Pascal immune to corneal biomechanics

March 1, 2007

Intraocular pressure (IOP) measurements with the Pascal dynamic contour tonometer (PDCT) are relatively immune to changes in corneal biomechanics and pachymetry, according to a study published in the January issue of the American Journal of Ophthalmology.

Intraocular pressure (IOP) measurements with the Pascal dynamic contour tonometer (PDCT) are relatively immune to changes in corneal biomechanics and pachymetry, according to a study published in the January issue of the American Journal of Ophthalmology.

Dr Jay Pepose and colleagues from the Pepose Vision Institute and the Washington University School of Medicine, St Louis, USA, conducted a prospective, non-randomized study to compare the preoperative and postoperative measurements of corneal biomechanical properties and IOP using Goldmann applanation tonometry (GAT), the ocular response analyser (ORA) and the PDCT in eyes undergoing myopic LASIK.

A total of 66 myopic eyes were measured for IOP before and after LASIK using the three devices in a randomized sequence. Metrics of corneal biomechanical properties were also recorded. After LASIK, there was a reduction in mean corneal pachymetry of 90.2 µm and in IOP measurements with GAT (Delta= -1.8±2.8 mmHg; p<0.01), ORA-Goldmann (Delta= -4.6±2.8 mmHg; p<0.01) and ORA-corneal compensated (Delta= -2.1±2.6 mmHg; p<0.05). There was, however, no statistically significant difference between pre- and postoperative IOP measurements taken by PDCT (Delta= -0.5±2.6 mmHg).

New combination keeps inflammation down

S. Russo and colleagues from the Medical department at SIFI S.p.A., Italy and the Military Hospital, Romania, enrolled 223 patients to receive either I mg/ml dexamethasone plus 3 mg/ml netilmicin (n=148) or 1 mg/ml dexamethasone plus 3 mg/ml tobramycin (Tobradex) (n=75), four times a day for seven days after cataract surgery. Efficacy and safety were analysed one and seven days postoperatively, in addition to a follow-up visit 142 days postoperatively. The extent of anterior chamber inflammation, measured by slit-lamp according to a standard scoring system, was used as the primary efficacy parameter.

At seven days both fixed combinations were equally effective in reducing inflammation and the dexamethasone/netilmicin combination demonstrated a good safety profile, with no evidence of poor local tolerance or adverse reactions.

It was concluded that this new fixed combination is both effective and safe as a treatment for ocular inflammation following cataract surgery.

Mircochip helps blind cats see

Kristina Narfstrom works primarily with Abyssinian and Persian cats who are often affected by retinitis pigmentosa. Cat's eyes are good models as they are similar to the human eye in size and construction and share many of the same diseases that affect humans.

Implantation involves making two small cuts in the sclera and, after removing the vitreous, creating a small blister in the retina and a small opening for the microchip, which is just 2 mm in diameter and 23 µm thick. The chip contains several thousand microphotodiodes that react to light and produce small electrical impulses in parts of the retina.

It is hoped that this technology will be of benefit, not just to cats, but to humans and other animals too.

Four-point scale for AMD risk

A presentation given at Hawaiian Eye 2007 meeting in January, outlined a four-point scale that may help to simplify the assessment of a patient's risk of developing age-related macular degeneration (AMD).