Mehran Taban

Fluoroquinolone therapy in multiple-drug resistant staphylococcal keratitis after lamellar keratectomy in a rabbit model ☆

PURPOSE To assess the effectiveness of a fourth-generation fluoroquinolone for prophylaxis against multiple drug-resistant staphylococcal keratitis after lamellar keratectomy in a rabbit model. DESIGN Experimental study. METHODS Twenty-eight New Zealand white rabbits underwent unilateral lamellar keratectomy using a manual microkeratome followed by the placement of 1000 colony-forming units (CFUs) of log-phase Staphylococcus aureus bacteria under each flap. Eyes (seven in each group) were randomized and treated with one of the following agents: sterile balanced salt solution, gatifloxacin (0.3%), ciprofloxacin (0.3%) or levofloxacin (0.5%) immediately and 6, 12, and 18 hours after surgery. Inflammation was graded by two masked observers at 24 and 48 hours, and the presence or absence of infectious infiltrates was determined. The means and standard deviations were calculated, and differences among the groups were statistically analyzed. RESULTS There were no flap complications encountered during surgery. Eyes treated with ciprofloxacin, levofloxacin, and balanced salt solution developed infectious infiltrates in five of seven eyes per group. Gatifloxacin-treated eyes did not develop clinical infection and exhibited lower mean inflammation scores (P <.01 compared with the other groups). CONCLUSION The fourth-generation fluoroquinolone, gatifloxacin, is an effective prophylaxis against the development of keratitis after lamellar keratectomy in rabbits with an organism resistant to methicillin, levofloxacin, and ciprofloxacin.

Lower eyelid position after transconjunctival lower blepharoplasty with versus without a skin pinch.

Purpose: To evaluate the effect of transconjunctival lower blepharoplasty with or without a skin pinch on lower eyelid position. Methods: Retrospective analysis of patients undergoing bilateral lower blepharoplasty using a transconjunctival approach with or without a skin pinch. Patients undergoing other surgical procedures that could affect lower eyelid position were excluded. Twenty-five patients (50 eyes) underwent transconjunctival blepharoplasty without skin pinch and 20 patients (40 eyes) underwent transconjunctival blepharoplasty with a skin-pinch technique. Preoperative and postoperative photographs were measured for the horizontal corneal diameter and distance from light reflex to lower eyelid margin (MRD2). The ratio of MRD2 to corneal diameter was multiplied by 11 to standardize to a corneal diameter of 11 mm. Student t test was used for statistical analysis. Results: There were 8 male and 37 female patients. Average follow-up was 4 months. Mean preoperative standardized MRD2 was 4.68 mm and 4.65 mm for transconjunctival blepharoplasty without and with skin pinch, respectively. Mean postoperative standardized MRD2 was 4.73 mm and 4.70 mm for transconjunctival blepharoplasty without and with skin pinch, respectively. The mean change in lower eyelid position was 0.05 mm after each technique. The change in lower eyelid position was not statistically significant for either group (p > 0.5). There was no significant difference in lower eyelid position change between the 2 groups (p > 0.99). Conclusions: Transconjunctival lower blepharoplasty with or without a skin pinch yields a stable postoperative lower eyelid position.

Fluoroquinolone therapy in Mycobacterium chelonae keratitis after lamellar keratectomy

Purpose: To characterize a rabbit model of Mycobacterium chelonae keratitis after lamellar keratectomy and assess the effectiveness of fluoroquinolone therapy. Setting: University Laboratory, University of California, Irvine, California, USA. Methods: Twenty‐eight New Zealand white rabbits had unilateral lamellar keratectomy with placement of 2.5 × 105 colony‐forming units of log‐phase M chelonae under each flap. Eyes (7 per group) were randomized and treated with sterile balanced salt solution, gatifloxacin 0.3%, ciprofloxacin 0.3%, or levofloxacin 0.5% 4 times daily. Two masked observers examined all eyes on days 2, 5, and 7 and weekly for 4 weeks. Severity of disease and bacterial culture results were the main outcomes measured. The means and standard deviations were calculated, and differences between the groups were statistically analyzed. Results: All eyes developed clinical disease. At the time the rabbits were killed, eyes treated with balanced salt solution, ciprofloxacin, levofloxacin, and gatifloxacin were culture positive in 6 (85.7%), 7 (100%), 6 (85.7%), and 3 (42.9%) of 7 eyes per group, respectively. Frequency of positive culture and the severity of clinical disease in gatifloxacin‐treated eyes were significantly less (P<.05) than in the other groups combined. Conclusions: The rabbit model of M chelonae keratitis was successfully developed in our study. A fourth‐generation quinolone (gatifloxacin) showed the best performance among the fluoroquinolones tested in our experimental approach. The fourth‐generation fluoroquinolone, gatifloxacin, could be effectively used for the treatment of mycobacterial keratitis.

