Extended incubation times improve corneal endothelial cell transplantation success.

To investigate the ability of extended incubation times to improve the success of endothelial cell transplantation, eight human donor corneas were denuded of their native endothelium, seeded twice during a 1-hr interval with a suspension of cultured infant human corneal endothelial cells, and then incubated for 144 hr under standard conditions. Subsequently the corneas were transplanted into African green monkeys using routine penetrating keratoplasty techniques. Rotational autografts and corneas devoid of endothelial cells served as controls. The seeded corneas appeared hazy at the time of surgery (mean pachymetry 48 hr postoperatively, 0.794 mm). Six corneas (75%) subsequently cleared, yielding a mean corneal thickness of 0.541 +/- 0.040 and 0.554 +/- 0.040 at 6 and 12 postoperative months, respectively. All control eyes showed advanced edema (thickness, greater than 1.0 mm) and developed extensive neovascularization. Clinically, the extended postseeding incubation corneas were observed to clear more rapidly and stabilize their thickness earlier than corneas incubated for only 24-48 hr. Scanning electron microscopy of extended postseeding incubation corneas revealed an intact monolayer of contact-inhibited cells with the hexagonal mosaic typical of corneal endothelium in vivo and improved intercellular contact compared with corneas incubated for only 24-48 hr.

Ciprofloxacin iontophoresis for aminoglycoside-resistant pseudomonal keratitis.

Studies using ciprofloxacin for the therapy of experimental aminoglycoside-resistant keratitis caused by Pseudomonas aeruginosa were conducted using transcorneal iontophoresis as the drug-delivery system. Corneas infected with P. aeruginosa ATCC 27853/pMG6 were treated 22 hours postinfection with ciprofloxacin delivered by iontophoresis (0.8 mA X 10 min), mock iontophoresis (eyecup with no current), or frequently applied topical drops. Iontophoresis of 10 mg/ml or 25 mg/ml of ciprofloxacin significantly reduced the number of viable bacteria per cornea by more than 5 log units compared with untreated controls (P less than 0.0001). Five hours after the initiation of treatment, mock iontophoresis (10 mg/ml or 25 mg/ml) or 11 applications of topical ciproflaxicin drops (7.5 mg/ml) decreased the viable bacteria relative to the untreated controls by 5 log units (P less than 0.0001). One treatment with an eyecup was as effective as 11 treatments with topical drops (P greater than 0.75). One hour after treatment with iontophoresis or mock iontophoresis of 10 mg/ml of ciprofloxacin, aqueous humor concentrations were 83.75 +/- 8.85 micrograms/ml and 24.87 +/- 4.0 micrograms/ml (mean +/- standard error of the mean), respectively. One hour after the last of five applications of 7.5 mg/ml of ciprofloxacin (every 15 min for 1 hr) the aqueous humor concentration was 4.2 +/- 1.14 micrograms/ml. These results show the value of ciprofloxacin in treating aminoglycoside-resistant infections caused by P. aeruginosa and suggest that ciprofloxacin can be efficiently delivered by iontophoresis.

Quinolones in collagen shields to treat aminoglycoside-resistant pseudomonal keratitis.

Rabbit corneas were infected with a tobramycin-resistant (minimum inhibitory concentration, 31.25 micrograms/ml) strain of Pseudomonas aeruginosa 27853 (10(3) colony-forming units) and were treated 22 hours later with collagen corneal shields hydrated in either 25 mg/ml ciprofloxacin, 40 mg/ml norfloxacin, 40 mg/ml tobramycin, or deionized water. Shields were removed at 26 hours postinfection, and 1 hour later, corneas were harvested for bacterial enumeration. Application of shields hydrated in ciprofloxacin reduced the number of viable bacteria per cornea approximately 4 log units compared with the application of shields containing tobramycin or deionized water (P less than 0.0001). Use of shields hydrated in norfloxacin reduced the number of P. aeruginosa organisms by greater than 2 log units compared with shields containing tobramycin or deionized water (P less than 0.0001). Ciprofloxacin was significantly more effective than norfloxacin in reducing the number of bacteria per cornea (P less than 0.0001). There was no significant difference in the number of bacteria recovered from corneas treated with tobramycin or deionized water (P less than 0.56).

Topical antibiotic therapy for the treatment of experimental Staphylococcus aureus keratitis.

