Corneal biomechanical data and biometric parameters measured with Scheimpflug-based devices on normal corneas

AIM： To analyze the correlations between ocular biomechanical and biometric data of the eye,measured by Scheimpflug-based devices on healthy subjects.METHODS： Three consecutive measurements were carried out using the corneal visualization Scheimpflug technology（Cor Vis ST） device on healthy eyes and the 10 device-specific parameters were recorded.Pentacam HR-derived parameters（corneal curvature radii on the anterior and posterior surfaces;apical pachymetry;corneal volume;corneal aberration data;depth,volume and angle of the anterior chamber） and axial length（AL） from IOLMaster were correlated with the 10 specific CorV is ST parameters.RESULTS： Measurements were conducted in 43 eyes of 43 volunteers（age 61.24±15.72y）.The 10 specific Cor Vis ST data showed significant relationships with corneal curvature radii both on the anterior and posterior surface,pachymetric data,root mean square（RMS） data of lower-order aberrations,and posterior RMS of higher-order aberrations and spherical aberration of the posterior cornea.Anterior chamber depth showed a significant relationship,but there were no significant correlations between corneal volume,anterior chamber volume,mean chamber angle or AL and the 10 specific CorV is ST parameters.CONCLUSION： Cor Vis ST-generated parameters are influenced by corneal curvature radii,some corneal RMS data,but corneal volume,anterior chamber volume,chamber angle and AL have no correlation with the biomechan-ical parameters.The parameters measured by CorV is ST seem to refer mostly to corneal properties of the eye.

Comparison of two Nd:YAG laser posterior capsulotomy: cruciate pattern vs circular pattern with vitreous strand cutting

AIM： To investigate the effects and safety of neodymium： yttrium-aluminium-garnet（Nd：YAG） laser posterior capsulotomy with vitreous strand cuttingMETHODS： A total of 40 eyes of 37 patients with symptomatic posterior capsular opacity（PCO） were included in this prospective randomized study and were randomly subjected to either cruciate pattern or round pattern Nd：YAG posterior capsulotomy with vitreous strand cutting（modified round pattern）. The best corrected visual acuity（BCVA）, intraocular pressure（IOP）, refractive error, endothelial cell count（ECC）, anterior segment parameters, including anterior chamber depth（ACD） and anterior chamber angle（ACA） were measured before and 1 mo after the laser posterior capsulotomy. RESULTS： In both groups, the BCVA improved significantly（P〈0.001 for the modified round pattern group, P=0.001 for the cruciate pattern group）; the IOP and ECC did not significantly change. The ACD significantly decreased（P〈0.001 for both） and the ACA significantly increased（P=0.001 for the modified round pattern group and P=0.034 for the cruciate group）. The extent of changes in these parameters was not significantly different between the groups.CONCLUSION： Modified round pattern Nd：YAG laser posterior capsulotomy is an effective and safe method for the treatment of PCO. This method significantly changes the ACD and ACA, but the change in refraction is not significant. Modified round pattern Nd：YAG laser posterior capsulotomy can be considered a good alternative procedure in patients with symptomatic PCO.