According to the AMD Practice Patterns of the American Academy of Ophthalmology, fundus fluorescein angiography (FFA) is the confirmatory diagnostic test for nAMD onset, but researchers say it may not be the best test to perform and that clinical practice guidelines for monitoring onset of nAMD may need revision. 

“Once nAMD has developed in the first eye, around one quarter of persons will develop neovascularization in their fellow eye within three years,” the researchers explained. “Several strategies are used to detect the onset of nAMD promptly in the unaffected fellow eyes, but these haven’t been compared to inform what would now be best practice.”

During hospital visits, patients typically undergo visual acuity testing, fundus examination and spectral domain OCT (SD-OCT) of the fellow eye. In contrast to FFA, OCT is a non-contact, user-friendly, non-invasive technology, according to the researchers. 

 Accurate and efficient modes of detection are key because confirmed nAMD eyes treated promptly are more likely to maintain good vision. However, the researchers noted there’s a lack of robust evidence for the diagnostic accuracy of commonly used monitoring tests. “We conducted a prospective diagnostic accuracy study to evaluate the best test or combination of monitoring tests that can be performed to robustly and efficiently detect nAMD in the second eyes of those with nAMD in the first eye.” Their findings suggest that practice guidelines may need to change.

The cohort study took place in 24 eye clinics in the UK, over a span of three years, and included older adults over the age of 50 who had been recently diagnosed with unilateral nAMD and no nAMD in the fellow eye. Tests included self-reported vision, Amsler test, clinic-measured visual acuity, fundus assessment and SD-OCT. FFA was used as a reference standard.

A total of 145 patients (26.3%) of 552 developed active nAMD in the study eye. The primary analysis cohort consisted of 120 patients who had FFA at detection. The researchers reported the following index test positives at nAMD detection in those confirmed by FFA: self-reported vision much worse 5, distortion on Amsler 33, 10-letter decrease in acuity from baseline 36, fundus examination 64 and OCT 110.

Index test sensitivities varied widely: 4.2% for self-reported vision, 33.7% for Amsler, 30% for visual acuity, 53.8% for fundus exam and 91.7% for OCT. All five index test specificities were high: 97% for self-reported vision, 81.4% for Amsler, 66.3% for visual acuity, 97.6% for fundus exam and 87.8% for OCT.

“The combination of OCT with one other index test, which was a secondary outcome measure, increased sensitivity marginally and decreased specificity for all combinations except fundus examination,” the researchers reported. They concluded that self-reported VA change, unmasking of new distortion, acuity measurements and fundus checks performed poorly in diagnosing active nAMD, in contrast to OCT. They suggest revising clinical practice guidelines for monitoring onset of nAMD.