#5 of 10: Top Reasons for Poor Premium IOL Outcomes and How to Remedy Them: Addressing Cystoid Macular Edema

The etiology of visual loss in cataract surgery can be multifactorial, including but not exclusive to ocular surface disease (dry eye, blepharitis, allergy, EBMD), astigmatism (regular, irregular, keratoconus, FFKC), pre-existing retinal pathology (ERM, AMD, diabetic retinopathy), posterior capsular opacification (PCO), and cystoid macular edema (CME).  Any of these problems become even more magnified in a premium patient paying premium prices for premium IOL technology.

Cystoid Macular Edema is the most common cause of significant visual loss in patients without pre-existing disease and is readily under-diagnosed until more frequent use of OCT testing postoperatively has allowed earlier detection.  The current definition of CME includes an ophthalmoscopic appearance of cystic yellow foveal appearance, petaloid leakage on fluorescein angiography, any visual deficit including metamorphopsia and decreased contrast sensitivity.

Angiography is the “gold standard,” but Flach has published that macular thickening correlates better with vision loss, and visual acuity does not always correlate with the degree of angiographic leakage.

Angiography is useful, however, to confirm the presence or absence of CME.  OCT is a much faster, easier, safer, and even better look at retinal structure and is especially helpful for determining preoperative retinal pathology (ERM, AMD, DR) and postoperative CME diagnosis and monitoring of therapeutic response. 

Onset of CME is typically delayed starting at 4-6 weeks postoperatively.  Pathophysiology of CME
includes inflammation, surgical trauma of ocular tissue, retained lens fragments, vitreous traction, photic toxicity, and possibly pharmacologic (epinephrine, tamoxifen).  High risk patients include diabetics (even without diabetic retinopathy), previous central/branch retinal vein occlusion, epiretinal membranes, uveitis history, previous CME, CME in fellow eye, previous ocular surgery, and prolonged operative time.  The decision to perform premium IOL surgery should be reassessed based on a patient’s risk factors to develop CME.

Treatment of CME can be primarily addressed based on the inflammation etiology model:

Topical steroids and non-steroidals (NSAIDs) work synergistically at the arachidonic acid cascade level to reduce inflammation.  NSAIDs primarily act on cyclooxygenase pathway (COX-1 and COX-2) by decreasing prostaglandin formation and steroids act on phospholipase A2 by decreasing arachidonic release.

There are many FDA-approved NSAIDs and steroids for pain and inflammation after cataract surgery including Bromday, Acuvail, Nevanac, and Durezol.  A large prospective, randomized, double-masked, multicenter trial by Wittpenn et al showed, statistically, significantly less clinical CME and less mean retinal thickening on OCT in patients taking NSAID+steroid combined versus steroids alone in low-risk patients, those typically receiving premium IOL technology.

In my premium IOL patients (low-risk CME cases), I will start topical NSAID therapy 3 days prior to surgery and continue them 4 weeks postoperatively.  OCT is an excellent way to guide withdrawl of NSAID therapy.  I always perform an OCT at the 1 month postoperative visit to be sure there are no subtle CME changes prior to NSAID withdrawl. The main precaution with topical NSAID therapy is to avoid usage in patients with severe dryness and/or unstable autoimmune disease so as to avoid corneal melts.  These latter patients are not typically candidates for premium IOL technology anyway.  With patients who typically develop CME non-responsive to steroid/NSAID combination therapy, referral to a retinal specialist for intravitreal steroid and/or anti-VEGF therapy may be indicated.

Recognizing high-risk CME patients, efficient cataract surgery, and prophylactic topical NSAID usage in premium IOL patients will regularly give a visual outcome free of CME expected from your premium patients.

Stay tuned for managing the ocular surface in your premium IOL patient in my next blog.

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