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Objective To observe the corneal biomechanical changes of patients in the early stage after small inci-sion lenticule extraction(SMILE),and to analyze the correlation between the corneal biomechanical changes and changes in corneal volumes and higher-order aberrations.Methods A total of 72 patients(72 eyes)with myopia or myopic astig-matism who were scheduled for SMILE in the Optometric Center of Second People's Hospital of Foshan from January to August 2021 were included.The right eye was selected for observation.Before and 3 months after the SMILE,novel corne-al biomechanical parameters,such as biomechanical intraocular pressure(bIOP),DA ratiomax(2 mm)(DA2 ratio),inte-grated radius(IR),Ambrósio's relational thickness(for evaluation of the morphology and quality of the cornea,ARTh),stiffness parameter applanation 1(SP-A1),Corvis biomechanical index(CBI)and stress-strain index(SSI),were meas-ured by the new generation of Corvis? ST.The Pentacam anterior segment analysis system was used to measure corneal bi-omechanical parameters,including corneal volume(CV3 mm,CV5 mm,CV7 mm and CV10 mm);total root mean square of whole cornea,anterior and posterior corneal surface[RMS(Cornea,CF,CB)];root mean square of high-order aberrations of total cornea,anterior and posterior corneal surface[RMS HOA(Cornea,CF,CB)].Paired t-test or Wilcoxon singed-rank test was used to compare the changes in parameters before and after SMILE.Spearman correlation analysis and partial least squares regression were used to study the correlation between changes in novel corneal biomechanical parameters with cor-neal volume changes and high-order corneal aberration changes after the SMILE.Results Three months after SMILE,the bIOP,ARTh,SP-A1 and SSI decreased significantly,while the DA2 ratio,IR and CBI increased significantly(all P＜0.05).Three months after SMILE,CV3 mm,CV5 mm,CV7 mm and CV10 mm decreased significantly(all P＜0.05).The corneal volume changes from small to large were CV3 mm,CV5 mm,CV7 mm and CV10 mm,with a maximum decrease in the outmost periphery.The RMS(Cornea,CF,CB)and RMS HOA(Cornea,CF,CB)increased significantly(all P＜0.05);compared with the changes in high-order aberration on the anterior corneal surface,the changes in higher-order aberration on the posterior corneal surface were relatively stable.Correlation analysis shows that △ARTh was positively correlated with △CV3mm and△CV5mm,and negatively correlated with △CV10mm(all P＜0.05);△bIOP was negatively correlated with △CV3mm,△CV5mm,△RMS HOA(CF)and △RMS HOA(Cornea)and positively correlated with △CV10mm(all P＜0.05);△IR was negatively correlated with △CV10 mm(P＜0.05);△SP-A1 was positively correlated with △CV10 mm(P＜0.05);△ CBI was negatively correlated with △CV3 mm and △CV5 mm,and positively correlated with △CV10mmand △RMS(CF)(all P＜0.05).Conclusion The changes in corneal biomechanical parameters occur in the early stage after SMILE,with a certain corre-lation with the corneal volume changes in different regions and high-order corneal aberration changes.
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@#AIM: To compare the anterior chamber volume and corneal volume using Pentacam in people with early keratoconus, subclinical keratoconus, and healthy subjects.<p>METHODS: This epidemiologic study was performed on 63 patients who were candidates for refractive surgery. We classified our patients into three groups as normal, subclinical keratoconus, and early keratoconus according to the Amsler-Krumeich criteria. We collected demographic information, including age and sex, and obtained a full medical history of the patients. Complete visual examination was performed for all patients. Then, using Pentacam, corneal volume and anterior chamber volume were measured among three groups. <p>RESULTS: Corneal volume in the control group was significantly higher than the subclinical keratoconus and early keratoconus groups(<i>P</i><0.05), but the anterior chamber volume was not significantly different between the groups(<i>P</i>>0.05).<p>CONCLUSION: Measuring the corneal volume can help to distinguish the eyes with subclinical keratoconus and early keratoconus from normal eyes. The chamber volume might not differ remarkably among people with subclinical keratoconus, early keratoconus, and those with normal eyes.