Abstract
Purpose :
This study aimed to determine the comparability of two visual acuity (VA) tests, HOTV logMAR and Sheridan Gardiner (SG), their impact on referral criteria and whether additional orthoptic tests improved accuracy of referrals.
Methods :
The Statewide Eyesight Preschooler Screening (StEPS) program is a free vision screening program for all 4 year olds in NSW; which originally used SG but has now transitioned to HOTV. This study recruited 147 children through StEPS. VA was tested twice, alternating the order of the HOTV and SG between children, followed by a comprehensive orthoptic examination. Referral criteria was classified: routine VA<6/9-2 or high priority VA≤6/18. Informed consent was obtained from all parents/guardians of participating children. This study was approved by the Human Research Ethics Committee, University of Technology Sydney and adhered to the tenets of Declaration of Helsinki.
Results :
HOTV had higher testability (98.0%) than SG (95.2%), although not statistically significant. However, the difference in mean VA was significant (HOTV: 6/7.5-1, SG: 6/9-1, p<.001). On testing with HOTV, 12 children qualified for routine referrals, and one high priority referral. Using SG, there were 35 routine and 6 high priority referrals, representing an additional 28 children who would have been referred using the SG measures. Additionally, HOTV has a line between 6/12 and 6/18 (6/15) that is not present in SG. Consequently one child with HOTV VA 6/15, using SG would have a high priority referral but became routine. When examining an inter-ocular difference (IOD) in VA of at least two lines, 3 children who did not previously meet the referral criteria were detected. A further 3 children (2%) were detected on orthoptic assessment alone, case of anisocoria, gaze-evoked nystagmus and intermittent exotropia, respectively.
Conclusions :
HOTV was more testable than SG and substantially reduced false positive referrals in this vision screening program of children aged four. Further analysis is required to determine whether the high priority referral criteria should change to acknowledge the 6/15 line in the HOTV chart. While VA better than 6/9-2 is normally a pass, the data indicates that a greater than two line IOD in VA should also be considered in vision screening referral criteria. While orthoptic testing did detect additional cases, the proportion and the level of skill required to conduct these tests may not be appropriate in the context of screening.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.