Decompensated exophoria at near, convergence insufficiency and binocular instability: diagnosis and the development of a new treatment regimen

Evans, Bruce J. W.

doi:10.1016/b978-0-7506-4713-7.50009-6

Cited by 6 publications

(6 citation statements)

References 20 publications

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“…However, there will inevitably be cases where the symptoms of Meares–Irlen syndrome might at least partly result from accommodative insufficiency and/or decompensated heterophoria. Both these conditions can be treated refractively (Evans, 2000a) or orthoptically (Evans, 2000a, b). Lightstone and Evans (1995) recommended that if a patient with suspected Meares–Irlen syndrome has the clinical signs of a decompensated heterophoria or of accommodative dysfunction then these ocular motor factors should be treated in the first instance.…”

Section: Discussionmentioning

confidence: 99%

Coloured overlays in schools: orthoptic and optometric findings

Scott

McWhinnie

Taylor³

et al. 2002

Ophthalmic Physiologic Optic

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In two studies, the first in a school in Peterborough and the second in a school in Norwich, more than 233 children aged 8-12 years received either an orthoptic examination, or an optometric examination, together with an examination using coloured overlays and a test of reading fluency. In both studies more than one-third of the children reported visual symptoms. More than one-third of the children chose to use an overlay, and they read more quickly with it than without. The colour of the overlay chosen was weakly related to the binocular amplitude of accommodation: overlays reflecting greater energy at long wavelengths were chosen more frequently by children with a higher amplitude of accommodation. Although the visual symptoms were strongly related to the use of an overlay, in neither study was the benefit from an overlay strongly related to the orthoptic or optometric findings. Nevertheless, children who used an overlay had slightly, but significantly, reduced mean binocular amplitude of accommodation and fusional reserves. On average, children with 'sensory' or 'motor' instability of the nonius strips of the Mallett unit read more slowly than others, as did those with poor stereopsis. However, 60% of those demonstrating sustained overlay use gave a normal response on the Mallett aligning prism test, compared with 80% of those who did not use an overlay for a sustained period. Another indicator of decompensated heterophoria, Sheard's criterion, did not differentiate subjects who used overlays from those who did not. Although binocular and accommodative anomalies do not appear to be the underlying mechanism for the benefit from coloured filters in most cases, there may be some individuals who respond to coloured filters and in whom these ocular motor factors require treatment. Children with visually precipitated symptoms and/or reading difficulties need both a careful evaluation of their accommodative and binocular status, and an investigation of the effect of coloured filters.

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Section: Discussionmentioning

confidence: 99%

Coloured overlays in schools: orthoptic and optometric findings

Scott

McWhinnie

Taylor³

et al. 2002

Ophthalmic Physiologic Optic

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“…The effect of short‐term MD has physiological correlates in the primary visual cortex of humans 9–11 . Recently, researchers have attempted to introduce repeated periods of short‐term MD across days or months to restore the vision of young adults with binocular imbalance, which is a common feature of dissociative visual disorders that affect up to 18% of the population 12 . Amblyopia, a developmental visual disorder that affects 3%–5% of the population, is an extreme example of imbalanced binocular vision where there can be almost total reliance on one eye when both eyes are open.…”

Section: Introductionmentioning

confidence: 99%

Daily dose–response from short‐term monocular deprivation in adult humans

Zou,

Zhou,

Hess

et al. 2024

Ophthalmic Physiologic Optic

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Short‐term monocular deprivation (MD) shifts sensory eye balance in favour of the previously deprived eye. The effect of MD on eye balance is significant but brief in adult humans. Recently, researchers and clinicians have attempted to implement MD in clinical settings for adults with impaired binocular vision. Although the effect of MD has been studied in detail in single‐session protocols, what is not known is whether the effect of MD on eye balance deteriorates after repeated periods of MD (termed ‘perceptual deterioration’). An answer to this question is relevant for two reasons. Firstly, the effect of MD (i.e., dose‐response) should not decrease with repeated use if MD is to be used therapeutically (e.g., daily for weeks). Second, it bears upon the question of whether the neural basis of the effects of MD and contrast adaptation, a closely related phenomenon, is the same. The sensory change from contrast adaptation depends on recent experience. If the observer has recently experienced the same adaptation multiple times for consecutive days, then the adaptation effect will be smaller because contrast adaptation exhibits perceptual deterioration, so it is of interest to know if the effects of MD follow suit. This study measured the effect of 2‐h MD for seven consecutive days on binocular balance of 15 normally sighted adults. We found that the shift in eye balance from MD stayed consistent, showing no signs of deterioration after subjects experienced multiple periods of MD. This finding shows no loss of effectiveness of repeated daily doses of MD if used therapeutically to rebalance binocular vision in otherwise normal individuals. Furthermore, ocular dominance plasticity, which is the basis of the effects of short‐term MD, does not seem to share the property of ‘perceptual deterioration’ with contrast adaptation, suggesting different neural bases for these two related phenomena.

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“…1 Evans defined CI as a condition that involves the inability of the eyes to obtain or maintain sufficient convergence for comfortable binocular vision at near distance. 2 Convergence insufficiency is a typical condition in young and aging adults and may be Correspondence: Izmal Urooj Isra School of Optometry, Isra University Karachi Email: izmalurooj@gmail.com Received: September 16, 2020 Accepted: November 12, 2020 isolated and idiopathic or associated with other neurologic diseases. 3 It can cause problem in reading, for which parents or teachers might think of the child having problem in learning rather than having an eye disorder.…”

Section: Introductionmentioning

confidence: 99%

Frequency of Convergence Insufficiency in a Refraction Clinic of Karachi

Urooj¹,

Ali

Ghayas

et al. 2020

pak J Ophthalmol

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Purpose: To find out the frequency of convergence insufficiency in a refraction clinic of Karachi. Study Design: Cross Sectional Study. Place and Duration of Study: Al-Ibrahim Rye Hospital, Karachi from June to December 2019. Methods: A total of 150 patients were included in the study (52 males and 98 females). Patients with un-corrected visual acuity of ≥6/9 and age between 16 – 35 years were included. Patients who had received treatment for convergence insufficiency (CI), mentally retarded patients, patients with Manifest strabismus or any other ocular pathology were excluded. Near point of convergence (NPC), near phoria and positive fusional vergence (PFV) were measured for the diagnosis of CI. Results: Mean age of the patients was 23.55 years. Gender wise distribution showed that 52 (34.7%) were males and 98 (65.3%) were females. Out of 150 patients, 64 patients had CI and 42 were normal with no reduction in NPC, PFV or exophoria. Rest of the patients had only one of the three criteria of CI but did not qualify our definition of CI. Twenty-five male patients and 39 female patients had CI. CI was more common in teenagers. With increasing age, the frequency of CI was reduced. CI due to remote NPC was seen in 12 (8%) and CI due to decreased PFV was seen in 21 (14%). Conclusion: Females are affected more with CI than males especially in the younger age group. Keywords: Convergence insufficiency, near point of convergence, Positive fusional vergence.

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Decompensated exophoria at near, convergence insufficiency and binocular instability: diagnosis and the development of a new treatment regimen

Cited by 6 publications

References 20 publications

Coloured overlays in schools: orthoptic and optometric findings

Coloured overlays in schools: orthoptic and optometric findings

Daily dose–response from short‐term monocular deprivation in adult humans

Frequency of Convergence Insufficiency in a Refraction Clinic of Karachi

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