Evaluating a new logMAR chart designed to improve visual acuity assessment in population-based surveys

Abstract

Aims This study aimed to evaluate a new chart designed to improve the collection of visual acuity data in population-based surveys. The Reduced logMAR E chart (RLME) employs three letters per line, 'tumbling E' optotypes, and conforms to accepted contemporary design principles. Methods The performance of the chart was assessed within a population-based glaucoma survey in Thailand. Performance indices were test-retest variability (TRV) and agreement with acuity data measured using the ETDRS logMAR chart which acted as the 'gold standard'. Results The 95% confidence limits for TRV of RLME acuity data were 70.15 logMAR. This figure is consistent with published data on the TRV of acuities measured using five-letter-perline logMAR charts. The mean difference between RLME and ETDRS acuity data was 0.00 logMAR (95% confidence intervals of 70.05 logMAR) indicating that RLME acuities agreed well with those of the ETDRS chart. The chart and its method of use was readily accepted by the local ancillary staff who required only minimal training before acuity measurement could be delegated to them. Conclusions The study demonstrated that the RLME chart is capable of accurate and repeatable acuity measurements. Certain aspects of the design of the RLME chart may be particularly pertinent to the measurement of vision in population-based surveys.

The Pakistan National Blindness and Visual Impairment Survey—Research Design, Eye Examination Methodology and Results of the Pilot Study

“…21 Prior to this study, the chart had been extensively validated in clinic-based 22 and population-based studies 23 in advance of its use in the National Blindness and Low Vision Survey of Bangladesh. 3,4 The RLM chart is based on the illiterate E, a necessity in a population with only 47% adult literacy.…”

Supporting the development of inclusive products: the effects of everyday ambient illumination levels and contrast on older adults' near visual acuity

“…The advantages of using these charts for assessment in clinical and population based surveys have been well documented (Bailey and Lovie, 1976;Ferris et al, 1982;Ferris and Bailey, 1996;Lovie-Kitchin, 1998;Colebrander, 2002;Bourne et al, 2003). In particular, their design/layout means that task difficulty increases in equal steps, letter size is the sole determinant of difficulty on a given line, each letter has an equal chance of being recognised and the acuity data produced from the charts is classed as interval data which lends itself to parametric statistical analyses.…”

“…Logarithm of Minimum Angle of Resolution (LogMAR) charts (see Figure 1) were developed for the purposes of this study to measure VA as they are regarded as the gold standard of VA tests (Bourne et al, 2003;Hazel and Elliot, 2002). The advantages of using these charts for assessment in clinical and population based surveys have been well documented (Bailey and Lovie, 1976;Ferris et al, 1982;Ferris and Bailey, 1996;Lovie-Kitchin, 1998;Colebrander, 2002;Bourne et al, 2003).…”

Argon laser photocoagulation for diabetic macular oedema

“…The Snellen visual acuity (converted to LogMAR), 5 number of treatments, and fluorescein angiographies performed were recorded. The patients were followed for 3 years, and the proportion of patients with MVL at 1, 2, and 3 years was compared to ETDRS data ( Figure 1).…”