All professional attendances after the first, being those attendances regarded as a single service, in a single course of attention involving the prescription and fitting of contact lenses, for patients with irregular astigmatism in either eye, being a condition the existence of which has been confirmed by keratometric observation, topographic or quantitative corneal morphology if:(a) the maximum visual acuity obtainable with spectacle correction is worse than 0.3 logMAR (6/12); and(b) if that corrected acuity would be improved by an additional 0.1 logMAR by the use of a contact lens;being a course of attention for which the first attendance is a service to which item 10905, 10907, 10910, 10911, 10913, 10914, 10915 or 10916 appliesApplicable once in a period of 36 months