Effects of Lidocaine on Mitomycin C Cytotoxicity

PURPOSE

Intra-Tenon or subconjunctival injection of a solution of mitomycin C (MMC) and 1% preservative-free lidocaine (as an anesthetic) has gained popularity for its use in trabeculectomy, a filtering surgery for glaucoma. To our knowledge, no studies have analyzed the impact of lidocaine on the cytotoxic effects of MMC in this setting. This study was conducted to evaluate in vitro fibroblast cytotoxicity to a solution of MMC (0.2 mg/ml) and 1% preservative-free lidocaine.

DESIGN

Experimental study.

PARTICIPANTS

Nonhuman subject research.

METHODS

Cultured human conjunctival fibroblasts were incubated in phosphate-buffered saline (PBS) (control), MMC (0.2 mg/ml), a mixture of 0.2 mg/ml MMC + 1% preservative-free lidocaine, or 1% preservative-free lidocaine. Samples were taken at 2, 5, 10, 30, and 60 minutes, and a 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT) assay with photoabsorbance testing was used to assess conjunctival cell viability.

MAIN OUTCOME MEASURE

Mean photoabsorbance.

RESULTS

Mean photoabsorbance across all time intervals was 0.680 for solutions incubated in PBS, 0.642 for MMC, 0.612 for MMC + 1% preservative-free lidocaine, and 0.605 for 1% preservative-free lidocaine. A 2-way analysis of variance analyzing solution, time, and solution-time interaction on photoabsorbance showed that PBS was least cytotoxic and an optimal control for this study. Tukey post hoc comparisons showed that MMC was more cytotoxic than PBS (P < 0.001). However, both MMC + 1% preservative-free lidocaine and 1% preservative-free lidocaine were more cytotoxic than MMC and PBS (P < 0.01 for all). No significant differences in cytotoxicity comparing lidocaine-containing solutions were observed.

CONCLUSIONS

In this in vitro study, we found an increase in cytotoxicity when MMC (0.2 mg/ml) was combined with 1% preservative-free lidocaine. We note that lidocaine did not inhibit MMC cytotoxicity and exhibited a significant cytotoxic effect on its own.

Polarizable Material from a Conjunctival Biopsy in a Patient with Sarcoidosis

PURPOSE

Conjunctival biopsies may contain polarizable material in patients with sarcoidosis despite no history of prior trauma or eye surgeries.

PROCEDURES

A 39-year-old male with uveitic glaucoma presented with decreased vision and throbbing pain in his right eye. His intraocular pressure was elevated, and his vision was reduced to hand motion. Due to persistently elevated intraocular pressure refractory to medical treatment, the patient underwent a glaucoma drainage device procedure. During the procedure, a yellow, nodular conjunctival growth was noted and biopsied.

RESULTS

Histopathological examination revealed multiple nonnecrotizing granulomata, some of which contained polarizable material.

CONCLUSIONS

Biopsies of patients with sarcoidosis may contain polarizable material without evidence of foreign body inoculation.

Trimanual Anterior Vitrectomy: A Novel Technique to Manage Vitreous Loss during Phacoemulsification

We report 2 cases illustrating the use of a new technique to manage vitreous loss during phacoemulsification, which we have termed 'trimanual' anterior vitrectomy. In each case, after recognizing posterior capsule tear, the remaining nuclear pieces were removed with low-parameter phacoemulsification. The remaining cortical material was then removed using bimanual irrigation and aspiration handpieces while the assistant surgeon inserted the vitrectomy probe through a separate 1-mm limbal incision. The vitrectomy probe was held below the plane of the posterior capsule tear, used to cut the vitreous and to provide a mechanical blockade to potentially descending lens material. While this technique involves the potentially awkward simultaneous use of 3 intraocular instruments, we believe that there are several advantages over standard bimanual anterior vitrectomy.

Bilateral acute iris transillumination following systemic moxifloxacin for respiratory illness: report of two cases and review of the literature

PURPOSE

To describe two cases of bilateral acute iris transillumination following systemic administration of moxifloxacin and review the literature.

METHODS

Review of clinical records, and review of the literature using the PubMed database.

RESULTS

A 75 year-old man and 33 year-old woman presented with bilateral conjunctival injection, photophobia, and atonic, distorted pupils. The symptoms began acutely following a respiratory illness, for which both were treated with moxifloxacin. Both patients demonstrated profound iris transillumination, sectoral posterior bowing of the iris, corneal endothelial pigment dusting, and trabecular meshwork hyperpigmentation. One patient had a cotton-wool spot. A literature review identified 59 previous reports in 5 publications, including 17 patients with no antecedent fluoroquinolone use.

CONCLUSIONS

Increased awareness of this recently described clinical entity should lead to a decrease in unnecessary diagnostic evaluations. It is currently unclear whether this disease represents an adverse effect of fluoroquinolone use or a sequela of a systemic illness.