Abstract
Purpose: :
To compare spectral-domain OCT/SLO and CSLO measurements of six optic disk topographic parameters (disk area, cup area, rim area, cup/disk area ratio, mean cup depth, maximum cup depth).
Methods: :
The study involved 70 eyes of 70 patients, 50 healthy volunteers and 20 primary open-angle glaucoma patients. Inclusion criteria were: spherical and astigmatic defect within 3 dioptres, clear lens, no history of diabetes or neurophthalmological disorders. All subjects underwent complete ophthalmological evaluation and optic nerve head imaging on the same day with spectral-domain OCT/SLO (Spectral OCT/SLO Combo System, Ophthalmic Technologies Inc., Toronto, Canada) and confocal scanning laser ophthalmoscope (Heidelberg Retina Tomograph, HRT II; Heidelberg Engineering GmbH, Dossenheim, Germany). An experienced examiner (FD) drew the contour lines for HRT II, while optic disc margins were automatically defined by Spectral OCT/SLO software-based algorithm. We compared the mean values for the six parameters using the Student t-test. Agreement between Spectral OCT/SLO and HRT II was evaluated by Bland-Altman plots; we also calculated the limits of agreement
Results: :
Spectral OCT/SLO mean values for disk area, cup area and cup/disc area ratio were significantly higher than HRT II, while mean values for mean and maximum cup depth were significantly lower. No significant difference was found for rim area. The difference between spectral OCT/SLO and HRT II disk area estimates was within ± 1.4 mm, and the difference between Spectral OCT/SLO and HRT II C/D ratio estimates was within ± 0.3 in 95% of the patients.
Conclusions: :
Spectral OCT/SLO and HRT II differ significantly when measuring optic disk topographic parameters. The two instruments cannot be used interchangeably.
Keywords: optic disc • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • optic nerve