The calculation of the intraocular lens power based on raytracing methods: a systematic review

Methodological quality of the review: Low confidence

Author: Steiner D, Hoffmann P, Goldblum D.

Region: Details not provided

Sector: Cataract surgery

Sub-sector: Raytracing, intraocular lens calculation/formula

Type of cataract: Age-related cataract

Equity focus: None specified

Review type: Other review

Quantitative synthesis method: Narrative analysis

Qualitative synthesis methods: Not applicable

Background

The problem addressed in the review is the preoperative identification of the appropriate intraocular lens (IOL) power in cataract surgery. It compares different calculation approaches, in particular raytracing methods.

Research objectives

To give ‘a systematic overview of the different raytracing calculations available and described in the literature and compare their results.’

Main findings

Authors included six studies describing different raytracing methods to calculate IOL power. All raytracing software applications provide a reliable and precise calculation of the intraocular lens power. However, these were not directly compared. Nevertheless, only very few and heterogeneous studies were available, which made it difficult to compare different techniques. Authors noted the need for further research in order to directly compare the different raytracing methods.

Methodology

Authors included all relevant studies describing raytracing methods. They conducted a search on PUBMED and direct search on the internet (no further information provided). Search terms used included: raytracing, IOL formula, cataract surgery, IOL calculation. Details in regards to methods used to screen full-text articles for inclusion and data extraction of included articles were not provided in the review. Additionally, authors did not report quality assessing risk of bias of included studies.

Applicability/external validity

It was not possible to determine applicability/external validity of results as different types of raytracing methods were not directly compared.

Geographic focus

No particular geographic focus was given. Although preoperative calculation of IOL power is an essential aspect of cataract surgery, the results have only limited relevance in low- and middle-income countries (LMICs) since raytracing methods are particularly useful in eyes that underwent previous refractive surgery, which is rarely the case in LMICs at the moment.

Quality assessment

Low confidence was attributed in the conclusions about the effects of this study as major limitations were identified. Due to the lack of details provided by the authors in terms of search strategy, methods used to select and extract data of included studies, it was not possible to be confident that relevant studies were not omitted and it was not possible to assess whether appropriate methods were used to avoid risk of bias. Additionally, authors did not report quality assessing risk of bias of the included studies.