James J. Reidy

The efficacy of topical ciprofloxacin and norfloxacin in the treatment of experimental Pseudomonas keratitis.

&NA; An aminoglycoside‐resistant strain of Pseudomonas aeruginosa was injected intrastromally into the corneas of rabbits, and keratitis was allowed to develop over a 22‐h period. Rabbits were treated with either 0.75% ciprofloxacin, 1% norfloxacin, or 1.36% tobramycin administered topically every 15 min for 1 h and then every 30 min for the following 3 h. All therapy ceased 26 h postinoculation. Rabbits were killed 1 h after the treatment, and the number of bacteria per cornea were quantified in terms of bacterial colony‐forming units. Aqueous humor specimens were obtained from rabbits receiving norfloxacin and ciprofloxacin, and bioassays were performed to determine drug concentration. Ciprofloxacin caused a 5 log reduction in the number of bacterial colony‐forming units, as compared with untreated controls (p < 0.0001); it also produced a significantly greater reduction in bacterial colony‐forming units than either norfloxacin or fortified tobramycin drops (p < 0.0001). Norfloxacin produced a 2 log reduction in bacterial colony‐forming units, as compared with untreated controls (p < 0.0001). The mean aqueous concentration of norfloxacin (7.5 μg/ml) was substantially less than that achieved by ciprofloxacin (30.5 μg/ml). We conclude that ciprofloxacin may be a useful broad spectrum, topical chemotherapeutic agent in the therapy of aminoglycoside‐resistant P. aeruginosa keratitis.

A New Vehicle for Delivery of Cyclosporin A to the Eye

Collagen shields were tested as a means of delivering the immunosuppressive drug, cyclosporine A (CsA), to the cornea and aqueous humor in rabbit eyes. Gelatinous collagen was mixed with crystalline CsA and then, during drying, was formed into contact lens-shaped shields which were applied to rabbit eyes. The amount of CsA in the corneas and aqueous humor (AH) samples from shield-treated eyes was compared with samples from rabbit eyes treated with CsA in olive oil. CsA concentrations were measured by radioimmunoassay (RIA) at 2, 4, and 8 h after application of the shields or drops. Both the corneal and aqueous humor concentrations of CsA achieved with the shield delivery system were 10-fold higher than those obtained with topical CsA-olive oil drops. The CsA levels achieved in the cornea using the collagen shield are sufficient to inhibit cellular immune reactions in vivo. These results demonstrate that collagen shields may be useful as an ocular delivery system for the drug CsA.

EFFECTIVENESS OF SPECIFIC ANTIBIOTIC/STEROID COMBINATIONS FOR THERAPY OF EXPERIMENTAL PSEUDOMONAS AERUGINOSA KERATITIS

Ciprofloxacin and prednisolone, but not an aminoglycoside and dexamethasone, were previously found to be effective in killing bacteria and reducing inflammation for the treatment of Pseudomonas keratitis. We investigated the therapeutic effectiveness of tobramycin/prednisolone and ciprofloxacin/dexamethasone in a rabbit model of experimental keratitis to increase our understanding of the effectiveness of antibiotic/steroid combinations. To our knowledge, this is the first analysis of the effectiveness of a combination of ciprofloxacin and dexamethasone for experimental keratitis. Two experiments were conducted. In the first experiment, 36 rabbits were divided into six groups: 1) untreated; 2) prednisolone acetate, 1.0%; 3) prednisolone phosphate, 1.0%; 4) tobramycin, 1.36%; 5) tobramycin plus prednisolone acetate; 6) tobramycin plus prednisolone phosphate. In the second experiment, 23 rabbits were divided into four groups: 1) untreated; 2) ciprofloxacin, 0.3%, plus dexamethasone alcohol, 0.1%; 3) ciprofloxacin; 4) dexamethasone alcohol. Topical antibiotic and/or steroid was given for 10 h, from 16 to 26 h postinfection, one drop every 15 min for the first hour and then every 30 min for the remaining 9 h. At 27 h postinfection, eyes were evaluated by slit lamp examination (SLE) and assayed for the presence of bacteria in terms of colony forming units (CFU) per cornea. Both prednisolone acetate and prednisolone phosphate reduced ocular inflammation (as determined by SLE), compared with no treatment (P < or = 0.036); the phosphate was more effective (P = 0.005). Tobramycin alone and in combination with prednisolone also significantly reduced SLE, compared with no treatment (P < or = 0.006). The bactericidal activity of tobramycin was not affected by either steroid formulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Penetrating keratoplasty in active Acanthamoeba keratitis.

Purpose: To report the results of penetrating keratoplasty (PK) in active Acanthamoeba keratitis (AK). Methods: Nine patients with deep stromal infiltrates because of AK were treated with intensive antiamoebic medical therapy followed by PK during the acute infectious phase because of poor clinical response or poor compliance. Antiamoebic therapy was tapered after PK. Results: Visual acuity ranged from 20/15 to 20/50 after an average of 17 months after PK with no signs of recurrences. Patients had rapid resolution of symptoms. Conclusion: PK is a viable option for active AK not responding to maximum medical treatment.

