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In my 28 years of practice, age-related macular degeneration (AMD) has claimed the independence of many of my patients. It is the leading cause of vision loss for people over age 65. One in 10 individuals from age 65 to 75 and one in three over age 75 are affected by AMD.1 AMD is three times more prevalent than glaucoma.2
When a patient becomes clinically and legally blind, there is no small effect on his or her life and the lives of those loved ones, like a ripple in a pond. The effect is huge, in effect, like a tidal wave. Patients lose their independence, their ability to drive, read, and maintain their own finances. They become embarrassed in social situations because they are unable to recognize old friends. They give up favorite sports and crafts. They are no longer able to manage their medication administration. Many times, their living arrangements need to change, and they give up their home and may move in with a family member or be forced to move into an assisted-living facility. They often become depressed. Individual and family counseling may be needed to help cope with this tidal wave of change.
I believe that the professions of optometry and ophthalmology now have a new tool available to help prevent central vision loss from AMD. In April 2014, AdaptDx (MacuLogix), developed by Gregory R. Jackson, PhD, and colleagues was made available for clinical use. The device was developed at the Hershey Center for Applied Research in Hummelstown, Pennsylvania.
My practice was asked to assess how AdaptDx could contribute to the management of AMD. My hope for the instrument was that it would be affordable enough for private practitioners to buy, small enough to fit in an office, and fast enough to be a palatable test for patients to take. The device has delivered on all three of these criteria.
My associate Steve Baer, OD, and I were asked by MacuLogix to be one of three private practices in Pennsylvania to initiate use of AdaptDx. We felt that the best way to utilize the device was to recommend it as screening for all patients aged 60 years and older. We wanted to determine whether a private family practice seeing a regular mix of patients would (1) be able to accurately predict the high risk of AMD onset in patients with no other clinical signs of the disease, (2) assess the acceptance from patients of the screening, and (3) be able to support the cost of the device.
We introduce AdaptDx screening at the end of our routine examinations by providing patients with pertinent information on AMD such as prevalence and treatment options. We explain that our challenge is to predict the potential onset of macular degeneration before vision loss occurs and then prescribe preventive measures. This discussion takes only a few minutes. Our experience during 7 months has revealed a high awareness among patients of AMD and its effects. As a result, the acceptance rate among patients aged 60 years and older to return to our office for screening with the unit has been nearly 90%. Our staff then schedules a separate diagnostic appointment for screening following the patient’s routine examination.
The AdaptDx has 90% sensitivity and specificity for identifying a delay in dark adaptation time associated with AMD.3 Research has shown that AMD damage starts before the structural defects we see with fundus cameras, biomicroscopy, optical coherence tomography, and RHA (Annidis) multispectral imaging evaluation.4 AdaptRx reveals functional impairment consistent with early macular problems such as AMD. Because functional impairment occurs prior to structural impairment, the results of the test allow us to determine if the patient has a high risk of developing AMD and other macular problems earlier than before.
It is a practical test that is easy for staff to administer, and the results are equally easy to understand. If a patient’s dark adaptation time is longer than the normal range of 6.5 minutes or less, we know that patient likely has a high risk of developing AMD.
Our results from screening 190 patients (Table 1) showed that 48% of patients had impaired dark adaptation recovery times in one or both eyes. This was remarkable considering that only 24% of those showing impairment had been previously diagnosed with AMD, and only 31% had a previous diagnosis of drusen. This means that routine examination and documentation was neglecting to identify a large number of patients with a future high risk of AMD. In fact, 45% of those identified by the AdaptDx as high risk for AMD had no previous AMD or drusen diagnosis.
Furthermore, 80% of eyes testing as impaired had a BCVA of 20/20 to 20/30, and 19% of eyes testing as impaired had a BCVA 20/40 to 20/60 (Table 2). This indicates that visual acuity is not a good identifier for patients with high risk of developing AMD and should not be used to make clinical decisions regarding AMD prevention and treatment.
COUNSELING AND FOLLOW-UP
All patients with adaptation time longer than 6.5 minutes were counseled on their risk of developing AMD. We advised patients on preventive treatment for AMD, which we explained was the same as the current treatment for dry AMD. Patients were educated on the benefits of good nutrition and placed on Age-Related Eye Disease Study 2 (AREDS2) vitamin therapy. Each patient was given an Amsler grid to monitor central vision for metamorphopsia. Patients were advised to wear glasses that provide adequate blockage of ultraviolet light and blue light. Patients were also asked to have their general health—specifically blood pressure, A1C level, and cholesterol monitored by their primary care physician. We educated patients that there is a connection between blood vessel health and retinal health. If patients were smokers, they were advised to quit smoking immediately. They were also taught about the need for continued ocular health monitoring.
In our practice, patients pay for the screening if there is no prior medical diagnosis. If there is a prior medical diagnosis related to retinal health or impaired night vision, the diagnostic testing is submitted to the patient’s major medical insurance (Current Procedural Terminology code 92284, dark adaptation examination). Based on the test results of the AdaptDx, a plan for monitoring the patient every 3 to 6 months, documenting retinal anatomy with RHA or optical coherence tomography, measuring macular pigment optical density levels with the QuantifEye MPS II (ZeaVision), and obtaining baseline central visual fields all become part of the patient’s treatment plan.
My colleague and I are convinced that the AdaptDx can help us identify many patients at high risk of developing AMD in the future and can help to slow its tidal wave effect on patients and their families. The device will continue to have an important place in our practice, and many eye care practices can benefit from implementing this type of early AMD screening. Use of this instrument does not require a change in state license scope-of-practice legislation or hundreds of hours of continuing education for optometrists. Optometrists and ophthalmologists can start providing this service immediately.
I look forward to reporting the results of this screening service from year 1 and beyond to confirm that we are able to make a difference in the incidence of legal blindness caused by AMD.
- Klein R, Chou CF, Klein BE, et al. Prevalence of age-related macular degeneration in the US population. Arch Ophthalmol. 2011;129(1):75-80.
- Kempen JH, O’Colmain BJ, Leske MC, et al; Eye Diseases Prevalence Research Group. The prevalence of diabetic retinopathy among adults in the United States. Arch Ophthalmol. 2004;122(4):552-563.
- Jackson GR, Scott IU, Kim IK, et al. Diagnostic sensitivity and specificity of dark adaptometry for detection of age-related macular degeneration. Invest Ophthalmol Vis Sci. 2014;55(3):1427-1431.
- Jackson GR, Owsley C, Curcio CA. Photoreceptor degeneration and dysfunction in aging and age-related maculopathy. Ageing Res Rev. 2002;1(3):381-396. Review.
Gary S. Kirman, OD
• In practice at Kirman Eye in Hummelstown, Pennsylvania
• (717) 566-3216; email@example.com
• Financial disclosure: key opinion leader and speaker for MacuLogix