Role Of Optical Coherence Tomography (OCT) And Optical Coherence Tomography Angiography (OCTA) To Early Chronic Angle-Closure Glaucoma Diagnosis

Objective:Using spectral-domain optical coherence tomography(SD-OCT),optical coherence tomography angiography(OCTA),and Humphrey visual field analyzer,we evaluated the structural changes,vascular perfusion in the peripapillary and macular areas,and visual field defects of patients with early-stage chronic angle-closure glaucoma(CACG),and compared the differences in structural and vascular parameters between the normal control group and early CACG group.By comparing the correlation between OCT parameters,OCTA parameters,and visual field parameters,and comparing the diagnostic efficacy,sensitivity,and specificity of OCT parameters and OCTA parameters in the early CACG group,we aim to evaluate the role of OCT and OCTA in the diagnosis of early-stage chronic angle-closure glaucoma.Methods:This study included 31 patients(40 eyes)diagnosed with CACG who visited our hospital from November 2021 to August 2022 as the experimental group and 24 healthy individuals(40 eyes)as the normal control group.All enrolled subjects underwent routine ophthalmic examinations,including visual acuity examination,slit-lamp examination,gonioscopy,intraocular pressure measurement,axial length measurement,visual field examination,SD-OCT,and OCTA.The OCT parameters included the thickness of each quadrant of the circumpapillary retinal nerve fiber layer(cp RNFL),parafoveal ganglion cell layer-inner plexiform layer complex(para GCL-IPL),and perifoveal ganglion cell layer-inner plexiform layer complex(peri GCL-IPL).The OCTA parameters included the vessel density of each quadrant and the mean circumpapillary vessel density(cp VD),superficial macular vessel density,including whole image vessel density(wi VD),parafoveal vessel density(para VD),and perifoveal vessel density(peri VD).The visual field parameter included the mean deviation(MD).According to the Hodapp-Parrish-Anderson(H-P-A)criteria,CACG eyes with MD<-6d B were included in the early glaucoma group.Finally,the gathered data underwent statistical analysis.Results:1.Comparison of cp RNFL thickness,para GCL-IPL thickness,and peri GCL-IPL thickness: The temporal cp RNFL thickness,overall para GCL-IPL thickness,and overall peri GCL-IPL thicknesses in the early CACG group were significantly thinner than those in the normal control group,and the difference was statistically significant(P < 0.05).2.Comparison of VD in peripapillary and macular areas: The average,temporal and superior cp VD,macular wi VD,overall,and average peri VD in the early CACG group were significantly lower than those in the normal control group,with statistical significance(P<0.05).However,there was no significant difference in all quadrants and average para VD between the two groups(P>0.05).3.Correlation between vascular and structural parameters with visual field defects:There was a positive linear correlation(r > 0.25,P < 0.05)between cp RNFL thickness(inferior and temporal),para GCL-IPL thickness(all quadrants),peri GCL-IPL thickness(superior and temporal),cp VD(average,superior and temporal),wi VD in the macular area,para VD(average and all quadrants),peri VD(average and all quadrants)and visual field MD values.The structure parameter with the strongest correlation(superior para GCL-IPL thickness)was higher than the best vascular parameter(nasal peri VD)(r=0.61>0.56).In the peripapillary region,the correlation between structural parameters and visual field MD values was similar to that of vascular parameters,and both structural and vascular parameters had the highest correlation in the temporal quadrant(r=0.56 and 0.55,respectively).In the parafoveal region,the correlation between structural parameters and visual field MD was better than that of vascular parameters,and both structural and vascular parameters had the highest correlation in superior quadrants(r=0.61 and 0.43,respectively).In the perifoveal region,the correlation between structural parameters and visual field MD was comparable to that of vascular parameters,with the structural parameter having the highest correlation in the temporal quadrant(r= 0.56),while the vascular parameter had the highest correlation in the nasal quadrant(r= 0.56).4.Diagnostic efficacy,sensitivity,and specificity of OCT parameters and OCTA parameters for early CACG: The diagnostic efficacy of each parameter for early CACG varies in different regions and quadrants.Overall,structural parameters had higher diagnostic efficacy than vascular parameters,with the temporal RNFL thickness being the highest(AUC=0.914)among structural parameters,and the macular area wi VD being the highest(AUC=0.787)among vascular parameters.At the maximum Youden index,the sensitivity for temporal RNFL thickness and macular area wi VD were 80.0%and 77.5%,respectively,and the specificity were 90.0% and 70%,respectively.In the peripapillary region,structural parameters showed significantly higher diagnostic performance than vascular parameters,with both structural and vascular parameters being optimal in the temporal quadrant(AUC,sensitivity,and specificity at maximum Youden index were 0.914,80.0%,and 90.0% for structural parameters,and 0.756,92.5%,and 52.5% for vascular parameters,P <0.05).In the parafoveal region,structural parameters showed overall significantly higher diagnostic performance than the corresponding quadrant of vascular parameters(AUC,sensitivity,and specificity at maximum Youden index were 0.758-0.862,77.5%-95.0%,and 60.0%-82.5% for structural parameters,and 0.553-0.623,27.5%-85.0%,and 35.0%-95.0% for vascular parameters,P < 0.05).In the perifoveal region,the diagnostic performance of structural parameters was comparable to that of vascular parameters(AUC,sensitivity,and specificity at maximum Youden index were 0.645-0.823,47.5%-70.0%,and 65.0%-92.5% for structural parameters,and 0.689-0.768,55.0%-92.5%,and 47.5%-87.5% for vascular parameters,P > 0.05).Conclusion:1.The cp RNFL thickness,macular GCL-IPL thickness,cp VD,macular wi VD,and peri VD were all significantly lower in early CACG compared to the normal group,indicating that both OCT and OCTA can play an important role in the early diagnosis of glaucoma.2.The structural parameters measured by OCT and vascular parameters measured by OCTA showed good correlations with visual field MD values.The optimal structural parameter had a stronger correlation with visual field MD values than the optimal vascular parameter.In the parafoveal region,the correlation between structural parameters and visual field MD values was stronger than that of vascular parameters in the corresponding quadrant.The parafoveal GCL-IPL thickness can serve as a good indicator for evaluating early-stage glaucoma.3.OCT measurements of structural parameters and OCTA measurements of vascular parameters demonstrated good diagnostic performance,sensitivity,and specificity in distinguishing early chronic angle-closure glaucoma patients from healthy individuals.The diagnostic performance of structural parameters was superior to that of vascular parameters,with the temporal cp RNFL thickness demonstrating the highest diagnostic efficacy,and significant differences observed within the corresponding quadrants of the parafoveal region.OCT had higher diagnostic value for early chronic angle-closure glaucoma.