Paranasal sinusitis, orbital abscess, and inflammatory tumors of the orbit.

We present the clinical, radiological, and histopathological findings from a case of unilateral inflammatory mass of the right orbit, originating in the ipsilateral paranasal sinuses. A connection between inflammatory tumors of the orbit and paranasal sinusitis has been suspected for many years. This case shows a definite association between chronic paranasal sinusitis, orbital cellulitis, subperiosteal abscess, and formation of an inflammatory orbital tumor. Early diagnosis combined with appropriate therapeutic measures is essential in order to prevent adverse consequences, which can include severe visual loss.

Immunogenicity of Epikeratophakia Tissue Lenses Containing Living Donor Keratocytes

The purpose of this study was to compare the survival of epikeratophakia tissue lenses prepared with cryolathing and lyophilization (frozen lenses) and without (fresh lenses) in donor-sensitized recipients with vascularized corneas. Fresh lenses placed in vascularized corneas of immune recipients were subjected to immune attack. Frozen lenses placed in vascularized corneas of immunized recipients did not elicit an immune reaction. Neither fresh nor frozen lenses elicited immune reactions in nonvascularized corneas of immune recipients or in nonvascularized, nonimmune recipients. These results indicate that although the fresh lenses are more antigenic than the lenses in which the cells have been killed by freezing and lyophilization, the fresh lenses prepared using the BKS-1000 technique containing living stromal keratocytes are not likely to stimulate allograft immune reactions in unsensitized patients with avascular graft sites.

Comparison of Corneal Epithelial Wound Healing After Photorefractive and Lamellar Keratectomy

BACKGROUND The rate of corneal epithelial wound healing may be determined, in part, by the characteristics of the stromal surface. The excimer laser has the ability to produce a highly uniform ablated surface, which may facilitate reepithelialization after photorefractive keratectomy (PRK). METHODS The rate of corneal epithelial wound healing after excimer laser PRK was compared with the rate of reepithelialization after manual lamellar keratectomy. Ten rabbits received a 4-mm diameter ablation in one eye (fluence = 160 mJ/cm2) and a shallow, 5-mm diameter, manual lamellar keratectomy in the contralateral eye. At 0, 4, 8, 12, 24, 36, 48, 60, and 72 hours after wounding, sodium fluorescein was instilled, and photographs were taken, converted to video images, and digitized. Wound area was calculated for each time point and converted to wound radius; the slopes of the wound radius, plotted over time, were compared to determine rates of healing. Scanning electron microscopy was performed immediately after wounding to examine surface regularity. RESULTS By 24 hours after wounding, corneas that had undergone PRK demonstrated a significantly faster rate of epithelial wound healing compared with eyes that underwent lamellar keratectomy (33.4 +/- 1.9 microns/hr vs 27.8 +/- 1.4 microns/hr, respectively, for 12 to 72 hours) (p < 0.0001). Scanning electron microscopy showed greater stromal surface irregularity in the corneas that had undergone lamellar keratectomy, compared with the laser-ablated corneas. CONCLUSIONS This study demonstrates that the rate of epithelial wound healing is significantly faster after excimer laser PRK than after lamellar keratectomy in the rabbit. Variations in surface regularity and wound edge profile may contribute to differences in wound healing.

Clinical Features of Bleb Disorder of the Cornea

BACKGROUND Bleb disorder of the cornea is a rare corneal epithelial disorder that has previously been described in asymptomatic patients or those with recurrent nontraumatic corneal erosions. METHODS We report two cases of bleb disorder, each presenting with blurred vision from irregular astigmatism secondary to the bleb changes. We also report on the detection of bleb disorder in siblings. RESULTS Both patients underwent surgical debridement of the epithelium with resolution of symptoms on epithelial resurfacing. CONCLUSION The diagnostic clues, inheritance pattern, differential diagnosis, and treatment options of bleb disorder of the cornea are discussed.

Effect of intracanalicular collagen implants on the absorption of topically applied sodium fluorescein.

Absorbable intracanalicular collagen implants were placed in both canaliculi of one eye of nine human volunteers. The other eye served as a control. Twenty-four hours later 2% sodium fluorescein was placed into both conjunctival sacs. Serial corneal fluorescein concentrations were measured with a scanning ocular fluorophotometer from 2 to 90 min after fluorescein administration. The mean corneal fluorescein concentration averaged over all time points was greater in 7 of 9 eyes with collagen implants compared to unimplanted controls. When the data from each subject were analyzed collectively, the mean corneal fluorescein concentration in the implanted eyes (1,218 µg/ml ± SEM 83) was significantly greater (p<0.001) than the mean concentration in the control eyes (823 µg/ml ± SEM 83). The use of absorbable intracanalicular collagen implants may increase the bioavailability of topically applied ocular solutions.