Changes in stimulus and response AC/A ratio with vision therapy in Convergence Insufficiency

Singh, Neeraj; Mani, Revathy; Hussaindeen, Jameel Rizwana

doi:10.1016/j.optom.2016.10.001

Cited by 12 publications

(6 citation statements)

References 27 publications

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“…The refractive error of the basic IXT group was more myopic than that in the CI IXT group. Patients with CI IXT typically have a reduced near point of convergence (NPC) and positive fusional vergence (PFV) for near viewing, as well as a low accommodative convergence to accommodation (AC/A) ratio [ 21 ]. However, higher AC/A ratios was related to a greater lag of accommodation and have been reported as a risk factor for myopia in children [ 22 , 23 ].…”

Section: Discussionmentioning

confidence: 99%

Comparing myopic error in patients with basic and convergence insufficiency intermittent exotropia in China

et al. 2023

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Purpose To compare the degree of myopia between the dominant and non-dominant eyes in teenagers with intermittent exotropia (IXT) in China. Methods A total of 199 IXT patients with myopia were included in this retrospective study and were divided into two groups according to the difference between near and distance exodeviation: basic IXT and convergence insufficiency (CI) IXT. Refractive errors were analyzed by spherical equivalent (SE) values. Patients were further stratified into anisometropia group and non-anisometropia group based on binocular SE values difference greater than 1.0D or not. Results There were 127 patients in the CI IXT group, with a near deviation of 46.94 ± 20.53 prism diopters (PD) and a distance deviation of 28.36 ± 14.34 PD, and there were 72 (36.2%) patients in the basic IXT group, with a near deviation of 37.68 ± 22.21 PD and a distance deviation angle of 33.21 ± 23.96 PD. The near exodeviation was significantly larger in the CI group than in the basic IXT group(P < 0.001). In the CI IXT group, the mean SE was − 2.09 ± 1.45 diopters (D) in the dominant eye and − 2.53 ± 1.44D in the non-dominant eye, while in the basic IXT group, the mean SE was − 2.46 ± 1.56D in the dominant eye and − 2.89 ± 1.37D in the non-dominant eye. The anisometropia group included 43 patients, while non-anisometropia group included 156 patients. The near and distance exodeviation in the anisometropia group were 45.26 ± 24.41 PD and 33.53 ± 23.31 PD, respectively, and those in the non-anisometropia group were 43.42 ± 20.69 PD and 29.07 ± 16.84 PD, respectively. There were no significant differences in near and distance deviation (P = 0.78 and P = 0.73 respectively) between the two groups. The SE of the dominant eye was less myopic than of the non-dominant eyes in both the CI and anisometropia groups (P = 0.002 and P < 0.001, respectively). Conclusions Our study revealed that convergence insufficiency IXT is more common than the basic type in pediatric myopic population and is characterized by higher inter-eye differences of myopia. The dominant eye was found to be less myopic in IXT patients, particularly in those with convergence insufficiency and anisometropia.

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Section: Discussionmentioning

confidence: 99%

Comparing myopic error in patients with basic and convergence insufficiency intermittent exotropia in China

et al. 2023

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“…Thus, the asymmetry between converge and divergence observed in the present research, and the dependence of stereo-localization accuracy on the AC/A ratio are relevant in vision therapy, particularly when working with vectograms eliciting the SILO effect. Singh and co-workers found an improvement rate in stimulus and response AC/A ratio after 10 sessions of vision therapy [ 19 ], in contrast with the results described by Bratauset and Jennings, using stimulus AC/A ratio and gradient method, although improvements were observed in fast and slow vergence mechanisms [ 20 ]. These discrepancies may be explained with the high variability in stimulus AC/A ratio described by some researchers [ 21 , 22 , 23 ].…”

Section: Discussionmentioning

confidence: 99%

Vergence and Accommodation Cues in Stereo-Localization during the Small-In Large-Out (SILO) Effect

Argilés

Cardona

Hosa-Vila

et al. 2022

Vision

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A typical procedure in vision therapy is the use of Quoits vectograms to train fusional vergence ranges by improving stereo-localization, which is the ability to correctly locate the target stimulus in space. With this procedure, the Small-In Large-Out (SILO) effect is usually reported in patients with normal binocular vision and accommodation. In this study, the influence of vergence and accommodation cues, as determined with the accommodative-convergence over accommodation (AC/A) ratio, to correctly locate the Quoits vectograms in space was investigated. Twenty participants, aged 29.2 ± 2.8 (mean ± standard deviation) years, without amblyopia or strabismus, were recruited. A geometrical formula was obtained to calculate the theoretical distance to the target stimulus for different vergence demands. Theoretical values were compared with measured distances to the perceived stimuli and stereo-localization accuracy was determined. Stereo-localization accuracy was significantly worse at 10∆ Base In vergence demand (p < 0.001). A statistically significant positive correlation was found between AC/A ratio and stereo-localization accuracy (i.e., worse accuracy) at 10Δ Base Out vergence demand (rho = 0.446, p = 0.049). These findings highlight that AC/A ratio may be a secondary cue for stereo-localization when using vectograms in which the SILO effect is manifest. These results assist in the understanding of the physiological basis of vision therapy procedures.

