Purpose
To prospectively assess morphological and functional factors predicting neovascular age-related macular degeneration (nAMD) development among patients with intermediate AMD.
Methods
72 eyes of 72 participants in a clinical trial of dietary supplementation for intermediate AMD were prospectively assessed 3-monthly for at least 12 months. Spectral-domain optical coherence tomography(OCT), microperimetry(MP) and multifocal-electroretinography(mfERG) factors from the baseline visit and visit immediately preceding nAMD occurrence were assessed for characteristics associated with nAMD development. OCT factors included central macular thickness(CMT), maximal drusen height at any location(DH), maximal subfoveal drusen height(SFDH), retinal pigment epithelium(RPE) thickness and inner segment/outer segment(ISOS) integrity. MP and mfERG points were grouped into concentric rings from the centre of fixation for analysis(3 MP rings at 1°, 6°, 10° and 6 mfERG rings at 0-1°, 1-4°, 4-8°, 8-12°, 12-17°, 12-17°). Analysis of variance and t-tests were used to compare eyes that developed nAMD with those that did not.
Results
At baseline, greater mean DH at any point(186vs84µm) and SFDH(296vs104µm), worse ISOS integrity, greater CMT(329vs290µm) and decreased mean foveal(rings 1 and 2) and overall MP sensitivities(24.5vs21.75dB) were all associated with nAMD development(p<0.05 for all). Except CMT, all of these factors were also associated with nAMD at the visit preceding nAMD development(p<0.05). Mean RPE thickness, ring 3 MP sensitivity, and mfERG ring 1-5 response densities were not predictive of neovascularisation at either timepoint(p>0.05 for all).
Conclusions
Morpho-functional analysis using currently clinically available methodology can identify patients at high risk of progression to nAMD. Patients with larger drusen, significant ISOS impairment and/or lower overall and foveal MP sensitivity may be at increased risk of developing nAMD. These patients may benefit from more intense monitoring to achieve early nAMD diagnosis.