High Agreement between Barrett Universal II Calculations with and without Utilization of Optional Biometry Parameters

Purpose: To examine the contribution of anterior chamber depth (ACD), lens thickness (LT), and white-to-white (WTW) measurements to intraocular lens (IOL) power calculations using the Barrett Universal II (BUII) formula. Methods: Measurements taken with the IOLMaster 700 (Carl Zeiss, Meditec AG, Jena, Germany) swept-source biometry of 501 right eyes of 501 consecutive patients undergoing cataract extraction surgery between January 2019 and March 2020 were reviewed. IOL power was calculated using the BUII formula, first through the inclusion of all measured variables and then by using partial biometry data. For each calculation method, the IOL power targeting emmetropia was recorded and compared for the whole cohort and stratified by axial length (AL) of the measured eye. Results: The mean IOL power calculated for the entire cohort using all available parameters was 19.50 ± 5.11 diopters (D). When comparing it to the results obtained by partial biometry data, the mean absolute difference ranged from 0.05 to 0.14 D; p < 0.001. The optional variables (ACD, LT, WTW) had the least effect in long eyes (AL ≥ 26 mm; mean absolute difference ranging from 0.02 to 0.07 D; p < 0.001), while the greatest effect in short eyes (AL ≤ 22 mm; mean absolute difference from 0.10 to 0.21 D; p < 0.001). The percentage of eyes with a mean absolute IOL dioptric power difference more than 0.25 D was the highest (32.0%) among the short AL group when using AL and keratometry values only. Conclusions: Using partial biometry data, the BUII formula in small eyes (AL ≤ 22 mm) resulted in a clinically significant difference in the calculated IOL power compared to the full biometry data. In contrast, the contribution of the optional parameters to the calculated IOL power was of little clinical importance in eyes with AL longer than 22 mm

High Agreement between Barrett Universal II Calculations with and without Utilization of Optional Biometry Parameters

Purpose: To examine the contribution of anterior chamber depth (ACD), lens thickness (LT), and white-to-white (WTW) measurements to intraocular lens (IOL) power calculations using the Barrett Universal II (BUII) formula. Methods: Measurements taken with the IOLMaster 700 (Carl Zeiss, Meditec AG, Jena, Germany) swept-source biometry of 501 right eyes of 501 consecutive patients undergoing cataract extraction surgery between January 2019 and March 2020 were reviewed. IOL power was calculated using the BUII formula, first through the inclusion of all measured variables and then by using partial biometry data. For each calculation method, the IOL power targeting emmetropia was recorded and compared for the whole cohort and stratified by axial length (AL) of the measured eye. Results: The mean IOL power calculated for the entire cohort using all available parameters was 19.50 ± 5.11 diopters (D). When comparing it to the results obtained by partial biometry data, the mean absolute difference ranged from 0.05 to 0.14 D; p < 0.001. The optional variables (ACD, LT, WTW) had the least effect in long eyes (AL ≥ 26 mm; mean absolute difference ranging from 0.02 to 0.07 D; p < 0.001), while the greatest effect in short eyes (AL ≤ 22 mm; mean absolute difference from 0.10 to 0.21 D; p < 0.001). The percentage of eyes with a mean absolute IOL dioptric power difference more than 0.25 D was the highest (32.0%) among the short AL group when using AL and keratometry values only. Conclusions: Using partial biometry data, the BUII formula in small eyes (AL ≤ 22 mm) resulted in a clinically significant difference in the calculated IOL power compared to the full biometry data. In contrast, the contribution of the optional parameters to the calculated IOL power was of little clinical importance in eyes with AL longer than 22 mm

The Optimal Axial Interval in Estimating Depth from Defocus

We analyze the effect of perturbations on the estimation of Depth from Defocus (DFD) implemented by changing the focus setting (e.g., axially moving the sensor). The analysis yields the optimal change of focus setting, and the spatial frequencies for which estimation is most robust. For stable estimation at all spatial frequencies, the change in focus setting should be less than twice the depth of field. For the most robust estimation in the highest spatial frequencies the axial interval should be equal to the depth of field. 1. Introduction In recent years, range imaging based on the limited depth of field (DOF) of lenses has been gaining popularity. Depth from Defocus (DFD) is an elegant method since it enables depth estimation based on only two images of the scene, taken from the same viewpoint. The defocus blur is made different in the two images by changing the internal settings of the imaging system. The effect of those changes on the defocus blur can be modeled either empirica..

Descemet stripping automated endothelial keratoplasty in phakic eyes: Incision modification reducing cataract formation

AIM: To evaluate the efficacy of a technical modification to reduce the incidence of traumatic cataract induced by Descemet stripping automated endothelial keratoplasty (DSAEK) performed in phakic eyes. METHODS: A retrospective cohort study. The records of all patients with a clear crystalline lens and endothelial failure that underwent modified DSAEK at our insitution were reviewed. In this modification, in order to avoid inadvertent touch of the insertion forceps against the exposed crystalline lens while passing across the anterior chamber, the incision sites were shifted from the standard 9 and 3 oâ\u80\u99clock positions, superiorly to the 10 and 2 oâ\u80\u99clock position respectively. Formation of typically traumatic, anterior subcapsular cataract in these patients was compared to that observed in a cohort including all the patients with a clear crystalline lens and endothelial failure that underwent conventional DSAEK at our institution. RESULTS: The study group included 49 eyes following modified DSAEK and the control group included 35 eyes following DSAEK with conventional incision sites. Anterior subcapsular cataract occurring 4mo or less postoperatively was identified in 2 of 49 (4%) eyes in the study group and 7 of 35 (20%) eyes in the control group. The rates of traumatic cataract were significantly higher in the control group in comparison to the study group (P=0.03, RR=4.9, 95%CI 1.08-22.1). CONCLUSION: Traumatic cataract formation following phakic DSAEK may be avoided with a simple modification to the position of the incision sites

Tectonic descemet stripping automated endothelial keratoplasty for the management of sterile corneal perforations in decompensated corneas

Purpose: To report the use of Descemet stripping automated endothelial keratoplasty (DSAEK) for treatment of sterile corneal perforations accompanying endothelial decompensation. Methods: In this multicenter interventional case series, we reviewed the medical records of all tectonic DSAEK surgeries performed at Villa Serena-Villa Igea private Hospitals (Forlì, Italy) and Rabin Medical Center (Petach Tikva, Israel) between January 2014 and March 2016. Results: Three patients with endothelial decompensation and sterile corneal perforation (n 2) or impending corneal perforation (n 1) underwent DSAEK between 2014 and 2015 at Villa Igea Hospital, Forlì, Italy, and Rabin Medical Center, Petach Tikva, Israel. All 3 surgeries were performed in eyes with a history of progressive stromal thinning without signs of infection, using the standard DSAEK technique. In 1 eye, surgery was complicated by bleeding into the graft-recipient interface that resolved after intraoperative interface washout. The other 2 procedures were uneventful. In all cases, the graft formed an airtight and watertight barrier, restoring the globe's mechanical integrity. All grafts remained clear throughout follow-up. One eye underwent deep anterior lamellar keratoplasty (DALK on DSAEK) with resulting improvement of visual acuity. Conclusions: Standard DSAEK can be performed in the presence of corneal perforation. Surgery can be a simple technique for closure of sterile corneal perforations while treating endothelial decompensation. Internal tamponade by a lamellar graft can possibly be used in cases of corneal perforations in eyes with a healthy endothelium