Cornea and External Disease

This landmark article was a multiceneter, prospective, randomized, parallel group study conducted across Europe, the U.S. and India. 324 patients were identified and enrolled. Positive cultures were obtained in 188 (58%) of whom 176 met all criteria and were studied. Cipro was used in 82 (47%) and fortified antibiotics in the remaining 94 (53%).

Dosing schedule:
q 30 min for 6 hours; q 1 hour for 18 hours; q 1 hour for days 2 - 3; q 2 hours for days 4-5; q 4 hours for days 6-14.

Drug One follwed by Drug Two 5-15 minutes later
Fortified Tobra - Fortified cefazolin
Cipro - Cipro

RESULTS:

1. Clinical Efficacy:
   Equal regarding ulcer depth or diameter.
   Equal as per clinician's judgement.
   Equal at resolving clinical signs - erythema, cell and flare, discharge, epithelial disease, etc
2. Microbiologic Efficacy:
   Cipro: cured/improved = 76% - worse = 6%
   Fortifieds: cured/improved = 77% - worse = 10%
3. Events related to therapy:
   Cipro: 17.6% - white precipitate (no clinical concerns); 10.1% had corneal burning or stinging
   Fortifieds: 13.4% with burning or stinging; 3.7% - ocular hyperemia; and 2.4% with ocular pruritis.

CONCLUSION:

Ciprofloxacin is equally effective and somewhat better tolerated than the traditional fortified antibiotics regimen when used in the treatment of bacterial corneal ulcers.

Raymond Magauran, MD
West Bloomfield, MI

Cornea and External Disease

A great deal of controversy and concern exists over potential transmission of central nervous system diseases by corneal transplant. The purpose of this study was to evaluate the available data relative to this question, pertaining especially to transmission of infectious dementia. From these data, determination of conveyance risks are possible, and rational policies for donor inclusion criteria can be constructed. Retrospective analysis of available published data regarding transmission of infectious dementias was performed. Risk of disease transmission was calculated from population data. Of the various forms of dementia, only rabies, hepatitis B, and Creutzfeldt-Jakob disease (CJD) have been transmitted by corneal transplantation. Transmission of the first two viruses is preventable by serologic testing. Prevention of CJD transmission relies on clinical history. Despite the possibility of transmission and the lack of available testing, slow virus disease (CJD) has been transmitted only once. That this case represents an extremely rare event is supported by a lack of successful transmission via corneal transplant in monkeys; lower levels of infectious agent in cornea than in brain; lack of successful transmission of similar human dementias, including Alzheimer's disease to primates; the apparent requirement for homozygosity at codon 129 of chromosome 20 for transmission; lack of transmission in 5-10% of CJD cases even after brain inoculation; and low numerical risk of transmission based on population data. Only 0.5-4 CJD-infected donors per year would be expected. Current Eye Bank Association of America criteria for donor exclusion based on suspicious history are adequate to protect against accidental conveyance of transmissible dementia.

Authors' abstract, Cornea
Dallas, Texas

Cornea and External Disease

This study examined 6 eyes from five patients whose axial lengths were less than 20mm. The authors used two intraocular lenses in the capsular bag to approach emmetropia. This article compares what was actually required to what each of the lens power formulas predicted. The authors do not state how they achieved their postoperative results howe ver. Did they streak the patients while on the table? Did they refract the patients and bring them back to the OR for a lens exchange? Did they guess?

Either way, this is how the lens power formulas faired:

The current formulas are clearly inadequate when one considers short eyes. The reason why such large variations exist rests in the factors leading to microphthalmia. An eye with an axial length can be symmetrically small (nanophthalmus) or have a normal anterior segment with a blunted posterior segment. The anterior segment and lens measurements are needed in addition to the standard keratometry readings and axial length measurements. Also, errors in axial length measurements have a greater effect on the final refractive error.

We are sure to see improvements in the next generation of lens power formulas. Until then, each surgeon should review their refractive results for their patients with axial lengths less than 20 mm. From these, you should develop a set of guidelines for choosing which lens powers to use. I also suggest obtaining a separate consent form from each patient you plan on placing two (or more) intraocular lenses in the capsular bag explaining the potential risks and benefits and alternate treatment options. We hope to have a clear set of guidelines and formulas to aid us in tackling this challenging clinical dilemma.

Raymond G. Magauran, M.D.
Kresge Eye Institute
Detroit, MI