Abstract
Purpose :
Recent studies have suggested the superior diagnostic ability of swept-source optical coherence tomography (SSOCT), versus spectral-domain OCT (SDOCT), in localizing glaucomatous defects in eyes with low to moderate myopia. Here, we compare SSOCT and SDOCT retinal nerve fiber layer thickness (RNFL) measurements in highly myopic (HM) eyes, to determine if the difference in SSOCT and SDOCT RNFL (diffRNFL) is correlated with axial length (AL).
Methods :
43 eyes from 34 HM patients (AL 28.0±1.6, 24.0 to 31.6mm) were scanned with SSOCT (PLEX Elite) and SDOCT (Cirrus). RNFL was measured and segmented into 4 quadrants and 12 clock-hour segments. Linear regression analysis was performed to evaluate the association between diffRNFL and potential baseline predictor variables (AL, age, gender, laterality, lens status, glaucoma diagnosis [GLC], myopic macular degeneration [MMD] severity, peripapillary atrophy [PPA] severity, disc tilt severity, and presence of intrachoroidal cavitation [ICC]).
Results :
In univariate regression analysis, AL was significantly associated with diffRNFL in the inferior quadrant (β=13.50μm, p<0.001), but not in the overall mean, nasal, superior or temporal quadrants (all p>0.05). After adjusting for potential confounding variables (MMD, tilt, ICC, GLC and PPA), multivariate analysis demonstrated that every 1mm increase in AL was associated with a 9.33μm increase in inferior quadrant diffRNFL (p=0.03). When holding potential confounders (including AL) constant, there was a 12.29μm greater inferior quadrant diffRNFL per unit increase in PPA severity (p=0.046).
In multivariate analysis of SDOCT RNFL values, after adjusting for potential confounders (MMD, tilt, ICC, GLC and PPA), every 1mm increase in AL was associated with a 7.47μm decrease in inferior quadrant RNFL (p=0.001). In contrast, multivariate analysis of SSOCT RNFL, after adjusting for potential confounders (MMD, tilt, ICC, GLC and PPA), showed that inferior quadrant RNFL was not significantly associated with AL (p=0.64).
Conclusions :
The difference in SSOCT and SDOCT measurements of inferior quadrant RNFL was shown to increase with longer AL. Moreover, inferior quadrant RNFL was unaffected by AL on SSOCT, but decreased with longer AL on SDOCT. Taken together, this suggests SSOCT may provide more robust RNFL measurements in HM eyes in which there is suspicion for myopic glaucoma.
This is a 2021 ARVO Annual Meeting abstract.