ABSTRACT
Objective To investigate the correlations between corneal biomechanical properties and corneal high-order aberrations (HOAs) in myopic eyes.Methods In this retrospective study,263 right eyes with myopia or myopic astigmatism were enrolled from January to October 2015 in Tianjin Eye Hospital.The values of first applanation time (A1T),first applanation length (A1L),first applanation velocity (A1V),second applanation time (A2T),second applanation length (A2L),second applanation velocity (A2V),highest concavity time (HCT),highest concavity deformation amplitude (HCDA),highest concavity peak distance (HCPD),highest concavity radius (HCR) and non-contact intraocular pressure (IOPnct) were measured using the corneal visualization Scheimpflug technology (Corvis ST).The central corneal thickness (CCT) and wavefront aberrations of the anterior,posterior surface,and the total cornea were measured with Pentacam.Pearson correlation and stepwise multivariate linear regression analysis were applied to analyze the correlations between biomechanical properties and corneal HOAs.This study follows the Helsinki declaration.The experiment was approved by the Ethic Committee of Tianjin Eye Hospital.Informed consent was signed from each patient.Results There was a correlation between biomechanical properties and corneal HOAs.Negative correlations were found between A1L and the spherical aberration,HOAs RMS of anterior surface,total RMS and HOAs RMS of the posterior surface and HOAs RMS of the total cornea (P＜0.05).HCRs were negatively correlated with total RMS of the total cornea and the anterior surface (P＜0.05).The A2V was correlated with various aberrations.Multiple stepwise linear regression model analysis showed that,the correlation between the aberrations of anterior surface and biomechanical parameters,and the correlations between the total corneal aberration and biomechanical parameters were weak,the correlations between the aberrations of posterior surface and biomechanical parameters were strong.Conclusions There is a correlation between the biomechanical properties and corneal HOAs.The changes of the corneal biomechanical properties are mainly associated with the posterior corneal aberrations,which may contribute to the early diagnosis of subclinical keratoconus or dilated corneal disease.
ABSTRACT
Este trabajo tiene como objetivo conocer los avances más novedosos relacionados con el estudio de las características biomecánicas de la córnea y su posible relación en el diagnóstico del glaucoma. Se realizó una búsqueda en la plataforma Infomed, específicamente en la Biblioteca Virtual de Salud, con el objetivo de conocer los avances más novedosos relacionados con el estudio de las características biomecánicas de la córnea y su posible relación en el diagnóstico del glaucoma. La biomecánica corneal es la facultad de resistencia y flexión simultánea de las moléculas de colágeno en las diferentes capas de la córnea. Trata del equilibrio y de la deformación del tejido corneal sometido a cualquier acción exterior. La histéresis corneal, junto con el factor de resistencia corneal, son medidas que pueden ser proporcionadas por el analizador de respuesta ocular. La existencia de un bajo valor de estas dos medidas pudiera considerarse como un factor de riesgo de progresión en el glaucoma(AU)
The purpose of this work is to know the more novel advances related with the study of the biomechanic characteristic of the cornea and its possible relationship in the diagnosis of the glaucoma. A search was made in Infomed platform, particularly in the Virtual Library of Health, to find out the most advanced in the study of the corneal biomechanical properties and its possible relation with the diagnose of glaucoma. Corneal biomechanical is the power of the resistance and flexion simultaneity of collagen molecules of the different corneal layer. It is the balance and deformity of the corneal tissue submitted to an external action. Corneal hysteresis and corneal resistance factor are two corneal biomechanical properties measured by the Ocular Response Analyzer. The existence of a low value of these two properties may be considered as progression factors in glaucoma(AU)
Subject(s)
Humans , Cornea/physiopathology , Glaucoma/diagnosis , Review Literature as Topic , Technological Development/adverse effectsABSTRACT
Background Corneal biomechanical properties is important in the safety assessment of corneal refractive surgery.Corvis is a new device for measuring corneal biomechanics properties.Objective This study was to observe the correlation among corneal thickness, Corvis intraocular pressure and corneal biomechanical properties with Corvis.Methods A prospective observational study was performed.One hundred and fifty eyes of 75 patients with corneal thickness from 501 μm to 590 μm were divided into three groups according to the corneal thickness:low corneal thickness group (corneal thickness range from 501 μm to 530 μm), middle corneal thickness group (corneal thickness range from 531 μm to 560 μm) ,and high corneal thickness group (corneal thickness range from 561 μm to 590 μm);and 50 eyes of 25 patients for each group.The difference of intraocular pressure, corneal thickness and deformation amplitude (DA) among the three groups were analyzed by one-way ANOVA and the correlation among the groups were analyzed by liner regression.Results The DA in the low corneal thickness group and middle corneal thickness group were significantly higher than that in the high corneal thickness group (P ＜ 0.05).The intraocular pressure was statistically different among the 3 groups (F =9.98, P＜0.05).DA was negatively correlated with intraocular pressure and corneal thickness (r=-0.84,-0.33;both at P＜0.01), with the linear regression DA =1.69-0.04×IOP (F=366.19, t=-19.14,P＜0.01).Conclusions Corneal thickness cannot simply represent the corneal biomechanical properties in the safety assessment of corneal refractive surgery,IOP should be considered.