A rabbit model of Staphylococcus aureus keratitis was developed to study the chemotherapeutic efficacy of ciprofloxacin, vancomycin, and cefazolin. Intrastromal injection of 100 colony forming units of log phase S. aureus ATCC strain 25923 resulted in rapid growth in the cornea, peaking at 10(7) cfu/cornea by 12 hr post-infection. Slit-lamp examination revealed that infected eyes reached 30% of maximum inflammation by 10 hr and 60% by 22 hr post-infection. Antibiotic therapy (one drop every 15 min for 5 hr) was initiated at 4 hr post-infection (experiment 1) or 10 hr post-infection (experiment 2). Another group was initiated at 10 hr post-infection and treated for 10 hr (experiment 3). In experiment 1, treatment from 4-9 hr post-infection with 0.3% ciprofloxacin drops decreased the cfu per cornea 6.1 logs, compared to placebo-treated controls (P = 0.0001), and rendered 50% of inoculated eyes sterile. Vancomycin (5.0%) and cefazolin (5.0%) each lowered the cfu per cornea 4.6 logs (P = 0.0187) but did not sterilize any eyes. In experiment 2, therapy from 10-15 hr post-infection with 0.3% ciprofloxacin reduced the cfu per cornea 0.9 logs (P = 0.0001). Vancomycin (5.0%) and cefazolin (5.0%) decreased the cfu per cornea 0.2 logs (P = 0.3973) and 0.3 logs (P = 0.1307), respectively. In experiment 3, therapy from 10-20 hr post-infection with 0.3% ciprofloxacin reduced the cfu per cornea 3.9 logs (P < 0.0001). In this keratitis model, ciprofloxacin was more effective than vancomycin or cefazolin in killing S. aureus.

EGF cell surface receptor quantitation on ocular cells by an immunocytochemical flow cytometry technique.

A method is presented for the rapid flow cytometric determination of epidermal growth factor (EGF) receptor densities on the surface of cultured ocular cells. The technique uses a biotinylated monoclonal antibody directed against the EGF receptor in conjunction with a streptavidin-bound fluorochrome and requires the specific fluorescence per cell to be measured as a function of ligand and receptor concentration. Because the measurement is noninvasive and restricted to cell surface-bound material, the cells can be kept in a physiologic environment, even at the moment of assay. Calculated receptor densities ranged from 5142/cell (infant human corneal endothelium) to 35,678/cell (infant human keratocytes) to greater than 5 x 10(5)/cell for an A431 control cell line. Species and donor age differences were noted, as was transient receptor downregulation after EGF administration. Flow cytometry represents a valuable time saving procedure for large scale applications while providing the same level of sensitivity as standard radioimmunoassays. This technique is applicable to quantitation of other growth factor cell surface receptors and could greatly expand the use of flow cytometry in the research laboratory.

Intraocular pressure by noncontact tonometry with and without soft contact lenses.

We compared the intraocular pressure of 43 eyes (23 patients) with and without soft contact lenses. Two measurements were taken on each eye while the patients were wearing their soft contact lenses, and then immediately after the lenses were removed. Intraocular pressure measurements were taken by noncontact tonometry. The results showed that the power of the contact lens was a significant predictor of the change in intraocular pressure. In addition, when the 43 eyes were broken down into two groups, those with hyperopic lenses and those with myopic lenses, the difference in intraocular pressure was significantly larger for the group with hyperopic lenses than for the group with myopic lenses.

Visual field constriction caused by colored contact lenses.

Goldmann visual field testing was performed on ten patients while they were wearing the recently released DuraSoft 3 colored soft contact lenses. All patients but one had visual field constriction ranging from 5 degrees to 20 degrees. When the areas inside the three tested isopters were averaged, the amount of field loss ranged from 21% to 47%. Contact lens fitters as well as wearers should be warned of this potential complication.

Analysis of corneal thickness and endothelial cell density in pseudophakic and aphakic patients undergoing penetrating keratoplasty.

We studied the effects of the presence or location of an intraocular lens on 54 eyes with a penetrating keratoplasty. Endothelial cell density and corneal thickness measurements were compared in the four subgroups (14 aphakic, 14 anterior chamber lenses, 11 iris-supported lenses, and 15 posterior chamber lenses), using analysis of covariance, with the covariable being months since transplant. There was no statistical difference in these parameters among the four groups. The correlation between endothelial cell density and postoperative time (P less than .0022) and between corneal thickness and elapsed time (P less than .05) was, however, significant in all categories. Based on our analysis, we believe the presence or location of an intraocular lens is not detrimental to the corneal endothelium in penetrating keratoplasty.

