ABSTRACT
Background Measurement of corneal thickness is of great significance for the design of refractive surgery and the diagnosis of eye diseases,measuring equipments and technology develop rapidly in recent years.Optovue iVue OCT is a new frequency-domain optical coherence tomography (OCT),to compare its results with those of Pentacam and Visante OCT is helpful to objectively assess the clinical value of Optovue iVue OCT.Objective This study was to investigate the repeatability of corneal thickness measurement with Optovue iVue OCT and the comparatbility with Pentacam three-dimensional anterior segment analysis diagnostic system and Visante OCT.In addition,this study attempted to analyze the distribution of average corneal thickness in each quadrant by Optovue iVue OCT.Methods The corneal thicknesses of the corneal thinnest point,the central point and 3:00,6:00,9:00,12:00 zones 1 mm away from the center of the cornea were measured in 45 right eyes of 45 subjects with myopia using Optovue iVue OCT,Pentacam and Visante OCT in Tianjin Eye Hospital.Interclass correlation coefficient (ICC) was used to analyze the repeatability of measurement by Optovue iVue OCT.The agreements between Optovue iVue OCT and Pentacam or Visante OCT were evaluated by Bland-Altman test.The corneal area of 1.0-2.5 mm away from the center was divided into eight quadrants and the average corneal thickness of each quadrant was measured and analysis with Optovue iVue OCT.Results No significant difference was found in corneal thickness values for 3 times by Optovue iVue OCT (P=0.546).The ICC by Optovue iVue OCT was 99.92％,99.99％,99.96％,99.99％,99.99％ and 99.97％ at the corneal thinnest point,the central point and 3:00,6:00,9:00,12:00 zones respectively.There were significant differences among the 3 kinds of methods (P =0.000,0.001,0.000,0.003,0.002,0.000).The measured values of Optovue iVue OCT were significantly lower mean 24.20 μm than those of Pentacam (P=0.000,0.001,0.000,0.003,0.004,0.000),but only the value at 12:00 zone of Optovue iVue OCT was evidently declined in comparison with that of Visante OCT (P =0.016),there were no significant differences between all the other zones (P =1.000,0.447,0.239,1.000,1.000).While the mean corneal thickness value from Pentacam lowed by 14.01 μm in comparison with Visante OCT,all zones had significant differences (P =0.009,0.005,0.034,0.017,0.008) except the central point (P =0.056).Based on the Optovue iVue OCT,the thinnest zone was at temporal quadrant in 23 eyes (accounting for 51.11％) and at superior quadrant or super nasal quadrant in 21 eyes (both at 46.66％).Conclusions Optovue iVue OCT measurement of corneal thickness is of high repeatability and is consistent with Visante OCT in myopic eye.Optovue iVue OCT shows evident difference from Pentacam in the measurement of corneal thickness.The thinnest point of the cornea is mainly in the inferior temporal quadrant and the thickest point is commonly in superior quadrant and nasal superior quadrant based on Optovue iVue OCT.
ABSTRACT
PURPOSE: To obtain the average values of anterior segment structures of adult Koreans using Visante OCT in relation to age and sex, and to compare the central corneal thickness values with these measurements using an A-scan ultrasonic pachymeter. METHODS: Anterior segment images were obtained in 185 Korean (298 eyes) using Visante OCT. Four different parameters (central corneal thickness, anterior chamber depth, anterior chamber angle, and internal anterior chamber diameter) were measured at four meridians (vertical, horizontal, 45 degrees, and 135 degrees). Afterwards, the same examiner performed A-scan ultrasonic pachymetry to measure central corneal thickness. RESULTS: Central corneal thickness values measured using Visante OCT were significantly less than those obtained using an A-scan ultrasonic pachymeter (p=0.000). Central corneal thickness, anterior chamber angle, and internal anterior chamber diameters were all smaller in females than in males (p<0.05). Anterior chamber depth, anterior chamber angle, and internal anterior chamber diameter showed a significant decrease according to increasing age in both sexes (p<0.05). CONCLUSIONS: Average values and changes of anterior segment structures in relation to age and sex were established using Visante OCT in Korean adults. These results may be useful as standard values in anterior segment surgeries as well as in the diagnosis and follow-up of certain anterior segment diseases.