Gaffney Allannah J, Binns Alison M, Margrain Tom H
School of Optometry and Vision Sciences, Cardiff University, Cardiff, UK.
Optom Vis Sci. 2011 Sep;88(9):1080-7. doi: 10.1097/OPX.0b013e3182223697.
Despite widespread agreement that dark adaptation is abnormal in age-related maculopathy (ARM), the optimal retinal location for detection of this deficit is unclear. We quantified the diagnostic potential of cone dark adaptation as a function of retinal eccentricity and compared this with the diagnostic potential of the time to the rod-cone-break (RCB).
Cone dark adaptation was monitored after an 80% cone photopigment bleach in 10 subjects with ARM and 10 age-matched controls, using four achromatic annuli (0.5, 2, 7, and 12° radius) centered on the fovea. Threshold recovery data were modeled and the time constant of cone recovery (τ), final cone threshold, and time to RCB were determined. Diagnostic potential was evaluated by constructing receiver operating characteristic curves for these parameters.
Cone τ was significantly longer for the ARM group at 2, 7, and 12°. The greatest difference between groups was observed at 12° from fixation. At this location, the mean τ was 3.49 (±2.02) min and 0.64 (±0.38) min for ARM and control subjects, respectively (p = 0.002), and time to RCB was 17.68 (±5.37) min and 9.05 (±2.11) min for ARM and control subjects, respectively (p = 0.001). Correspondingly, receiver operating characteristic curves showed that the diagnostic potential of dark adaptometry is greatest for stimuli presented 12° from fixation; for cone τ, the area under the curve = 0.99 ± 0.02 and for time to RCB, area under the curve = 0.96 ± 0.04.
This study has shown cone-mediated dark adaptation to be significantly impaired in ARM. Our results provide compelling evidence in support of the diagnostic potential of cone dark adaptation and the use of annular stimuli at 12°. The observation that cone τ is highly diagnostic at this eccentricity is significant clinically because this parameter may be quantified within a few minutes.
尽管人们普遍认为年龄相关性黄斑病变（ARM）患者的暗适应异常，但检测这种缺陷的最佳视网膜位置尚不清楚。我们量化了视锥细胞暗适应作为视网膜离心率函数的诊断潜力，并将其与视杆-视锥细胞转折点（RCB）时间的诊断潜力进行比较。
对10例ARM患者和10例年龄匹配的对照者进行80%视锥细胞光色素漂白后，使用以中央凹为中心的四个消色差环（半径分别为0.5、2、7和12°）监测视锥细胞暗适应。对视锥细胞阈值恢复数据进行建模，并确定视锥细胞恢复的时间常数（τ）、最终视锥细胞阈值和RCB时间。通过构建这些参数的受试者工作特征曲线来评估诊断潜力。
在2°、7°和12°处，ARM组的视锥细胞τ显著延长。两组之间最大的差异出现在距注视点12°处。在此位置，ARM组和对照组受试者的平均τ分别为3.49（±2.02）分钟和0.64（±0.38）分钟（p = 0.002），ARM组和对照组受试者的RCB时间分别为17.68（±5.37）分钟和9.05（±2.11）分钟（p = 0.001）。相应地，受试者工作特征曲线表明，暗适应测量对视距注视点12°处呈现的刺激的诊断潜力最大；对视锥细胞τ而言，曲线下面积 = 0.99 ± 0.02，对RCB时间而言，曲线下面积 = 0.96 ± 0.04。
本研究表明ARM患者视锥细胞介导的暗适应明显受损。我们的结果提供了令人信服的证据，支持视锥细胞暗适应的诊断潜力以及使用12°环形刺激。视锥细胞τ在此离心率下具有高度诊断价值这一观察结果在临床上具有重要意义，因为该参数可在几分钟内进行量化。
