Active Vision Therapy in Management of Amblyopia

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  • Active Vision Therapy in Management of Amblyopia

    Maharajgunj Medical Campus, IOM, Nepal

    Bikash SapkotaB. OptometryFinal Year

  • Active Vision Therapy in AmblyopiaIt is designed to improve visual performance by the

    conscious involvement in a sequence of a specific, controlled

    visual task that provide feedback

    i. Pleoptics

    ii. Near activities

    iii. Active stimulation therapy using CAM vision

    iv. Syntonic phototherapy

    v. Role of perceptual learning

    vi. Binocular stimulation

    vii. Software-based active treatments

    viii. Exposure to dark

    ix. Pharmacological Therapy

  • Pleoptics

  • Pleoptics: Gr. meaning full vision

    Used for active stimulation of the fovea to overcome eccentric fixation and improves the visual acuity

    In this technique

    - the peripheral retina is dazzled with an intense light protecting

    foveal area

    - after the light source is turned off, the fovea functions better

    as the surrounding retinal area is in a state of hypofunction

    - this can be followed by direct stimulation of fovea

    by pleoptophore (Bangerters method)

    or indirectly by producing after image (Cuppers method)

  • Demerits

    The technique is complex and requires an absolute co-operation of the pt. and intelligence to appreciate after-images

    Daily sitting for a longer period of time is required

    Since occlusion of the dominant eye is a very successful simple and inexpensive method of treating eccentric fixation, so the use of pleoptics methods is abandoned

    Only indication is co-operative and intelligent child older than6yrs having eccentric fixation

  • Pleoptics VS Occlusion of sound eye

    Visual acuity outcomes in children who have had conventional occlusion are found to be better than in those who have gone through pleoptic treatment (VerleeDL, Iacobucci 1967)

    Visual acuity improvements are significantly greater in the direct occlusion group than in the group undergoing pleoptic therapy and inverse occlusion(Veronneau T.S. et al 1974)

  • Treatment using grating stimuli(Active stimulation therapy using CAM

    vision stimulator)

  • Method

    Non amblyopic eye is occluded

    Amblyopic eye is stimulated for 7 mins by slowly rotating (at about 1 revolution per min) high contrast square wave grating of different spatial frequencies

    The treatment is carried out once in a week for 3 to 4 weeks

    Advantages over the conventional occlusion therapy

    o The sound eye remains open between the weekly treatment sessions

  • Principle

    Assumption that rotating grating provides specific stimulation for cortical neurons

    Present status of CAM vision stimulator

    This technique is not as effective as conventional occlusion therapy

    So it has failed to replace time tested conventional occlusion therapy for the treatment of amblyopia

    Some workers use this technique as supplementary to occlusion therapy in co-operative pts. with supportive who can carry out the treatment at home

  • Recently a new treatment has been described based on a similar principle, namely, the use of grating stimuli to activate certain cortical cells (Angelika Shanshinova et al, 2008)

    The treatment is computer-based and is intended to supplement occlusion treatment, particularly in patients beyond childhood

    The treatment comprises a computer game viewed on a monitor against the background of a low spatial frequency drifting sine wave grating

  • The stimulus is a drifting sinusoidal grating of a spatial frequency of 0.3 cyc/deg and a temporal frequency of 1 cyc/sec, reciprocally coordinated with each other to a drift of 0.33 deg/sec

    Based on the idea that stimulation of motion-sensitive cells might help to improve function of form-sensitive cells by synchronisation of responses

    Efficacy of treatment is higher for the computer based method combined with occlusion than for occlusion only

  • Syntonic phototherapy in the treatment of amblyopia

  • Syntonics is the branch of ocular science dealing with the application of selected visible light frequencies through the eyes

    For the purposes of treatment, syntonic optometrists define four syndromes as follows: acute, chronic, emotional fatigue and lazy eye

    In lazy eye syndrome, amblyopia, strabismus, vergenceanomalies, suppression, ARC or visual field constrictions are treated using red/orange filters

  • It is based on work by Spitler, in which 2,791 of 3,067 individuals responded positively to syntonic phototherapy

    However, there is no published studies on the effectiveness of this technique in amblyopia therapy

    In the absence of studies providing good quality evidence that amblyopic patients will be helped by syntonic phototherapy, there seems to be no basis for prescribing this treatment

    Wallace LB. The theory and practice of syntonic phototherapy 2009

    Spitler HR. The Syntonic Principle. Pennsylvania: Science Press Printing Company, 1941.

