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Comments on some interesting articles in this issue
Gerald E. Lowther, OD, PhD, Co-editor
CL Commentary
Comments on Some Interesting Articles in this Issue
I believe you will find the articles in this issue very interesting. Correcting moderate amounts of astigmatism with contact lenses, especially with soft toric lenses, is always a concern for patients with visually demanding tasks. When the cylinder is due to corneal toricity we usually assume that rigid lenses will result in better visual performance. In addition, patient complaints while using computers are very common and one would expect that patients wearing soft tories would have greater problems than with spherical RGPs or spectacles. The article by Snyder, Wiggins, and Daum studies the differences between spherical RGPs and soft tories including tests using video display terminals (VDT). It was surprising to me that in their study they found no difference in visual comfort, quality, or stability of vision between the soft tories and spherical RGPs during the VDT use, even when the task included looking away from the computer screen into
124
ICLC, Vol. 21, July/August
1994
the upper, lateral gaze every 4 minutes. Obviously, the soft toric lenses did not have significant rotation. I believe this attests to the great improvement in recent toric lens design. It was not surprising that overall the patients rated the comfort of hydrogels better than RGPs in the short term comparison. However, the rating of RGPs as more difficult with respect to handling and more symptoms of dryness was surprising. The thicker toric lenses, as compared to spherical lenses, may be the cause for reduced dryness symptoms. The fact that three-quarters of the patients chose to wear soft tories with one-quarter choosing rigids is important. I have felt for a long while that a mix of 60-80% of patients fitted with soft and 20-40% with RGPs is appropriate. Fitting all patients with soft lenses does not give the best correction to all patients. Another interesting concept is reported by Winkler. In the past it has
been impossible to give patients lateral prism with contact lenses except with haptic (scleral) lenses. Winkler has used a unique idea to prescribe lateral prism by gluing a small rigid lens with prism onto a nonrotating soft toric lens (Ciba Torisoft). This is not something that every practitioner is going to try or that even may be recommended, but it certainly does open up the possibility to correct this type of patient. There is potential for this to be further developed into a simpler, more viable lens design to give lateral prism with contact lenses. The availability of new gas permeable scleral lenses offers another potential of giving lateral prism in a contact lens correction. Other articles in this issue cover orthokeratology, a new patient orientated mechanical cleaning device for cleaning soft lenses, and a method of care of a patient with Pellucid Marginal Cornea1 Degeneration.
0 1994 Butterworth-Heinemann
CL Commentary
Comments on Some Interesting Articles in this Issue
I believe you will find the articles in this issue very interesting. Correcting moderate amounts of astigmatism with contact lenses, especially with soft toric lenses, is always a concern for patients with visually demanding tasks. When the cylinder is due to corneal toricity we usually assume that rigid lenses will result in better visual performance. In addition, patient complaints while using computers are very common and one would expect that patients wearing soft tories would have greater problems than with spherical RGPs or spectacles. The article by Snyder, Wiggins, and Daum studies the differences between spherical RGPs and soft tories including tests using video display terminals (VDT). It was surprising to me that in their study they found no difference in visual comfort, quality, or stability of vision between the soft tories and spherical RGPs during the VDT use, even when the task included looking away from the computer screen into
124
ICLC, Vol. 21, July/August
1994
the upper, lateral gaze every 4 minutes. Obviously, the soft toric lenses did not have significant rotation. I believe this attests to the great improvement in recent toric lens design. It was not surprising that overall the patients rated the comfort of hydrogels better than RGPs in the short term comparison. However, the rating of RGPs as more difficult with respect to handling and more symptoms of dryness was surprising. The thicker toric lenses, as compared to spherical lenses, may be the cause for reduced dryness symptoms. The fact that three-quarters of the patients chose to wear soft tories with one-quarter choosing rigids is important. I have felt for a long while that a mix of 60-80% of patients fitted with soft and 20-40% with RGPs is appropriate. Fitting all patients with soft lenses does not give the best correction to all patients. Another interesting concept is reported by Winkler. In the past it has
been impossible to give patients lateral prism with contact lenses except with haptic (scleral) lenses. Winkler has used a unique idea to prescribe lateral prism by gluing a small rigid lens with prism onto a nonrotating soft toric lens (Ciba Torisoft). This is not something that every practitioner is going to try or that even may be recommended, but it certainly does open up the possibility to correct this type of patient. There is potential for this to be further developed into a simpler, more viable lens design to give lateral prism with contact lenses. The availability of new gas permeable scleral lenses offers another potential of giving lateral prism in a contact lens correction. Other articles in this issue cover orthokeratology, a new patient orientated mechanical cleaning device for cleaning soft lenses, and a method of care of a patient with Pellucid Marginal Cornea1 Degeneration.
0 1994 Butterworth-Heinemann