Abstract
Purpose: :
To evaluate and compare the optic disc (OD) parameters in normal and glaucomatous eyes using Cirrus OCT and Heidelberg Retinal tomography HRT-III.
Methods: :
Four hundred and thirty eyes (193 normals and 237 glaucomatous) were included. The eyes were classified according to three groups of OD size from HRT-III (small, average and large OD size) and considering OD size quartiles. OD contour lines in HRT-III were placed in the OD margin by an experienced examiner and were reviewed by the first author using the 3-dimensional OD view. Cirrus placed automatically the contour line. OD parameters evaluated were OD area, rim area, cup volumen and vertical cup/OD ratio (C/D). Bland-Altmann limits of agreements (LoA) and coefficient of variation (CV) were used to compare OD parameters.
Results: :
The mean OD area, rim area, cup volumen and C/D were 1.87 mm2, 0.97 mm2, 0.34 mm3, and 0.64 respectively for the Cirrus and 1.92 mm2, 1.14 mm2, 0.21 mm3 and 0.60 respectively for the HRT-III in total eyes. The LoA varied between -0.16 to 0.41 for the cup volumen, and -0.79 to 0.44 for the rim area in total eyes. Lowest CV was 14.9 for the OD area and highest CV was 52.3 for the cup volumen. LoA and CV were similar in normal and glaucomatous eyes. In the small OD size group and the lowest quartile group (0.55 to 1.65 mm2), the agreement between both devices was poor (CV = 104.4 for the cup volumen and 91.2 for the C/D). In average and large OD size groups (and 2nd-4th quartiles), the agreement between Cirrus and HRT was acceptable.
Conclusions: :
OD parameters evaluated were similar in Cirrus and HRT-III in all eyes. The agreement was low in small OD size, especially in C/D ratio. Cirrus does not rely on a manually drawn contour line, avoiding the influence on the results of the operator-dependent contour line placement.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)