Vision with CLs
Does It Matter?
BY JOSEPH T. BARR, OD, MS, FAAO, EDITOR
Some contact lens wearers who report poor vision have good (high contrast) Snellen visual acuity. I tell my students not to think patients are whining or too demanding because they say their vision is poor just because we measure 20/20 or better (high contrast) visual acuity. A recent study (Bailey M 2002) reported that GP lens wearers had worse high contrast VA than spectacle wearers, but spectacle wearers and GP wearers had better low contast acuity than soft contact lens wearers. Also, the soft contact lens wearers had a larger difference between their high and low contast VA (their low contrast VA was even lower).
We have observed that keratoconus patients also have greatly reduced low contast VA compared to their high contrast VA. In the study cited above, the lower VA for GP wearers compared to spectacle wearers likely resulted from uncorrected refractive error not present under best-corrected acuity (with over-refraction). The study measured
Bailey-Lovie VA. Even with best correction (with over-refraction), the soft contact lens wearers had worse low contrast VA compared to the other groups.
Will the results differ with silicone hydrogel lenses? Does vision with contact lenses matter? What about soft toric contact lenses?
Anyone who has been in this field as long as I have knows that great vision with contact lenses is not necessary. Remember how bad vision was with decentered early spin-cast lenses? And what about today's refractive surgery patients who have reduced low contrast VA and uncorrected refractive error? By far the majority of them are happy. 20-happy and overall comfortable visual quality of life seem to be the important variables.
Clearly, carefully prescribed GP lenses provide the best vision with contact lenses.
Does it matter?
Contact Lens Spectrum, Issue: March 2003