98th Annual Meeting DOG 2000

K 44

Optimization of local therapy in the cornea by microtrephination

H. Wüstemeyer1, S. Kompa1, A. Midelfart2, N. F.Schrage1

Purpose: In most cases of keratitis, the causative agents respond to broad-spectrum antibiotics. Problems occur when drug concentrations at the site of infection are not sufficient to kill infective organisms. The microtrephine was designed to obtain diagnostic corneal biopsies. This study evaluates its therapeutical effect on the bioavailibility of drugs in the healthy rabbit cornea.

Methods: 8 rabbits were involved in the study. Microbiopsies were performed in 4 rabbit corneas. The rabbits were treated with 50µl iodine-solution (11%) every 15 min. over 2 h. 4 corneas without microbiopsies served as control. The rabbits were sacrificed after 2 h. X-ray analysis of the excised corneas was performed to quantify the concentrations of iodine in the different layers of the cornea. The distribution of iodine in the cornea was visualised by means of X-ray mapping.

Results: 40 microbiopsies were performed. Iodine was detected in all corneas. Corneas with microbiopsies showed higher concentration levels than the control corneas. The concentration of iodine detected in the epithelium was higher than in posterior parts of the cornea, whereas the highest stromal iodine concentrations were detected around the microbiopsies. X-ray mapping showed the accumulation of iodine in the epithelium of all corneas and in the stromal tissue around the microtrephinations.

iodine(mol/kg)

whole cornea

epithelium

central stroma

deep stroma

microbiopsy

0.183± 0.419

0.890± 0.437

0.289± 0.489

0.003± 0.060

control

0.101± 0.201

0.483± 0.372

0

0

Conclusions: As the microtrephination biopsy exposes the corneal infection, there is not only a reduction of infectious agents, but also the bioavailibility of antimicrobial agents to infections is improved. Therefore microbiopsy has been proven to not only be a diagnostic method, but also a therapeutic tool possibly improving the treatment of keratitis.

1University Eyeclinic: RWTH Aachen, Pauwelsstr. 30, D-52057 Aachen; 2NTNU Trondheim, Olaf Kyrres Gate 3, N-7005 Trondheim, Norway



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