Purpose

To estimate the number of OCT scans necessary to detect moderate and rapid rates of retinal nerve fiber layer (RNFL) thickness worsening at different levels of accuracy using a large sample of glaucoma and glaucoma-suspect eyes.

Design

Descriptive and simulation study.

Participants

Twelve thousand one hundred fifty eyes from 7392 adult patients with glaucoma or glaucoma-suspect status followed up at the Wilmer Eye Institute from 2013 through 2021. All eyes had at least 5 measurements of RNFL thickness on the Cirrus OCT (Carl Zeiss Meditec) with signal strength of 6 or more.

Methods

Rates of RNFL worsening for average RNFL thickness and for the 4 quadrants were measured using linear regression. Simulations were used to estimate the accuracy of detecting worsening—defined as the percentage of patients in whom the true rate of RNFL worsening was at or less than different criterion rates of worsening when the OCT-measured rate was also at or less than these criterion rates—for two different measurement strategies: evenly spaced (equal time intervals between measurements) and clustered (approximately half the measurements at each end point of the period).

Main Outcome Measures

The 75th percentile (moderate) and 90th percentile (rapid) rates of RNFL worsening for average RNFL thickness and the accuracy of diagnosing worsening at these moderate and rapid rates.

Results

The 75th and 90th percentile rates of worsening for average RNFL thickness were –1.09 μm/year and –2.35 μm/year, respectively. Simulations showed that, for the average measurement frequency in our sample of approximately 3 OCT scans over a 2-year period, moderate and rapid RNFL worsening were diagnosed accurately only 47% and 40% of the time, respectively. Estimates for the number of OCT scans needed to achieve a range of accuracy levels are provided. For example, 60% accuracy requires 7 measurements to detect both moderate and rapid worsening within a 2-year period if the more efficient clustered measurement strategy is used.

Conclusions

To diagnose RNFL worsening more accurately, the number of OCT scans must be increased compared with current clinical practice. A clustered measurement strategy reduces the number of scans required compared with evenly spacing measurements.

中文翻译：

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检测青光眼恶化所需的视乳头周围 OCT 扫描次数的循证指南

 目的

使用大量青光眼和青光眼疑似眼样本，估计以不同准确度水平检测视网膜神经纤维层 (RNFL) 厚度中度和快速恶化所需的 OCT 扫描次数。

 设计

描述性和模拟研究。

 参加者

2013 年至 2021 年，威尔默眼科研究所对 7392 名患有青光眼或疑似青光眼的成年患者的 12,155 只眼睛进行了随访。所有眼睛在 Cirrus OCT (Carl Zeiss Meditec) 上至少进行了 5 次 RNFL 厚度测量，并带有信号强度6以上。

 方法

使用线性回归测量平均 RNFL 厚度和 4 个象限的 RNFL 恶化率。使用模拟来估计检测恶化的准确性，定义为当 OCT 测量的恶化率也等于或小于这些标准恶化率时，RNFL 恶化的真实率等于或小于不同标准恶化率的患者百分比- 对于两种不同的测量策略：均匀间隔（测量之间的时间间隔相等）和集群（周期每个端点的测量值大约一半）。

 主要观察指标

平均 RNFL 厚度的 RNFL 恶化的第 75 个百分位（中度）和第 90 个百分位（快速）率以及在这些中度和快速速率下诊断恶化的准确性。

 结果

平均 RNFL 厚度恶化的第 75 个百分位数和第 90 个百分位数分别为 –1.09 μm/年和 –2.35 μm/年。模拟显示，对于我们样本中 2 年期间约 3 次 OCT 扫描的平均测量频率，中度和快速 RNFL 恶化的准确诊断率分别仅为 47% 和 40%。提供了达到一系列准确度水平所需的 OCT 扫描数量的估计值。例如，如果使用更有效的集群测量策略，60% 的准确度需要 7 次测量才能检测 2 年内的中度和快速恶化。

 结论

为了更准确地诊断 RNFL 恶化，与目前的临床实践相比，必须增加 OCT 扫描的数量。与均匀间隔测量相比，集群测量策略减少了所需的扫描次数。