Abstract
Purpose: :
To establish age- and gender-specific testability rates for the electronic visual acuity (EVA) tester using HOTV letters in Australian preschool children and to compare these findings with the standard LogMAR visual acuity (VA) chart.
Methods: :
The Sydney Paediatric Eye Disease Study (SPEDS) is a population-based, cross-sectional study of children aged 6 months to 6 years. Measurement of presenting monocular distance VA using the ATS HOTV protocol on the EVA tester (Jaeb Center for Health Research, Tampa, Florida, USA, 3m) was attempted on all children examined, who were aged 30 to 84 months. Testability was determined by the ability of the children to have VA tested monocularly in both eyes. Age- and gender-specific testability rates were calculated. Children aged >60 months also had repeat VA tested with the LogMAR chart (EDTRS or HOTV letter presentation, CSV1000 vector vision, 2.44m). VA findings for right eyes only are presented.
Results: :
EVA testing was attempted on 865 children (50.2% female). Testability was 93.0% in female children and 88.3% in male children. Age-specific testability rates were 55.9% for children aged 30 to <36 months, 91.4% for children aged 36 to <48 months, 98.5% for children aged 48 to <60 months, 98.9% for those 60 to <72 months, and 99.1% for those aged 72 months or older. Of the children aged 60+ months, 247 had their vision tested using both EVA and LogMAR charts, with a LogMAR testability of 84.5%. Average VA for the EVA and the EDTRS and HOTV logMAR charts was 54, 50 and 48 letters respectively. There was a statistical and clinically significant mean difference of 5 letters between the EVA and EDTRS (p<.0001), and between the EVA and HOTV LogMAR charts (p<.0001). Gender and the presence of refractive error did not alter the number of letters read when comparing the EVA and LogMAR charts. There was a trend for the difference between the EVA and EDTRS charts to decline with age (p=0.005), but this was not found for the HOTV chart.
Conclusions: :
Monocular threshold VA testing using the EVA can be completed by the majority of Australian pre-school children at most ages, with 97% testability in children aged at least 36 months. The EVA overestimated VA by comparison with the logMAR, although testability with the logMAR chart was not as high as with the EVA.
Keywords: visual acuity • clinical (human) or epidemiologic studies: systems/equipment/techniques • clinical research methodology