OBL astigmatism could require additional correction

Correcting pre-existing astigmatism could be necessary for achieving excellent visual outcomes in eyes with oblique (OBL) astigmatism.

A team headed by Dr Hidenaga Kobashi, Department of Ophthalmology, University of Kitasato School of MedicineKanagawa, Japan, conducted an investigational simulation on 38 healthy participants with no ophthalmic complaints apart from refractive errors.

Cycloplegic refraction was fully corrected in all volunteers with a 3.0 mm artificial pupil. With-the-rule (WTR), against-the-rule (ATR), and oblique (OBL) astigmatism of 1.0 D, 2.0 D and 3.0 D were created using trial lenses in all participants.

Trial lenses under cycloplegia enforced distance visual acuity and visual performance with uncorrected astigmatism. The Minnesota Low Vision Reading Test acuity charts were used to assess maximum reading speed and reading acuity was used to determine reading performance.

Axis orientation at each dioptre of astigmatism significantly affected distance visual acuity, reading acuity and maximum reading speed with uncorrected astigmatism. Significantly better values were identified in eyes with WTR or ATR astigmatism in all parameters, compared to eyes with OBL astigmatism.

The abstract can be found in the Journal of Cataract and Refractive Surgery.