Question about vertical prism

[wishless]

I have a right hyperphoria, and my optometrist prescribed me vertical prism that is 1/2 BU on the right eye, and 1 1/2 BD on left eye.

My question is: if it is my right eye that turns upwards, why is it that the base down prism is over my left eye? Of course, I'm assuming that base down prisms shift the image downwards, and vice versa for base up prisms. Please correct my understanding if it is wrong.

Thanks.

[John C Hagan III, MD, FACS, FAAO]

It is a tiny amount and infrequently prescribed also once prism put in glasses the eye gets lazy and cannot do without prism and may have more double vision without glasses.

Suggest you see an Eye MD ideally a strabismus/pediatric specialist. Find one near you at www.geteyesmart.org

JCH MD

[wishless]

Dr. Hagan,

"Also very very very few people need this little amount of prism in their glasses."

By this, do you mean that this is more prism than most people need, or less?

[John C Hagan III, MD, FACS, FAAO]

The prism is prescribed wrong. The prism moves the image to the apex or sharp tip of the prism. Thus to correct a right hypertrophia the right eye should have base down prism and the left eye base up.

Also very very very few people need this little amount of prism in their glasses.

JCH MD