眼动如何补偿视锥细胞丢失：Oz Vision 系统模拟视锥丢失揭示视力韧性机制
Revealing the benefit of eye motion for acuity under emulated cone loss
研究团队用 Oz Vision 系统在健康眼中选择性关闭随机选取的部分视锥细胞（称为“cone dropout”），模拟视锥细胞丢失，发现视力随视锥丢失比例增加呈非线性下降。在最高丢失水平下，有眼动的视觉系统与采样元素数量接近两倍的静态条件具有等效视力。对眼动与刺激数据的分析表明，这一补偿收益来自“存活”视锥细胞通过注视性眼动采样到更多字母信息。此前研究已显示，即使多达 50% 视锥细胞丢失，临床正常视力（20/25 或更好）仍可维持。
来源：eLife · doi.org
Retinal degenerative diseases progressively erode the cone photoreceptor mosaic, reducing the retina’s spatial sampling power, yet visual acuity is remarkably resilient to cone loss. Prior work has shown that clinically normal visual acuity (20/25 or better) can persist despite up to 50% of cone cells being lost (Ratnam et al., 2013; Foote et al., 2018). However, studies on individuals with retinal degeneration cannot control for patients’ stage of disease progression, creating the need for an experimental paradigm that can mimic these diseases in healthy subjects. The Oz Vision system creates visual percepts through programmable, per-cell stimulation of thousands of cone cells. We reprogram this system to emulate cone loss in healthy eyes by withholding stimulation from a subset of randomly selected cones, rendering them inactive, in a method we term ‘cone dropout’. Using this approach, we characterize the visual system’s robustness to cone loss, showing that visual acuity declines nonlinearly with increasing cone dropout. Importantly, we uncover the compensatory benefit that eye motion provides under cone-deprived conditions, finding that at the highest level of dropout, a visual system with eye motion has an equivalent acuity to a static dropout condition with nearly twice as many sampling elements. Through analysis of eye motion and stimulation data, we find that this benefit arises from the additional information accumulated by ‘surviving’ cones as they sample more of the letter through fixational eye motion.