Inefficacy of Aspheric Soft Contact Lenses for the Correction of Low Levels of Astigmatism

Abstract

For small pupil sizes, there is little difference in HCVA and LCVA between various refractive corrections. However, for larger pupils, HCVA and LCVA are superior with TS contact lenses and SC versus AS contact lenses by approximately a half-line or more, which is considered to be clinically significant. Superior vision can be achieved for low astigmatic contact lens wearers using TS rather than AS contact lenses.

Low toric soft contact lens acceptance study

“…Efron et al [4] suggest five possible reasons that eye care professionals do not routinely correct refractive cylinder of 0.75 DC or less: (1) The small visual improvement is not offset sufficiently by the increased chair time or potential for variability in vision due to axis mislocation. (2) The belief that higher modulus soft contact lenses mask astigmatism. (3) Patient concern over cost.…”

“…Another theory is that using aspheric soft contact lenses corrects low amounts of astigmatism. However, Morgan et al [2] found that toric lenses do this much more effectively. Therefore, when astigmatic patients are fit in non-toric soft lenses their refractive error is not fully corrected.…”

“…Interestingly, there has been a steady increase in toric soft contact lens fitting as a proportion of all soft contact lens fitting for over a decade now. In 2008, toric soft contact lenses represented 34% of all soft contact lens fits [2] that is, astigmatism of 1.00 D or more is being routinely corrected in soft contact lenses.…”

Visual performance in cataract patients with low levels of postoperative astigmatism: full correction versus spherical equivalent correction

“…Clinical studies have demonstrated that subjects with low levels of astigmatism who were being fitted for contact lenses experienced greater improvements in visual acuity with the use of toric contact lenses compared with either spherical6 or aspheric lenses,7 suggesting that correction of even low levels of astigmatism can positively influence visual outcomes. This study investigated whether improvements in visual performance could be demonstrated by correcting low levels of postoperative astigmatism using full correction, instead of spherical equivalent correction, in pseudophakic subjects.…”

Non-Surgical Treatment of Astigmatism

“…(9) Visual acuity with toric lenses is better than with spherical or aspheric lenses, but initially lens quality and stability was a problem. Nowadays, improved lens designs and the availability of disposable toric contact lenses have resulted in improved health benefits and adaptation (10) Well-fitted hydrogel toric lenses can provide visual acuity and visual performance equivalent to that of spherical RGP lenses. (9) All the literature agrees that the best way to fit a soft lens is by considering the response to the trial lens fitting.…”