in the inflammatory cascade that may lead to CME.
Dr. Warren’s research found that combination therapy including NSAIDs was more effective in improving visual acuity, reducing retinal thickness and maintaining reduced retinal thickness compared to corticosteroids and anti-VEGF therapy without NSAID use.
CME treatment is usually stratified by the duration of disease, he continued. Acute CME that appears 4 to 6 weeks postop responds well to topical difluprednate plus an NSAID.
For persistent CME lasting 8 weeks or longer, he recommends periocular (sub-tenon’s) steroid injection plus an NSAID. Chronic CME lasting 12 weeks or longer may require an intraocular steroid plus a topical NSAID. Recalcitrant CME lasting four months or longer needs more potent treatment including an intraocular steroid, anti-VEGF and NSAID. If tolerated, a long-acting steroid implant should be considered.
Vitrectomy is usually the last resort, and as a rule has mixed results.
“Keep in mind that about 20% of patient’s with CME may recur,” he said. “Patients recover, then a month later they are edematous again. For these cases, you can use a (potent) topical steroid and an NSAID. The combination has already demonstrated efficacy, now you just need to deal with the rebound effect.”
The most frequent complication from treatment is increased IOP, which are more common if given parentally than with topical treatments. CME patients who have not had prior cataract surgery are also more prone to form cataracts. But the consequences of not treating CME are even worse.
“These patients lose vision,” Dr. Warren said. “They may see well, but they all complain that color perception and contrast sensitivity are lost. That’s why prevention of CME is so important.”
Several retinal diseases appear to share the inflammatory pathway that can lead to CME, including uveitis, endophthalmitis, diabetic macular edema, retinal veno-oclusive disease and age-related macular degeneration. This common pathway suggests that patients with any pre-existing ocular inflammation, epiretinal or vitreoretinal interface membrane problems or ocular vascular disease; diabetes; macular degeneration, or any intraocular surgery are at increased risk for CME.
There are no formal guidelines for the prophylaxis of CME, Dr. Warren noted. But early clinical data suggest that pre-treatment with a nonsteroidal anti-inflammatory as well as pre- or intraoperative corticosteroid use may reduce the incidence of CME in high-risk patients.
Preoperative retinal photographs and OCT may also help identify high-risk patients who are more likely to benefit from prophylactic treatment.
Keith Warren, MD
This article was adapted from Dr. Warren’s presentation at the 2015 meeting of the American Society of Cataract and Refractive Surgery. Dr. Warren serves as a consultant and speaker for Alcon Laboratories, DORC (Dutch Ophthalmics), and Genentech.