Studies in Vertical Fixation Disparity

Rutstein, Robert P.; Eskridge, Jess B.

doi:10.1097/00006324-198608000-00007

Cited by 6 publications

(5 citation statements)

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“…In the literature, the reported rates of adaptation to vertical phoria vary considerably (Brautaset & Jennings, 2005; Eskridge, 1988; Henson & North, 1980; Kono et al, 1998; Ogle & Prangen, 1953; Rutstein & Eskridge, 1986; Sethi, 1986). Some studies suggest that symptomatic subjects with hyperphoria adapt less completely to vertical prism than subjects without hyperphoria (Ogle & Prangen, 1953; Rutstein & Eskridge, 1986). On average, the subjects in Experiment 2 averaged approximately 25% adaptation after 10 minutes, which is less than the value of approximately 50% reported after a 10-minute period of adaptation by Kono et al (1998).…”

Section: Discussionmentioning

confidence: 99%

Vertical Heterophoria and Susceptibility to Visually Induced Motion Sickness

Jackson

Bedell²

2012

Strabismus

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Motion sickness is reported to be a common symptom in patients with vertical heterophoria. The goal of this study was to assess the relationship between vertical phoria and susceptibility to motion sickness in a non-clinical sample of 43 subjects. Vertical phoria was measured with a Maddox rod after 30 s of occlusion. To evaluate susceptibility to motion sickness, subjects read text while sitting inside a rotating optokinetic drum for 10 min. Subjects rated their level of motion sickness at 1 min intervals during drum rotation and the magnitude of 13 motion-sickness symptoms after drum rotation ended. The magnitude of vertical phoria ranged from 0 to 2.13 prism diopters (pd) with a mean of 0.46 pd and correlated significantly with both the maximum rating of motion sickness during drum rotation and the summed symptom score following rotation. A vertical phoria of 0.75 pd discriminated best between subjects with low vs. high summed motion-sickness-symptom scores (p < 0.0001). Introducing a prism to artificially increase the phoria of 12 subjects with vertical phorias < 0.75 pd increased motion-sickness symptoms in only 1 subject. Prisms that reduced the phoria of subjects with vertical phorias > 0.75 pd reduced motion-sickness symptoms in 2 of the 4 subjects tested. The results confirm an association between vertical phoria and motion sickness, but suggest the relationship may not be causal.

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Section: Discussionmentioning

confidence: 99%

Vertical Heterophoria and Susceptibility to Visually Induced Motion Sickness

Jackson

Bedell²

2012

Strabismus

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“…We did not find that vertical aligning prisms improved the WRRT score, and this may be due to a variety of reasons, including low subject numbers. It has been shown that some patients will easily adapt to vertically orientated prisms placed before the eyes (Rutstein and Eskridge, 1986; Rutstein, 1989), in that the amount of heterophoria with the prism reverts to the amount present without any prismatic correction within only 2–3 min (Henson and North, 1980). Indeed this phenomenon of prism adaptation has made some practitioners wary of prescribing prismatic corrections.…”

Section: Discussionmentioning

confidence: 99%

“…Indeed this phenomenon of prism adaptation has made some practitioners wary of prescribing prismatic corrections. However, studies have shown that this prism adaptation only occurs in those patients who have normal vertical fixation disparity curves (Rutstein and Eskridge, 1986; Rutstein, 1989) and that prism adaptation usually fails in patients with abnormal binocular vision (North and Henson, 1981, 1982, 1992). The research summarised in the introduction demonstrates that the presence of a fixation disparity on the Mallett Unit usually indicates abnormal binocular vision.…”

Section: Discussionmentioning

confidence: 99%

Double‐masked randomised placebo‐controlled trial of the effect of prismatic corrections on rate of reading and the relationship with symptoms

