Parallel rarebits: A novel, large‐scale visual field screening method

Abstract

Background

Rarebit perimetry () is a computer‐based perimetric testing program with sensitivity and specificity for detection of visual field defects comparable to traditional automated perimetry. To make large‐scale screening more efficient, we developed a parallel rarebit perimetric method to screen groups of subjects simultaneously. We then used this method to report the mean hit rate (MHR) among subjects aged 13 to 19 years.

Methods

Rarebit perimetry was installed on computers in an existing school computer laboratory. All subjects provided medical and demographic information and underwent a basic visual examination. Testing instructions were provided to groups of up to 35 subjects and rarebit perimetry was subsequently administered. Two or three test supervisors answered questions and ensured that subjects were well aligned with their test screens. Mean hit rate, reaction times, error rates and testing time were calculated, and time estimates for rarebit, frequency doubling perimetry and Humphrey 24‐2 Swedish Interactive Thresholding Algorithm (SITA) fast test were compared.

Results

A total of 364 rarebit perimetric tests were conducted on 182 subjects. Of these, 154 subjects met our inclusion criteria for the reference range (three testing errors or less and visual acuity 6/9 or better). The average mean hit rate was 94.3 ± 4.63 per cent. Screening of 500 subjects using this parallel rarebit perimetric method would require approximately nine hours, which is far less than an estimated 77 hours required for frequency doubling perimetry ‐20 screening tests or an estimated 127 hours required for Humphrey 24‐2 SITA fast tests.

Conclusion

Using our methods, rarebit perimetry can be administered in parallel to groups of subjects. The mean hit rate was comparable to that reported in previously published studies. This parallel technique may improve the efficiency of large‐scale visual field screenings.

Key words:

• paediatric eye screening
• rarebit perimetry
• visual field screening

Acknowledgements

We would like to thank the Ngan Po Ling Secondary School in Hong Kong, SAR and Saint Theresa Secondary School in Hong Kong, SAR for their support.

We are grateful to the Chinese University of Hong Kong (CUHK) Eye Hospital with special thanks to Dr Fan and Dr Tam for all their support.

We also thank Lam Siu Chuen, without whom this work would not have been possible.

This research was supported by a Stanford Travelling Scholars Research Grant, the Stanford School of Medicine, Medical Scholars Research Program and an American Glaucoma Society MAPS Grant.

Additional information

Funding

Stanford Travelling Scholars Research Grant

Stanford School of Medicine, Medical Scholars Research Program

American Glaucoma Society MAPS Grant