Abstract
Purpose :
To compare the Welch-Allyn VS100 Spot handheld infrared vision screener (VS100) to four common methods of measuring monocular interpupillary distance (IPD) in a cohort of children with myopia and ascertain its accuracy for the dispensing of corrective spectacles.
Methods :
The mean of four measurements of monocular IPD for both eyes were measured in a cohort of children with myopia (N=56), mean age 10.15±2.65years using the VS100, pupil distance ruler (PD Ruler), CT4113 pupilometer, Essilor Eye Ruler 2 (iPad), and Grand Seiko WAM-5500 open field autorefractor (WAM) prior to dispensing spectacles. The VS100 and WAM both measure binocular IPD, therefore, monocular IPD was calculated by dividing the binocular IPD by 2. Data was found to be normally distributed using Shapiro-Wilk test(p>.05), a one-way repeated measures ANOVA was used for statistical analysis.
Results :
Monocular IPD was measured as 28.67±2.05mm for each eye with the VS100. Right IPD was larger than the PD Ruler(28.03±1.74mm), pupillometer(27.84±1.84mm) and WAM (28.06±1.90mm), but smaller than the iPad(29.23±2.16mm), all of which were statistically significant (p <.05). For the left IPD the VS100 was significantly larger than the iPad(27.38±1.77mm) and WAM(28.06±1.90mm), and smaller than the PD Ruler(28.76±1.78mm) and pupilometer(28.79±1.87mm), but not statisctically significant (p >.05). this equates to an increase of up to 4.50% and a reduction of up to -2.13% in comparison to the other devices. Differences in monocular IPD can be explained by natural facial asymmetry present in the participants.
Conclusions :
The VS100 can accurately measure monocular IPD when compared to the other methods tested, but may over and underestimate the result. Although some differences were statistically significant, all were within the British Standard for horizontal optical centration of ±1mm, except when compared to the iPad. This could indicate the VS100 can be used to aid the dispensing of spectacles in children aged under 16 years with myopia allowing the practitioner a greater working distance that avoids invading the childs personal space.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.