O'Leary

Evans

2006

Ophthalmic Physiologic Optic

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Practitioners' decisions on when to intervene in decompensated heterophoria are often based on symptoms, which are in some cases an unreliable indicator of whether an intervention will be helpful. The aim of our study was to determine when prismatic corrections improve performance at a measure of dynamic visual function: the Wilkins Rate of Reading Test (WRRT). All participants manifested an aligning prism (associated heterophoria) on the near Mallett Unit of 0.5Delta or greater. There were 80 participants, of whom 58 had exophoria, 15 esophoria, and seven hyperphoria. The effect of the aligning prism on the WRRT was compared with a control lens using a double-masked randomised design. For exophoria, an aligning prism of 2Delta and above has a sensitivity of 67% and a specificity of 79% for improving performance at the WRRT by 5% or more. It is not possible from our data to achieve a good compromise between sensitivity and specificity for the other types of heterophoria. Patients in the horizontal (but not vertical) heterophoria groups had significantly more symptoms than a control group. The patients whose visual performance is improved by prismatic correction are not necessarily those who report the most symptoms. Our data suggest that exophoric patients of any age are likely to have improved visual performance with an intervention if they have an aligning prism of 2Delta or more, even in the absence of symptoms. We stress that although the Mallett Unit Fixation Disparity test provides useful information, its results need to be considered in the overall context of the patient's symptoms, lifestyle, and the results of other optometric tests. Although this study evaluated prismatic corrections, we note that interventions for decompensated heterophoria include not only prismatic corrections, but also eye exercises and refractive modification.

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“…The focus of this article is on horizontal fixation disparity, although cyclorotational fixation disparity and vertical fixation disparity have been recognized and extensively studied. [9][10][11]…”

mentioning

confidence: 99%

“…Binocular capture is a phenomenon whereby the perceived visual direction of a monocularly viewed object is shifted in the direction of the fused or cyclopean percept of a nearby binocular stimulus. The focus of this article is on horizontal fixation disparity, although cyclorotational fixation disparity and vertical fixation disparity have been recognized and extensively studied 9–11 …”

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confidence: 99%

Topical Review: Methodological Variables in Clinical and Laboratory Measurements of Fixation Disparity

Fogt

2023

Optom Vis Sci

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Significance Fixation disparity is a small vergence error that does not disrupt fusion. Fixation disparity measures correlate with binocular symptoms. This paper covers methodological differences between clinical fixation disparity measurement devices, findings when objective and subjective fixation disparities are compared, and the potential impact of binocular capture on fixation disparity measurements. Fixation disparity is a small vergence error that occurs in non-strabismic individuals and does not disrupt fusion. This paper reviews clinical fixation disparity variables and their clinical diagnostic value. Clinical devices that are used to measure these variables are described as are studies in which the output from these devices have been compared. Methodological differences between the devices such as the location of the fusional stimulus, the rate at which judgments of dichoptic alignment are made, and the strength of the accommodative stimulus are all considered. In addition, the paper covers theories of the neural origins of fixation disparity and control systems models incorporating fixation disparity. Studies in which objective fixation disparities (oculomotor portion of fixation disparity assessed with an eye tracker) and subjective fixation disparities (sensory portion of fixation disparity assessed psychophysically with dichoptic Nonius lines) have been compared are also examined, and consideration is given to why some investigators find differences in these measures while other investigators do not. The conclusion thus far is that there are likely complex interactions between vergence adaptation, accommodation, and the location of the fusional stimulus that lead to differences in objective and subjective fixation disparity measures. Finally, capture of the visual direction of monocular stimuli by adjacent fusional stimuli and the implications for fixation disparity measures are considered.

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Studies in Vertical Fixation Disparity

Cited by 6 publications

References 0 publications

Vertical Heterophoria and Susceptibility to Visually Induced Motion Sickness

Vertical Heterophoria and Susceptibility to Visually Induced Motion Sickness

Double‐masked randomised placebo‐controlled trial of the effect of prismatic corrections on rate of reading and the relationship with symptoms

Topical Review: Methodological Variables in Clinical and Laboratory Measurements of Fixation Disparity

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