June 2023
Volume 64, Issue 8
Open Access
ARVO Annual Meeting Abstract  |   June 2023
Relative Importance of Confounders Affecting the Variability of Glaucoma Diagnostic Parameters Measured by OCT
Author Affiliations & Notes
  • Ou Tan
    Oregon Health & Science University Casey Eye Institute, Portland, Oregon, United States
  • Dongseok Choi
    Oregon Health & Science University Casey Eye Institute, Portland, Oregon, United States
  • Aiyin Chen
    Oregon Health & Science University Casey Eye Institute, Portland, Oregon, United States
  • david Greenfield
    University of Miami Health System Bascom Palmer Eye Institute, Miami, Florida, United States
  • Brian Francis
    Doheny Eye Institute, Los Angeles, California, United States
  • Rohit Varma
    4Southern California Eyecare and Vision Research Institute, Los Angeles, California, United States
  • Joel S Schuman
    Ophthalmology, NYU Langone Health, New York, New York, United States
  • David Huang
    Oregon Health & Science University Casey Eye Institute, Portland, Oregon, United States
  • Footnotes
    Commercial Relationships   Ou Tan Visionix/Optovue, Code P (Patent), Visionix/Optovue, Code R (Recipient); Dongseok Choi None; Aiyin Chen None; david Greenfield None; Brian Francis None; Rohit Varma None; Joel Schuman None; David Huang Boeringer Ingelheim, Code C (Consultant/Contractor), Visionix/Optovue, Code F (Financial Support), Visionix/Optovue, Code P (Patent), Visionix/Optovue, Code R (Recipient)
  • Footnotes
    Support  Supported by grant grants R01EY023285, R21 EY032146, P30 EY010572 from the National Institutes of Health (Bethesda, MD), and by unrestricted departmental funding from Research to Prevent Blindness (New York, NY)
Investigative Ophthalmology & Visual Science June 2023, Vol.64, 2033. doi:
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      Ou Tan, Dongseok Choi, Aiyin Chen, david Greenfield, Brian Francis, Rohit Varma, Joel S Schuman, David Huang; Relative Importance of Confounders Affecting the Variability of Glaucoma Diagnostic Parameters Measured by OCT. Invest. Ophthalmol. Vis. Sci. 2023;64(8):2033.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : To evaluate the significance of factors that may confound glaucoma diagnosis using structural OCT parameters such as retinal nerve fiber layer (RNFL) and ganglion cell complex (GCC) thickness measurements.

Methods : This study analyzed the peripapillary RNFL thickness and macular GCC thickness of healthy participants in the Advanced Imaging for Glaucoma study. In this longitudinal study, Healthy eyes were scanned with spectral domain OCT every year. OCT Data were selected between 2009 and 2013. Confounding factors, including age, gender, race, axial length, and disc area, were evaluated. The disc area was obtained from OCT and corrected for magnification. A linear mixed model followed by ANOVA was used to get the relative variance (partial R2 ) explained by each factor, suggesting its contribution to the variance. In calculation of the contribution percentage of factors, variance due to repeated measurements was exclude from the total variance. To test the significance of magnification adjustment, we compared two models: 1) the full model with all confounding factors, and 2) the reduced model without axial length and disc area.

Results : 210 eyes from 106 Healthy participants were analyzed. The participants had an average of 3 visits. The average age was 61.3±9.7 years; 66% were female; 86.8% were white, 5.7% were black, and 7.5% were Asian. The average RNFL thickness was 99.2±8.2 µm; the average GCC thickness was 95.4±6.8 µm. In the reduced models, age contributed to most of the variance among confounding factors (Table 1). In the full model, axial length contributedto most of the variance. We also noticed that the contribution of age was reduced in the full model. Disc area and race had small borderline contributions to RNFL thickness. Subgroup analysis showed that Asians had significantly thicker RNFL thickness than white (p=0.032). The contribution of gender was negligible.

Conclusions : Axial length variation affects the transverse image magnification and is by far the largest source of measurement bias in glaucoma diagnostic parameters measured by OCT. Age and Asian race are two significant demongraphic confounders, but of less importance than axial length variation. Accounting for axial length or other axial refractive error variables could greatly improve the diagnostic accuracy of OCT measurements.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.

 

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