Diagnosis, laboratory analysis, and treatment of bacterial corneal ulcers.

This paper describes the diagnosis, analysis, and management of ophthalmic bacterial corneal infections, with emphasis on the various risk factors, culture techniques, relations to other pathologic states, prophylaxis, sensitivity trends, and treatment protocols associated with bacterial corneal ulcers. New antiinfective agents and their role in the management of current bacterial ophthalmic infections are also discussed.

Refractive corneal surgery with the Draeger rotary microkeratome in human cadaver eyes.

BACKGROUND: Instrumentation for performing a uniform lamellar keratoplasty has been undergoing various stages of refinement. Reliable reproduction and uniform thickness and diameter of lamellar resections is required before lamellar refractive keratoplasty can be considered safe and effective. METHODS: The authors used the Draeger rotary microkeratome with mechanical blade advance for lamellar dissections in 61 human cadaver eyes prepared by injecting Swinger-Kornmehl (SK) solution into the anterior chamber to a pressure of 35 to 40 mm Hg and by soaking for 30 minutes in SK solution. Spacer sizes of 0.25 to 0.40 units were utilized using an anterior lamellar disc diameter estimate between 8.0 and 8.5 mm and a stromal lamellar disc diameter estimate between 5.5 and 6.5 mm. Preoperative pachometry, anterior and stromal lamellar disc thicknesses, and anterior and stromal lamellar disc diameters were measured. RESULTS: The Draeger unit created anterior lamellar thickness between 100 and 268 microns. Stromal lamellar disc thicknesses were consistently between 90 and 161 microns. The continuous, unidirectional, rotary blade and the uniform mechanical advance of the instrument produced a generally uniform bed as evaluated by scanning electron microscopy, although undulations were still present. CONCLUSION: The Draeger microkeratome produced regular lamellar dissections; however, predictability of the thickness of the lenticules varied 10% to 20%, and of the diameter, 1.5% to 15%. Predictability improved with experience. This variability may reduce predictability of refractive outcome.

Photography of shock waves during excimer laser ablation of the cornea. Effect of helium gas on propagation velocity.

Shadow photography of shock waves excited by means of a xenon chloride excimer laser was performed to determine the shock wave propagation velocity in air, nitrogen and helium. Energy densities between 500 and 2,000 mJ/cm2 were used to ablate a rotating rubber cylindrical target and porcine corneas. In ablating the rubber cylinder, a shock wave velocity of 3.3 km/s was generated in air and nitrogen at 40 ns; this decreased to 1.4 km/s at 320 ns. When helium was blown on the target, the velocity increased by a factor of approximately two, to 5.9 km/s at 40 ns and 2.7 km/s at 320 ns. We suggest that blowing helium on the surface of the cornea during excimer laser ablation may speed the dissipation of high-energy acoustic waves and gaseous particles, and thus reduce the exposure and transfer of heat energy to the surrounding tissue.

Peters' anomaly: a review of 26 penetrating keratoplasties in infants.

We reviewed the specimen records log of the McGee Eye Institute Histopathology Service from January 1979 to December 1990 for penetrating keratoplasty specimens submitted with a clinical diagnosis of Peters' anomaly. The records of the 19 cases thereby identified were reviewed for clinical outcome and visual rehabilitation, and the histopathology of all specimens was reviewed and correlated with the clinical diagnosis. Two specimens from the same patient were eliminated as histopathologically inconsistent with Peters' anomaly; one patient's data were not used because the patient was an adult when first grafted. Six eyes were grafted two or more times, for a total of 26 grafts on 16 eyes in 10 patients. Mean age at the time of first transplant was 18 weeks (range, 3 weeks to 40 months). Mean follow up was 30 months (range, 7 months to 6 1/2 years). Five eyes had preoperative glaucoma which persisted postoperatively. Ten eyes developed glaucoma postoperatively. Of the 15 eyes with glaucoma, 14 were uncontrolled medically and 12 underwent cyclodestructive or Molteno filtering procedures, or both, to control pressure. Graft rejection developed in 9 of the 10 eyes that required a cyclodestructive procedure, with partial or complete graft failure occurring shortly after the procedure. Glaucoma did not develop in one eye; in one other eye, it was medically controlled. These 2 eyes maintained clear grafts. Of the 6 eyes that were regrafted, only 1 obtained ambulatory vision. Of the 26 eyes receiving grafts, the grafts failed completely in 17 and partially in 5; 4 have remained clear. Five patients maintain ambulatory vision.

