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Takumi Hara, Tatsuya Inoue, Marie Kitano, Han Peng Zhou, So Makino, Ryo Obata; Quantification of residual ellipsoid zone in patients with cone-rod dystrophy. Invest. Ophthalmol. Vis. Sci. 2019;60(9):5034.
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© ARVO (1962-2015); The Authors (2016-present)
Cone-rod dystrophy (CRD) is a retinal inherited disorder that results in central vision loss and decreased visual acuity. To evaluate the status of cone photoreceptors in CRD, visual acuity(VA) measurement, visual field tests, electroretinogram and optical coherence tomography (OCT) are usually performed. Recently, we identified the quantification method of residual ellipsoid zone (rEZ) in resolved central serous chorioretinopathy. The aim of our current study is to quantify the index of rEZ and to investigate the correlation between OCT parameters and visual functions in patients with CRD.
We examined 20 eyes of 10 patients (7 males and 3 females). All the eyes were diagnosed as CRD and tested with the Humphrey Visual Field Analyzer (HFA 10-2 program; Carl Zeiss Meditec, USA). We obtained spectral domain OCT (SD-OCT) images using the Spectralis OCT (Heidelberg Engineering, Heidelberg, Germany). For each eye, the area of decreased EZ intensity was identified (EZa). OCT images were then converted into binary images using the Niblack method. With the binarized images, the percentage of the residual EZ for each eye (3x3-mm area at the macula) was analyzed (rEZ). The rEZ index for each eye was measured by two investigators and intraclass correlation coefficient (ICC) was calculated to clarify interrator reproducibility. Central retinal thickness (CRT), and central choroidal thickness (CCT) were also measured. The correlation between OCT parameters and visual functions was investigated.
The mean age of the patients was 51.2±18.1 years and the mean logMAR VA was 0.51±0.52. The mean MD value was -17.8±12.7 dB. The mean CRT and CCT were 131.8±59.7μm and 245.3±72.9μm, respectively. The mean EZa and rEZ were 22.4±24.0μm2 and 42.4±30.7%, respectively. The ICC of each rEZ index was 0.924 (95% confidence interval: 0.82<ICC<0.969). Univariate analysis suggested that among OCT parameters, rEZ and EZa had a significant correlation with MD value (p=0.003, p=0.0003, linear mixed model). On the other hand, no OCT parameters showed significant associations with logMAR VA. Multivariate analysis indicated rEZ, EZa and CRT were significantly associated with MD value (AICc=127.6, p=0.04, p=0.001, p=0.07, respectively). Similarly, only rEZ was closely related to logMAR VA, using AICc model selection (AICc=30.3, p=0.08).
In CRD patients, rEZ index may be a useful parameter predicting for visual functions.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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