Scandinavian Journal of Optometry and Visual Science

Prevalence and incidence of keratoconus in Sweden. A nationwide register study between 2010 and 2020.

Jonathan Binder, Vibeke Sundling — Tue, 23 May 2023 00:00:00 +0200

The purpose of this study was to estimate the prevalence and incidence of keratoconus in Sweden. The study had a cross-sectional descriptive design, using data from the Swedish Patient Register. Data about keratoconus registered from 1st January, 2010, to 31st December, 2020, were analysed. Prevalence was estimated from the total number of patients registered. Incidence was estimated from the number of first-time registrations per year for the age group 0 to 40 years and stratified by decades of age.

From 2010 to 2020, 16,055 patients were registered with keratoconus in the Swedish Patient Register, giving a total estimated keratoconus prevalence of 169.5 per 100,000 (95% CI: 144.9–194.1), 74.2% were male. The estimated annual incidence of keratoconus was 11.8 per 100,000 (95% CI: 5.1–18.5). The average annual incidence was highest in the decade 21 to 30 years, 26.1 per 100,000 (95% CI: 16.1–36.1). For the age group 0 to 40 years, the estimated incidence of keratoconus was 22.5 per 100,000 (95% CI: 13.7–32.3).

Keratoconus should not be regarded as an uncommon condition. The prevalence of keratoconus may be even higher because of under-registration among older citizens. The estimated prevalence and incidence of keratoconus in Sweden is comparable to estimated prevalence in Norway.

Refractive trends in 15-year-old adolescents at optometric practices in southern Sweden between 2007 and 2020

Tomas Bro, Rune Brautaset — Fri, 28 Jul 2023 00:00:00 +0200

The purpose of this study was to analyse the distribution of refractive errors in 15-year-old adolescents at optometric practices in southern Sweden between 2007 and 2020. Refractive data were collected retrospectively from clinical records in five optometric practices in southern Sweden. The inclusion criteria were individuals visiting the practice at an age of 15 years between 2007 and 2020. The refractive errors were classified by the spherical equivalent (SE) (sphere + 1⁄2 cylinder) as follows: myopia (SE ≤ -0.5 D), hyperopia (SE ≥ 0.5 D), emmetropia (-0.5 > SE < 0.5 D). The astigmatism axis (-1.5 DC) was analysed as with-the-rule, against-the-rule and oblique according to traditional methods. To examine trends, the average refraction and distribution of refractive errors were compared between two selected time periods, 2007–2013 and 2014–2020. During the time frame 500 adolescents aged 15 years were examined in the selected optometric practices. Myopia was found in 34%, emmetropia in 35% and hyperopia in 31%. Among 37 individuals with astigmatism, the most common axis was with- the-rule (41%), followed by oblique (32%) and against-the-rule (27%). No significant differences could be found in the distribution of different refractive errors between the periods 2007–2013 and 2014–2020. Nor could any significant difference in average refraction be found. In contrast to the expected global rise in myopia as predicted by WHO and the high prevalence of myopia reported in some parts of the world, we could not find convincing changes in distribution between myopia and hyperopia in this cohort of Swedish adolescents.

The need for cycloplegic refraction in adolescents and young adults

Lene A. Hagen, Stuart J. Gilson, Rigmor C. Baraas — Fri, 28 Jul 2023 00:00:00 +0200

Cycloplegic refraction is considered the gold standard method when examining children and for ensuring accurate refractive error assessment within epidemiological studies. Recent reports underline that cycloplegia is equally important for ensuring accurate refractive error assessment in Chinese adolescents and young adults (Sun et al., 2018). The aim of this study was to assess whether cycloplegia is of equal importance for refractive error assessment in Norwegian adolescents and young adults. Non-cycloplegic and cycloplegic autorefraction (Huvitz HRK-8000A), and cycloplegic ocular biometry (IOLMaster 700), were undertaken in 215 Norwegian adolescents (101 males) aged 16–17 years. Topical cyclopentolate hydrochloride 1% was used for cycloplegia. Two years later, autorefraction and ocular biometry were repeated in 93 of the participants (34 males), both non-cycloplegic and cycloplegic. Non-cycloplegic spherical equivalent refractive errors (SER = sphere + 1⁄2 cylinder) were more myopic (less hyperopic) than cycloplegic SER in 93.6% of the participants (overall mean ±SD difference in SER: -0.59 ±0.50 D, 95% limit of agreement: -1.58 – 0.39 D). Refractive error classification by non-cycloplegic SER underestimated the hyperopia frequency (10.4% vs. 41.4%; SER ≥ +0.75 D) and overestimated the myopia frequency (12.1% vs. 10.7%; SER ≤ -0.75 D), as compared with refractive error classification by cycloplegic SER. Mean crystalline lens thickness decreased and mean anterior chamber depth increased with cycloplegia, with the largest changes in the hyperopes compared with the emmetropes and myopes (p ≤ 0.04). The individual differences between non-cycloplegic and cycloplegic SER varied by more than ±0.25 D between first and second visit for 31% of the participants. Accurate baseline measurements — as well as follow-up measurements — are imperative for deciding when and what to prescribe for myopic and hyperopic children, adolescents, and young adults. The results here confirm that cycloplegia is necessary to ensure accurate measurement of refractive errors in Norwegian adolescents and young adults.

Framework analysis for Vision Scientists: a clear step-by-step guide

Joel Somerville, Sven Jonuscheit, Niall Strang — Fri, 28 Jul 2023 00:00:00 +0200

Vision sciences has traditionally been a quantitative discipline. However, to fully capture all aspects of clinical vision care, researchers increasingly need to be conversant in both quantitative and qualitative methodologies. This has resulted in qualitative methodologies becoming more common in vision sciences research literature. From the authors’ perspective, vision researchers often struggle to identify suitable qualitative methodologies when coming from a tradition of a realist ontology, or the view that independent truth exists. This study explores the ontological and epistemological considerations when approaching qualitative research in vision sciences and proposes framework analysis as a qualitative methodology that is accessible for vision scientists. Framework analysis is a flexible and highly utilitarian qualitative analysis method which complements quantitative methodologies. This paper also presents a step-by-step guide for conducting framework analysis in a logical, transparent, and repeatable way that will provide a clear audit trail of how results are obtained from subjective data. This is done using a worked example from a recent eye care study.

SOPTI Meeting Abstracts 2023

Alberto Recchioni — Fri, 28 Jul 2023 00:00:00 +0200

What is happening in Sweden?

António Filipe Teixeira Macedo; Oskar Johansson, Rigmor C. Baraas — Fri, 28 Jul 2023 00:00:00 +0200