Subretinal fluid is associated with better visual outcomes in nAMD. Photo: Steven Ferrucci, OD, and Jay M. Haynie, OD. Click image to enlarge.

While several studies have shown that intraretinal fluid (IRF) has detrimental effects on visual acuity and that subretinal fluid (SRF) helps preserve visual acuity in patients with neovascular AMD (nAMD), none have investigated the functional association of these fluid volumes. Researchers of a recent study aimed to evaluate these associations in patients who received anti-VEGF treatment over 24 months.

IRF and SRF fluid volumes were segmented automatically on monthly SD-OCT images and were included as covariates into longitudinal mixed effects models to model BCVA trajectories.

Foveal IRF corresponded to decreased visual acuity at baseline and subsequent months but did not show any difference in long-term visual acuity trajectories. “However, the negative impact of IRF on BCVA at subsequent visits was clearly maintained beyond baseline,” the authors explained. “It is important to consider total amounts of volumes for the individual patient. As all fluid volumes were very low and hardly extended beyond 10nl after the first injection, their absolute impact on function was low as well.”

The authors noted the poor correlation of IRF with visual function became even more apparent for persistent fluid. “Patients with persistent IRF presented with reduced baseline BCVA, reduced functional response to treatment after the first injection and lower BCVA gains after 24 months, suggesting they were more severely affected by the disease and neurosensory recovery was no longer possible,” the authors explained. “Bearing in mind that in numerous trials, lower baseline BCVA was associated with greater visual improvement, the combination of decreased baseline BCVA with lower overall functional improvement in patients with persistent IRF further highlights the distinct nature of this subgroup.”

Foveal baseline SRF corresponded to higher BCVA with no effect on BCVA trajectories. At follow-up visits, SRF volumes had a positive effect on BCVA. These results are somewhat similar to a previous study, in which the trend of higher BCVA in patients with foveal SRF weakened at one year and increased again by 24 months.