A Review of Smartphone Apps Used for Toric Intraocular Lens Calculation and Alignment.

Yarrow Scantling-Birch,Ritika Mukhija,Mayank A Nanavaty,Hasan Naveed

doi:10.3390/vision6010013

Abstract

Smartphone apps are becoming increasingly popular in ophthalmology, one specific area of their application being toric intraocular lens (IOL) surgery for astigmatism correction. Our objective was to identify, review and objectively score smartphone apps applicable to toric IOL calculation and/or axis alignment. This review was divided into three phases. A review was conducted on four major app databases (phase I): National Health Service (NHS) Apps Library, Google Play Store, Apple App Store and Amazon Appstore. A systematic literature review (phase II) was conducted to identify studies for included apps in phase I of our study. Keywords used in both searches included: “toric lens”, “toric IOL”, “refraction”, “astigmatism”, “ophthalmology”, “eye calculator”, “ophthalmology calculator” and “refractive calculator”. Included apps were objectively scored (phase III) by three independent reviewers using the mobile app rating scale (MARS), a validated tool that ranks the quality of mobile health apps using a calculated mean app quality (MAQ) score. Phase I of our study screened 2428 smartphone apps, of which six apps for toric IOL calculation and four apps for axis marking were eligible and were selected for quantitative analysis. Phase II of our study screened 477 studies from PubMed, Medline and Google Scholar. Three studies validating two apps (toriCAM, iToric Patwardhan) in a clinical setting as adjunct tools for preoperative axis marking were identified. Phase III ranked Toric Calculator for iPhone (Apple iOS, MAQ 4.13; average MAQ 3.34 ± 0.54) as the highest-scoring toric IOL calculator, and iToric Patwardhan (Android OS, MAQ 4.13; average MAQ 3.41 ± 0.44) was the highest-scoring axis marker in our study. Our review identified and objectively scored ten smartphone apps available for toric IOL surgery adjuncts. Toric Calculator for iPhone and iToric Patwardhan were the highest-scoring toric IOL calculator and axis marker, respectively. Current literature, though limited, suggests that axis marking smartphone apps can achieve similar levels of misalignment reduction when compared to digital systems.

Highlights

Toric intraocular lens (IOL) implantation is one of the most effective ways to correct corneal astigmatism during cataract surgery; its practical use relies on accurate calculation, selection and alignment of the toric IOL [1,2]
Implanting the IOL at the correct axis is of utmost importance as deviations as small as 3 degrees from the intended axis can result in a clinically significant 10% loss in astigmatism correction, with a rotation of 30 degrees resulting in a 100% loss of astigmatic correction [1,4]
Two thousand two hundred and fifty-eight smartphone apps were excluded based on title and thumbnail alone

Summary

Introduction

Toric intraocular lens (IOL) implantation is one of the most effective ways to correct corneal astigmatism during cataract surgery; its practical use relies on accurate calculation, selection and alignment of the toric IOL [1,2]. There are multiple steps involved in the preoperative planning for toric IOL implantation, including patient selection, accurate biometry, consistency with regular and symmetric corneal astigmatism on corneal topography and reference markings [3]. In an extensive retrospective review of 4949 eyes, the primary sources of error identified during toric IOL surgery included preoperative measurements of the cornea (27%), IOL misalignment (14.4%) and IOL tilt (11.3%) [5]. These errors, subsequently, may require further treatment in the form of IOL repositioning, exchange or laser refractive surgery [6]. 72% of the eyes with preoperative astigmatism between 0.75 and 2.5 diopters (D) were within 0.5 D of residual manifest astigmatism and 63% of eyes had an astigmatic error of ≤0.5 D relative to the expected residual astigmatism at 12 months after toric IOL implantation [1]

Results

Discussion

Conclusion