Application of optical coherence tomography measuring RNFL thickness in the early diagnosis of primary angle-closure glaucoma

AIM: To investigate the application of optical coherence tomography(OCT)measurement of retinal nerve fiber layer(RNFL)thickness in early diagnosis of primary angle closure glaucoma(PACG). <p>METHODS:Totally 100 patients(174 eyes)with PACG treated in our hospital from April 2015 to April 2017 were selected and divided the into early stage group(30 cases, 50 eyes), mild stage group(45 cases, 78 eyes)and late stage group(25 cases, 46 eyes)according the degree of the visual field defect. At the same time, 30 patients(60 eyes)with matched age and sex were included into control group and received routine examination. The OCT was used to check the average RNFL thickness, and the visual field was examined by automatic vision method. The correlation between RNFL thickness and mean defect(MD)was analyzed, then the thickness of RNFL in the superior, inferior, nasal and temporal quadrants of each group were measured. <p>RESULTS: The difference of mean RNFL thickness between the four groups was statistically significant, the RNFL thickness in control group was significantly higher than that of the PACG group, and the early stage group was significantly higher than the mild stage group and the late stage group, while the mild stage group was significantly higher than the late stage group, the difference was statistically significant(<i>P</i><0.05). The difference of visual field MD between the four groups was statistically significant, the visual field MD in control group was significantly lower than that of the PACG group, and the early group was significantly lower than the mild stage group and the late stage group, while the mild stage group was significantly lower than the late stage group, the difference was statistically significant(<i>P</i><0.05). The thickness of RNFL in the early stage group, the mild stage group and the late stage group was negatively correlated with visual field MD(<i>r</i>=-0.546, <i>r</i>=-0.654, <i>r</i>=-0.864, <i>P</i><0.05). There was no correlation between the RNFL thickness and the visual field MD in the control group(<i>r</i>=-0.075, <i>P</i>=0.321). The thickness of RNFL in the superior and inferior part of PACG group was lower than that of the control group, and the difference was statistically significant(<i>P</i><0.05). The thickness of the nasal and temporal RNFL in the mild stage group and the late stage group was significantly lower than that in the control group(<i>P</i><0.05). There was no significant difference in the nasal and temporal RNFL between the early stage group and the control group(<i>P</i>>0.05). <p>CONCLUSION: RNFL of PACG patients is gradually thinning with the exacerbations; RNFL is negatively correlated with visual field MD, and RNFL is able to objectively reflect the degree of PACG optic nerve damage. The detection of the superior and inferior RNFL thickness had a certain value in the early diagnosis of PACG