The Topographic Profile Of The ONH And Macular And Their Related Analysis Among Young Myopic Patients

Part one: Spectral-and time-domain optical coherence tomographymeasurements of nerve fiber layer thickness in young myopic patientsPurpose：To evaluate the topographic profile and influential factors of peripapillary retinalnerve fiber layer（RNFL） thickness （RNFL） in the young myopia before the refractivesurgery.Methods:95eyes of95consecutive refractive surgery candidates were included in thisstudy, The mean age of the subjects was23.47（SD3.56） years old, the average sphericalequivalent （SE） was-6.18（SD3.28） D with a range of-0.75D to-11D, of47eyes werelow–moderate myopia with the mean SE was-3.85（SD1.61） D,48eyes were high myopiawith the mean SE was-8.19（SD1.39）D. All subjects underwent ophthalmic examinationand the imaging with the time-domain optical coherence tomography （Stratus TD OCT）and spectral-domain optical coherence tomography （Cirrus HD OCT）.Results: The RNFL thickness were measured by Cirrus HD OCT and Stratus TD OCT ofthe global were99.01（SD7.75）μm and91.03（SD7.82）μm, the superior quadrant were122.17（SD13.73）μm and107.38（SD11.76）μm, the nasal quadrant were64.79（SD9.90）μmand55.75（SD9.05）μm, the inferior quadrant were124.82（SD15.51）μm and109.10（SD14.92）μm, the temporal quadrant were84.66（SD12.96）μm and92.38（SD15.61）μm,respectively. The correlation coefficient between the RNFL thickness of the global, thesuperior, the nasal, the inferior, the temporal and axial length were r₁=-0.442（P=0.000）、r₂=-0.252（P=0.014）, r₁=-0.442（P=0.000）、r₂=-1.372（P=0.032）, r₁=-0.431（P=0.000）、r₂=-0.180（P=0.022）, r₁=-0.521（P=0.002）、r₂=0.317（P=0.002）, r₁=0.314（P=0.002）、 r₂=0.159（P=0.045）, respectively.Conclusion: The topographic profile of peripapillary RNFL thickness was the inferiorquadrant> the superior quadrant> the temporal quadrant> the nasal quadrant in theseyoung myopia. The RNFL thickness of the global and nasal quadrant decreased with theaxial length, also in the superior quadrant and the inferior quadrant, while the RNFLthickness of the temporal quadrant was increased. Part two: Spectral-and time-domain optical coherence tomographymeasurements of macular thickness in young myopic eyesPurpose: To evaluate the variation in macular retinal thickness and volume in youngChinese myopic subjects by using time-domain optical coherence tomography （Stratus TDOCT） and spectral-domain optical coherence tomography （Cirrus HD OCT）.Methods:92eyes of92myopic subjects were recruited in this study, the mean age of thesubjects was22.89（SD3.27） years old, the average spherical equivalent （SE） was-5.64（SD2.66）D with a range of-0.38D to-11.00D. According to spherical equivalent （SE）the subjects were divided into two groups: low to moderate myopia group （-0.5D≤SE<-6.0D）, high myopia group （SE≥-6.0D）.44eyes were the low to moderate myopia with amean SE was-3.34D （SD1.28D）,48eyes were the high myopia with an average SE of-7.75D （SD1.65D）. Macular retinal thickness and volume were measured by Stratus TDOCT and Cirrus HD OCT compared between the two groups. Using the Bland–Altmanmethod and Pearson correlation to measure agreement between two OCT systems.Results: The average macular retinal thickness and macular volume were measured byCirrus HD OCT and Stratus TD OCT of low to moderate myopia group were283.52（SD12.14） μm and245.38（SD8.55） μm,10.08（SD0.37） mm³and6.85（SD0.26） mm³, ofhigh myopia group were269.58（SD10.72） μm and235.65（SD7.54） μm,9.71（SD0.36）mm³and6.52（SD0.25） mm³, respectively. The measurements of two OCTs showed macular retinal thickness of the parafovea were significantly lower in the high myopiagroup compared with the low-to moderate myopia group except at the fovea（All P value<0.001except at the fovea）. The measurements of macular thickness in nine macularretinal subfields and macular volume had shown a good agreement between the two OCTsin myopic eyes in all macular subfields by the Bland–Altman method and Pearsoncorrelation （All P value <0.001）, with better agreement in low to moderate myopia groupthan in high myopia group.Conclusion: Average the macula retinal thickness of the fovea does not vary with myopia,while the volume and the retinal thickness of parafovea was thinner with myopia. A goodagreement between the two OCTs in myopic eyes in all macular subfields, and the CirrusHD OCT system provided thicker macula retinal thickness measurements than the StratusOCT system. Part three: The influence of corneal astigmatism on ONH parametersand retinal nerve fibre layer thickness measurement in people with highmyopiaPurpose: To evaluate the effect of corneal astigmatism on peripapillary retinal nerve fiberlayer （RNFL） thickness and ONH parameters measurement in high myopia patients beforethe refractive surgery.Methods：70eyes of35consecutive refractive surgery candidates were included in thisstudy, All the people were18～39years old. The spherical equivalent refraction were-6.00～-15.00D. The corneal astigmatism was-0.20～-3.30D, total astighmatism were0.00～-2.500D. All subjects underwent ophthalmic examination and the imaging with theCirrus HD OCT.Results：the disc area, Rim area, vertical cup-to-disk ratio, average cup-to-disk ratio andCup volume of the high myopia with low astigmatism group and the high myopia with high astigmatism group were1.70（SD0.32） mm²and1.95（SD0.58） mm²,1.25（SD0.30）mm²and1.44（SD0.34） mm²,0.44（SD0.13） and0.41（SD0.18）,0.48（SD0.13） and0.44（SD0.16）,0.096（SD0.09） mm³and0.097（SD0.10） mm³. No significant difference wasnoted in average cup-to-disk ratio, vertical cup-to-disk ratio and Cup volume （All Pvalues>0.05） between two groups. Campared with the low astigmatism group, the highastigmatism group had more larger disc area and Rim area, thinner RNFL thickness in thetemporal quadrant, The superotemporal and inferotemporal peaks were farther to thetemporal horizon（All P value <0.05）. There were no significant difference between twogroups for the RNFL thinkness of the global average, superior, nasal and inferior quadrants（All P values>0.05）.Conclusion：The high myopia with high astigmatism group had more larger disc area andrim area, thinner RNFL in the temporal quadrant, The superotemporal and inferotemporalpeaks were farther to the temporal horizon in the high astigmatism group, so the degree ofcorneal astigmatism should be considered when interpreting the ONH parameters andRNFL thickness measured by the Cirrus HD OCT.