The radioprotective effects of WR-2721 on radiation-induced goblet cell loss.

We assessed the efficacy of the radioprotective effects of WR-2721 in radiation-induced goblet cell loss. Fourteen female New Zealand white rabbits were divided into radioprotected, radiounprotected, and control groups. Ten rabbits received 5,000 rad of beta irradiation to the temporal conjunctiva of both eyes. The right eyes were pretreated with topical applications of WR-2721 30 minutes and 1 minute before irradiation. The left eyes received irradiation only. Four additional rabbits received neither irradiation nor pretreatment with WR-2721. After a 2-month waiting period, each animal was killed and goblet cell densities per high-power field (GCD/HPF) were determined over the areas in question and compared using paired sample t tests. The mean GCD/HPF for the radioprotected, unprotected, and control groups were 10.93, 4.68, 23.15 (right eye), and 26.25 (left eye). Paired sample t tests showed a significant radioprotective effect when comparing WR-2721-treated animals with those receiving radiation only (p less than 0.003). Independent sample t tests showed significant goblet cell loss in both the radioprotected (p less than 0.018) and radiounprotected eyes (p less than 0) when compared with control groups. These data suggest a radioprotective effect of WR-2721 in radiation-induced goblet cell loss.

Infectious endophthalmitis following sutureless cataract surgery.

Within the last 6 months, three cases of infectious endophthalmitis following sutureless cataract surgery have been referred to us. Two of these cases followed uncomplicated sutureless phacoemulsification with intraocular lens implantation. One case was complicated by a postoperative hyphema with additional surgery for clot removal 2 days following the initial procedure.

Ocular infections associated with Comamonas acidovorans.

Comamonas acidovorans (Pseudomonas acidovorans) is a ubiquitous gram-negative rod. Although generally considered nonpathogenic, we found C. acidovorans to be associated with six cases of ocular infections. The organism was the only isolate in three cases, whereas an association of other organisms was present in three cases. The multiple resistance patterns of these strains to antibiotic susceptibility testing emphasizes the need for culturing ocular infections. We recommend the identification and susceptibility testing of all ocular gram-negative rod isolates.

Hematoma of the optic nerve sheath after penetrating trauma.

We have presented a case involving the diagnosis and management of optic nerve sheath hematoma. Our patient's positive outcome demonstrates the usefulness of megadose steroid therapy for acute optic nerve injury.

Topical application of all-trans-retinoic acid. A look at the cornea and limbus.

A 0.1% all-trans-retinoic acid in petroleum-base ointment was applied daily in eight normal rabbit eyes. Epithelial samples were collected from the cornea and limbus of six rabbits by impression cytology at 3- to 4-day intervals. Cytological changes were followed for 21 days and the eyes subsequently harvested for histochemical, scanning electron microscopic (SEM), and transmission electron microscopic (TEM) analysis of corneal and limbal structures. Two rabbits were treated with 0.1% all-trans-retinoic acid for 24 days without impression cytology until the 21st day. On the 24th day these eyes were harvested for similar studies. Impression cytology studies of the corneal epithelium demonstrated perinuclear halos and vacuolization of the cytoplasm. Additionally, vacuolization of the cytoplasm was observed by TEM, with attendant extrusion of the cytoplasmic contents and a subjective increase in surface microvilli as seen by SEM. Histochemical analysis revealed mucinlike staining of the corneal epithelium.