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Ophthalmology & Optometry/Slanting and trapezoid effect with new glasses

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Dear Dr. Berger,

About two months ago I decided to buy new glasses, since I noticed that my eyesight, even with glasses, has worsened by a little bit. The prescription for my old glasses is as following:

       Sphere        Cyl        Axis
R   -0.25   -1.25   91
L   -0.25   -1.25   85

The optician at the shop measured my eyesight and after a week I received my new glasses, with the following prescription:

       Sphere        Cyl        Axis
R   -0.25   -0.75   90
L   -0.25   -1.50   88


I had crystal clear vision with these out on the street, but sitting in front of a computer monitor, I noticed severe slanting. The right side of the monitor seemed huge, while the left side seemed tiny in comparison.

The optician assured me that I have to get used to the new glasses, but even after four weeks of constant wearing I still noticed the computer screen being a bit wonky. Not quite straight but not quite slanted either. When I took them off, I noticed the same extreme slanting I noticed when I first put them on, but in opposite directions. The left side of the screen now seemed huge, the right side seemed tiny.

I went back to the optician, explaining my problem. They sat me in front of a computer screen and let me adjust the Cylinder until I was satisfied with the proportions of the screen. After another week, I received my new glasses (made from a different material) with the following prescription:

       Sphere        Cyl        Axis
R   -0.75   -1.25   90
L   -0.75   -1.50   93


The moment I put them on I felt dizzy and things seemed to wobble as I walked down the street. I also felt a lot taller. I'm 5"7 and I felt at least a foot taller when walking. The clarity wasn't as great as with the first glasses I received and sure enough the computer monitor was slanted as well, but this time the top half seemed smaller and the bottom half seemed bigger, sort of like this: /__\

I don't think these will be any better after four weeks than the first ones I received, but when I put on my very old glasses I notice very slight slanting like this: \__/
It's almost not noticeable, probably because I've been wearing them for years and my brain has gotten used to it.

I plan on going back to the optician and try on a prescription like this:

       Sphere        Cyl        Axis
R   -0.25   -1.00   90
L   -0.25   -1.50   89


I think the slanting in front of the screen was caused by the severe difference between the Cylinders, but changing them seems to impair the clarity of my vision. Also, the change in Sphere from -0.25 to -0.75 could have something to do with that. The axes don't seem to be the main problem here.

What do you think?

Many thanks
Vik

Answer
Abnormal "slanting" or perceptual distortion can occur from many things among which are: base curves differences, size and shape of frame, e.g., going to a larger more curved frame, P.D., center and edge thickness, going from one material to another, e.g. ploycarbonate to CR-39 or visa versa, prescription changes, especially if they are large changes (which yours doesnt seem to be), unwanted prism, that is the optical centers don't match the anatomical interpupilarry distance, aberration and waves, coma, spherical aberration, etc., etc.

dr. ken

Ophthalmology & Optometry

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DR. KENNETH BERGER

Expertise

Any and all questions with regard to ocular ailments, eye diseases as cataracts, glaucoma, macular degeneration, diabetic retinopathy, etc , eye and visual sympomatology, eyeglasses, contact lenses, low or subnormal vision, pediatric vision conditions,and special and unique ailments will be discussed.

Experience

36 years of clinical experience in opticianry and therapeutic optometry. Still in private practice with special interests in vision conditions, diagnosing and treating ocular ailments, prescibing treatment plans which include medicine, eyeglasses, and contact lenses primarily. Although surgery is not within the realm of my area of expertise, I co-manage many pre and post -op surgical cases which include Lasik and PRK procedures.

Organizations
New Jersey Society of Optometric Physicians American Optometric Association

Education/Credentials
B.A.,1968, Hunter College of the City University of New York B.S.,1970, Pennsylvania College of Optometry O.D.,1973, Pennsylvania College of Optometry Therapeutic Pharmaceutical Administration Certification, New Jersey 1992

Awards and Honors
Clinical Efficiency Award, 1973, Pennsylvaania College of Optometry

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