JCRS

Astigmatic outcomes with toric IOLs

The management of pre-existing corneal astigmatism has become clinically more important with the advent of improved IOLs and surgical techniques. Japanese researchers conducted a large prospective study of long-term astigmatic outcomes and rotational stability of the Acrysof IQ toric SN6AT IOL in 378 eyes. Using serial digital photographic analysis of anterior segment landmarks to assess absolute and relative rotational alignment, the authors documented a mean rotational misalignment of 4.1 degrees ± 3.0 (SD) at two years with an overall reduction in refractive astigmatism from 1.92 ± 1.45 dioptres to 0.67 ± 0.9 D. The mean IOL rotation was greatest by postoperative day one (4.5 ± 4.9 degrees) and changed little in the subsequent two years. Six eyes demonstrated more than 20 degrees of rotation, and all these eyes had axial eye lengths greater than 25 mm, with-the-rule astigmatism, and early postoperative rotation. This suggests that misalignment is still an important source of postoperative residual astigmatism.

T Miyake et al, JCRS, “Long-term clinical outcomes of toric intraocular lens implantation in cataract cases with pre-existing astigmatism”, Volume 40, No 10, 1654-60.

Astigmatic outcome with corneal relaxing incisions

Corneal relaxing incisions present an entirely different intraoperative challenge with respect to astigmatic outcomes. Unlike toric IOLs, relaxing incisions maintain a fixed rotational alignment once placed. However, the magnitude of astigmatic effect is less predictable and standard nomograms are notoriously imprecise in eyes with altered corneal biomechanical states owing to previous corneal surgery, ectatic disease, or keratoplasty. A three year follow-up study of 20 eyes of 20 patients that underwent small incision cataract surgery concludes that manual peripheral corneal relaxing incision effects are more limited in range and take longer to stabilise.

R Lim et al, JCRS, "Long-term stability of keratometric astigmatism after limbal relaxing incisions", Volume 40, No 10, 1676-81.

Best analgesia after PRK?

PRK is less popular than LASIK, primarily due to problems of slower visual recovery and discomfort in the immediate post-op period. Numerous drugs are used to provide pain relief for PRK patients. A new review surveyed 23 prospective, randomised trials in an attempt to determine which approach provided the most pain relief. The studies found that although the efficacy of drugs tended to be similar, tetracaine one per cent and nepafenac 0.1 per cent tended to have the most analgesic effect.

E Faktorovich et al, JCRS, “Efficacy and safety of pain relief medications after photorefractive keratectomy: Review of prospective randomised trials”, Volume 40, No 10, 1716-30.