| Objective: Based on optical coherence tomography angiography(OCTA)to assess vessel density(VD)and retinal nerve fiber layer(RNFL)thickness in healthy people and people with varying degrees of myopia,and the association with axis length(AL),we analyzed the variation of VD morphology and VD structure and possible mechanisms of change.Methods: Prospective case-control studies were used.Volunteers were recruited from May 2020 to January 2021 at the Ophthalmology Clinic of the First Affiliated Hospital of Anhui University of Science and Technology.A total of 51 people met the final criteria,including 17 healthy people,17 people with low and moderate myopia and 17 people with high myopia,for a total of 102 eyes.Eight eyes were excluded due to OCTA angiography quality < 6 or poor angiography,resulting in the inclusion of 94eyes(31 emmetropia,32 low and medium myopia,and 31 high myopia).OCTA scanned the optic disc with a range of 4.5×4.5 mm,and internal algorithms automatically quantified parameters related to optic disc morphology and vessel density and retinal nerve fiber layers thickness in different areas.AL measured by IOL master.Kruskal-Wallis H test to compare the differences between three groups.Using the Bonfenoni method evaluates the differences between the two groups.Results: Among three groups,age,gender and intraocular pressure were no significant difference(P>0.05).There was a statistically significant difference between groups with horizontal diameter,vertical diameter,visual disc area,and DTA degree(P<0.05),while there was no significant difference between groups with cup disc area ratio(P>0.05).Comparisons between groups showed that the horizontal diameter and disc area were higher in the HM group than in the EM group(P<0.01),while the vertical diameter and DTA was lower in the EM and L-MM group than the HM group(P<0.01).For RNFL thickness,under the ETDRS partition,RNFL thickness of each quadrants of the three groups both have statistically significant differences(P<0.05).The comparison between the two groups showed that the RNFL thickness of HM were significantly lower than EM and L-MM in the nasal,inferior and superior quadrant(P<0.05),while the temporal quadrant showed is thickening(P<0.05).In the Garway Heath,RNFL thickness of the three groups was statistically significant only in the TS,NS,NI and IN quadrants(P<0.05),RNFL thickness in the residual quadrant showed no significant difference between groups(P>0.05).Pairwise comparison showed that RNFL thickness in NS,NI and IN quadrant of HM group was lower than that EM and L-MM group(P<0.01).The RNFL thickness of TS quadrant in EM group was lower than that in HM group(P<0.01).In terms of blood perfusion in optic disc area,there were statistically significant differences among the three groups of the peripapillary VD,inside disc VD,NS,NI and IN quadrant VD(P<0.05).Further pwise comparison showed that NS and NI quadrant VD in EM and L-MM groups were higher than those in HM group(P<0.01).In peripapillary and IN quadrant VD,HM group was lower than that EM group(P<0.01).The inside disc VD in HM groups were higher than EM and L-MM group(P<0.01).The correlation analysis between VD and AL showed that there was a negative correlation between the vessel density and the axial length in the inferior nasal quadrant,the nasal superior quadrant and the nasal inferior quadrant,and the difference was statistically significant(r=-0.316,-0.304,-0.361,-0.241;P<0.05).There was a positive correlation between intradiscal VD and AL(r=0.376,P<0.05).There was no significant correlation between vessel density and axial length in the superior nasal quadrant,superior temporal quadrant,temporal superior quadrant,inferior temporal quadrant,and temporal inferior quadrant(P>0.05).The correlation analysis between RNFL thickness and AL showed that: in the ETDRS classification criteria,the temporal RNFL thickness was positively correlated with AL(r=0.343,P<0.05),and the RNFL thickness in the superior,inferior and nasal quadrants was negatively correlated with AL(r=-0.341,-0.289,-0.269;P<0.05).In the Garway Heath division method,only the RNFL thickness in the temporal superior quadrant was positively correlated with AL(r=0.382,P<0.05),and the RNFL thickness of the nasal superior quadrant,nasal inferior quadrant and inferior nasal quadrant were negatively correlated with AL(r=-0.226,-0.242,-0.369;P<0.05).There was no correlation between RNFL thickness and AL in the superior temporal quadrant,inferior temporal quadrant,superior nasal quadrant and temporal inferior quadrant(P>0.05).Conclusion:The changes of optic disc shape,VD and RNFL thickness of optic disc are closely related to AL.Among the morphologic parameters,the changes of optic disc area and DTA were most significant in HM group.In the tissue structure,the RNFL thickness of NS,NI and IN quadrants was the thinnest and VD was the sparsest in HM.Interestingly,overall VD increased with the increase of AL,while the VD around disk decreased with the increase of AL.Figure 11 Table 7 Reference 37... |
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