Biological and Methodological Variability in Retinal Nerve Fiber Layer OCT: The Framingham Heart Study

Area of Science:

• Ophthalmology
• Biomedical Engineering
• Gerontology

Background:

• Retinal nerve fiber layer (RNFL) thickness is a key indicator of optic nerve health.
• Variability in RNFL thickness measurements can arise from biological factors and technical aspects of optical coherence tomography (OCT) imaging.
• Understanding these factors is crucial for accurate diagnosis and monitoring of eye conditions.

Purpose of the Study:

• To investigate participant-level biological attributes and scan-level methodological attributes influencing RNFL thickness variability.
• To analyze these associations in a population-based sample of elderly United States adults.

Main Methods:

• Cross-sectional analysis of data from the Framingham Heart Study, including 1347 eyes from 825 participants.
• Utilized multivariable linear mixed models to assess associations between RNFL thickness and biological factors (age, gender, race, ethnicity, axial length) and signal strength (SS).
• Assessed methodological variability using the standard deviation (SD) of repeated RNFL scans.

Main Results:

• Older age, male gender, greater axial length, and lower SS were significantly associated with thinner RNFL thickness.
• Race and ethnicity were not significantly associated with RNFL thickness in the general population.
• Higher RNFL thickness and lower SS were associated with greater measurement variability (SD).
• In a subgroup without self-reported glaucoma, African American race was associated with thicker RNFL compared to Whites.

Conclusions:

• RNFL thickness is influenced by age, gender, axial length, and SS.
• Measurement variability is linked to RNFL thickness and SS.
• These biological and methodological variations are important considerations for OCT interpretation in clinical practice.