Imaging and investigating the effects of incision angle of clear corneal cataract surgery with optical coherence tomography

Effects of incision angle in construction of clear corneal cataract incision are studied with optical coherence tomography (OCT). A stable incision angle range is found to be existent for single-planed, clear corneal cataract incisions. When well pressurized, incision angles within this stable range result in well-apposed incision edges that resist gapping while incision angles falling outside this range have a larger tendency for wound leakage. It is also shown that a two-planed incision can effectively expand the stable range. For incision angles outside the stable range, the farther the incision angle is away from stable range, the larger the gap between incision wound edges when well pressurized. These findings emphasize the significance of incision construction to the self-sealing property of clear corneal cataract incisions. Finally, we demonstrate that OCT could be an effective modality for imaging and monitoring corneal surgery.

Subchoroidal Release of VEGF and bFGF Produces Choroidal Neovascularization in Rabbit

ABSTRACT Purpose: Intravitreal vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) produced florid retinal neovascularization and hemorrhage in the rabbit. This study seeks to determine whether sustained subchoroidal release of both VEGF and bFGF can induce robust choroidal neovascularization (CNV) in the rabbit. Methods: Subchoroidal implantation through the sclera of polymeric pellets containing both 15 μg VEGF and 15 μg bFGF was performed on adult pigmented male Dutch belted rabbits (N = 6) and NZW albinos (N = 8). As negative controls, blank pellets with no growth factors were implanted in both Dutch belted rabbits (N = 6) and NZW albino rabbits (N = 4). Development of CNV was documented weekly over a 4-week period with indirect ophthalmoscopy, color fundus photography, and fluorescein angiography. Eyes were enucleated and prepared for histologic and immunohistochemical analyses at the end of the study. Amounts of VEGF and bFGF that were released in vitro from the pellets were measured by ELISA. Results: In all eyes with subchoroidal implants containing both VEGF and bFGF, strong fluorescein leakage was observed at 2, 3, and 4 weeks (P < 0.005); no leakage was seen initially in week 1. Negative control groups with blank implants showed no fluorescein leakage throughout the 4-week study period. Histologic analysis confirmed the presence of experimental CNV. New subretinal blood vessel growth occurred in all eyes with VEGF/bFGF implants. Negative control eyes with blank implants showed no vascular changes. In vitro sustained release of both VEGF and bFGF was confirmed by ELISA. Conclusion: Sustained subchoroidal release of both VEGF and bFGF produced experimental CNV rapidly in the rabbit. Understanding how these growth factors induce CNV may suggest novel therapeutic strategies in the large rabbit eye.

Visualizing morphological changes of clear corneal cataract incisions with optical coherence tomography

Dynamic morphological changes of clear corneal cataract incisions are studied with Optical Coherence Tomography (OCT). Two opposite types of dynamic incision wound behaviors are documented. A stable incision angle range is found to be existent for single-planed, clear corneal cataract incisions. When well pressurized, incision angles within this stable range result in well-apposed incision edges that resist gapping while incision angles falling outside this range have a larger tendency for wound leakage. It is also shown that a two-planed incision can effectively expand the stable range. For incision angles outside the stable range, the farther the incision angle is away from stable range, the larger the gap between incision wound edges when well pressurized. Thus, incision construction method has a major impact on the self-sealing capability of the incision wounds. In this investigation, OCT has been demonstrated as an effective modality for imaging and monitoring corneal surgery.