EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.
Issue link: https://digital.eyeworld.org/i/233841
26 EW CATARACT January 2014 Glare testing issues persist by Michelle Dalton EyeWorld Contributing Writer Measuring glare EpiGlare device attached to the phoropter Source: Terrence P. O'Brien, MD Clinically speaking, glare is more relative than loss of contrast sensitivity, but harder to quantify G lare can adversely affect a patient's life to the point where "standard" activities such as driving at night or being outside on a bright, sunny day are problematic. So while patients may have good Snellen acuity (and possibly even as good as 20/20), the decision to remove their cataract due to the visual debilitation is not only difficult to quantify, but differs among patients. Almost no one will argue with the decision to remove a cataract if Snellen acuity is reduced to 20/100 from lenticular opacity. Yet clinicians know Snellen acuity alone is not a good predictor of functional vision loss and is not an accurate reflection of "real life." Further, the loss of contrast sensitivity is greater in those with glare than in those without, regardless of Snellen acuity. Medicare recognizes that reduced vision due to glare is justification for cataract surgery, yet the tools most clinicians use do not provide an objective measure and leave much open to interpretation. With the increased physician accountability aspects of the Affordable Care Act, justifying when to operate and when to wait may become even more important. At its most simplistic, "glare can be considered a subjective visual response to light."1 Over the years, "there have been different efforts to try and quantify glare," said Terrence P. O'Brien, MD, Charlotte Breyer Rodgers Distinguished Chair in Ophthalmology, and director of the refractive surgery service, Bascom Palmer Eye Institute, Palm Beach Gardens, Fla. To date, "there's not a universal device that has measured up to providing a truly reliable, reproducible quantification of glare, contrast sensitivity and impact on visual functioning." Samuel Masket, MD, clinical professor, Jules Stein Eye Institute, Los Angeles, and in practice, Advanced Vision Care, Los Angeles, said most clinicians believe "to truly evaluate the effect of glare, you need to consider its effect on visual function alone and its effect on contrast sensitivity." Clinically, however, Sonia H. Yoo, MD, professor of ophthalmology, Bascom Palmer Eye Institute, Miami, said glare is "much more" relative than contrast sensitivity loss. "People complain about glare at night when they drive, from the street lights, from a computer screen. We test for glare with various lights of low, medium, and high intensity, and when they look through the light sources their Snellen acuity does drop, but it's not an objective metric." Understanding glare Glare testing first came about in an attempt to both understand and quantify reduced vision in the presence of good VA, Dr. Masket said. Because the Snellen charts use high contrast optotypes, "many people could function well under circumstances of the examination lane, but not in the real world." Plus, the type of cataract may have a unique effect on glare as well, he said. Nighttime glare, for instance, "most typically comes from a central opalescence and is more obvious in nuclear cataracts, whereas cortical and posterior subcapsular cataracts may be more prone to daytime glare," Dr. Masket said. One of the aspects of the Affordable Care Act is accountability by physicians, and that will make identifying and quantifying glare even more important, Dr. O'Brien said. "Regulatory groups are looking to create standards as thresholds for surgical procedures, and the issue of glare has always been a gray zone," Dr. O'Brien said. "In Florida, glare is a big issue—the social dynamic of many of our communities changes when glare prevents someone from driving at night or day. We need better methods to determine what is disabling glare and what is not." People with posterior subcapsular cataracts who live in cloudier environments may not be as affected by glare as those in the Sunshine State, he said. "Patients complain about glare but they read 20/20 or 20/40; clinicians have to document with glare testing that a patient's vision will drop X number of lines in order to justify surgical correction. Without proper documentation, reimbursement can be an issue," Dr. Yoo said. A number of testing devices are commercially available, "each with its strengths and weaknesses; the most popular is the Brightness Acuity Test [BAT, Marco Ophthalmic, Jacksonville, Fla.]," Dr. Masket said, mainly because it is a very simple handheld device. The BAT gained popularity because it was more precise than previous methods; it consists of three different light settings "and some patients will do fine at low and medium, but will drop out at the high intensity light settings, but it's still tough to interpret the results," Dr. O'Brien said. Patients with tremor, for instance, do not fare well with the BAT. The level of battery charge may also influence results and interpretations. Dr. Masket said he's "not a major proponent of the BAT—the illumination source is very close to the eye, and may cause the pupil to constrict. There can be paradoxical effects because of the pupil in certain cataract cases, much like super pinhole testing for potential acuity." While Dr. Yoo appreciates that the BAT is calibrated with different intensity lights, "it does not provide an objective number. It's as good as it can be." The Optical Quality Analysis System (OQAS, Visiometrics, Tarrasa, Spain) "gives us a number value for the light scatter," Dr. Yoo said. "It measures scatter due to lenticular changes, so it's objectifying what was previously subjective responses." The device analyzes an image as it passes through a refractive medium, allowing for indirect measurement of veiling glare independent of low- or high-order aberrations. "Photophobia can be an issue— patients complain about light in general, not necessarily glare specifically," she said. "I like the OQAS because it provides real-time readings relative to aberrations, blink times, and tear break-up times." "Other multifunctional devices such as the C-Quant [Oculus, Arlington, Wash.] and HARK 599 [Carl Zeiss Meditec, Jena, Germany] have features that also attempt to provide quantification of glare, but they lack portability," said Dr. O'Brien. A newer portable device, the EpiGlare (Epico, Columbus, Ohio) "provides a more realistic assessment of true glare mimicking the disability patients experience at nighttime," Dr. O'Brien said. The EpiGlare can easily attach to a standard phoropter, Dr. Masket said, and has a consistent light source that simulates oncoming auto headlights or street lights. "I think it's going to prove to be a useful tool if it finds its way into the marketplace," Dr. Masket said. (At press time, the device was not yet commercially available in the U.S.) EW Reference 1. Masket S. Preoperative evaluation of the patient with visually significant cataract. In: Cataract Surgery: Technique, complications, and management—Second Edition. Steinert R. and Fine I.H. (eds). Elsevier Science. 2004:Philadelphia. Editors' note: The physicians have no financial interests related to this article. Contact information Masket: 310-229-1220, avcmasket@aol.com O'Brien: 561-515-1544, tobrien@med.miami.edu Yoo: 305-326-6322, syoo@med.miami.edu