Jiang Xiaoyun, Liu Teng, Pandiyan Vimal Prabhu, Slezak Emily, Sabesan Ramkumar
Department of Ophthalmology, University of Washington School of Medicine, Seattle, WA 98109, USA.
Department of Bioengineering, University of Washington, Seattle, WA 98195, USA.
Biomed Opt Express. 2022 Oct 24;13(11):5989-6002. doi: 10.1364/BOE.473475. eCollection 2022 Nov 1.
Optoretinography (ORG) has the potential to be an effective biomarker for light-evoked retinal activity owing to its sensitive, objective, and precise localization of retinal function and dysfunction. Many ORG implementations have used adaptive optics (AO) to localize activity on a cellular scale. However, the use of AO restricts field-of-view (FOV) to the isoplanatic angle, necessitating the montaging of multiple regions-of-interest to cover an extended field. In addition, subjects with lens opacities, increased eye movements and decreased mobility pose challenges for effective AO operation. Here, we developed a coarse-scale ORG (CoORG) system without AO, which accommodates FOVs up to 5.5 deg. in a single acquisition. The system is based on a line-scan spectral domain OCT with volume rates of up to 32 Hz (16,000 B-frames per second). For acquiring ORGs, 5.5 deg. wide OCT volumes were recorded after dark adaptation and two different stimulus bleaches. The stimulus-evoked optical phase change was calculated from the reflections encasing the cone outer segments and its variation was assessed vs. eccentricity in 12 healthy subjects. The general behavior of ΔOPL vs. time mimicked published reports. High trial-to-trial repeatability was observed across subjects and with eccentricity. Comparison of ORG between CoORG and AO-OCT based ORG at 1.5°, 2.5°, and 3.5° eccentricity showed an excellent agreement in the same 2 subjects. The amplitude of the ORG response decreased with increasing eccentricity. The variation of ORG characteristics between subjects and versus eccentricity was well explained by the photon density of the stimulus on the retina and the outer segment length. Overall, the high repeatability and rapid acquisition over an extended field enabled the normative characterization of the cone ORG response in healthy eyes, and provides a promising avenue for translating ORG for widespread clinical application.
由于视网膜电图（ORG）对视网膜功能和功能障碍具有敏感、客观且精确的定位能力，它有潜力成为光诱发视网膜活动的有效生物标志物。许多ORG实施方案都使用了自适应光学（AO）技术在细胞尺度上定位活动。然而，AO的使用将视野（FOV）限制在等晕角范围内，因此需要拼接多个感兴趣区域以覆盖更大的视野。此外，患有晶状体混浊、眼球运动增加和活动能力下降的受试者对有效的AO操作构成了挑战。在此，我们开发了一种无需AO的粗尺度ORG（CoORG）系统，该系统在一次采集过程中可容纳高达5.5度的视野。该系统基于线扫描光谱域光学相干断层扫描（OCT），体素速率高达32Hz（每秒16,000个B帧）。为了获取ORG，在暗适应和两次不同的刺激漂白后记录了5.5度宽的OCT体数据。根据包裹视锥细胞外段的反射计算刺激诱发的光学相位变化，并在12名健康受试者中评估其随离心率的变化。光程差（ΔOPL）随时间的总体变化趋势与已发表的报告相似。在不同受试者以及不同离心率条件下均观察到了较高的试验间重复性。在两名受试者中，比较CoORG和基于AO-OCT的ORG在离心率为1.5°、2.5°和3.5°时的结果，显示出了极好的一致性。ORG反应的幅度随离心率增加而降低。视网膜上刺激的光子密度和外段长度很好地解释了不同受试者之间以及不同离心率下ORG特征的变化。总体而言，高重复性和在大视野上的快速采集使得能够对健康眼睛的视锥细胞ORG反应进行标准化特征描述，并为将ORG转化为广泛的临床应用提供了一条有前景的途径。