  • Role of perceptual learning in amblyopia treatment

  • Perceptual Learning Any relatively permanent and consistent change in the

    perception of stimulus array following practice or experience with this array- Gibson (1963)

    No. of studies suggest that perceptual learning (PL) may provide an important new method for treating amblyopia

    Principle

    PL is reported to operate via a reduction of internal neural noise and/ or through more efficient use of stimulus information by returning weighting of the information

  • PL employs repeatedly practicing a visual discrimination

    task, e.g: positional acuity, contrast sensitivity,

    stereo-acuity, etc

    Recommended period for PL: 2hrs/ day, 5 days/ week, for a period of 9 months

    Significant improvements found in VA and CS (Chen P. et al 2008, Huang C. et al 2006)

    Role of PL is still controversial, but utility is reported in adult amblyopes

  • Video Game Play & Brain Plasticity

    The intense sensory-motor interactions are immersed video-game play

    This might push brain functions to the limit

    Enables the amblyopic visual system to learn, on the fly, to recalibrate and adjust, providing the basis for functional plasticity

  • Video Game Play & Brain Plasticity

    Game playing requires the allocation of spatial detection, and localization of low contrast, fast moving targets, and aiming

    Video games may include several essential elements for active vision training to boost visual performance

    According to C. S. Green and co workers (2003) action video game modifies visual selective attention

    Thus, it could potentially be useful in improving amblyopic vision

  • Video-Game Play Induces Plasticity in the Visual System of Adults with Amblyopia(Roger W. Li1 et al, August 30 2011)

    o 10 amblyopic adults: Action Video Game, 40 hrs, 2hrs/day

    o 3 amblyopic adult: Non-action Video Game, 40 hrs, 2 hrs/ day

    o Non-amblyopic eye: Occlusiono Control Group 7 adults: Only patching

    Action Game: Medal of Honor: Pacific AssaultNon-Action Game: SimCity Societies

  • PL is an area with clear potential for treating amblyopia

    Significant improvements in vision can result from training periods that are relatively short using tasks that are relatively engaging, compared to conventional occlusion

    It is important to be aware that the way in which these improvements arise is not yet fully understood

    Further research is needed before optimal training strategies can be devised and before the way in which those strategies modify visual function can be fully understood

  • Binocular stimulation in thetreatment of amblyopia

  • During occlusion therapy, the non-amblyopic eye is occluded i.e. binocular vision is not encouraged during these periods

    It has been recognized that binocular stimulation may be important in the treatment of amblyopia

    Animal research (Mitchell DE 2008) and recent studies (Baker DH et al 2007, Mansauri et al 2007) indicate that binocular stimulation encourages binocular cortical connections during recovery from deprivation amblyopia

    Offers support for binocular stimulation when treating amblyopia

  • One existing approach to treating amblyopia that allows binocular stimulation is the use of Bangerter foils (Baker and colleagues 2007)

    Another long-standing and widely used approach is atropine penalization

    In both cases, the image at the fovea of the non-amblyopic eye is degraded (for near vision in the case of atropine), while input to the amblyopic eye is not affected

    In these therapeutic scenarios, vision is binocular in the sense that both eyes receive light stimulation and peripheral resolution is not significantly impeded (Wang YZ et.al 1997)

  • Comparisons between occlusion and atropine (LI T et al 2009)or between occlusion and Bangerter foils (PEDIG 2010) as treatments for amblyopia show no significant difference in outcome

    Suggests that this type of binocular stimulation does not offer significant advantages over the combination of binocular and monocular vision allowed by periods of occlusion

  • The monocular fixation in a binocular field (MFBF) technique

    Introduced with the intention of training the amblyopic visual system to integrate information from both eyes (Cohen AH. Monocular fixation in a binocular field. J Am Optom Assoc 1981)

    This technique involves the presentation of peripheral stimuli to both eyes, while only the amblyopic eye is stimulated at the fovea

  • The monocular fixation in a binocular field (MFBF) technique

    Applied in a range of paper-based formats.

    E.g, pt. may be instructed to complete tasks such as crossword

    puzzles or placing dots in the o letters in a text, using a

    pen and wearing red-green glasses, with the red lens in

    of the non-amblyopic eye (Wick B. et al 1992)

  • I-BiT Interactive Binocular Treatment for Amblyopia

    Concept Present separate images to each eye Dynamic visual scene Preferentially stimulating amblyopic eye

    Patient motivation Interactive games and videos Encourage patient compliance

    Shutter Glasses Technologyo Shutter glasses o High definition screens o Faster processing speeds

  • Adaptations for use with the I-BiT system Shutter glasses with I-BiT software is to change the ratio

    of information presented to each eye in order to stimulate one eye more than the other

    This creates a 2D view rather than the intended 3D stereoscopic view

    DVD Player

    o Border with controls common to both eyes

    o Only amblyopic eye sees the DVD

    NUX Game

  • Evidence Six children treated with prototype and gained 2 lines of

    vision (Waddingham et al Eye 2006)

    10 treated with I-BiT and improvement of 0.189 logMAR,

    almost 2 lines (Herbison et al Eye 2013)

    Other groups: e.g. Hesss group with the game Tetris in adults (required a minimum of 6 hrs play before any effect is discernible)

  • Fig: Visual acuity in LogMAR units for all patients from baseline to week 10.

