Endoscopy-guided in vivo evaluation of ciliary sulcus location in children with ectopia lentis

Objective To assess a new method to measure the distance of the needle passage from the ciliary sulcus to the corneal limbus anterior border (CTC) in eyes with ectopia lentis directly in vivo via endoscopy and to further evaluate the correlations among the CTC, age, automated horizontal white-to-white distance (WTW), and ocular axial length (AL). Methods The WTW and AL were measured using an optical biometer. An intraocular endoscope was used during transscleral suture fixation of posterior chamber intraocular lenses to identify the true location of the ciliary sulcus. Linear regression analysis was used to assess the correlation between the CTC and other ocular biological parameters, including age, WTW, and AL. Results Thirty eyes of 30 children with ectopia lentis were evaluated. A statistically significant correlation was found between age and the CTC. The CTC could be predicted by the equation CTC = 0.1313 × Age + 0.9666. No statistically significant correlations were found between CTC and WTW, CTC and AL, WTW and AL, or WTW and age. Conclusion Endoscopy is useful for precisely suturing intraocular lens haptics in the real ciliary sulcus. Age can be used as an equivalent parameter for prediction of the true ciliary sulcus location.

Comparison of Central Corneal Thickness Measurements Using Specular Microscope, Optical Biometer and Corneal Topographer

Purpose: To compare the Central Corneal Thickness (CCT) measurements by three different devices in normal eyes. Study Design: Cross sectional observational study. Place and Duration of Study: Dow University of Health Sciences and Dr. Ruth K.M. Pfau Civil Hospital, Karachi, from October 2020 to January 2021. Methods: 80 eyes of healthy subjects aged between 20 to 50 years were included in the study. Patients with corneal pathologies, systemic disease, history of ocular surgery or trauma, high intraocular pressure and high refractive error were excluded. Subjects underwent full ophthalmic examination. Central Corneal Thickness was measured by specular microscope (Shin-Nippon SPM-700; Rexxam Co. Ltd, Takamatsu, Japan), optical biometer (AL-Scan; Nidek, Gamagori, Japan) and corneal topographer (TMS-5; Tomey corporation, Nagoya, Japan). All data entry and analysis was done on SPSS version 23. For correlation among devices, Pearson correlation coefficient was used. Scatter plot was drawn for graphical presentation. Results: 80 eyes of 80 healthy subjects (50 males, 30 females) were recruited in the study by convenient sampling. The mean age was 37.76 ± 8.35 years. Mean Central Corneal Thickness values were 515.57 ± 31.54 µm, 510.21 ± 30.11 µm, 522.03 ± 29.78 µm with specular microscope, optical biometer and corneal topographer respectively. Measurements by these devices strongly correlate with each other using Pearson correlation coefficient (r = 0.927 to 0.966, p ? 0.001). Conclusion: The results of Central Corneal Thickness measurements obtained from these three devices positively correlate with each other so any of these devices can be used for its measurement. Key Words: Central Corneal Thickness (CCT), Specular microscope, Optical biometer, Corneal topographer.

Prediction accuracy of standard and total keratometry by swept-source optical biometer for multifocal intraocular lens power calculation

We aimed to compare the refractive outcomes of cataract surgery with diffractive multifocal intraocular lenses (IOLs) using standard keratometry (K) and total keratometry (TK). In this retrospective observational case series study, a total of 302 patients who underwent cataract surgery with multifocal IOL implantation were included. Predicted refractive outcomes were calculated based on the current standard formulas and a new formula developed for TK using K and TK, which were obtained from a swept-source optical biometer. At 2-month postoperatively, median absolute prediction errors (MedAEs) and proportion of eyes within ± 0.50 diopters (D) of predicted postoperative spherical equivalent (SE) refraction were analyzed. There was no significant difference between MedAEs or proportion of eyes within ± 0.50D of predicted refraction from K and TK in each formula. In TFNT00 and 839MP IOL cases, there was no difference between MedAEs from K and TK using any formula. In 829MP IOL cases, MedAE from TK was significantly larger than that from K in Barrett Universal II/Barrett TK Universal II (P = 0.033). In 677MY IOL cases, MedAE from TK was significantly larger than that from K in Haigis (P = 0.020) and Holladay 2 (P = 0.006) formulas. In the subgroup analysis for IOL, there was no difference between the proportion of eyes within ± 0.50 D of predicted refraction from K and TK using any formula. TFNT00 and 839MP IOLs were favorable with TK, with 677MY IOL with K and 829MP IOL being in a neutral position, which necessitates the study that investigates the accuracy of the new TK technology.

Inter-device measurement variability of vital data parameters for keratorefractive and cataract refractive surgery

Introduction: The measurements of corneal white-to-white (WTW) diameter and pupil size are critical for decision making in refractive surgery. Currently, automatic measurement of keratometry, corneal WTW, and pupil size are implemented in several ocular devices. The purpose of this study was to examine the agreement between two commonly used devices, an autorefractor and an optical biometer, for these parameters. Methods: Measurements were performed with both a Lenstar LS-900 and Nidek ARK-1 by an experienced examiner in random order. The devices were placed in close proximity within the same dimly lit room. Results: The measurements of 65 right eyes were analyzed. The results of the flat, steep, and mean keratometric reading were not significantly different ( p = 0.96, p = 0.90, p = 0.93, respectively). Corneal WTW distances showed only moderate agreement between devices and were found to be significantly different ( r = 0.8071; p < 0.01). Pupil diameters showed poor agreement between devices and were significantly different ( r = 0.4890; p < 0.01). Agreement between implantable contact lens sizing, based on the measurements obtained by the two devices, was achieved for 19 of the 51 eyes (37.3%). Conclusion: We found a significant difference in WTW and pupil size measurements between ARK-1 and Lenstar. Results for both of the devices cannot be considered interchangeable for these data parameters.