In The Journal Of Cataract & Refractive Surgery March 2010

Intraocular lens exchange in patients with negative dysphotopsia symptoms Peter Vamosi, M.D., Ph.D., Bela Csakany, M.D., Janos Nemeth, M.D., D.Sc.
In this study, investigators set out to see how troubling symptoms of severe negative dysphotopsia are affected by intraocular lens exchange and to consider what impact the distance between the iris and the IOL optic had on this problem. Investigators found that out of 3,806 cataract procedures there were severe negative dysphotopsia symptoms in just five eyes. In one case symptoms persisted even after the capsular bag was reopened and a secondary IOL was implanted. However, in two other cases symptoms resolved when the IOL was implanted in the ciliary sulcus. Investigators found that for those in the symptomatic group the mean iris optic distance was 0.45 mm while for those in the control group this was 0.59 mm and for those in the sulcus-fixated group was 0.00 mm. The conclusion reached was that although there was not much difference in iris-optic distance between those with negative dysphotopsia and controls, severe symptoms ultimately resolved when IOL exchange reduced this distance.

Keratorefractive effect of microwave keratoplasty on human corneas
Allon Barsam, M.R.C.Ophth., Anne Patmore, Ms.C., David Muller, Ph.D., John Marshall, Ph.D.
The aim here was to determine the quantitative impact of microwave keratoplasty application on dioptric power of excised human corneal scleral buttons as well as the qualitative effect of the technique. Investigators here applied 28.12 Watts for one second using the prototype microwave keratoplasty ring, with a 6 mm diameter inner conductor and an 8.4 mm diameter outer conductor. Investigators found that there was a mean reduction in curvature of 3.07 D for the six donor buttons used. Qualitatively they found that while there was shrinkage of the corneal stroma there was little disturbance of the epithelium. Investigators concluded that this technique has therapeutic potential for non-invasively reducing corneal curvature for myopia correction and as a treatment for corneal ectasia.

Effect of varying microkeratome parameters on laser in situ keratomileusis interface surfaces R. Krishna Sanka, M.D., Evan S. Loft, M.D., J. Bradley Randleman, M.D.,
Investigators here considered how varying oscillation rates and head advance speeds, as well as repeated blade usage would affect interface quality in human and porcine LASIK. Using the Amadeus microkeratome investigators used the blade just once for 18 porcine cadaver eyes and five times in another 15 porcine eyes. The blades were used twice in 18 human eyes. Investigators found that there was no difference in bed quality with multiple blade use. In addition, the smoothness of the bed was not consistently influenced by oscillation rates nor head advance speeds in any group. The beds, however, were consistently smoother in porcine compared with human eyes. Investigators concluded that future studies on corneal stromal beds should be conducted entirely in humans since there was no subjective linkage in bed quality between human and porcine eyes.