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Comparative Evaluation of the Repeatability and Reproducibility of Manual and Novel Automated Measuring DAF and DDAF Lesions in Stargardt Disease.

Presenter:

Mohamed I. Ahmed

Authors:

Mohamed I. Ahmed, Hikmet Yucel, Thales A. Guimarães, Romaisa Kiran, Isabel Sendino, Nam N. Nn, Rubbia Afridi, Sidrah Khan, Mauro Campigotto, Amir Hariri, Quan D. Nguyen, Yasir J. Sepah

1. Ocular Imaging Research and Reading Center (OIRRC), Sunnyvale, CA, United States.

2. Ophthalmology, Stanford University School of Medicine, Palo Alto, CA, United States.

Affiliation:

Purpose:

To evaluate the repeatability and reproducibility of lesion area measurements for decreased autofluorescence (DAF) and definitely decreased autofluorescence (DDAF) lesions in patients with Stargardt disease, comparing manual methods to a Novel automated method. Additionally, to assess the impact of square root transformation on measurement reliability.

Methods:

In study on 100 images from 50 subjects with confirmed Stargardt disease, three masked readers independently measured DAF and DDAF lesion areas twice, with a washout period between readings. The first two readers used manual measurement techniques, while the third employed an automated method. Repeatability and reproducibility were assessed using mean differences, standard deviations (SD), intraclass correlation coefficients (ICC), standard error of measurement (SEM), and minimum detectable change (MDC). Square root transformation of lesion areas was performed to evaluate its effect on measurement indices.

Results:

For DAF measurements, the automated method demonstrated the highest repeatability (ICC = 0.996) with a mean difference of -0.2mm2 (SD = 0.78), SEM of 0.55mm2, and MDC of 1.53mm2. Manual readers had ICCs of 0.988 and 0.985, mean differences of -0.06mm2 (SD = 1.51) and -0.35mm2 (SD = 1.85), SEMs of 1.07mm2 and 1.31mm2, and MDCs of 2.968mm2 and 3.616mm2, respectively. Square root transformation improved ICCs for manual readers to 0.993 and reduced SEM and MDC values.

For DDAF measurements, the automated method achieved an ICC of 0.995, mean difference of -0.19mm2 (SD = 0.56), SEM of 0.39mm2, and MDC of 1.09mm2. Manual readers showed ICCs of 0.974 and 0.923, mean differences of -0.25mm2 (SD = 1.46) and -1.49mm2 (SD = 1.92), SEMs of 1.03mm2 and 1.36mm2, and MDCs of 2.86mm2 and 3.75mm2, respectively. Square root transformation slightly improved ICCs and reduced SEM and MDC for manual readers.

Conclusions:

In patients with Stargardt disease, the automated measurement method exhibited superior repeatability and reproducibility compared to manual methods for both DAF and DDAF lesion area measurements. Square root transformation improved measurement reliability for manual readers by reducing variability and increasing ICCs. Implementing automated

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