Short-Term Adaptive Modification of Dynamic Ocular Accommodation

Vedamurthy, Indu; Schor, Clifton M.

doi:10.1167/iovs.08-2577

Cited by 7 publications

(17 citation statements)

References 42 publications

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“…The first paradigm replicated the adaptation method used by Bharadwaj et al (2009), their “increasing paradigm,” in which the focus stimulator first stepped from 0 to 2D and after 350 msec stepped from 2D to 4D. Bharadwaj et al did not test to see whether a double step was necessary for adaptation.…”

Section: Methodsmentioning

confidence: 99%

“…Bharadwaj, Vedamurthy and Schor (2009) did not examine patients undergoing VT but examined the ability of young subjects (age 18–34) to modify the dynamics of accommodation using a paradigm which was designed to mimic the type of changes in compliance of the ocular lens that occur with age. These researchers pointed out that, even though the lens becomes less compliant during nascent presbyopia, the dynamics of accommodation change much less than might be expected (Heron, Charman & Schor, 2001).…”

Section: Introductionmentioning

confidence: 99%

“…Likewise, vergence is driven primarily by disparity but is also driven by accommodation by way of accommodative-vergence crosslinks. While the dynamics of accommodation following VT have been measured objectively (Liu et al, 1979; Bobier & Sivak, 1983; Radhakrishnan et al, 2007; Bharadwaj et al, 2009; Allen et al, 2010) the associated accommodative-vergence has not. The present experiment essentially repeat the adaptation experiment of Bharadwaj et al (2009) with the addition of recording eye position for both eyes in order to measure accommodative-vergence.…”

Section: Introductionmentioning

confidence: 99%

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Short-term adaptation of accommodation, accommodative vergence and disparity vergence facility

2012

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Previous studies have found that subjects can increase the velocity of accommodation using visual exercises such as pencil push ups, flippers, Brock strings and the like and myriad papers have shown improvement in accommodation facility (speed) and sufficiency (amplitude) using subjective tests following vision training but few have objectively measured accommodation before and after training in either normal subjects or in patients diagnosed with accommodative infacility (abnormally slow dynamics). Accommodation is driven either directly by blur or indirectly by way of neural crosslinks from the vergence system. Until now, no study has objectively measured both accommodation and accommodative-vergence before and after vision training and the role vergence might play in modifying the speed of accommodation. In the present study, accommodation and accommodative-vergence were measured with a Purkinje Eye Tracker/Optometer before and after normal subjects trained in a flipper-like task in which the stimulus stepped between 0 and 2.5 diopters and back for over 200 cycles. Most subjects increased their speed of accommodation as well as their speed of accommodative vergence. Accommodative vergence led the accommodation response by approximately 77 msec before training and 100 msec after training and the vergence lead was most prominent in subjects with high accommodation and vergence velocities and the vergence leads tended to increase in conjunction with increases in accommodation velocity. We surmise that volitional vergence may help increase accommodation velocity by way of vergence-accommodation cross links.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Short-term adaptation of accommodation, accommodative vergence and disparity vergence facility

2012

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“…Studies have shown that voluntary control of accommodation can be learned and transferred to a variety of conditions, 14,15 and objective improvements in the dynamics 16 and accuracy of accommodation following vision therapy have been documented. 17,18 …”

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confidence: 99%

Treatment of Accommodative Dysfunction in Children: Results from a Randomized Clinical Trial

Scheiman¹,

Cotter²,

Kulp³

et al. 2011

Optometry and Vision Science

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Purpose To report the effectiveness of various forms of vision therapy/orthoptics in improving accommodative amplitude and facility in children with symptomatic convergence insufficiency (CI) and co-existing accommodative dysfunction. Methods In a randomized clinical trial, 221 children 9 to 17 years with symptomatic CI were assigned to one of four treatments. Of the enrolled children, 164 (74%) had accommodative dysfunction; 63 (29%) had a decreased amplitude of accommodation with respect to age, 43 (19%) had decreased accommodative facility, and 58 (26%) had both. Analysis of variance models were used to compare mean accommodative amplitude and accommodative facility for each treatment group after 4, 8, and 12 weeks of treatment. Results After 12 weeks of treatment, the increases in amplitude of accommodation [office-based vergence/accommodative therapy with home reinforcement group (OBVAT) 9.9D, home-based computer vergence/accommodative therapy group (HBCVAT+) 6.7D, home-based pencil push-up therapy group (HBPP) 5.8D] were significantly greater than in the office-based placebo therapy group (2.2D) (p-values ≤ 0.010). Significant increases in accommodative facility were found in all groups (OBVAT: 9cpm, HBCVAT+: 7cpm, HBPP: 5cpm, OBPT: 5.5cpm); only the improvement in the OBVAT group was significantly greater than that found in the OBPT group (p = 0.016). One year after completion of therapy, reoccurrence of decreased accommodative amplitude was present in only 12.5% and accommodative facility in only 11%. Conclusions Vision therapy/orthoptics is effective in improving accommodative amplitude and accommodative facility in school-age children with symptomatic CI and accommodative dysfunction.

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“…In addition, the dynamics of human accommodation involve peak velocities in excess of 12 diopters/sec [9,10] and the accommodative state of the eye is variable even during steady fixation [11]. Experimental OCT systems with line rates in the MHz range [12,13] can significantly reduce motion artifacts, but associated increases in complexity and cost may limit their clinical applications.…”

Section: Introductionmentioning

confidence: 99%

Pupil Tracking for Real-Time Motion Corrected Anterior Segment Optical Coherence Tomography

et al. 2016

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Volumetric acquisition with anterior segment optical coherence tomography (ASOCT) is necessary to obtain accurate representations of the tissue structure and to account for asymmetries of the anterior eye anatomy. Additionally, recent interest in imaging of anterior segment vasculature and aqueous humor flow resulted in application of OCT angiography techniques to generate en face and 3D micro-vasculature maps of the anterior segment. Unfortunately, ASOCT structural and vasculature imaging systems do not capture volumes instantaneously and are subject to motion artifacts due to involuntary eye motion that may hinder their accuracy and repeatability. Several groups have demonstrated real-time tracking for motion-compensated in vivo OCT retinal imaging, but these techniques are not applicable in the anterior segment. In this work, we demonstrate a simple and low-cost pupil tracking system integrated into a custom swept-source OCT system for real-time motion-compensated anterior segment volumetric imaging. Pupil oculography hardware coaxial with the swept-source OCT system enabled fast detection and tracking of the pupil centroid. The pupil tracking ASOCT system with a field of view of 15 x 15 mm achieved diffraction-limited imaging over a lateral tracking range of +/- 2.5 mm and was able to correct eye motion at up to 22 Hz. Pupil tracking ASOCT offers a novel real-time motion compensation approach that may facilitate accurate and reproducible anterior segment imaging.

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Short-Term Adaptive Modification of Dynamic Ocular Accommodation

Cited by 7 publications

References 42 publications

Short-term adaptation of accommodation, accommodative vergence and disparity vergence facility

Short-term adaptation of accommodation, accommodative vergence and disparity vergence facility

Treatment of Accommodative Dysfunction in Children: Results from a Randomized Clinical Trial

Pupil Tracking for Real-Time Motion Corrected Anterior Segment Optical Coherence Tomography

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