Maintain vision by identifying subclinical AMD using dark adaptation

The “Practice Insights” page presents a firsthand perspective of how a device, system or service has impacted patient care and practice management in an optometric practice.

Measuring dark adaptation (DA), the ability of the eyes to adjust from light to darkness, has significantly changed the way we diagnose and manage AMD in our practice. DA measures rod-intercept time, a function that is impaired in AMD patients up to three years before clinical signs are visible during funduscopic examination, according to the 2014 ALSTAR study. Among ALSTAR study group participants, all ages 60 or older, 24% exhibited subclinical AMD, defined as AMD without clinical signs but with impaired DA. By identifying patients sooner, they are educated, treated and monitored to detect the earliest signs of conversion from dry to wet AMD.

In introducing the AdaptDx automated dark adaptometer (MacuLogix) as a screening mechanism, we have identified “healthy retina” patients whose extended rod-intercept time categorizes them as early AMD patients. This gives patients the best opportunity to maintain good vision, with their AMD.

PROCEDURE

At our practice, we treat subtle macular changes as we do glaucoma suspects. Specifically, we identify clinical risk factors, such as drusen and/or changes in the retinal pigment epithelium, which then warrants structural and functional testing to determine whether a patient has early AMD. In addition to DA, this testing includes VA, Amsler Grid, color photography, autofluorescence and OCT.

DIAGNOSE AND MONITOR

We offer an AMD screening for patients who have risk factors, such as age, smoking and family history, but who present without clinical signs. The screening modality is an out-of-pocket cost to the patient, but initial DA testing can be reimbursed when a patient presents with a night vision complaint.

If the DA time is normal: The patient is considered to have isolated drusen and is monitored annually with serial DA to monitor for conversion to true AMD.

If the DA screening is abnormal: The patient returns for a full work up that includes extended DA. When the screening DA is abnormal, the full extended DA testing is reimbursable using procedure code 92284 with ICD-10 code H53.61, abnormal DA curve. If the extended DA is also abnormal, the patient is diagnosed with subclinical AMD.

For the patient who is diagnosed with subclinical AMD, our management strategy then is extensive patient education about the disease and DA results, which aid in compliance, recommendation of AREDS2 therapy, prescription UV-blocking sunglasses and blue-blocking indoor lenses. We then monitor disease progression, at least twice a year, with dilated examination, OCT, DA and others, as appropriate.

MAINTAIN VISION

If the rod-intercept time is progressively worsening, according to serial DA, that patient has a rapidly worsening disease and is more likely to convert to wet AMD. Those patients are monitored in two- to three- month intervals. We have had several instances of diagnosing CNVM, without patient symptoms, at the follow-up visits. As a result, patients were referred for anti-VEGF therapy and were able to maintain 20/20 vision with treatment. By diagnosing and managing drusen and AMD, we help preserve our patients’ vision, independence and quality of life. OM

DR. CORBIN practices comprehensive eye care at Wyomissing Optometric Center, with three locations and seven optometrists. He is a speaker, advisory board member and/or consultant for Alcon, Shire, MiBo Medical Group, Maculogix and PRN.

DR. LEGGE practices primary care optometry at Wyomissing Optometric Center and serves as a member of the Allied Health Professional Staff at Penn State Health/St. Joseph Medical Center. She is also a speaker for Maculogix.