The Magic Glasses


Derrick Lui and and Lee Chee Tian are independent film makers who debuted their short film for children called “Colours” at the Tiburon International Film Festival.  Colours is a modern fairytale about a color-blind girl’s struggles to find colors in her life, how she got more than she bargained for with a pair of magic glasses, and how she finally attained harmony of colors in the world around her. The synopsis is that of  a girl’s catapultic journey from zero to overflow, and her eventual realization that if something seems too good to be true, it usually is.

I make mention of this film because it is illustrative of a problem in the vision care field when great expectations are placed upon what a pair of glasses can do in isolation.  I have blogged before about the significant and in some cases profound impact that yoked prism prescriptions can have on a variety of visual conditions, from Autistic Spectrum Disorders to Acquired Brain Injury.  Even relatively more conventional uses of compensatory prism, as for patients who have strabismus, can have an immediate and profound impact in select cases.  This message is encapsulated in the story of  Stereo Sue, for whom prism was an effective tool that allowed her to benefit more fully from active vision therapy.

In the high majority of cases that we have seen, prism glasses can be a useful adjunct to optometric vision therapy but much less frequently serve as a stand-alone replacement for vision therapy.  It would be very convenient if there were a “pill”, in glasses form, that one could take to avoid all the time and effort involved in vision therapy.  In the only scientific study to date of base-in prism glasses for children with convergence insufficiency, the prism glasses worked no better than placebo glasses.  There is risk if not danger when prism glasses are presented to the public as a panacea rather than a tool that can be of assistance for select patients.  They are not, by any means, magic glasses.

– Leonard J. Press, O.D., FCOVD, FAAO

2 thoughts on “The Magic Glasses

  1. Len; nice discussion about prism. I would caution about the caution raised in the study against Base-in prism: I have raised serious concern about the methodology when they used a plastique-like material to mask the lenses from the clinical doctors. Such masking increases peripheral stimulation and creates a condition of instrument vergence. (Even placed one’s hands alongside one’s face results in spatial changes in most observers.)

    In their conclusion, they did not say that the prism didn’t work, they just said that there was no statistical difference between the Experimental Subjects and the Controls. Both groups were required to wear the clunky frames illustrated in the article for ther final measure.

    I am more impressed by ophthalmogical studies like the poster done at the 1998 AAPOS Scientific Meeting:

    A comparative study of reading abilities with and without base in prism glasses for convergence Insufficiency
    Monte 1. Stavis, MD; Martha Murray, COT; Robert Wood, MPH;
    Becky Brenham, Ed. Cons.; Patricia Jenkins, CO;
    Pediatric Ophthalmology of Houston
    Houston, Texas

    Their conclusion:

    RESULTS: Reading rates improved from 8.81 to 10.04, reading accuracy from 8.85 to 10.96, and comprehension from 9.52 to 11.78. The sum of these three standard scores showed an improvement 18.37 tc 22.30. This equals an oral reading quotient improvement of 951148 to 106/148. The overall mean improvement in reading abilities, when comparing regular glasses to glasses with base in prisms, was from the 37th to the 65th percentile.

    Pretty significant stuff.

    Great blog, keep it up.

    Merrill

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