1. P-WT-294
Comparison of red-free photography, swept-source OCT and spectral-domain OCT for evaluation of retinal nerve fiber layer defects.
Gilda WK Lai, Christopher KS Leung
Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong
Purpose:
To compare the performance of red-free retinal fiber layer (RNFL) photography, swept-source optical coherence tomography (SS- OCT), and spectral-domain optical coherence tomography (SD- OCT) for detection of RNFL defects in glaucoma.
Table 1. Number of eyes with RNFL defects detected by different devices.
Eyes with glaucomatous VF defects
RNFL defects detected by SS-OCT
RNFL defects detected by SD-OCT
RNFL defects detected by Red-free RNFL photography
58 (100%)
57 eyes (98.3%)
51 eyes (91.3%)
23 eyes (39.7%)
Methods:
Fifty-eight eyes from 44 glaucoma patients with mild visual field defects (visual field mean deviation (MD) >-8dB) were randomly selected from a glaucoma clinic for red-free RNFL photography (Topcon TRC-50DX)(50-degree field), SS-OCT (Triton OCT, Topcon, Tokyo, Japan) (12x9mm cube scan covering the macula and the optic disc) and SD-OCT (Cirrus HD, Carl Zeiss Meditec, Dublin, CA) (6x6mm cube scan of the optic disc region) RNFL imaging (Figure1).
14 eyes with clear boundaries of RNFL defects in red-free RNFL photographs were selected for measurement of area of RNFL defects in the red-free RNFL photographs and the SS-OCT/SDOCT RNFL thickness maps. The span of 95% limits of agreement of the area of RNFL defects between red-free RNFL photograph and SS-OCT RNFL thickness map was smaller (1.49mm2) than that between red-free RNFL photograph and SD-OCT RNFL thickness map (3.93mm2) (Figure 2).
Figure 2. Bland Altman Plots showing the agreement of the area of RNFL defects measured between red-free photographs and SS-OCT/SD OCT RNFL thickness map.
Figure 1. Defects detected by (A) red-free RNFL photography, (B) SS-OCT thickness map and (C) SD-OCT thickness map. A B C
Average of Red-free photography and SS-OCT (RNFL defect area)
Difference between Red-free photograph and SS-OCT (RNFL defect area)
Difference between Red-free photograph and SD-OCT (RNFL defect area)
Average of Red-free photography and SD-OCT (RNFL defect area)
Eyes with clear boundaries of RNFL defects detected in red-free RNFL photographs were selected for measurement of the area of RNFL defects. Corresponding retinal regions were outlined and registered for measurement of RNFL defects in the RNFL thickness map obtained from the SS-OCT and SD-OCT. Ratio of pixel to millimeter of each RNFL thickness map was calculated by MATLAB software. The agreement of the area of RNFL defects between red-free RNFL photographs and SS-OCT/SD-OCT RNFL thickness map was evaluated with Bland Altman plots.
Conclusions:
While both SS-OCT and SD-OCT were able to detect RNFL defects missed by red-free RNFL photographs, SS-OCT showed a better agreement with red-free photography for measurement of the area of RNFL defects.
Financial disclosure: None
Results:
The mean age and visual field MD were 52.9 ± 13.6 years and ± 2.04 dB, respectively. Among the 58 eyes with glaucomatous VF defects, SS-OCT (57 eyes, 98.3%) and SD-OCT (51 eyes, 91.3%) detected significantly more eyes with RNFL defects than red-free RNFL photography (23 eyes, 39.7%, p<0.001) (Table1).
Correspondence: Gilda Lai
Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong
Hong Kong Eye Hospital, 147K Argyle Street, Kowloon, Hong Kong