EyeWorld Asia-Pacific September 2012 Issue

41 EWAP RETINA September 2012 Using OCT to diagnose retinal disorders by Michelle Dalton EyeWorld Contributing Editor Before the imaging device was popularized, it was next to impossible to diagnose some disorders with any confidence I n an era when every premium lens patient not only expects perfect vision but also expects no complications from the surgery, any and every diagnostic tool in a surgeon’s armamentarium becomes even more important to weed out the most minute of potential issues. “In this era of multifocal/ premium IOLs, patient expectations post-cataract surgery are extremely high,” said Nalin J. Mehta, MD, Colorado Retina Center, Lakewood, Colo., USA. “A good number of cataract surgeons are not using optical coherence tomography (OCT) to evaluate the macula for subclinical, preoperative macular disorders that may affect final visual outcomes.” For example, a recent study found deeper and wider lamellar defects are associated with poor visual outcomes—and only 28% of lamellar holes diagnosed by OCT had been detected clinically on fundus exam. 1 A major advantage in using OCT to assess retinal diseases is its ability to provide cross- sectional images of the retina and to perform quantitative analysis of retinal morphology. “Every ophthalmologist should become familiar with OCT images, as we can no longer trust our eyes in the evaluation of retinal status,” said Roberto Bellucci, MD, Hospital and University of Verona, Italy. During the 2012 ASCRS•ASOA Symposium & Congress, David S. Boyer, MD, clinical professor of ophthalmology, Keck School of Medicine, University of Southern California, Los Angeles, Calif., USA, told symposium attendees vitreomacular traction and epiretinal membranes were underdiagnosed before the use of OCT became so widespread. A key pearl, he said, is to remember cataracts don’t cause distortions— retinal disorders do. Steven G. Safran, MD, in private practice, Lawrenceville, NJ, USA, agreed, saying some retinal pathologies such as vitreomacular traction, lamellar macular holes, and age-related choroidal atrophy were impossible to visualize and in some cases were only identified once the retinal surgeon began doing a dissection. “With OCT, you can see the posterior hyaloid, and you can determine its relationship with the macula,” Dr. Safran said. “The vitreomacular interface is now understood to play a role in macular edema and macular degeneration.” OCT is also the “only way” to view choroidal abnormalities, Dr. Safran said.”We’re just beginning to understand how many disease states are affected by the choroid.” People with very thin choroids (age-related choroidal atrophy) may be at a higher risk for glaucoma, especially if those patients present with peripapillary atrophy, according to a study. 2 These patients may not see well even if the macula is clear, Dr. Safran said, and myopes are at a greater risk of vision loss due to myopic degeneration with a thin choroid as well. “Cataract surgery can infrequently accelerate/induce vitreous degeneration, with subsequent posterior vitreous detachment,” Dr. Mehta said. “This could in turn result in antero-posterior vitreomacular traction or the evolution of an epimacular membrane; increased symptomatology from preexisting epimacular membranes/macular pucker may also occur; and posterior vitreous detachment (PVD) conceivably leads to macular hole formation or progression. In one study, 3 20% of eyes developed PVD at 1 week after surgery.” When to image, what to look for Dr. Safran advises “anyone who is implanting premium lenses” to get an OCT of the retina before surgery. “It is an avoidable error to recommend to patients with undiagnosed macula pathology a premium lens that can’t live up to expectations. In some cases a multifocal that the patient pays extra for may do more harm than good,” Dr. Safran said. “The important thing is that surgeons must be aware of the macula pathology beforehand if they are recommending (and charging extra) for the lens, and not having an OCT is just not a good excuse anymore.” In his opinion, epiretinal membranes should be a contraindication for multifocal lenses, and patients should be An epiretinal membrane denoted by the arrow distorts the retinal anatomy and may decrease vision. The macular hole seen here through OCT will necessitate immediate surgery to avoid vision loss. Source: Roberto Bellucci, MD, and Miriam Cargnoni, OD continued on page 42