This prospective study examined the prevalence, incidence and natural history of subclinical macular neovascularization (MNV) in eyes with unilateral dry AMD.

Study design

The authors followed patients with dry AMD in one eye and wet AMD in the fellow eye for an average of 2 years using swept-source OCT angiography (OCTA). They examined the overall risk of exudation, and the association between neovascular lesion size and the risk of exudation.

Outcomes

Of the 227 eyes imaged, 30 (13.2%) eyes had subclinical MNV when first imaged and 12 (8.9%) developed subclinical MNV during follow-up. Of 191 eyes with more than one visit, 19 developed exudation, of which 14 had pre-existing subclinical MNV. The incidence of exudation from the time of first observation of any subclinical MNV was 24.2% at the 1 year follow-up and 34.5% at the 2 year follow-up visit. The relative risk of exudation after detection of subclinical MNV was 13.6 times greater than in the absence of MNV (P < 0.001).

Limitations

Patients had variable follow-up intervals, so the exact time to the onset of exudation may not be accurate. Investigators also used 3 different SS-OCTA prototypes, which limited their ability to reliably measure the growth of MNV lesions.

Clinical significance

These findings suggest that OCTA may be an essential clinical tool for detecting subclinical MNV in eyes with apparent dry AMD. These eyes need to be monitored closely for development of exudation due to their heightened risk.