Improving Visual Performance through Volitional Focus Control

Roscoe, Stanley N.; Couchman, Donald H.

doi:10.1177/001872088702900305

Cited by 15 publications

(4 citation statements)

References 22 publications

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“…In contrast, those for whom the blur cues provided by the Badal system were inadequate, possibly because they habitually made use of binocular, proximity or other cues to drive their accommodation, had low levels of both accommodation response and pupil constriction. It may also be that, under the cue‐poor conditions of Badal stimulation, some individuals can exercise a greater degree of voluntary control over both accommodation (Marg, 1951; Cornsweet and Crane, 1973; Provine and Enoch, 1975; Roscoe and Couchman, 1987; McLin and Schor, 1988) and, perhaps indirectly, pupil diameter (Gislén et al. , 2003, 2006).…”

Section: Discussionmentioning

confidence: 99%

Accommodation, pupil diameter and myopia

Charman

Radhakrishnan

2008

Ophthalmic Physiologic Optic

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Concurrent measurements of steady-state accommodation response/stimulus curves and of pupil diameter were made in groups (n = 20) of young, adult myopes [age (mean ± SD) 23.1 ± 4.5 years, mean-sphere error (MSE) )3.06 ± 2.35 D, range )0.60 to )8.54 D] and emmetropes (mean age 25.3 ± 5.7 years, mean MSE )0.07 ± 0.26 D, range )0.50 to +0.50 D). The aim of this study was to explore the possibilities that pupil diameters with relaxed accommodation were larger, and that accommodative miosis was weaker, in the myopic group. Such behaviour would lead to relatively greater degradation of the retinal images in the myopic group, even though aberrations at constant pupil diameter and dioptric accommodative lags in the two groups were the same: this might result in excessive axial growth and further myopia development. No evidence for any systematic refractive dependence of pupillary characteristics or accommodative responses was found. Interestingly, those subjects whose response/stimulus curves had a higher slope tended to display greater accommodative miosis, irrespective of their refractive error.

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Section: Discussionmentioning

confidence: 99%

Accommodation, pupil diameter and myopia

Charman

Radhakrishnan

2008

Ophthalmic Physiologic Optic

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“…Three studies have investigated accommodation responses to distant targets in the presence of intervening screens under natural viewing conditions. 1,8,11 In two of these studies, accommodation responses were inferred rather than measured. 1 12 From this formula the degree of induced myopia would probably have been greater than 0.5 D. Roscoe and Couchman 8 had subjects view Snellen charts at three, six or 12 metres through a screen placed at the individual dark focus distance or at 50 centimetres beyond the dark focus distance.…”

Section: Effect Of An Intervening Screen On Accommodation To a Distanmentioning

confidence: 99%

“…In the home, office and school, specular reflections in the screens of visual display terminals can act as conflicting stimuli to accommodation, although their effect on accommodation is negligible (less than 0.125 dioptres). 5 Even though there have been many studies of the Mandelbaum effect [1][2][3][4][5][6][7][8][9][10][11] there is little information on the likely magnitude of the effect in many natural viewing situations ( Table 1). The largest effects have been reported when viewing in the…”

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confidence: 99%

Effect of an intervening screen on accommodation to a distant object

Stark

Atchison

1998

Clinical and Experimental Optometry

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Background: An intervening screen has been suggested to induce an inward shift of accommodation when viewing a distant object. This is an example of the Mandelbaum effect. However, there have been no objective measures of the magnitude of this effect in this particular situation. Methods: Accommodation was recorded with an infra-red optometer, while subjects (n = 16) viewed a distant letter target with or without an intervening screen. Screens were placed near the individual dark focus distance or at 50 cm. In a second experiment the contrast of the distant target was varied and subjects (n = 5) viewed the target directly or through a screen placed near the individual dark focus distance. Results: In the main experiment, the Mandelbaum effect was not significantly different from zero and was less than 0.5 D in every subject. In addition, accommodation was not more variable when viewing through the screen. However, it may be that some subjects do demonstrate a Mandelbaum effect while others do not. The individual dark focus level did not predict susceptibility to the Mandelbaum effect for a screen at the dark focus. Subjects reported their perceptions of the tasks and some noted changes in the perceived distances of objects when viewing through a screen. In the second experiment, the Mandelbaum effect (< 0.6 D) did not vary with distant target contrast. Conclusions: When viewing a distant object through a screen there is a small (< 0.6 D) or negligible inward shift of accommodation.

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“…18 The average dD/dt (8.7 D/sec) from a 30 cm to a 40 cm was more than 3 times greater than the response speed, suggesting a blurred image may be elicited by the training. Under the cue-poor conditions of Badal stimulation, some individuals can exercise a greater degree of voluntary control over both accommodation [39][40][41] and pupil diameter. 42 Figure 5b also indicates that a blurred image may induce pupillary constriction.…”

Section: Discussionmentioning

confidence: 99%

Training regimen involving cyclic induction of pupil constriction during far accommodation improves visual acuity in myopic children

Yuda¹,

Uozato²,

Hara³

et al. 2010

OPTH

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Myopia in school-age children has become increasingly prevalent in industrialized countries, especially in Asia. A large population of school-age children still suffers from low visual acuity. We have developed a novel, safe and noninvasive training method to activate a pupillary constriction response during far accommodation that results in improved visual acuity. Methods: Myopic children (n = 95) were treated for 3-minute sessions up to twice a week for 12-106 weeks. We stimulated quick cycles of near/far accommodation by displaying a visual object on a LCD screen and moving the screen in cycles from a near (25 cm) to a far (70 cm) point and back, while keeping the retinal projection size and brightness of the object constant. Results: Mechanistically, we noted pupillary constriction upon far accommodation in trained myopic children, which was not seen in normal subjects or in untrained myopic children. Eighty five percent (52/61) of trained myopic right eyes with two sessions weekly experienced improved visual acuity (VA) by more than 0.1 logMAR units with an average improvement of 0.30 ± 0.03 standard error of mean (SEM) logMAR units. With maintained training, most eyes' improved VA stayed almost constant, for more than 50 weeks in the case of 12 long trained subjects. Conclusions: This simple, short and safe accommodation training greatly improves the quality of vision in a large population suffering from refractive abnormalities.

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Improving Visual Performance through Volitional Focus Control

Cited by 15 publications

References 22 publications

Accommodation, pupil diameter and myopia

Accommodation, pupil diameter and myopia

Effect of an intervening screen on accommodation to a distant object

Training regimen involving cyclic induction of pupil constriction during far accommodation improves visual acuity in myopic children

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