|Studies have shown that the Foresee PHP (from Reichert) is more sensitive and reliable than the Amsler grid for monitoring changes.|
It’s estimated that more than nine million people have age-related macular degeneration (AMD) in the U.S. and that approximately 1.75 million are in the late stages of the disease. Another seven million are believed to be at high risk of developing advanced AMD. This is clearly a disease that requires the use of testing technology to aid early diagnosis and to monitor progression, and we need to help educate our patients about how best to prevent progression.
There are many in-office tools that can be incorporated into the testing of patients with AMD. Some enable the optometrist to detect early disease and progressive changes in structure and function, while others allow the optometrist to decide on frequency of follow-up and to possibly prevent progression by determining the best vitamin supplements for those with intermediate AMD.
OPTICAL COHERENCE TOMOGRAPHY (OCT)
Spectral domain OCT systems allow for the detection of both atrophic and exudative structural changes in AMD due to its high resolution of the macula. It’s possible to monitor patients with cuticular drusen that aren’t affecting vision because the overlying outer retinal layers are intact. Someone who has drusen and wet AMD changes (serous detachment due to the development of choroidal neovascularization and hemorrhage) may be asymptomatic because the fovea was not affected, but this patient would need prompt treatment.
SD-OCT systems are available from a number of manufacturers: Cirrus OCT (Carl Zeiss Meditec, Inc.), iVue’ and RTVue’ Premier (Optovue, Inc.), 3D OCT-2000 (Topcon, Inc.), SPECTRALIS’ OCT (Heidelberg Engineering, Inc.), and OCT RS 3000 Advance (Nidek, Inc.). The billing code for performing an OCT of the macula is 92134. Some OCT systems like Topcon’s 3D OCT-2000, Heidelberg Engineering’s SPECTRALIS and Carl Zeiss Meditec, Inc.’s Cirrus Photo perform fundus photography and OCT. However, these two procedures cannot be billed on the same day.
|Testing with ZeaVision’s QuantifEye takes just two to three minutes to perform.|
The mainstay of patient monitoring has always been the Amsler grid. Although it can be an inexpensive and useful tool for monitoring possible changes, the Amsler Grid may miss early exudative or wet changes and may also result in false positives. Therefore, more valid monitoring devices are needed. In 2006 the Foresee PHP’ from Reichert Technologies/Ametek, Inc. was introduced as a second-generation of an earlier device, the Preview PHP, which debuted in 2004. PHP is based on the principal of hyperacuity perimetry, which is based on Vernier acuity, or the ability to detect a deviation in a line. It tests the central 14Â° and tests over 500 points several times. The stimulus may either be presented as a straight line or with a “bump” in the middle. The patient holds a stylus in their hand and while looking straight ahead, they touch the stimulus in the periphery where they perceive a bump in the line. Studies have demonstrated the PHP to be more sensitive and reliable than the Amsler grid for monitoring change. It can also be billed as a visual field test if done in office. The screening code is 92082 and when threshold values are determined, it’s billed as 92083.
For years, research has suggested that macular carotenoids or macular pigments, specifically lutein and zeaxanthin, are essential for macular health. They absorb the harmful effects of UV light that may play a role in the pathogenesis and progression of AMD. The AREDS2 study addressed the addition of these two carotenoids into some of their study population of subjects with intermediate AMD and found a benefit in reducing the risk of progression in certain subjects, especially when macular pigment optical density (MPOD) was low. Therefore, vitamin supplements today often include one or both of these carotenoids.
ZeaVision, LLC’s QuantifEye’ is a device that measures MPOD and works by the principle of flicker photometry. The patient looks directly at a blue/green light, then presses a button when they see the light flicker. This is repeated at various intensities throughout the test until the patient’s macula is fully saturated and then the test reduces the intensity for an additional series of clicks. The test, which takes two to three minutes to perform, only needs to take a central measurement, though peripheral readings can also be performed.
There’s no billing code for this test but if patients are found to have a low MPOD, the practitioner can offer vitamins such as EyePromise, which are sold exclusively through the practice and obtained from ZeaVision, LLC. The test can also be repeated as the patient takes the supplements to monitor MPOD improvements. Generally, the practice charges a small out-of-pocket amount for the test but can make additional profits from the sale of the vitamins.
|Arctic Medical Laboratories’ Macula Risk PGx test helps predict a patient’s risk for progression to advanced AMD within two, five, and 10 years.|
In-office genetic testing has gained momentum over the last few years and will continue to do so as evidence mounts that patients with the same disease may indeed be very different. Why do only some patients develop AMD and why do some advance more quickly than others? Should all patients be followed with the same frequency? Should all patients be on the same supplements? These questions may possibly be answered by the use of genetic testing. The AREDS study was the first to introduce the importance of vitamin supplements in reducing the risk of AMD progression in patients with intermediate AMD. Since that original study was performed, evidence is accumulating that not all intermediate AMD patients should be on the same formulation. In fact, there’s evidence that some patients may actually increase risk of progression if they are on the wrong formulation.
Genetic testing as an in-office tool has been available for a few years and the tests are easy to perform and involve no outlay of cash from the optometrist. Testing involves taking a sample from the inside of the patient’s cheek during an office visit and sending it to a commercial genetic testing laboratory. Testing should be targeted to patients that have drusen and/or AMD. If they do, insurance will cover the cost of testing and an analysis report is available in about three weeks. The patient’s insurance will pay the labs directly and the optometrist doesn’t bill for the test.
One commercial testing option is the Macula Risk’ PGx test from Arctic Medical Laboratories. The test predicts a patient’s risk for progression to advanced AMD within two, five, and 10 years using an analysis of genetic variants associated with AMD, clinical AMD status, body mass index, and significant non-genetic risk factors, e.g., smoking. In 2013, the company added its Vita Risk pharmacogenetic analysis to the Macula Risk PGx test, providing a genotype-directed selection of appropriate ocular vitamin treatments for intermediate AMD patients based on their testing results. Vita Risk is also available as a stand-alone test.
Sherry Bass is a distinguished clinical professor at the State University of New York State College of Optometry in Manhattan.
WHERE TO FIND IT:
Arctic Medical Laboratories •866-964-5182 •macularisk.com
Carl Zeiss Meditec, Inc. •925-557-4100 •zeiss.com/med
Heidelberg Engineering, Inc. •800-931-2230 •HeidelbergEngineering.com/us
NIDEK, Inc. •800-223-9044 •usa.nidek.com
Optovue Inc. •866-344-8948 •optovue.com
Reichert Technologies/AMETEK, Inc. •716-686-4500 •reichert.com
Topcon Medical Systems, Inc. •800-223-1130 •topconmedical.com
ZeaVision, LLC •866-833-2800 •zeavision.com