Backgroud:To evaluate the symmetry of corneal biomechanical metrics,measured using an ocular response analyzer(ORA)and self-built corneal inflation test platform,in bilateral rabbit corneas and to investigate their re...Backgroud:To evaluate the symmetry of corneal biomechanical metrics,measured using an ocular response analyzer(ORA)and self-built corneal inflation test platform,in bilateral rabbit corneas and to investigate their relationship with physical intraocular pressure(IOPp).Methods:Twenty fresh enucleated eyes from ten rabbits were used for ex vivo whole ocular globe inflation.IOP was increased from 7.5 to 37.5 mmHg with 7.5 mmHg steps and biomechanical metrics were acquired using the ORA.At least 3 examinations were performed at each pressure stage.Two biomechanical metrics,corneal hysteresis(CH)and corneal resistance factor(CRF)were recorded and analyzed as a function of IOPp.Corneal specimens were then excised from the intact ocular globe and tested under inflation conditions up to 45.7 mmHg posterior pressure.The experimental pressure-deformation data was analyzed using an inverse modeling procedure to derive the stress-strain behavior of the cornea.Results:A comparison of corneal shape parameters showed no statistically significant difference(P>0.05)between bilateral eyes.Similarly,there were no statistically significant differences in values of CH,CRF and corneal stiffness(as measured by the tangent modulus,Et)between bilateral eyes(CH:F=0.94,P=0.54;CRF:F=4.42,P=0.35;Et:F=3.15,P=0.12)at different pressure levels.IOPp was highly correlated with CRF while the relationship with CH was less pronounced.Conclusions:An obvious interocular symmetry in biomechanical metrics is found in this research.IOP has been shown to have important influences on the value of CRF provided by ORA.展开更多
Background:In this retrospective randomized case series,we compared bilateral symmetry between OD and OS eyes,intercorneal differences and Functional Optical Zone(FOZ)of the corneal aberrations.Methods:Sixty-seven nor...Background:In this retrospective randomized case series,we compared bilateral symmetry between OD and OS eyes,intercorneal differences and Functional Optical Zone(FOZ)of the corneal aberrations.Methods:Sixty-seven normal subjects(with no ocular pathology)who never had any ocular surgery were bilaterally evaluated at Augenzentrum Recklinghausen(Germany).In all cases,standard examinations and corneal wavefront topography(OPTIKON Scout)were performed.The OD/OS bilateral symmetry was evaluated for corneal wavefront aberrations,and FOZ-values were evaluated from the Root-Mean-Square(RMS)of High-Order Wavefront-Aberration(HOWAb).Moreover,correlations of FOZ,spherical equivalent(SE),astigmatism power,and cardinal and oblique astigmatism for binocular vs.monocular,and binocular vs.intercorneal differences were analyzed.Results:Mean FOZ was 6.56±1.13 mm monocularly,6.97±1.34 mm binocularly,and 7.64±1.30 mm intercorneal difference,with all strongly positively correlated,showing that the diameter of glare-free vision is larger in binocular than monocular conditions.Mean SE was 0.78±1.30 D,and the mean astigmatism power(magnitude)was 0.46±0.52 D binocularly.The corresponding monocular values for these metrics were 0.78±1.30 D and 0.53±0.53 D respectively.SE,astigmatism magnitude,cardinal astigmatism component,and FOZ showed a strong correlation and even symmetry;and oblique astigmatism component showed odd symmetry indicating Enantiomorphism between the left and right eye.Conclusions:These results confirm OD-vs.-OS bilateral symmetry(which influences binocular summation)of HOWAb,FOZ,defocus,astigmatism power,and cardinal and oblique astigmatism.Binocular Functional Optical Zone calculated from corneal wavefront aberrations can be used to optimize refractive surgery design.展开更多
基金This study was supported by the Science and Technology Plan Project of Wenzhou Science and Technology Bureau(C20120009-04)Science Foundation of the Affiliated Eye Hospital of Wenzhou Medical University(YNCX201312,YNCX201405,YNZD201501)the National Natural Science Foundation of China(81300807).
文摘Backgroud:To evaluate the symmetry of corneal biomechanical metrics,measured using an ocular response analyzer(ORA)and self-built corneal inflation test platform,in bilateral rabbit corneas and to investigate their relationship with physical intraocular pressure(IOPp).Methods:Twenty fresh enucleated eyes from ten rabbits were used for ex vivo whole ocular globe inflation.IOP was increased from 7.5 to 37.5 mmHg with 7.5 mmHg steps and biomechanical metrics were acquired using the ORA.At least 3 examinations were performed at each pressure stage.Two biomechanical metrics,corneal hysteresis(CH)and corneal resistance factor(CRF)were recorded and analyzed as a function of IOPp.Corneal specimens were then excised from the intact ocular globe and tested under inflation conditions up to 45.7 mmHg posterior pressure.The experimental pressure-deformation data was analyzed using an inverse modeling procedure to derive the stress-strain behavior of the cornea.Results:A comparison of corneal shape parameters showed no statistically significant difference(P>0.05)between bilateral eyes.Similarly,there were no statistically significant differences in values of CH,CRF and corneal stiffness(as measured by the tangent modulus,Et)between bilateral eyes(CH:F=0.94,P=0.54;CRF:F=4.42,P=0.35;Et:F=3.15,P=0.12)at different pressure levels.IOPp was highly correlated with CRF while the relationship with CH was less pronounced.Conclusions:An obvious interocular symmetry in biomechanical metrics is found in this research.IOP has been shown to have important influences on the value of CRF provided by ORA.
文摘Background:In this retrospective randomized case series,we compared bilateral symmetry between OD and OS eyes,intercorneal differences and Functional Optical Zone(FOZ)of the corneal aberrations.Methods:Sixty-seven normal subjects(with no ocular pathology)who never had any ocular surgery were bilaterally evaluated at Augenzentrum Recklinghausen(Germany).In all cases,standard examinations and corneal wavefront topography(OPTIKON Scout)were performed.The OD/OS bilateral symmetry was evaluated for corneal wavefront aberrations,and FOZ-values were evaluated from the Root-Mean-Square(RMS)of High-Order Wavefront-Aberration(HOWAb).Moreover,correlations of FOZ,spherical equivalent(SE),astigmatism power,and cardinal and oblique astigmatism for binocular vs.monocular,and binocular vs.intercorneal differences were analyzed.Results:Mean FOZ was 6.56±1.13 mm monocularly,6.97±1.34 mm binocularly,and 7.64±1.30 mm intercorneal difference,with all strongly positively correlated,showing that the diameter of glare-free vision is larger in binocular than monocular conditions.Mean SE was 0.78±1.30 D,and the mean astigmatism power(magnitude)was 0.46±0.52 D binocularly.The corresponding monocular values for these metrics were 0.78±1.30 D and 0.53±0.53 D respectively.SE,astigmatism magnitude,cardinal astigmatism component,and FOZ showed a strong correlation and even symmetry;and oblique astigmatism component showed odd symmetry indicating Enantiomorphism between the left and right eye.Conclusions:These results confirm OD-vs.-OS bilateral symmetry(which influences binocular summation)of HOWAb,FOZ,defocus,astigmatism power,and cardinal and oblique astigmatism.Binocular Functional Optical Zone calculated from corneal wavefront aberrations can be used to optimize refractive surgery design.
