Eyeworld

EW RETINA 54 January 2015 T he development and utilization of anti-VEGF therapy for a variety of vasoproliferative retinal diseases has changed outcomes and expectations for millions of patients. These drugs now offer hope to patients with age-related macular degeneration, diabetic retinopathy, and venous occlusive disorders. Treatment protocols for these drugs, interpretation of clinical trial data and ancillary testing, and the access to retinal specialists have made real world outcomes less than demonstrat- ed in the clinical trials. Can the general ophthalmologist play a role in the provision of care to these patients, and if so, what would that role be? In this month's "Retina consultation corner," Steve Charles, MD, addresses some of the issues that shed light on the nuances of treating these patients and the complexity surrounding the use of these exciting new agents. Keith A. Warren, MD, Retina consultation corner editor by Steve Charles, MD, FACS, FICS Intravitreal injections and cataract practice contaminating the injection needle with their nasal or oral bacteria. Using a sterile, bladed speculum is critical to keep the lashes and lid margins from contacting the injection needle. A povidone-iodine prep is essential for all patients because it is the only safe and effective agent. Contrary to popular opinion, no patients are allergic to iodine; iodine is in our thyroid. Seafood allergies and contrast agents for radiology have nothing to do with iodine or Betadine (povidone-iodine, Purdue Products, Stamford, Conn.). Anaphylactic shock has never been reported for the povidone compo- nent of Betadine. Compounding pharmacies There have been many issues with compounding pharmacies; hopeful- ly 503B certification will improve quality. It is essential to use different lot numbers for each eye when doing simultaneous bilateral injections of Avastin. High intraocular pressure after injection A paracentesis should be performed if the patient is no light perception after the intravitreal injection. In summary In summary, treating retinal dis- ease with intravitreal injections is an enormously complex endeavor; the options are expanding at an explosive pace. This complexity is quite analogous to the huge array of strategies, options, and technologies utilized in modern refractive cataract surgery. EW Editors' note: Dr. Charles has no financial interests related to this article. Contact information Charles: scharles@att.net A s vitreoretinal surgeons, we are often asked whether cataract surgeons should do intravitreal injections. In our view the issue is far more complex than just performing intravitreal injec- tions. It is more about using OCT to make the correct diagnosis and the in-depth understanding of optimal treatment strategies, pharmacokinet- ics, and differences between avail- able anti-VEGF agents. There is a parallel question in vitreoretinal surgery; some vitreo- retinal surgeons perform elective combined phaco and vitrectomy. This is often not an optimal strategy because today's patients expect emmetropia, and vitreoretinal surgeons rarely master femtosecond lasers, toric IOLs, or intraoperative aberrometry, or utilize optimal power algorithms. OCT issues Time domain OCT systems, such as the Stratus OCT (Carl Zeiss Meditec, Jena, Germany), have insufficient resolution; spectral domain OCT is absolutely essential to making the correct diagnosis. Color encoding OCT images using auto-segmenta- tion algorithms is disadvantageous because it can result in an incorrect diagnosis. The ophthalmologist, not a technician or photographer, should look at all gray scale slices. It is inappropriate for a technician or photographer to select an image from an OCT dataset and insert it into the EMR system for the ophthalmologist. Thickness maps often lead to misinterpreting OCT images; increased thickness is not always edema—it also can be subretinal fluid, vitreomacular traction syndrome, epimacular membrane, or vitreomacular schisis. Understanding the clinical trials literature Understanding dosing intervals and pharmacokinetics is crucial; monthly intervals does not mean 6–8 weeks. The retinal and sub- retinal levels of anti-VEGF agents peak at 1–2 days post injection and decline over 4–6 weeks. Patients will often say that their vision improved soon after injection and declined at 4 weeks. The differences between bevaci- zumab (Avastin, Genentech, South San Francisco) and ranibizumab (Lucentis, Genentech) or aflibercept (Eylea, Regeneron Pharmaceuticals, Tarrytown, N.Y.) are very significant. The Comparison of AMD Treatment Trials (CATT) did not show equiv- alence between ranibizumab and bevacizumab; 40% more patients had subretinal fluid in the bevaci- zumab cohort. The near equivalence of ranibizumab and bevacizumab in CATT for wet AMD does not apply to diabetic retinopathy or retinal vein occlusion; retinal vascular disorders produce about 5,000 times more VEGF than wet AMD; ranibizumab and aflibercept have approximately 25 times greater molecular affinity for VEGF than bevacizumab. Ranibizumab and aflibercept are far more effective than bevacizumab in retinal vascular disorders. Role of intravitreal steroids The author is in a minority but never uses intravitreal steroids for diabetic macular edema or retinal vein occlusion, only for uveitis. In- travitreal steroids produce a 12–40% steroid glaucoma rate and common- ly result in cataract. The oft-quoted 6% frequency for steroid responders only applies to topical 1% prednis- olone. Diabetic macular edema and retinal vein occlusions often need treatment for years; repeated steroid injections can lead to steroid glau- coma and always lead to cataract. Using ranibizumab or aflibercept instead of bevacizumab and decreas- ing frequency between injections is a better strategy for retinal vascular disorders than using steroids. Sterile technique The surgeon, patient, and technician must all wear a mask to avoid Retina consultation corner " Treating retinal disease with intravitreal injections is an enormously complex endeavor; the options are expanding at an explosive pace. " –Steve Charles, MD, FACS, FICS

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