EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.
Issue link: https://digital.eyeworld.org/i/78788
50 EW CORNEA August 2012 Device focus More knowledge yields better diagnoses by Michelle Dalton EyeWorld Contributing Writer Liliana Werner, M.D., Depart- ment of Ophthalmology and Visual Sciences, John A. Moran Eye Center, Salt Lake City, and her group re- cently published a study1 showing Epithelial ingrowth in a LASIK flap with overlying epithelial modeling anterior segment OCT "can be useful in assessing intraoptic changes (which in turn may avoid a misdiag- nosis of IOL opacification and help avoid unnecessary procedures such as posterior capsulotomy or vitrec- tomy)," she said. Anterior segment OCT is either Epithelium downgrowth around a DSAEK graft; the same cornea identifies the source of the ingrowth as a venting incision time domain or spectral domain (sometimes referred to as Fourier domain); the former uses a moving reference mirror for measuring the time it takes for light to be reflected while the latter uses faster, non- mechanical technology to measure multiple wavelengths of reflected light across a spectrum, according to information on the Heidelberg Engi- neering (Carlsbad, Calif.) website. "It's a very specific way of look- ing at small pieces of the anterior segment anatomy," Dr. Safran said. Time domain machines such as the Visante (Carl Zeiss Meditec [CZM], Dublin, Calif.) "are relatively easy to use," Dr. Werner said. "The examination of a non-contact, non- immersion technique and images at different meridians can be obtained relatively fast." Dr. Safran prefers spectral do- main systems, which include the RTVue (Optovue, Fremont, Calif.), which proclaims imaging speed un- matched by other spectral domain systems, the Cirrus HD-OCT (CZM), and the Spectralis (Heidelberg). The Cirrus is able to image a 4 mm sec- tion of the cornea, the RTVue 7 mm, and the Spectralis angle-to-angle, Dr. Safran said. "In my opinion, spectral do- main is to time domain what com- puters are to slide rules," he said, citing better image quality potential from the spectral domain systems. Is intraoperative aberrometry the next big thing? Narrow angles before and after laser peripheral iridotomy vision of 20/25 or better since he began using the ORA System (WaveTec Vision, Aliso Viejo, Calif.). And that's for all his patients—post-LASIK, post-RK, those who only want monofocal IOLs. "Before the ORA, I was at about 80%," he said, adding that Warren Hill, I A partially detached DSAEK graft Source (all): Steven G. Safran, M.D. How anterior segment optical coherence tomography is making it easier to plan treatment strategies ing some abnormalities a bit easier for the anterior segment surgeon. "There's so much more informa- T tion we can have at our fingertips now, it's incredible," said Steven G. here is no doubt in most clinicians' minds that the technological advances witnessed in imaging devices has made diagnos- Safran, M.D., in private practice, Lawrenceville, N.J. Among the pathologies more easily identified with anterior segment optical coher- ence tomography (OCT) are epithe- lial ingrowth under LASIK flaps, determining residual stromal bed thickness, etc. "Anterior segment OCT is in- credibly important for evaluation of Descemet's stripping automated en- dothelial keratoplasty (DSAEK) and Descemet's membrane endothelial keratoplasty (DMEK) grafts," Dr. Safran said. "I think it will be neces- sary for any cornea surgeon doing this kind of work to have this tech- nology." M.D., Mesa, Ariz., has said that the majority of surgeons will be within a half diopter 80% of the time, which "is about 20/25 uncorrected," Dr. Cionni said. He added his IOL calculations have been off by as much as 2 D when re-evaluated intraoperatively with the ORA. According to WaveTec Vision, 83% of physicians interviewed said they had changed toric IOL cylinder power/axis or corneal relaxing incision plans after taking an intraoperative reading. Dr. Cionni said he still uses both relax- ing incisions and toric lenses to treat astigmatism; he's changed the power of the premium implant "probably 65% of the time," he said, although usually the change is no more than a half diopter. "Intraoperative aberrometry takes all the uncertainty out of the system," he said. "I don't have to rely on just the K readings when I can take an aphakic refraction." The downside, however, is that the additional intraoperative step results in a longer surgical time. Surgeons also have to have several different power IOLs on hand during each of the cases, and not all patients can be imaged. "If there's a lot of guttata, bad tear film, or a small pupil, you won't be able to get a good reading," Dr. Cionni said. He also won't take a reading in patients with tremor or in eyes that have been blocked. "I'm to the point where I don't want to take any post-refractive surgery patients into the OR for cataract surgery without this system," he said. Editors' note: Dr. Cionni has financial interests with WaveTec Vision. Contact information Cionni: 801-266-2283, rcionni@theeyeinstitute.com ntraoperative wavefront aberrometry is helping surgeons give cataract patients even better refractive outcomes, said Robert J. Cionni, M.D., medical director, The Eye Institute of Utah, Salt Lake City. He said more than 90% of his cataract patients achieve post-op, uncorrected distance