Abstract
Purpose :
Diagnosis of glaucoma is challenging in highly myopic eyes because high myopia itself shares some similarity with glaucoma, including peripapillary retinal nerve fiber layer (RNFL) thinning, optic disc tilting and non-progressive visual field defect. We performed a cross-sectional study to evaluate the GCIPL thickness in nonglaucomatous eyes with high myopia, and to determine its glaucoma diagnostic ability in highly myopic eyes.
Methods :
A total of 211 highly myopic eyes, 103 eyes with low to moderate myopia, and 225 emmetropic normal eyes (age-matched, F=2.526, P=0.089) were enrolled. The GCIPL thickness, RNFL thickness (average and RNFL thickness of 12 clocks) and optic nerve head parameters were measured using Cirrus high-definition optical coherence tomography. The GCIPL thickness of highly myopic eyes was compared with normal eyes. Correlation between GCIPL thickness and spherical equivalent refractive error was studied in myopic eyes. Glaucoma diagnostic ability of OCT parameters was accessed by the areas under the curves (AUROC) in another 35 highly myopic eyes with glaucoma and 40 age and refraction-matched highly myopic eyes.
Results :
The average, minimum, superotemporal, superior, superonasal, inferonasal, inferior, and inferotemporal GCIPL thickness of 211 highly myopic eyes was approximately 93.04%, 92.84%, 94.38%, 92.59%, 92.55%, 92.95 %, 92.12% and 93.47% of thickness in corresponding positions of normal eyes, which was significantly thinner (t=-9.626 to -6.269, all P<0.001). Significant positive correlation was found between GCIPL thickness and refraction in nonglaucomatous myopic eyes (r=0.286-0.466, all P<0.001). All AUROC of GCIPL parameters were greater than 0.75. The minimum GCIPL thickness, average RNFL thickness, and vertical C/D were parameters with highest diagnosic ability, whose AUROC was 0.909, 0.956 and 0.915, respectively. The latter two parameters showed no significant difference in diagnosic ability with minimum GCIPL thickness (Z=-1.140, P=0.254; Z=-0.137, P=0.891).
Conclusions :
The GCIPL thickness in highly myopic eyes was thinner than that of normal eyes. Significant positive correlation was found between GCIPL thickness and refraction in nonglaucomatous myopic eyes. The minimum GCIPL thickness, average RNFL thickness and vertical C/D were OCT parameters with highest glaucoma diagnosic ability in highly myopic eyes.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.