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 (Bangerter’s method)

or indirectly by producing after image (Cupper’s 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. Hess’s 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 <7 years)

VA improvement with this particular binocular iPad treatment is not as good as with 2 hrs of prescribed daily patching

• 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 system’s 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 9–37 yrs causes a temporary improvement in visual acuity without any side effects (Campos et al 1995)

Use of oral levodopa while continuing to patch 2 hrsdaily does not produce a clinically or statistically meaningful improvement in VA compared with patching (PEDIG 2015)

Advantages

o Augments conventional occlusion

o Speeds up recovery of visual functions

o Improves compliance

o Possibility for adult amblyopes

o Reduces cost and duration of treatment

Near activities used in thetreatment of amblyopia

Active vision therapies for amblyopia involve paper-based near activities such as reading, writing and word puzzles

Von Noorden and associates (1970) found that minimal (1 hrper day) occlusion combined with these exercises is beneficial in the treatment of amblyopia for older children

The latter studies (PEDIG 2005, 2008) provide high level evidence that the use of near activities is not helpful in the treatment of amblyopia

In the absence of reliable evidence to the contrary, there is not yet a sound basis for prescribing these tasks for pts. undergoing treatment for amblyopia

Amblyopia is still an unsolved problem, the best modality of treatment is still to be explored in

future

Thankyou