Eyeworld

EW RETINA 62 Month 2015 by Steve Charles, MD Vitreomacular surgery Dr. Charles gives a refresher on this effective surgery V itreomacular surgery is effective for a wide variety of vitreomacular disorders including epimacular membrane, vitreomacular traction syndrome, macular hole, and vitreomacular schisis. Microin- cisional vitrectomy (25 or 27 G) is the best option for all vitreoretinal surgery including complex retinal detachments but is most widely uti- lized for vitreomacular disorders. Common to all vitreomacular surgery cases is the need to peel one or more of the following layers: vitreous cortex attached to the vit- reous body, residual vitreous cortex after PVD, epimacular membrane, internal limiting membrane (ILM), or often a combination of these tissue layers. I recommend using end-grasping 25/27 G DSP ILM for- ceps (Alcon, Fort Worth, Texas) for all peeling and am strongly opposed to the use of picks, diamond dusted scrapers, asymmetric forceps, or any forceps requiring 1 blade to enter the potential space between the ret- ina and tissue to be peeled. There is no need to find an edge; inside-out pinch peeling is a better method. ILM peeling is necessary in virtually all cases; it increases retinal compli- ance in macular hole surgery facili- tating closure. ILM peeling reduces recurrence rates and eliminates reti- nal striae intraoperatively in epimac- ular membrane cases. ILM peeling is required for vitreomacular schisis, vitreomacular traction syndrome, macular folds caused by poorly exe- cuted fluid air exchange and internal drainage of subretinal fluid during retinal detachment repair and even hypotony maculopathy. The ILM is elastic and acts to maintain a distorted retinal surface even after the tissue that caused the distortion or traction is surgically removed. In addition, the ILM functions as an attachment substrate/scaffold for RPE or glial cells; removal reduces membrane recurrence rates. Optimal visualization is accom- plished by using a flat contact lens, not a non-contact viewing system; corneal asphericity is eliminated and axial and lateral resolution is improved. An endoilluminator provides focal, specular and retroil- lumination, which is far superior to chandelier illumination. Gas is required for both partial and full thickness macular hole surgery; bubble contact with the macula to produce inward directed surface tension force is required for at least 3 days. Face down position- ing is also required in phakic pa- tients to prevent rapid gas cataract. SF6 has sufficient duration, 7–10 days, for all vitreomacular surgery cases. There is no advantage of using longer duration C3F8 gas in macular hole surgery or any gas in epimacu- lar membrane cases. Epimacular membranes do not cause higher CME rates after cataract surgery. This common misconcep- tion seems to be driven by using OCT thickness measurements rather than viewing all OCT B-scans with- out pseudo-color. Thickness maps are misleading and offer no advan- tage. OCT should be performed before all cataract surgeries to avoid what I call visual surprises—an excellent refractive outcome with imperfect vision. This can create reimbursement questions, although there is no per scan cost other than labor. Many macular disorders are invisible by ophthalmoscopy—some CNV with serous subretinal fluid, central serous retinopathy, vitreo- macular schisis, vitreomacular trac- tion syndrome, and many others. I do not recommend combining vitrectomy with phacoemulsifica- tion (phaco-vit), although this is widely done, especially outside the U.S. This approach does not provide optimal refractive outcomes and may impact vitreomacular surgery outcomes because of visualization issues. Vitreoretinal surgeons simply do not have the expertise in the huge complex space of modern day refractive cataract surgery. Pars plana vitrectomy does not cause cataract de novo; it uniformly causes pro- gression of nuclear sclerosis because 900X viscosity reduction as a result of removing vitreous results in a 12 mm Hg increase in the partial pres- sure of oxygen. Nuclear sclerosis is largely an oxidative phenomenon. A period of observation is rarely indicated before operating on vitreomacular disorders. Vitre- oretinal surgeons self-identified as conservative often seem to take this position, in my view because of fear of operating on eyes with relatively good vision. Spontaneous resolution is only possible in vitreomacular traction syndrome and extremely rarely even in that case. None of the vitreomacular disorders progress over a period of many months or years; it is better in most cases to make a decision on initial examina- tion. Treating any of these disorders with topical steroids or NSAIDs has no merit; just because the macula is thicker on OCT doesn't mean there is increased capillary permeability or edema. EW Editors' note: Dr. Charles is in practice at Charles Retina Institute, Germantown, Tennessee. He has no financial interests related to this article. Contact information Charles: scharles@att.net Retina consultation corner ILM peeling with DSP ILM forceps Source: Steve Charles, MD August 2016 Steve Charles, MD

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