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Effect of Vergence Facility Testing on Horizontal Fusional Reserves Publisher Pubmed



Askarizadeh F1 ; Heirani M2 ; Khorraminejad M2 ; Khabazkhoob M3, 4 ; Narooienoori F5
Authors
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Authors Affiliations
  1. 1. Department of Optometry, Faculty of Rehabilitation Sciences, Tabriz University of Medical Sciences, Tabriz, Iran
  2. 2. Translational Ophthalmology Research Center, Farabi Eye Hospital, Tehran University of Medical Sciences, Tehran, Iran
  3. 3. Department of Medical Surgical Nursing, School of Nursing and Midwifery, Shahid Beheshti University of Medical Sciences, Tehran, Iran
  4. 4. Noor Research Center for Ophthalmic Epidemiology, Noor Eye Hospital, Tehran, Iran
  5. 5. Rehabilitation Research Center, Department of Optometry, School of Rehabilitation Sciences, Iran University of Medical Sciences, Tehran, Iran

Source: Optometry and Vision Science Published:2022


Abstract

SIGNIFICANCE: The effect of vergence adaptation on test sequences should be considered in clinical practice. PURPOSE: This study aimed to compare the effect of vergence adaptation after different vergence facility (VF) testing methods on following horizontal fusional reserve measurement at near. METHODS: This cross-sectional study was performed on 50 healthy subjects with a mean ± standard deviation age of 21.18 ± 1.41 years. The baseline horizontal fusional reserves were measured using base-in (BI) and base-out (BO) prisms (Δ) at near. Then, VF was measured using 3ΔBI/12ΔBI flip prism at near, and then the measurement of fusional reserves was repeated. In the next step, fusional reserves were measured after VF testing using 8ΔBI/ 8ΔBO flip prism. The values of fusional reserves were compared with their baseline findings. RESULTS: The results of negative fusional reserves after VF measurement using the 3ΔBI/12ΔBO prisms were significantly lower than the baseline values (blur [P = .03], break [P = .03], and recovery [P = .03]). There were no significant differences between the values of fusional reserves before and after VF testing using the 8ΔBI/8ΔBO prisms (P > .05). No correlation was observed between fusional reserves and VF responses (P > .05); however, the results revealed a positive correlation between the values of fusional reserves before and after VF testing using both methods (all P < .05). There was no significant difference in VF findings between the methods (P = .23). CONCLUSIONS: The measurements of horizontal fusional reserves followed by VF testing were not affected except for the responses of negative fusional reserves, which decreased after VF determination using the 3ΔBI/12ΔBO method. Although the vergence adaptation does not seem clinically significant, it is recommended to evaluate horizontal fusional reserves before VF measurement or long-enough time after VF testing for the vergence system to return to its nonadapted state. Copyright © 2021 American Academy of Optometry