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May 2007


Pterygium Redux 

The following is in response to “Pterygium Opinions” (Letters, November/December).

Regarding the extensive Tenon’s removal during pterygium surgery, there is another interesting aspect to this debate.

The Tenon’s capsule provides insulation to the globe. In cases where a large amount of it has been resected, some patients notice hypersensitivity of the eyeball in cold weather conditions, exacerbated by the wind.

In the warm climates, where most of the pterygia develop and are removed, this would not be problematic. I note that both Drs. Lawrence Hirst and Stan Feil are from such climates.

Lawrence S. Stone, MD

Vaseline Revisited 

We should always listen to our wives. Fifteen years ago my wife stated that with her keratitis sicca, she was greatly relieved of her dry eye symptoms when she used Vaseline petroleum jelly at bedtime and even during the day. I would smile and tell her that if it worked then by all means use it. Now, Dr. Lawrence Geisse has supported her belief in his “The Vaseline Routine” (Letters, January).

I have always listened to my wife, but now I listen even more intently when she has suggestions about ophthalmological managements.

Malcolm L. Mazow, MD

Mixed Contrast Cards 

Thank you for the extensive coverage of options for the correction of presbyopia in “Presbyopia Calls on a New Generation” (Feature, February). On one hand, the availability of so many choices is exciting. On the other, assessing the treatments may be confusing, as there is no standardized way to compare results.

It is encouraging that new developments in presbyopia correction seem to have extended the interest of practitioners from a narrow focus on visual function (the measurable parameters of how the eye functions) to the broader perspective of functional vision (the assessment of how the person functions in vision-related activities). The latter perspective contains both measurable and subjective elements. Patients’ subjective judgments are not to be ignored, and an increasing number of practitioners are using questionnaires to provide a more consistent basis for assessing the suitability of various solutions to various patients. I hope that exchanges among practitioners may lead to more standardized forms of assessment that can be compared from practice to practice.

At the same time it is important to standardize the more easily measured elements. Prime among these is the measurement of visual acuity at various distances. The traditional measurement of only distance and near acuity (a remnant of the time when bifocals could correct for only two distances) is no longer sufficient. Measurement only at the individual’s preferred distance (as required in some FDA protocols) fails to provide a comparison between individuals; it also ignores the fact that one individual may have different preferred distances for different tasks. It is well-known that contrast sensitivity also is an important variable. Yet, contrast sensitivity is rarely measured in routine practice, because it requires more time and special charts.

The Pelli-Robson and Mars charts that are used most often were designed with rather large characters to make them less sensitive to changes in measuring distance; this also makes them less well-suited to compare performance at different distances.

Thus, there is a need for simple, standardized charts for different distances and different levels of contrast. Based on my experience with other mixed contrast cards, I have developed (but have no financial interest in) similar charts for 40 cm (16 inches, reading distance), 63 cm (25 inches, computer distance) and 100 cm (40 inches, intermediate distance), a selection that covers many activities of daily living. I hope that these cards can provide a standardized measuring tool that can facilitate the exchange and comparison of objective results among practices.

August Colenbrander, MD
San Francisco

To learn more about the “Colenbrander Mixed Contrast Card Set,” see Products & Services.

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