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Woman using magnifying glass to read eccentrically

Training Eccentric Viewing Technique: MagnaFlyer and Central Vision Loss

 

A Vision Strategy for Macular Degeneration and Other Conditions that Impair Central Vision


When MagnaFlyer is being used for training a client with a diagnosis of central vision loss there are two dimensions to the training that are interrelated. The client must learn to habituate the fixed gaze of steady eye technique and combine that with enhancing their skill in eccentric viewing. Training with MagnaFlyer has the ability to elevate and refine both skills at the same time. The positioning dot on the MagnaFlyer screen is an integral part of training this combination of steady eye strategy and eccentric viewing. It was designed specifically to reinforce fixation to reliably compensate for damage to the fovea.

 

What is Eccentric Viewing?


The normal area of the central retina that is used to read or see detail is the fovea. Fixation with a normal fovea is very focused on a precise location when looking at a target. In the case of central vision loss there is a portion of the central visual field that is non-seeing called a scotoma. When, due to retinal disease, a different healthy area of the retina is substituted for the damaged fovea in order to see more clearly this alternate location is called a preferred retinal locus (PRL). This is the area of best vision for a sight impaired individual, in effect it's the “sweet spot” where your client's sight is the most acute. Viewing with this alternate area of retina is called eccentric viewing.

 


The Preferred Retinal Locus and Eccentric Viewing

graphical information about eccentric viewing

 

In other words the person looks slightly away from the target in order to see it using their peripheral sight.

 

Most people with central vision loss will naturally learn to some extent to use their Preferred Retinal Locus in daily life. However, without training this may be inefficient due to the difficulty of consistent focus using this peripheral retina. Poor fixation with the PRL, negatively impacts an individual's reading performance even when magnification is available. MagnaFlyer gives the trainer and client a means to practice and consistently reinforce this fixation skill.



 

Placing the Positioning Dot for Those with Central Vision Loss


The MagnaFlyer program materials include a template called the Intake Referral Guide. This is used to communicate information gained from the intake evaluation such as the placement of scotomas and the location of the PRL. This template enables the therapist to customize for the client the on-screen viewing location of the practice text. The template is marked out in a grid which corresponds to the markings on the MagnaFlyer screen.

 

positioning dot for evaluatorpositioning dot for instruction

From the reference made by the low vision specialist on the template the practitioner can place a "post-it” type marker on the screen itself. This will be the spot where the client will habituate their gaze in order to most clearly see the text using their PRL as they practice.

 

Early in the process of enhancing proficiency with steady eye and eccentric viewing, clinicians train the student to be aware of their scotoma and of the type of eye positioning needed to use their PRL. From that point the practitioner can then intensively train how to maintain steady fixation with that PRL when looking at targets or following lines of print. This skill is essentially learning how to reliably and consistently “see out of the corner of your eye”. The combination of the stability of the target placement across the exercises and the predictable location of the text provide a means of building the student’s confidence in the reliability of their ability to fixate their gaze to optimize their vision.

 

 

British Journal of Ophthalmology

Br J Ophthalmol doi:10.1136/bjo.2008.152231

Clinical Science

 

Effective rehabilitation of reading by training in the technique of eccentric viewing: evaluation of a four year programme of service delivery

 

Abstract

Background/Aims: Central visual loss caused by conditions such as age related macular degeneration is the commonest cause of blindness in the United Kingdom. Eccentric viewing training aims to teach the patients how to utilise the functioning areas of macula.

 

Conclusion: Eccentric viewing training is successful in improving the reading ability of individuals with a central scotoma.

 

as Reported in

Log for the British Journal of Opthal

12 October 2009

 

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