Topical vs systemic gentamicin penetration into the human cornea and aqueous humor.

Twenty-two patients undergoing penetrating keratoplasty received either topical fortified gentamicin (13.6 mg/mL) or a loading dose of intramuscular gentamicin before surgery. Cornea and aqueous humor samples were obtained and assayed by radioimmunoassay for gentamicin. In the topical group, the average gentamicin levels in the cornea and aqueous were 16.2 micrograms/g and 0.3 microgram/mL, respectively. Parenteral drug levels were less variable and averaged 6.1 micrograms/g in the cornea and 0.4 microgram/mL in the aqueous. Although this study demonstrates that parenteral therapy can be used to deliver adequate drug levels to the cornea, it requires far more antibiotic and subjects the patient to potentially toxic systemic side effects. Therefore, topical administration is the preferred route of delivery of antibiotic to the cornea.

Accuracy and precision of the Tono-Pen in measuring intraocular pressure after keratoplasty and epikeratophakia and in scarred corneas.

Intraocular pressure measurements with the Goldmann and Schiotz tonometers are unreliable when the cornea is irregular due to disease or surgery. The Tono-Pen (Oculab, Glendale, Calif) is an electronic applanation tonometer based on the same principle as the MacKay-Marg tonometer. We measured intraocular pressure in 37 eyes with irregular corneas, in 50 eyes that had recently undergone penetrating keratoplasty, in 16 eyes that had undergone epikeratophakia, and in 12 eyes with normal corneas with both the MacKay-Marg and Tono-Pen tonometers. The same two instruments were used, and the sequence of measurement was randomized. Analysis of variance demonstrated no significant difference between measurements obtained with the two tonometers in any of the groups. The data suggest that the Tono-Pen is as accurate as the MacKay-Marg tonometer in those situations where the Goldmann tonometer is inaccurate.

Gentamicin, tobramycin, amikacin, and netilmicin levels in tears following intravenous administration.

Peak and trough tear and serum concentrations were determined in 27 human volunteers undergoing intravenous (IV) gentamicin sulfate, tobramycin sulfate, amikacin sulfate, and netilmicin sulfate therapy. Although effective serum concentrations were achieved, tear levels were subtherapeutic. The mean peak tear concentrations were 0.4 microgram/mL, 0.5 microgram/mL, 1.7 micrograms/mL, and 0.3 microgram/mL for gentamicin, tobramycin, amikacin, and netilmicin, respectively. These levels did not approach the minimum inhibitory concentrations for Pseudomonas and raise some concern regarding the risk-benefit ratio of IV antibiotics for bacterial keratitis.

Treatment of experimental Pseudomonas keratitis using collagen shields containing tobramycin.

To study the effectiveness of collagen shields containing tobramycin sulfate in the treatment of Pseudomonas keratitis, rabbits were infected via an intrastromal injection of Pseudomonas aeruginosa and treated 22 hours later with either collagen corneal shields rehydrated in 4% tobramycin and applied to the cornea or 4% tobramycin drops. Bacterial killing was quantitated by culturing corneal homogenates and calculating the number of viable bacteria (colony-forming units) per cornea. Corneas receiving shields rehydrated in 4% tobramycin and applied for four hours demonstrated significantly reduced numbers of bacteria compared with untreated control corneas. The collagen shields were as effective in reducing the number of viable bacteria per cornea as 4% tobramycin drops applied every 30 minutes over a four-hour period. Over a nine-hour treatment period, the addition of four drops of 4% tobramycin to shields in situ was as effective as exchange with a new shield rehydrated in 4% tobramycin. These results suggest that collagen shields rehydrated in a water-soluble antibiotic such as tobramycin may be an effective and convenient mode of therapy for Pseudomonas keratitis.

Louisiana's Medical Review Panel.

Since 1975, professional liability claims against health care providers in the state of Louisiana have been screened by medical review panels, which are composed of three physicians and one attorney. The purpose of the panels is to weed out frivolous lawsuits and aid the prompt settlement of meritorious claims. In this article, the procedures, controversies, and findings of Louisiana's medical review panels are summarized.