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“…Schor reported that eso fixation disparity after orthoptic treatment for patients with convergence insufficiency (i.e., paradoxical fixation disparity) was a positive sign, and that the esodeviation would decrease after the discontinuation of therapy. 7 Several studies [8][9][10][11][12][13][14][15] have reported mean decreases in the near exophoria ranging from 0.4∆ to 3.5∆, with Kim and Chun 16 reporting a mean decrease of 8∆ after treatment with vision therapy or orthoptics. However, these investigations had small sample sizes, 8,[11][12][13][14][15] did not use masked examiners [8][9][10][11][12][13][14][15][16] or were not conducted on children.…”

Section: Introductionmentioning

confidence: 99%

“…7 Several studies [8][9][10][11][12][13][14][15] have reported mean decreases in the near exophoria ranging from 0.4∆ to 3.5∆, with Kim and Chun 16 reporting a mean decrease of 8∆ after treatment with vision therapy or orthoptics. However, these investigations had small sample sizes, 8,[11][12][13][14][15] did not use masked examiners [8][9][10][11][12][13][14][15][16] or were not conducted on children. 9,11,12,14,15 Multiple investigators have described the 'dual mode theory' as a possible mechanism that leads to a decrease in the exodeviation after vision therapy.…”

Section: Introductionmentioning

confidence: 99%

Effects of vision therapy on near exodeviation in children with convergence insufficiency treated during the convergence insufficiency treatment trials

Schulman,

Scheiman,

Kulp

et al. 2024

Ophthalmic Physiologic Optic

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PurposeTo report the change in the magnitude of near exodeviation in children with symptomatic convergence insufficiency successfully treated with office‐based vergence/accommodative therapy in the Convergence Insufficiency Treatment Trial–Attention and Reading Trial.MethodsA total of 131 children 9–14 years of age with symptomatic convergence insufficiency classified as successfully treated with office‐based vergence/accommodative therapy at the 16‐week outcome visit were included. Masked examiners measured the near ocular deviation by the prism and alternate cover test at baseline, primary outcome and 1‐year post‐treatment. The mean change in near deviation was calculated from baseline to primary outcome, from primary outcome to 1‐year post‐treatment and from baseline to 1‐year post‐treatment.ResultsOf the 131 participants successfully treated with vergence/accommodative therapy, 120 completed the 1‐year post‐treatment visit. A significant change in near exodeviation was observed at baseline to primary outcome (2.6Δ less exo, p < 0.001, moderate effect size d = 0.61) and at baseline to 1‐year post‐treatment (2.0Δ less exo; p < 0.001, small effect size d = 0.45). The change from primary outcome to 1‐year post‐treatment (0.6Δ more exo; p = 0.06, small effect size d = 0.11) was not significant. Forty per cent (48/120) of participants had a decrease in near exodeviation >3.5∆ (expected test/retest variability) between baseline and the primary outcome examination. Of the 120 participants, one (1.0%) was esophoric at the primary outcome and was subsequently exophoric at 1‐year post‐treatment. Four participants (3.3%) who were orthophoric or exophoric at the primary outcome were esophoric (all ≤3∆) at the 1‐year post‐treatment visit.ConclusionOn average, the near exodeviation was smaller in size immediately after the discontinuation of vergence/accommodative therapy (2.6∆, moderate effect size) and 1 year post vergence/accommodative therapy (2.0∆, small effect size) in children with convergence insufficiency who were successfully treated; 40% had a clinically meaningful decrease in exophoria. The development of near esophoria was rare.

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Changes in stimulus and response AC/A ratio with vision therapy in Convergence Insufficiency

Cited by 12 publications

References 27 publications

Comparing myopic error in patients with basic and convergence insufficiency intermittent exotropia in China

Comparing myopic error in patients with basic and convergence insufficiency intermittent exotropia in China

Vergence and Accommodation Cues in Stereo-Localization during the Small-In Large-Out (SILO) Effect

Effects of vision therapy on near exodeviation in children with convergence insufficiency treated during the convergence insufficiency treatment trials

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