The four microkeratome comparison

Published in the September/October 2005 edition of Journal of Refractive Surgery, Thomas Hammer and colleagues compared the quality and reproducibility of cuts produced by four automatic microkeratomes, and found that each performed similarly on overall quality of cut surface, with one out of the four, performing exceptionally better than the rest on quality of cut edge.

High quality of cut surface and a clean sharp cut edge are the results required by today's refractive surgeon when using a microkeratome in their surgical practice as both have been found to reduce the risk of corneal erosion, epithelial cell growth and scarring during wound healing.

Hammer, of Martin-Luther-University, Halle-Wittenberg, Germany, and co-workers studied the quality and reproducibility of cut edge and cut surface of the following microkeratomes: Amadeus, Hansatome, Summit-Krumeich-Barraquer (SKBM) and Supratome. The effects of oscillation frequency and blade feed rate were determined for both adjustable models - Amadeus and SKBM.

According to the researchers, each microkeratome performed similarly on overall quality of cut surface, with the Hansatome scoring the highest (88% of theoretical maximum), followed by SKBM (86%; 1.0 mm/s blade feed and 7000 rpm oscillation), Amadeus (84%; 2.5 mm/s, 8000 rpm), Supratome (84%; 16.6°/s, 12,500 rpm), Amadeus (81%; 3.0 mm/s and 13,000 rpm) and SKBM (78%; 1.5 mm/s, 14,000 rpm).

The Amadeus produced by far the highest quality of cut, seen in 62.5% of cases (at both settings), compared with the Supratome (25% of cases), SKBM (25% of cases; 1.0 mm/s, 7000 rpm), Hansatome (12.5% of cases) and in no cases with the SKBM at 1.5 mm/s and 14,000 rpm.

The authors concluded that a high frequency with low blade feed rate were characteristics desired in a microkeratome in order to reproduce sharp areas and maintain cut area quality. The study did, however, demonstrate that elevated levels of frequency could be detrimental as displacement of tissue and uneven cut area were demonstrated with the SKBM at 14,000 rpm. The authors recommended oscillation/feed quotients of 2000 to 4000 (rpm/mm^-s ).

Common diabetes medications may be linked to macular oedema

There may be a link between the use of glitazone therapies in diabetes and the onset of macular oedema, according to an announcement made by the European Medicine's Agency (EMEA) scientific committee.

Claims were made after the EMEA received reports of macular oedema in patients taking GlaxoSmithKline's Avandia/Avandamet (rosiglitazone) and Takeda/Lilly's Actos (pioglitazone).

According to an EMEA spokesperson, of the 63 reported cases (35 cases pioglitazone; 28 cases rosiglitazone), it was not known whether the ophthalmic disorder was a result of the medication.

A CHMP investigation has been initiated to consider the claims being made. Meanwhile, GlaxoSmithKline has issued a 'Dear Doctor' letter, which informs doctors of the issue but stresses the rarity of this incident.

Amphotericin B may clear fungal keratitis after PK

Intracorneal administration of amphotericin B may be an effective, less invasive method of treating fungal keratitis as an alternative to repeat penetrating keratoplasty (PK), according to a study published in the December edition of Archives of Ophthalmology.

Enrique Garcia-Valenzuela, MD of the University of Illinois and C. Diane Song, MD of the Emory University Eye Centre, Atlanta, USA, reported on the successful treatment of an 85-year old woman presenting recurrent fungal keratitis and endophthalmitis.