Assessment of Corneal Keratometric and Astigmatism Measurements Using Verion System and Other Instruments in Cataract Patient

Toric Intraocular Lens Calculations With the Barrett Calculator: A Comparison of the Calculator With and Without the Integrated K Method

PURPOSE

To compare the accuracy of the Barrett Integrated K (IK) toric calculator with the standard Barrett toric calculator.

METHODS

Consecutive patients who underwent cataract extraction with implantation of a toric intraocular lens at the Rabin Medical Center, Israel, were reviewed. Errors in predicted postoperative refractive astigmatism were calculated for the Barrett toric calculator using biometry measurements only and with the IK tool using biometry and tomography. Both methods were assessed with predicted and measured posterior corneal astigmatism (PPCA and MPCA, respectively).

RESULTS

The study included 73 eyes of 59 patients. The mean centroid prediction error using PPCA (0.08 ± 0.80 D @ 78°) was significantly different compared with MPCA (0.07 ± 0.80 D @ 48°, P = .016). In addition, a significant difference between IK-PPCA (0.06 ± 0.80 D @ 80°) and IK-MPCA (0.05 ± 0.80 D @ 38°) was found (P = .023). The median absolute prediction error ranged from 0.55 D using IK-PPCA to 0.60 D using PPCA, with no significant differences between the four calculation versions. No significant differences were found between the calculators in the predictability rates within ±0.50, ±0.75, and ±1.00 D. Analysis of one eye of each patient showed similar results.

CONCLUSIONS

The IK calculator yielded comparable outcomes to the standard Barrett calculator. Although differences in the mean centroid errors were found, they were clinically insignificant and predominantly seen in the axis of the predicted astigmatism error. These minor differences were mainly attributed to the incorporation of the MPCA in the calculation. [J Refract Surg. 2022;38(9):565-571.].

Time-efficiency assessment of guided toric IOL cataract surgery: a pilot study

PURPOSE

To compare the time spent on toric intraocular lens (IOL) implantation during cataract surgery using a manual-marking versus a digital image-guided system (the Verion) for toric IOL alignment.

SETTINGS

All procedures were performed at the Instituto Oftalmológico Quirónsalud ophthalmology clinic (A Coruña, Spain).

DESIGN

We designed an experimental and longitudinal (1-month follow-up) study.

METHODS

A total of 98 eyes of 65 participants (68.2 ± 12.2 years) were divided into two groups: 49 eyes operated with toric IOL alignment using a manual-marking technique (manual group) and another 49 eyes operated using image-guided marking (Verion group). The primary variable for comparison between both groups was cataract surgery time. Other outcomes such as toric IOL misalignment, spherical equivalent (SE), astigmatism, uncorrected distance visual acuity (UDVA), and corrected distance visual acuity (CDVA) were also measured.

RESULTS

The total cataract surgery time was 2:09 minutes shorter (p  < 0.001) with the Verion system (12:12 ± 2:20) compared to the surgical procedure performed using manual marking (15:27 ± 3:04). One month after surgery, there were no statistical differences in terms of toric IOL misalignment between the Verion (3.38° ± 2.95°) and the manual group (4.66° ± 3.95°). No statistical differences were observed between groups for refractive and visual outcomes either (p ≥ 0.05).

CONCLUSIONS

The cataract surgery time was reduced when the procedure was assisted using the Verion system to align the IOL compared to manual marking, maintaining the same efficacy in terms of toric IOL misalignment, residual refraction, and visual acuity.

Comparison of radius of anterior lens surface curvature measurements in vivo using the anterior segment optical coherence tomography and Scheimpflug imaging

Background

To assess the radius of anterior lens surface curvature (RAL) measurements with anterior segment optical coherence tomography (AS-OCT) in comparison with Scheimpflug imaging.

Methods

This prospective, cross-sectional study was carried out at Zhongshan Ophthalmic Center, Guangzhou, China. We enrolled 59 eyes, including 30 eyes from 30 cataractous volunteers (59 to 87 years) and 29 eyes from 29 young participants (19 to 49 years). After mydriasis, the RAL was measured automatically by the built-in software in the AS-OCT (CASIA 2). The Scheimpflug images were measured with the build-in caliper tool of the Scheimpflug camera (Pentacam), and RAL were further calculated with the principle of best-fitted circle. Intraobserver and interobserver reproducibility of RAL measurement using Scheimpflug camera were evaluated with limit of agreement (LoA) and intraclass correlation coefficient (ICC). Consistency between RAL measurement of Scheimpflug camera and AS-OCT were assessed with LoA, correlation analysis and linear regression.

Results

For all subjects, intraobserver (LoA: −0.25 to 0.23 mm, ICC: 0.996) and interobserver reproducibility (LoA: −0.85 to 0.92 mm, ICC: 0.947) of RAL were good using Scheimpflug imaging. Both AS-OCT and Scheimpflug imaging found that the age-related cataract participants had smaller RAL (P=0.010, P=0.001 respectively). LoA of RAL measurement between AS-OCT and Scheimpflug imaging was −3.83 to −0.79 mm, and the Pearson correlation efficient was 0.909 (P<0.001). The RAL values measured by AS-OCT were significantly greater than that by Scheimpflug camera with a mean difference of 2.31 mm for all participants (P<0.001). The RAL measurement could be converted using the equation: Y_{CASIA 2} =1.155 × X_Pentacam + 1.060.

Conclusions

Both Scheimpflug camera system with internal caliper tool and the AS-OCT are fast and non-contact tools that could measure RAL successfully. The two measurement results are highly correlated and interchangeable through linear regression equation.