Effect of an intervening screen on accommodation to a distant object

Stark, Lawrence; Atchison, David A.

doi:10.1111/j.1444-0938.1998.tb06730.x

Cited by 8 publications

(3 citation statements)

References 25 publications

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“…There is controversy in the literature regarding the existence and explanation of the Mandelbaum effect. 11,12 Our observations with the multivergence hologram are consistent with Owen's findings 5 described earlier in this section and suggest that the Mandelbaum effect exists and manifests itself strongly under certain viewing conditions. Leibowitz and Owens 13 have shown in the past that phenomena such as night myopia, empty field myopia, and instrument myopia correlate highly in magnitude to the dark focus.…”

Section: Discussionsupporting

confidence: 81%

Role of Mandelbaum-like effect in the differentiation of hyperopes and myopes using a hologram

Nguyen

Avudainayagam

2013

J. Biomed. Opt

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Abstract. Recently, we tested the vision of spectacle corrected subjects using a special hologram (http://dx.doi.org/ 10.1364/BOE.3.001173). A subject viewing through this hologram sees the images of various numbers at different distances from the eye. Each of these images subtends an angle of 50 0 at the eye. Each image corresponds to a different amount of divergence or convergence at the eye. The limit of convergence (positive blur) with which a subject can recognize the numbers was measured. Hyperopes could recognize numbers with 0.9 D more of positive blur in comparison with myopes. This difference was not obtained with a standard test chart under white light illumination using positive lenses to provide the blur. The observed difference with the hologram is then attributed to the multivergence nature of the target in the hologram and/or the monochromaticity of the illumination used. Using a hologram of a logMAR chart at a single distance of infinity we have now found that the observed difference is induced by the multivergence target and is due to an effect that is similar to the Mandelbaum effect. We present the details of this experiment and compare the results obtained with our earlier experiment. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

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Section: Discussionsupporting

confidence: 81%

Role of Mandelbaum-like effect in the differentiation of hyperopes and myopes using a hologram

Nguyen

Avudainayagam

2013

J. Biomed. Opt

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“…Their accommodative system tended to focus upon an intermediate, rather than far distance, depth plane. This small degree of myopic defocus (<0.6 D) also results in slightly reduced visual acuity 19 . Furthermore, it might slightly impair global visual perception under dynamic viewing conditions.…”

Section: Discussionmentioning

confidence: 96%

“…This small degree of myopic defocus (<0.6 D) also results in slightly reduced visual acuity. 19 Furthermore, it might slightly impair global visual perception under dynamic viewing conditions. These ideas should be explored in the laboratory to understand better the related visual consequences and possible localization of the responsible neural site/pathway.…”

Section: Discussionmentioning

confidence: 99%

Historical, Diagnostic, and Chromatic Treatment in Visual Snow Syndrome: A Retrospective Analysis

Han¹,

Ciuffreda

Rutner

2023

Optom Vis Sci

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SIGNIFICANCE:Visual snow syndrome is a relatively new medical condition, with presence of visual snow as the primary visual-perceptual symptom. Information from the present study will improve future clinical diagnostic and treatment aspects in this population.PURPOSE: This study aimed to determine the historical, diagnostic, and treatment aspects in patients with documented visual snow syndrome/visual snow in an academic, optometric setting.METHODS: A retrospective analysis was performed in patients (N = 40, aged 12 to 55 years) with documented visual snow syndrome/visual snow examined over a 4-year period. Information was collected by a detailed case history and the Visual Snow Syndrome Symptom Survey. Treatment assessment was performed using the Intuitive Colorimeter, and a wide selection of chromatic tints was assessed under the most provocative/exacerbating and other conditions. RESULTS: Visual snow was typically constant and monochromatic, with it being present on average 6.43 years. Bright and dark surfaces were the most provocative/exacerbating/revealing conditions, along with the viewing of computer screens. The most common etiology was mild traumatic brain injury. The most common primary and secondary symptoms were photosensitivity and tinnitus, respectively. There was a high frequency of occurrence of oculomotor deficits, especially accommodative and vergence insufficiency (~40 to 50%). Eighty percent of the patients were prescribed a chromatic tint with subjective visual reduction of visual snow ranging from 15 to 100% (mean, 45%). CONCLUSIONS:The present information will help in understanding this unusual medicoperceptual condition, especially with respect to simple treatment frequently using readily available chromatic tints.

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Emmetropization in chicks uses optical vergence and relative distance cues to decode defocus

Wildsoet

Schmid

2001

Vision Research

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When visual information is confined to one object plane, the emmetropization end-point is adjusted in accord with the corresponding incident optical vergence at the eye [Proceedings of the 7th International Conference on Myopia (2000) 113]. We now report the effect of adding extra visual information beyond the target plane. Visual conditions were controlled using a cone-lens system: black Maltese cross targets on white opaque backgrounds (OMX) were attached to the open faces of 2.5 cm translucent cones fitted with either 0, +25 or +40 D imaging lenses. An alternative target (TMX) was made by substituting the opaque target background for a transparent background, which allowed access to visual information beyond the target plane. The imaging devices were applied to 7-day-old chicks and worn for 4 days. Prior to this treatment, on day 2, some chicks underwent ciliary nerve section (CNS) to preclude accommodation. All treatments were monocular. Refractive errors and axial ocular dimensions were measured using retinoscopy and A-scan ultrasonography under halothane anesthesia. Treatment effects were specified as mean ( +/-S.D.) interocular differences. Eyes with the OMX/+40 D lens combination remained emmetropic (+0.73 +/-3.57 D), consistent with the target plane being approximately conjugate with the retina. Switching to the TMX caused a hyperopic shift in refractive error (+3.78 +/-3.41 D). This relative shift towards hyperopia in switching from the OMX to the TMX target also occurred for the other two lens powers. Thus, the OMX/+25 D lens induced myopia (-7.00 +/-5.88 D), corresponding to the imposed hyperopic defocus (target plane now imaged behind the retina), and switching to the TMX resulted in a reduction in myopia (-1.73 +/-5.36 D). The OMX/0 D lens combination produced the largest myopic shift, and here, switching to the TMX condition almost eliminated the myopic response (-15.50 +/-6.62 D cf. -0.56 +/-1.24 D). This relative hyperopic shift associated with switching from the OMX to the TMX target was eliminated by CNS surgery. Thus, the two CNS/TMX groups were both more myopic than the equivalent no CNS/TMX groups (+40 D lens: -2.66 +/-2.34 D; +25 D lens: -7.97 +/-6.87 D). When the visual information is restricted to one plane, incident optical vergence appears to direct emmetropization. Adding visual information at other distances produces a shift in the end-point of emmetropization in the direction of the added information. That these effects are dependent on the integrity of the accommodation system implies that accommodation plays a role in emmetropization and represents the first reported evidence of this kind.

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Effect of an intervening screen on accommodation to a distant object

Cited by 8 publications

References 25 publications

Role of Mandelbaum-like effect in the differentiation of hyperopes and myopes using a hologram

Role of Mandelbaum-like effect in the differentiation of hyperopes and myopes using a hologram

Historical, Diagnostic, and Chromatic Treatment in Visual Snow Syndrome: A Retrospective Analysis

Emmetropization in chicks uses optical vergence and relative distance cues to decode defocus

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