ABSTRACT
PURPOSE: To evaluate the effects of short-term prostaglandin analogues treatment on the corneal biomechanics of patients with normal tension glaucoma. METHODS: This study included 52 eyes of 52 patients who were diagnosed with normal tension glaucoma. All patients were divided into two groups; one group (27 eyes) received tafluprost while the other group (25 eyes) received travoprost. Intraocular pressure, Biomechanical properties were measured by using goldmann applanation tonometer, ocular response analyzer before treatment and at 8-week after treatment. RESULTS: The mean decrease in intraocular pressure, Goldmann-correlated IOP (IOPg), corneal-compensated intraocular pressure by using Goldmann applanation tonometer, and Ocular response analyzer were statistically significant in total patients, tafluprost, and travoprost group after using prostaglandin analogues (p < 0.001, p < 0.001, p < 0.001, respectively). Corneal hysteresis showed no statistical differences after treatment in total, tafluprost and travoprost group but corneal resistance factor (CRF) showed statistically significant decrease after using prostaglandin analogues in total, tafluprost, and travoprost group (p < 0.001, p = 0.025, p < 0.001). Upon multivariate analysis, the higher initial IOPg and the lower initial CRF checked, the variation of CRF (CRF in baseline – CRF at 8 weeks) got higher (β = 0.134, p = 0.017). CONCLUSIONS: It is needed to carefully monitor and evaluate the effects of prostaglandin analogues on intraocular pressure associated with initial intraocular pressure and the changes of CRF after prostaglandin treatment in normal tension glaucoma patients. CRF is sensitive factor to short-term changes of intraocular pressure after prostaglandin analogues treatment, and it is required to consider the properties of CRF when we evaluate between progression of glaucoma and corneal biomechanical properties.
Subject(s)
Humans , Glaucoma , Intraocular Pressure , Low Tension Glaucoma , Multivariate Analysis , Prostaglandins, SyntheticABSTRACT
PURPOSE: To evaluate the association between corneal biomechanical properties and progression of visual field loss in normal tension glaucoma. METHODS: This study enrolled 73 eyes of 73 patients with normal tension glaucoma who were undergoing medical treatment, and classified them into progressing and nonprogressing groups by visual field trend analysis. The corneal biomechanical properties measured by the Ocular Response Analyzer (ORA; Reichert Instruments, Depew, NY, USA), central corneal thickness, and Goldmann applanation tonometry were comparatively analyzed between the 2 groups. RESULTS: Twenty-six eyes reached a progression endpoint. The prevalence of hypertension was higher in the progressing group (42.3%, progressing, 17.0%, nonprogressing; p = 0.03). Progressing eyes had lower corneal hysteresis (9.1 +/- 1.3 vs. 9.8 +/- 1.5 mm Hg, p = 0.03) and lower corneal resistance factor (9.5 +/- 1.5 vs. 10.4 +/- 1.4 mm Hg, p = 0.01) compared with nonprogressing eyes. Upon multivariate analysis, the presence of hypertension (odds ratio [OR] = 3.46, p = 0.03) and corneal hysteresis (CH) (OR = 0.66 per mm Hg lower, p = 0.02) remained statistically significant. CONCLUSIONS: The CH measurement with ORA was significantly associated with risk of visual field progression in normal tension glaucoma. Eyes with lower CH had a greater risk of progression of visual field loss than those with higher CH.