prescribing for astigmatism

Making the Case for Taking a Good Case History

THOMAS G. QUINN, OD, MS
FEBRUARY 1998

It's like an obstacle course where your goal is to ferret out the most direct route to contact lens success. The astigmatic patient offers a unique set of roadblocks, but a thorough case history guides you to the express guides you down the express lane to success. Sound straight forward enough? Read on and see if you can avoid the pothole I hit.

The History

R.D., a 33-year-old electronic data specialist, was interested in resuming contact lens wear after a four-year absence. He had originally worn extended wear soft lenses successfully but switched to daily wear lenses due to concerns about safety. After a total of six years of lens wear, he discontinued them due to the hassle of daily removal and cleaning and the discomfort of the thicker design of daily wear lenses. Refractive findings were OD -4.00-0.75x 173, 20/20; OS -3.50-1.00x004, 20/20. Keratometry readings were OD 45.25@ 008/46.50@ 098, OS 45.50@010/47.00@100. Examination of the anterior ocular surface revealed clear corneal tissue and 1+ bulbar and palpebral injection OU.

R.D. reported a history of allergies to mold and cats. He was taking Allegra for allergic symptoms and Tagamet for ulcers. R.D. smoked less than a pack of cigarettes per day. Can you think of anything I forgot to ask?

A Critical Detail

Computer specialists require a high level of visual clarity for optimal performance. In addition, a reduced blink rate is common during computer use, predisposing soft contact lens wearers to problems with lens desiccation. RGPs would offer excellent visual correction of R.D.'s myopic astigmatism while minimizing the potential for lens drying while viewing the computer monitor. Additionally, high Dk RGP materials provide the possibility of a safer extended wear option.

I recommended that R.D. try RGPs, citing the above reasons. This is when he temporarily took the wind out of my sail. His intention, which I missed during my case history, was to wear contact lenses for social and athletic events and to wear spectacles to work. He enjoyed the ease and simplicity of spectacles during the somewhat frenetic pace of the work week, but found them to be a nuisance during sports and inhibiting in a social environment.

Back on Track

Because R.D. desired occasional wear, initial comfort became an overriding advantage offered by soft contact lenses. But should he be fit with spherical or toric soft lenses?

R.D.'s history listed discomfort with wear of a "thick" daily wear soft lens. Would he find prism ballasted toric soft lenses uncomfortable as well? This concern prompted me to initially fit a thin, spherical soft lens design. Although comfort was good, his visual acuity was unacceptable (20/30 OD and 20/40 OS) due to uncorrected astigmatism.

I then prescribed quarterly replacement toric soft lenses. R.D. was satisfied with the comfort and quite pleased with his enhanced vision. This option provided him with a comfortable part-time wear option, clear vision and a stream-lined care system. Once I clearly understood his goals, I was able to meet his needs.

What To Ask In A Case History

• Motivation for contact lenses
• Desired wearing schedule
• Visual needs
• Work/play environment
• History of contact lenswear
• If discontinued wear, why
• Medications
• Follow-up to inquiries above

Dr. Quinn is in group practice in Athens, Ohio, and has served as a faculty member at The Ohio State University College of Optometry.