Saturday, November 10, 2012

Therapy for Macular Degeneration

High-Power Glasses and Eccentric Viewing Therapy are two key factors for regaining reading ability for people with macular degeneration.   Patient motivation and adaptability are equally important.  Prescription low vision glasses and locating the patient’s best eccentric viewing position (preferred retinal locus: PRL) are challenging.
 
Telescopic Reading Glasses
PRL for Reading
 
 
 
With advancing macular degeneration, the center straight-ahead detail vision reduces.  The clarity is no longer there due to “blurry-blind” spots (scotomas).
 


NEI Central Scotoma
 

Eccentric viewing is particularly useful when scotomas affect both eyes.  When a person no longer looks directly at the object they want to see, they are eccentrically viewing (i.e., they are using a healthier part of the retina).  If they look directly at something, they cannot see it as well as if they look to the side.
 
With a central blind spot, looking slightly above, below or to one side of the object it can be seen better.  The view is not perfect, but better than if they were looking straight ahead.  For example, someone’s facial features may be better seen by looking over their shoulder or at their forehead.
 
"I recognize the body, but not the face"
 

Regaining Ability to Perform Everyday Reading Tasks
When reading, patients report different symptoms.  They will say letters are “missing”, “greyed-out”, “distorted”, “do not make sense” or “they come and go”. 
 
Reading speed is dramatically reduced.  With advancing disease it is not uncommon to hear patients say “I read like a first grader”.  Eye fatigue and body stress are also common symptoms leading to frustration and exasperation.
 
Most patients have one off-center position where they can see the best.  The challenges are to find this position and to be able to hold it consistantly so it can be use most effectively.  The position can be practiced while looking at people’s faces, watching television and reading.  For reading it is some times best to practice with single words.


Ways to Find the Best Eccentric View Point:
 
Amsler Grid













Clock Dial
 

 
 
 
 
 
 
 
 
 
 
 
Single  Letter or Words
 

 
       
      Bat


              
Steady-Eye Posture Therapy
Once the eccentric viewing position is determined high-powered glasses (prismatic, telescopic, or microscopic) are prescribed.  The patient views a word maintaining the eccentric position and the print is slowly moved to the left so that each word in turn is moved into the best area of vision.
 
With central scotomas, the patient must continue to view eccentrically or the glasses will only magnify a blurry image.
 


Monocular Reading Telescope
Binocular Reading Telescope


Experience has shown that it is best to have the patient sit back comfortably in a chair and bring the print up to the glasses (to the focal length of the prescription) keeping the back and neck straight. 
 
Depending on the size of the scotoma, it is often more challenging to place the reading material on the table and bend over close to it.  Using a clipboard to support and help stabilize the reading material is beneficial.


Telescope Reading With a Clipboard
 
Start with large print initially to establish consistency.  Patience is the key and the goal is to reduce the font size as reading speed increases.  Fluidity is one goal.  Reading one-word-at-a-time makes it difficult to get the context of the sentences. 
 
Returning back to the next line of print presents another challenge.  One technique is to slide the print back to the right to allow the patient to quickly scan back along the line of print that has just been read to the beginning and then move down to the beginning of the next line.
 
Another technique is to use a line guide across the sentence that is dropped down when the sentence is completed.
 
Experience has also shown that for some patients the power of the prescribed glasses (i.e., magnification) may be reduced after adapting Steady-Eye Posture strategies.  Reducing the power increases the field of view and the reading distance.


Powerful Reading Telescope
 
Therapy sessions are best in short duration and repeated several times throughout the day.  Length and duration depends on the level of vision loss and the print size goals.
 
For effective therapy, prescription glasses, eccentric viewing techniqes, and patient motivation are critical components.
 
(800) 756-0766
rkinkade@optonline.net

Call Dr. Kinkade for a free telephone consultation
Cheshire - Danbury - Farmington - Litchfield - Manchester - Norwalk - Waterford

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