The importance of pupil size in optical quality measurements following radial keratotomy.

This review considers the importance of pupil size when specifying the optical quality or visual performance of eyes following radical keratotomy. The experimental evidence presented includes measurements both before and after radial keratotomy of the eye's: 1) corneal curvature; 2) optical aberrations; 3) modulation transfer function; 4) visual acuity as a function of test beam entry; and 5) disability glare. Together these five lines of evidence demonstrate that pupil size is a key factor influencing both the optical quality of the eye and visual performance.

Flexure and residual astigmatism with Paraperm O2 and Boston II lenses on toric corneas.

It has been shown previously that thin polymethyl methacrylate (PMMA), cellulose acetate butyrate (CAB), and Polycon I contact lenses flex on toric corneas. We investigated the flexure and induced residual astigmatism of two gas permeable contact lens materials, Paraperm O2 and Boston II, and compared the results with those of other materials. Six subjects (12 eyes) with corneal toricities ranging from 1.75 to 3.25 D wore five Paraperm O2 lenses and five Boston II lenses with center thicknesses ranging from 0.10 to 0.20 mm. Flexure and induced residual astigmatism were measured on all corneas wearing all lenses in a double-masked fashion. All lenses studied showed flexure and induced residual astigmatism, which increased as center thickness decreased. For both lens types, lenses thinner than 0.15 mm flexed significantly more than thicker lenses. This critical center thickness should be considered when fitting these lens types on toric corneas.

[Creation of a stress-free laying pause in turkeys with TURISYNCHRON]. / Die Erzeugung einer stressarmen Legepause bei Puten durch TURISYNCHRON

Metallibure (TURISYNCHRON, VEB Jenapharm, GDR) at 40 mg per kg of food, given for 14 days, completely suppressed laying, and in a shorter time than that produced by conventional methods. Turkeys tolerated TURISYNCHRON well, and no adverse effects were seen. Egg production after TURISYNCHRON treatment was higher than that of untreated controls. This preliminary trial will be followed by more extensive trials.