    Herbison et al Eye 2013

  • Software-based active treatments for amblyopia for use at home or in office

  • The AmbP iNet program for the treatment of Amblyopia

    Marketed by Home Therapy Solutions

    System features 12 treatment programs, 6 of which are randomly assigned for completion by the patient each 5 days per week

    Involve activities like letter jump, among others

    The treatment involves visual search of certain target

  • The AmbP iNet program for the treatment of Amblyopia

    Treatment system is designed to improve hand eye co-ordination, VA, crowding effect and visual memory

    No published reports of clinical trials of this method, so it is not possible to know whether the design is effective as part of a treatment for amblyopia

    Thus, controlled trials of this treatment are needed

    (Cooper J. et al 2007)

  • Not a "lazy" eye, but a "lazy" brain

    Amblyopia therapy is:

    o Completed at home on a computer

    o 2-3 times per week

    o Each of the 40 sessions takes an average of 40 minutes

    Precise visual tasks consisting of patterned images with subtle differences in orientation, size and contrast

    Through repetitive practice the brain is trained to be efficient and to improve visual processing

    Specialized RevitalVision algorithms analyze

  • Binocular iPad Game VS Part-Time Patching

    2 studies (PEDIG 2016), (K.R. Kelly et al 2016) were done to compare VA improvement in children with amblyopia treated with a binocular iPad game vs part-time patching

    Effect of a Binocular iPad Game vs Part-time Patching in Children Aged 5 to 12 Years With Amblyopia A: Randomized Clinical Trial;Jonathan M. Holmes et; for the Pediatric Eye Disease Investigator Group, JAMA Ophthalmology, November-3, 2016

    Binocular iPad Game vs Patching for Treatment of Amblyopia in Children:ARandomized Clinical Trial; Krista R. Kelly, PhD; Reed M. Jost, MS; Lori Dao, MD; Cynthia L. Beauchamp, MD; Joel N. Leffler, MD; Eileen E. Birch, PhD, JAMA Ophthalmology, December 2016

  • Fig: Visual Acuity (VA) in Amblyopic Eyes From Baseline to 16Weeks

    (PEDIG 2016)

    VA improves with binocular game play and with patching, particularly in younger children (age 5 to

  • High-contrast red elements (miners and fireball) are seen by the

    amblyopic eye

    Low-contrast blue elements (gold and cart) are seen by the fellow

    eye

    Gray elements (rocks and ground) are seen by both eyes Both eyes must see the game for successful play

    Fig: Dig Rush Game

    (K.R. Kelly et al 2016)

  • Fig: Best-Corrected Visual Acuity (BCVA) at Baseline, the 2-Week Visit, and the 4-Week Visit

    (K.R. Kelly et al 2016)

    Binocular iPad game is a successful treatment for childhood

    amblyopia and is more effective than patching at the 2-week visit

  • Exposure to Darkness

  • Dark exposure promotes recovery from amblyopia

    It is based on Duffy and Mitchell (2013, current biology) animal (kittens) experiments

  • Three key parameters will have to be established first

    o What is the minimum period of dark exposure needed to trigger restoration of visual cortex plasticity?

    o What is the age dependence of this effect?

    o How absolute does the darkness have to be?

    The answers to these questions will ultimately determine the utility of this approach to treating amblyopia

  • Pharmacological Therapy

  • Levodopa & citicoline are the most extensively studied drugs

    Plasticity of visual system during the sensitive period is dependent on input from non-adrenergic neurons and thus can be subjected to pharmacological manipulation

    Precursor for the catecholamine dopamine, a neurotransmitter, known to influence visual system at retina and cortical level

    It either extends or reactivates the visual systems sensitive period of neural plasticity

    Catecholamine based medical treatment has been demonstrated to improve vision in amblyopic eyes.

  • Leguire and co-workers (1993) found that 1 hr after levodopa ingestion,VA, CS and PVEP temporarily improve but starts to decrease 5 hrs after drug ingestion

    They concluded that combination of levodopa and occlusion improves visual function more than levodopa-carbidopa alone in amblyopic children

    Dadeya et al (2009) concluded that there is more than two lines improvement in visual acuity, especially in children younger than eight years of age

  • Citicoline (cytidine 5-diphosphocholine) used in a dose of 1,000 mg I.M. for 15 days to patients aged 937 yrs causes a temporary improvement in visual acuity without any side effects (Campos et al 1995)

    Use of oral...

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