Search

: PurposeTo evaluate the precision, reproducibility, and applicability of an optical method based on partial coherence interferometry for intraocular lens (IOL) power calculation.: SettingUltrasound laboratory of a university eye hospital.: MethodsA prospective comparison of measurements made by the IOLMaster optical instrument (Carl Zeiss) and Ultrascan Digital 2000 contact ultrasound A-scan (Alcon) for IOL calculations was performed. Examined were 255 eyes of 134 persons (204 phakic, 47 pseudophakic, and 4 aphakic). The mean age of the patients was 67.9 years (range 7 to 94 years).: ResultsThe IOLMaster measurements were successful in more than 80% of cases: in 82%, 99%, and 99% for axial length (AL), anterior chamber depth (ACD), and keratometry measurements, respectively. The reproducibility of the AL and ACD measurements was very high (coefficient of variation 0.13% and 2.20%, respectively). The AL and ACD values were significantly larger with the IOLMaster (P < .001) than with the Ultrascan Digital 2000. The correlation between ultrasound and optical AL measurements was high (r = 0.985; P < .001); however, there was no correlation between ACD measurements (r = 0.079; P = .397). The corneal refractive power measurements of a Javal-type keratometer and the IOLMaster were highly correlated (r = 0.955; P < .001), with a mean difference of 0.2 diopter.: ConclusionsThe results show that measurements for IOL calculation are easy and precise with the optical method. It is a noncontact method, so no anesthesia is needed and there is no risk of infection. [Copyright &y& Elsevier]

Purpose: To visualize, using Fourier-domain optical coherence tomography (FD-OCT), the alterations in lid-parallel conjunctival fold (LIPCOF) morphology in eyes with contact lenses and after their removal., Methods: One randomly selected eye of each of 24 volunteers with normal ocular surface status was examined using FD-OCT. The study group included 18 female and 6 male subjects, with a mean age of 28.9 years (range, 18-50 years). The presence, height, and number of conjunctival folds and the tear meniscus area were evaluated by FD-OCT, and the difference between "before and after lens removal" were analyzed by the Wilcoxon signed-rank test. To determine the coverage of the folds, the OCT-LIPCOF grading system was applied. Visualization of the folds was compared on linear and raster scans. The Spearman rank test was applied for correlations (SPSS 16.0; SPSS Inc., Chicago, MI)., Results: OCT scans were able to visualize and objectively describe the LIPCOF and its relation to the tear film in contact lens wearers. Raster scanning provided more information about the folds, but the measurements were easier to carry out on the single line scans. After removal of the contact lens, the height of the conjunctival folds significantly decreased (p < 0.001), and the tear meniscus area significantly increased (p = 0.017). The number of LIPCOF did not change (p = 0.971), but LIPCOF coverage by the tear film increased after lens' removal and resulted in changes in the OCT-LIPCOF grading (p < 0.001)., Conclusions: FD-OCT could be a quick, non-invasive, quantitative method for the imaging of LIPCOF in contact lens patients. When grading LIPCOF, the mechanical forces of the lens and the tear meniscus changes caused by the lens should be taken into account as these factors influence results. Follow-up of the patients using the same methods is suggested with or without contact lenses.