Surgical management of corneal ulceration and perforation.

Corneal ulceration leading to perforation can occur secondary to a number of conditions, including infection, trauma, corneal dryness, and exposure keratitis. Because the ocular morbidity of corneal perforations is high, prompt diagnosis and treatment is critical. When persistent corneal ulceration does not respond to medical treatment, including antibiotics, therapeutic soft contact lenses, or tarsorrhaphy, surgical intervention is indicated. In this review, the evaluation of patients with recalcitrant ulceration or perforation is summarized, and indications and techniques for surgical treatment (epithelial transplantation, conjunctival flaps, lamellar and penetrating keratoplasty, tissue adhesives, periosteal grafts) are described.

The effects of hypotonic and hypertonic solutions on the fluid content of hydrophilic contact lenses.

Twenty healthy volunteers were fitted with a Bausch & Lomb plano O4 bandage contact lens (center thickness, 0.06 mm; water content, 38.6%) in one eye and a CooperVision therapeutic bandage Permalens (center thickness, 0.24 mm; water content, 70%) in the other eye. Ten received eyedrops every hour for six hours of a solution of 224 ml Osmol and the other ten received a solution of 670 ml Osmol. At the end of the examination period water loss was 21.05% and 20.36% in the Permalens group with the hypertonic and hypotonic solutions, respectively, and 8.86% and 10.74% in the Bausch & Lomb lens groups with the hypertonic and hypotonic solutions, respectively. These values were not significant when compared to those for five control patients (13.75% water loss for the Permalens and 7.28% for the Bausch & Lomb contact lens), suggesting that other factors may be more significant in controlling hydrogel contact lens dehydration.

Pigment dispersion syndrome in pseudophakic corneal transplants.

We observed the pigment dispersion syndrome in two patients after keratoplasty with posterior chamber intraocular lenses. In addition to a heavily pigmented trabecular mesh-work and iris transilluminating defects, an inferior linear pigmented endothelial line was seen in both patients. One patient developed glaucoma, which was well controlled with medication. Pigment dispersion syndrome in patients with penetrating keratoplasty should not be confused with an allograft reaction but should alert the transplant surgeon that a different process is occurring.

Visual results in repeat penetrating keratoplasty.

In a study of visual prognosis after repeat penetrating keratoplasty, we found that 18 of 29 eyes required only one regraft and 11 required multiple repeat penetrating keratoplasties. After an average follow-up of 15.7 months, six of the 18 eyes with only one regraft had achieved visual acuities of 20/100 or better. After an average follow-up of 27.5 months, only one of 11 eyes with multiple regrafts achieved a best corrected visual acuity of 20/100 or better.

Pseudomonas keratitis and folliculitis from whirlpool exposure.

A local outbreak of pseudomonal folliculitis from whirlpool exposure occurred in 12 persons. A corneal ulcer developed in one patient within 48 hours of using the whirlpool. Treatment with fortified gentamicin resolved the corneal infiltrate and vision returned to normal. A second patient, who had not showered immediately after leaving the whirlpool, was left with areas of skin hyperpigmentation and scarring despite treatment with ultraviolet rays and tetracycline. Although the skin rash may be self-limited, the potential for visual loss from pseudomonal keratitis emphasizes the need for proper disinfection of swimming and whirlpool water.

Candida albicans endophthalmitis after penetrating keratoplasty.

We examined two patients who received contaminated corneas from the same organ donor during penetrating keratoplasty. Both developed Candida albicans endophthalmitis, which responded to surgical and antifungal therapy. On follow-up examination one patient had a visual acuity of hand motions, a pupillary membrane, and a macular scar. The other had a visual acuity of 20/100 and a clear graft.

Contamination of donor cornea by gentamicin-resistant organisms.

Cultures of the donor corneoscleral rims in 70 consecutive penetrating keratoplasties showed microbial contamination in 14 cases. All positive cultures were tested by standard microdilution broth method for sensitivities to gentamicin, an antibiotic routinely used in McCarey-Kaufman transport medium. Seven of 15 organisms demonstrated resistance to gentamicin at concentrations above 100 micrograms/ml. These results indicated the selection of more antibiotic-resistant microorganisms in antibiotic-supplemented medium and the need for appropriate antibiotic prophylaxis at the time of surgery.