Jason Levine

Comparative penetration of moxifloxacin and gatifloxacin in rabbit aqueous humor after topical dosing

Purpose: To evaluate the aqueous penetration of the fourth‐generation fluoroquinolones moxifloxacin and gatifloxacin. Setting: University of Arizona, Tucson, Arizona, USA. Methods: Forty eyes of 20 New Zealand white rabbits were divided into 2 experimental groups. In Experiment I rabbits (20 eyes), a commercial preparation of topical gatifloxacin 0.3% was administered to 9 eyes and moxifloxacin 0.5% to 9 eyes; 2 eyes served as a control. Eyes were dosed according to a keratitis protocol; ie, every 15 minutes for 4 hours. The aqueous humor was sampled 10 minutes after the last dose. Experiment II rabbits (20 eyes) were dosed according to a cataract prophylaxis protocol; ie, 4 times a day for 10 days. The aqueous humor was sampled 1 hour after the last dose of antibiotic in 12 eyes and 24 hours after the last dose in 8 eyes. High‐performance liquid chromatography was used to determine the fluoroquinolone concentration. Results: In the keratitis dosing protocol, the mean concentration of moxifloxacin in the aqueous (n = 9) was 11.057 &mgr;g/mL (range 7.66 to 18.87 &mgr;g/mL), which was significantly higher than the mean concentration of gatifloxacin (n = 8) (7.570 &mgr;g/mL [range 4.75 to 10.86 &mgr;g/mL]) (P = .030). In the cataract prophylaxis dosing protocol, the mean aqueous concentration of moxifloxacin (n = 6) was 1.745 &mgr;g/mL (range 0.92 to 3.87 mg/mL). The mean concentration of gatifloxacin (n = 6) was 1.207 &mgr;g/mL (range 0.44 to 2.44 &mgr;g/mL). The difference was not statistically significant (P = .359). Conclusions: Higher mean levels (×1.46) of aqueous penetration were achieved with moxifloxacin than with gatifloxacin in the keratitis‐dosing model. There was no statistically significant difference between the 2 drugs in the cataract prophylaxis dosing model. Both antibiotics had aqueous levels in excess of the minimum inhibitory concentration for most pathogenic organisms in both models.

Comparison of open and endoscopic treatment of posttraumatic posterior urethral strictures

AbstractThe purpose of this study was to compare the invasiveness, morbidity, and outcomes of open versus endoscopic treatment of posttraumatic posterior urethral strictures. We compared two groups of men with strictures of the posterior urethra after pelvic fracture: Group I (n = 6) underwent cut-to-the-light procedures before 1995, and group II (n = 9) underwent perineal anastomotic urethroplasty after 1995. The operating time and blood loss were lower in the endoscopic group, but no other significant differences in morbidity or invasiveness were found. All six patients in group I required multiple secondary procedures: Three reached a stable voiding pattern after a mean of three interventions, two required subsequent urethroplasty, and one was lost to long-term follow-up. Normal voiding was achieved in all group II patients, although two (22%) required single internal urethrotomy within 3 months after surgery. The data show the comparable morbidity of open urethroplasty and cut-to-the-light procedures and support an aggressive surgical approach for the delayed treatment of posttraumatic posterior urethral strictures. Other than a reduced operating time, endoscopic procedures offered no compelling advantage over surgical reconstruction.

Relationship between glaucoma and selenium levels in plasma and aqueous humour

Aim: The aim of the study was to compare selenium levels in plasma and aqueous humour in subjects with and without primary open-angle glaucoma (POAG). Methods: Forty-seven POAG cases and 54 controls in this case–control study were recruited from surgery patients at the University Physician’s Ophthalmology Clinic in Tucson, Arizona, USA. Aqueous humour and plasma selenium were determined by high-performance liquid chromatography ion channel plasma mass spectrometry (HPLC ICP-MS). Potential confounders were assessed via a questionnaire. Biological samples were collected and processed at surgery and analysed for selenium content after collection was complete. Outcome measures included the odds of glaucoma in relationship to plasma selenium, aqueous humour selenium, and the ratio of levels of aqueous humour selenium to plasma selenium. Results: Tertile of selenium and its relationship to POAG was examined. After adjustment for common glaucoma risk factors, the odds of glaucoma in the highest tertile of plasma selenium (OR = 11.3; p = 0.03) and the middle tertile of aqueous humour selenium (OR = 0.06; p = 0.02) was significantly associated with glaucoma. Conclusion: Although a causal pathway cannot be inferred from our analysis, our data, added to that of others, suggest that the pathology is selenium-related.

Aqueous Penetration of Gatifloxacin and Levofloxacin into the Rabbit Aqueous Humor Following Topical Dosing

The aqueous penetration of the commercial preparations of the fluoroquinolone antibiotics ofloxacin, ciprofloxacin, levofloxacin, and gatifloxacin were compared following topical dosing in a rabbit model. Levofloxacin achieved the highest aqueous concentrations, with a mean aqueous level of 4.8014 microcg/mL (p = 0.002, p = 0.00002, p = 0.015.) Ofloxacin (2.5136 microcg/mL) and gatifloxacin (2.4817 microcg/mL) achieved statistically equal aqueous concentrations (p = 0.479). Ciprofloxacin reached the lowest levels in the aqueous humor (0.9616 microcg/mL, p = 0.00002, 0.00004, 0.008). Gatifloxacin alone achieved concentrations in excess of the MIC90s of gram-positive pathogens of concern.

Goldmann tonometer error correcting prism: clinical evaluation

Purpose Clinically evaluate a modified applanating surface Goldmann tonometer prism designed to substantially negate errors due to patient variability in biomechanics. Methods A modified Goldmann prism with a correcting applanation tonometry surface (CATS) was mathematically optimized to minimize the intraocular pressure (IOP) measurement error due to patient variability in corneal thickness, stiffness, curvature, and tear film adhesion force. A comparative clinical study of 109 eyes measured IOP with CATS and Goldmann prisms. The IOP measurement differences between the CATS and Goldmann prisms were correlated to corneal thickness, hysteresis, and curvature. Results The CATS tonometer prism in correcting for Goldmann central corneal thickness (CCT) error demonstrated a reduction to <±2 mmHg in 97% of a standard CCT population. This compares to only 54% with CCT error <±2 mmHg using the Goldmann prism. Equal reductions of ~50% in errors due to corneal rigidity and curvature were also demonstrated. Conclusion The results validate the CATS prism’s improved accuracy and expected reduced sensitivity to Goldmann errors without IOP bias as predicted by mathematical modeling. The CATS replacement for the Goldmann prism does not change Goldmann measurement technique or interpretation.