Evaluating the effect of splitting cylindrical power on improving patient tolerance to toric lens misalignment

Sandeep K Dhallu, Amy L Sheppard, James S Wolffsohn

Research output: Contribution to journalArticlepeer-review


PURPOSE: Evaluating the impact of splitting toric power on patient tolerance to misorientation such as with intraocular lens rotation.

SETTING: University vision clinic.

METHODS: Healthy, non astigmats had +1.50D astigmatism induced with spectacle lenses at 90°, 135°, 180° and +3.00D at 90°. Two correcting cylindrical lenses of the opposite sign and half the power each were subsequently added to the trial frame misaligned by 0°, 5° or 10° in a random order and misorientated from the initial axis in a clockwise direction by up to 15° in 5° steps. A second group of adapted astigmats with between 1.00 and 3.00DC had their astigmatism corrected with two toric spectacle lenses of half the power separated by 0°, 5° or 10° and misorientated from the initial axis in both directions by up to 15° in 5° steps. Distance, high contrast visual acuity was measured using a computerised test chart at each lens misalignment and misorientation.

RESULTS: Misorientation of the split toric lenses caused a statistically significant drop in visual acuity (F=70.341; p<0.001). Comparatively better acuities were observed around 180°, as anticipated (F=3.775; p=0.035). Misaligning the split toric power produced no benefit in visual acuity retention with axis misorientation when subjects had astigmatism induced with a low (F=2.190, p=0.129) or high cylinder (F=0.491, p=0.617) or in the adapted astigmats (F=0.120, p=0.887).

CONCLUSION: Misalignment of toric lens power split across the front and back lens surfaces had no beneficial effect on distance visual acuity, but also no negative effect.

Original languageEnglish
Pages (from-to)191-195
Number of pages5
Journal Contact Lens & Anterior Eye
Issue number3
Early online date22 Nov 2013
Publication statusPublished - Jun 2014


  • Adult
  • Astigmatism/diagnosis
  • Female
  • Humans
  • Lens Implantation, Intraocular/adverse effects
  • Lenses, Intraocular/adverse effects
  • Male
  • Patient Satisfaction
  • Prosthesis Fitting/adverse effects
  • Treatment Outcome


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