Abstract:

Objective To investigate if there are any differences and consistency of the glaucoma diagnostic parameters measured by FD-OCT and HRT-III in myopia. Design Prospective comparative case series. Participants 131 myopia patients and 82 emmetropia subjects recruited in Beijing from Oct 2012 to Mar 2013 were included. Methods All the subjects underwent FD-OCT(ONH module) and HRT-III(glaucoma module) in addition to routine ocular examination, refraction and axial length measurement. One eye of each subject was selected for this study by randomization. Myopia subjects were assigned into three groups according to their refractive power: low (≤-3.00 D), moderate (-3.00D to-6.00 D) and high(>-6.00 D). The difference between myopia groups and emmetropia control group regarding glaucoma diagnostic parameters of FD-OCT and HRT-III were analyzed with one-way ANOVA, LSD, and rank sum test respectively. Pearson correlation analysis was performed to investigate the association between those diagnostic parameters and refractive powers as well as axial length. Main Outcome Measures RNFL thickness parameters and optic disc parameters. Results (1)RNFL thickness analyses：The difference in mean RNFL(mRNFL) thickness between myopia and emmetropia group was significant (P＜0.05 with FD-OCT measurement (in moderate and high groups) and HRT-III measurements (in low and moderate groups). However, the mRNFL thickness measured by FD-OCT was thinner than that measured with HRT-III. For quadrants parameters, most of the 16 sectors values of FD-OCT were thinner in myopia group (P＜0.01 or P<0.05 ), especially in the moderate and high groups. On the contrary, for the 6 sectors of HRT-III, the RNFL was thicker in moderate myopia group than that of control group(P＜0.01 or P<0.05 ), while the high and low myopia groups showed no difference compared with emmetropia group. (2) Optic disc parameters: the disc area and rim area of myopia group obtained from both FD-OCT and HRT-III were found to be statistically less than those of the emmetropia group（P<0.01）whereas no significant difference of other disc parameters  (P＞0.05) was found. (3) Negative correlations were found in OCT between mRNFL thickness, RNFL thickness in some quadrants, rim area, rim volume and refractive power, axial length（P<0.01）, whereas no significant correlation was found in regard to HRT RNFL thickness with refractive power and axial length（P>0.05）. Conclusions The glaucoma diagnostic parameters of myopia patients showed difference and consistency between FD-OCT and HRT-III. RNFL related parameters  were thinner in myopia group comparared to that of emmetropia group measured by FD-OCT, but vise versa by HRT-III. With regard to parameters of optic disc measured by FD-OCT and HRT-III in myopia group, the disc area and rim area were both smaller comparared to emmetripia group. This would make early diagnosis of primary open-angle glaucoma with myopia more challenging. (Ophthalmol CHN, 2017, 26: 317-322)

Key words:  myopia, Optical Coherence Tomography, Heidelberg Retina Tomography, retinal nerve fiber layer thickness, optic disc