A novel cell-associated protection assay demonstrates the ability of certain antibiotics to protect ocular surface cell lines from subsequent clinical Staphylococcus aureus challenge.

In vivo effectiveness of topical antibiotics may depend on their ability to associate with epithelial cells to provide continued protection, but this contribution is not measured by standard antibiotic susceptibility tests. We report a new in vitro method that measures the ability of test antibiotics azithromycin (AZM), erythromycin (ERY), tetracycline (TET), and bacitracin (BAC) to associate with mammalian cells and to protect these cells from destruction by bacteria. Mammalian cell lines were grown to confluence using antibiotic-free medium and then incubated in medium containing a single antibiotic (0 to 512 µg/ml). After incubation, the cells were challenged with Staphylococcus aureus ocular isolates, without antibiotics added to the culture medium. Epithelial cell layer integrity was assessed by gentian violet staining, and the minimum cell layer protective concentration (MCPC) of an antibiotic sufficient to protect the mammalian cells from S. aureus was determined. Staining was also quantified and analyzed. Bacterial viability was determined by culture turbidity and growth on agar plates. Preincubation of Chang and human corneal limbal epithelial cells with AZM, ERY, and TET at ≥64 µg/ml provided protection against AZM-susceptible S. aureus strains, with increasing protection at higher concentrations. TET toxicity was demonstrated at >64 µg/ml, whereas AZM displayed toxicity to one cell line at 512 µg/ml. BAC failed to show consistent protection at any dose, despite bacterial susceptibility to BAC as determined by traditional antibiotic susceptibility testing. A range of antibiotic effectiveness was displayed in this cell association assay, providing data that may be considered in addition to traditional testing when determining therapeutic dosing regimens.

Evaluation of the effects of olopatadine ophthalmic solution, 0.2% on the ocular surface of patients with allergic conjunctivitis and dry eye.

PURPOSE: Olopatadine hydrochloride 0.2% (Pataday, Alcon, Fort Worth, USA) is a topical ocular anti-allergic agent that has shown high rates of efficacy in treating ocular itching, the primary symptom of allergic conjunctivitis, and allows for once-daily dosing. Since some patients suffer from signs or symptoms of dry eye in addition to ocular allergy, this study was designed to evaluate the safety of olopatadine 0.2% in a population of patients with both allergic conjunctivitis and dry eye. METHODS: This was a single-center, 3-visit, double-masked, randomized study. Fifty-two patients diagnosed with ocular allergy and mild-to-moderate dry eye were evaluated. After a run-in period, patients were randomized to receive either olopatadine hydrochloride 0.2% or a tear saline, and self-dosed once-daily for 1 week. Outcome measures included tear film break-up time, corneal and conjunctival staining, tear volume and flow as measured by fluorophotometry, Schirmer's test, injection, and symptom evaluations. RESULTS: No significant differences between the treatment groups were observed (p > 0.05). No serious adverse events occurred during the trial. Variability in the presentation of dry eye can hinder the observation of treatment effects. Although the study design facilitated the comparison of olopatadine 0.2% against an agent that was certain to not exacerbate dry eye, future comparison of olopatadine 0.2% against other agents in its drug class would provide useful information about relative drug tolerabilities. CONCLUSION: As there were no significant changes in the signs and symptoms of dry eye, olopatadine hydrochloride 0.2% is safe to use in ocular allergy patients with mild-to-moderate dry eye.

Valacyclovir inhibition of recovery of ocular herpes simplex virus type 1 after experimental reactivation by laser in situ keratomileusis.

PURPOSE: To determine whether the systemic administration of valacyclovir (Valtrex) reduces ocular shedding of herpes simplex virus type 1 (HSV-1) after laser in situ keratomileusis (LASIK) in the New Zealand White (NZW) rabbit latency model. SETTING: Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA. METHODS: New Zealand White rabbits latently infected with HSV-1 W strain were divided into 3 groups. The first received 100 mg/kg/day of valacyclovir; the second, 200 mg/kg/day of valacyclovir; and the third (control), saline. One half the total dose of valacyclovir was delivered via intraperitoneal injections twice daily for 7 days beginning with 1 dose before LASIK. The HSV-1 ocular shedding was determined from eye cultures for 7 days after LASIK. RESULTS: The administration of both 100 mg/kg/day and 200 mg/kg/day of valacyclovir significantly reduced the number of eyes (1/16 in both groups) and the total number of HSV-1 shedding days (1/122 and 2/122, respectively) from which HSV-1 was recovered compared to the control group (7/16 [P =.0396] and 14/129 [P <.007], respectively). CONCLUSIONS: Systemic administration of valacyclovir significantly reduced HSV-1 ocular shedding after LASIK in the NZW rabbit latency model. The clinical implications of this study suggest that patients with a history of recurrent ocular herpes may be able to safely have LASIK with less risk of a recurrent herpetic episode while on valacyclovir antiviral prophylaxis.

Migration of silicone oil into the brain: a complication of intraocular silicone oil for retinal tamponade.

PURPOSE: To report a case in which intravitreal silicone oil migrated along the intracranial portion of the optic nerve and into the lateral ventricles of the brain after the repair of a retinal detachment secondary to cytomegalovirus retinitis. METHODS: A 42-year-old man with acquired immunodeficiency syndrome (AIDS) developed a rhegmatogenous retinal detachment in his left eye secondary to a cytomegalovirus infection of the retina. The detachment was repaired using 5000 cs intraocular silicone oil for a long-term tamponade. Subsequently, the affected eye developed glaucoma, which was poorly controlled. Fifteen months after the retinal surgery, he developed a peripheral neuropathy that was thought to be AIDS related. Computed tomography and magnetic resonance imaging of the head were performed to investigate the neuropathy. RESULTS: The patient was found to have a foreign substance within his lateral ventricles that shifted with position and was identical with respect to its imaging properties to the remaining intraocular silicone oil. Additional material was found along the intracranial portion of his optic nerve. CONCLUSION: Under certain circumstances, intraocular silicone oil may migrate out of the eye, along the intracranial portion of the optic nerve, and into the lateral ventricles of the brain.