by Dan Roberts (Macular Degeneration Support) and Liz Trauernicht (Macular Degeneration Foundation)
OCT and nonmydriatic technologies are lessening discomfort and risk of eye exams.
MD Support and MD Foundation communicate with thousands of patients who undergo periodic eye exams for diagnosis and treatment of macular degeneration, glaucoma, diabetic retinopathy, and other chronic diseases. Many have asked if there is an alternative to the uncomfortable and potentially harmful practice of dilated-pupil fluorescein angiography (FA) and slit lamp examination.
One answer to this question has come during the past 15 years with simultaneous development of two effective imaging methods. Those methods are OCT (optical coherence tomography, a kind of “optical sonar” using invisible light) and nonmydriatic photography (requiring little or no dilation and a soft light flash). These improvements in clinical practice are helping to relieve patients’ fear of discomfort and possible photothermal damage. As a result, patient volume can be expected to increase, resulting in higher detection of chronic eye disease development and progression.
Fortunately, since OCT and nonmyd imaging have grown more common, patients are less frequently exposed to the bright flashes of FA. When they are, it is either because their doctors have not yet made the switch or because OCT and nonmyd cameras cannot provide sufficient information.
Another commonly-used instrument is a high-intensity slit lamp, with which the doctor scans the interior of the eye with a thin sheet of light. Since exposure of the retina is less than FA, it is more comfortable for patients, and it poses less risk to the tissue. A slit lamp is not a perfect solution to the issues of discomfort and photothermal damage, but for now it has to be an acceptable alternative to FA for obtaining a full view of the interior segments.
In a recent interview, Bruce Rosenthal, O.D. (Lighthouse Guild, New York City) said FA may be necessary in cases of “a sudden drop in vision, new or large floaters, high or pathological myopia, or histories of retinal detachments and other risk factors”. Except for those special circumstances, however, OCT is strongly favored for its high quality imaging and wide field of view. Though not used as frequently, nonmyd imaging, according to Dr. Rosenthal, is “incredible for patients and families for understanding functional vision loss. Also, we [at the Lighthouse Guild] have four ophthalmology residencies for which this is a great teaching tool.”
OCT is used by ophthalmologists to view cross sections of the retinal layers and anterior segment of eyes affected by glaucoma, retinal degenerative diseases, and diabetic eye diseases. The technology is invaluable for diagnosing and assessing without exposing the retina to visible light.
Nonmyd cameras can be used by both optometrists and ophthalmologists for:
- diabetic screening and early detection of glaucoma and other eye diseases where dilation is contraindicated
- follow-up exams for comparison to benchmark OCT or FA diagnostic results
- cursory exams where portability or expediency is an asset (eg. rural areas)
- a possible future in telemedicine
Janet Sunness, M.D. (Greater Baltimore Medical Center) commented that “nowadays with the availability of . . . infrared imaging with the OCT device, there is only rarely a need for fundus photographs.” Dr. Sunness also includes a nonmyd camera in her practice, but reports that she “doesn’t use it much”. This is a common response from eye care physicians who understand the patients’ concerns and who realize the importance of having all available options at hand for a variety of situations.
Many patients have been relieved of the burden of FA, but complaints continue to come in. Results from a small informal survey conducted in February 2017 suggest that likely half of patients continue to endure FA unnecessarily. 24 senior adults affected by macular degeneration were asked, “Have you had at least one retinal exam during the past two years which included fluorescein angiography?” Ten patients (42%) responded “yes”, and fourteen (58%) responded “no”. Two patients in the “yes” group had been newly-diagnosed during the two years, which may explain the use of FA as a baseline. A rationale for the remaining eight could be that unusual circumstances have required repeated FA. That, however, seems unlikely. These results, along with ongoing helpline conversations, appear to imply that a number of patients with well-established diagnoses may still be needlessly undergoing routine high intensity light exposure.
As more doctors make the transition to updated imaging options, and as even better methods are developed for quicker, safer, and less unpleasant techniques, a greater number of patients may start showing up for their important annual exams. This, in addition to the benefits to the clinical practice, could very well boost the success rates of early diagnosis and treatment. Until all patients receive the best available technology, it is up to the doctors to make the best choices; and their patients will benefit by being made aware of the feasible options.