The study of anterior sclera thickness and associated ocular parameters

Abstract

Background The condition of the sclera is associated with many ocular diseases.The measurement of human scleral thickness in vivo is helpful for us to understand the features of the sclera and related diseases.Objective The present study was to measure the anterior sclera thickness(AST) in patients with senile cataract and to analyze the relationship among AST and other associated ocular parameters.Methods This study was approved by the Ethic Commission of First Hospital of Peking University.Written informed consent was obtained from each individual prior to examination.One hundred and five senile cataract patients were recruited in this study.Central corneal thickness (CCT),corneal curvature (CCV) and axial length were measured using ultrasonic pachymeter,keratometer,and A-scan unit,respectively.The AST was measured at 2 mm posterior to the scleral spur in the temporal meridian using ultrasound biomicroscope (UBM).The differences of CCT,CCV,ocular axial length and AST between bilateral eyes and the different sexes were compared by the Paired test and independent sample t test.The correlations among various parameters were assessed by the Pearson linear correlation analysis.The differences of CCT and AST among different axial length groups were evaluated by one-way ANOVA.Results No significant differences were found in the CCT,CCV,axial length and AST between bilateral eyes (t =0.584,P =0.561 ; t =1.161,P =0.248 ; t =0.140,P =0.889 ; t =0.342,P =0.773).Temporal AST at 2 mm posterior to the sclera spur was (0.589 ±0.051)mm in the right eyes.An insignificant decline in CCT was found in the male group compared with the female group (right eyes:t =0.469,P =0.641 ; left eyes:t =0.465,P =0.643).However,compared with the female group,the increase of axial length,reduction of the mean CCV value and enhancement of the mean AST were observed(right eyes:all P＜0.01 ;left eyes:all P＜0.01).CCV showed a negative correlation with ocular axial length (r =-0.50,P＜0.01),but no significant correlation was found among age,CCT,ocular axial length and AST(P＞0.05).No remarkable differences were found in CCT and AST among the various axial length groups (CCT:F =0.998,P=0.372;AST:F=1.919,P=0.383).Conclusions In senile cataract patients,correlation is not found between AST and CCT;the increase of axial length is not associated with the thinning of the eyeball wall to a certain extent.Differences exist in some ocular parameters between different sexes. Key words: Bio-measurement; Scleral thickness; Central corneal thickness; Axial length; Ultrasound biomicroscopy