Effect of mitomycin-C on corneal endothelial cell parameters after refractive surface ablation procedures.

Background: The effect of mitomycin-C (MMC) on the reduction of endothelial cell count in the cornea remains controversial. We aimed to evaluate the effect of MMC on corneal endothelial cell parameters after refractive surface ablation procedures, including photorefractive keratectomy (PRK) and laser epithelial keratomileusis (LASEK). Methods: In this interventional, comparative, follow-up study, 342 eyes of 171 patients were followed up for 6 months. Patients undergoing PRK or LASEK were included and were divided into two groups: group one (188 eyes of 94 patients) with an ablation depth of ≥ 65 µm and who received intraoperative 0.02% MMC for 30 s, and group two (154 eyes of 77 patients) with an ablation depth of < 65 µm and who received balanced salt solution for 30 s. Changes in endothelial cell density (ECD), central corneal thickness (CCT), coefficient of variation (CV), and hexagonality values were compared between the groups at 3 and 6 months after surgery. Results: The mean (standard deviaiton [SD]) age of the patients was 28.11 (6.56) years. The mean (SD) ECD did not change significantly in either group between the baseline and at 3 and 6 months postoperatively. The baseline mean ECD was significantly higher in group one than that in group two (P < 0.001) and remained so at 3 (P = 0.002) and 6 months (P = 0.022) postoperatively. The baseline hexagonality value was lower in group one (P = 0.173), with a gradual decrease during the postoperative follow-up as compared with that in group two (P = 0.016 and 0.001 at 3 and 6 months postoperatively, respectively). Group one had a significantly lower CCT at 3 and 6 months postoperatively (both P < 0.001) and a higher mean CV (3 months: P = 0.028; 6 months: P = 0.328). Conclusions: A single intraoperative application of MMC for 30 s as prophylaxis for corneal haze development during refractive surface ablation procedures had no significant effect on ECD up to 6 months postoperatively. Future studies with a contralateral-eye design (to neutralize factors specific to the individual patient), a larger sample size, and longer follow-up are necessary to confirm or disprove our observations.

NMDA receptors interact with the retrieval memory enhancing effect of pioglitazone in mice.

PURPOSE: The present study has been undertaken to investigate the possible involvement of the glutamatergic pathway in the beneficial effects of pioglitazone on consolidation and retrieval phases of memory. MATERIALS AND METHODS: The Y-maze task was used to assess short-term spatial recognition memory in animals. Scopolamine (1mg/kg, i.p.) or MK-801 (dizocilpine) (0.03, 0.1 and 0.3mg/kg, i.p.) were administered immediately after the training session to impair memory consolidation or 30min before the retention trial to impair memory retrieval. Pioglitazone (10, 20, 40 and 80mg/kg, p.o.) was administered 2h before the retention session in memory retrieval experiments or immediately after the training session in consolidation experiments. And finally NMDA (N-methyl-d-aspartate) (75mg/kg, i.p) was administered 15min before the administration of pioglitazone. RESULTS: 1) MK-801 (0.3mg/kg) impaired the retrieval of spatial recognition memory. 2) Pioglitazone failed to improve MK-801 induced impairment of retrieval of spatial recognition memory. 3) The 20mg/kg dose of pioglitazone significantly improved memory in mice with scopolamine induced impairment of memory retrieval. 4) Sub-effective dose of MK-801 (0.1mg/kg) was capable of reversing the beneficial effect of pioglitazone on retrieval of memory in scopolamine-treated mice, 5) Administration of NMDA (75mg/kg) and a sub-effective dose of pioglitazone (10mg/kg) reversed the effect of scopolamine and promoted memory retrieval. 6) MK-801 did not affect the consolidation phase of spatial recognition memory. 7) Pioglitazone did not affect scopolamine-induced impairment of memory consolidation. CONCLUSIONS: Sub-effective dose of MK-801 is capable of reversing the protective action of pioglitazone on scopolamine-induced impairment of memory retrieval. Additionally, co-administration of 75mg/kg NMDA and a sub-effective dose of pioglitazone potentiated the effect of pioglitazone on memory retrieval impaired by scopolamine. These results support the idea that pioglitazone plays its memory retrieval enhancement role through the glutamatergic pathway.

Short-time mitomycin-C application during photorefractive keratectomy in patients with low myopia.

PURPOSE: To evaluate the safety and efficacy of 5 seconds of mitomycin-C (MMC) application during photorefractive keratectomy (PRK) for low myopia. SETTING: Basir Eye Clinic, Tehran, Iran. DESIGN: Prospective randomized sham-controlled double-masked clinical trial. METHODS: Patients with low myopia and an ablation depth of less than 65 µm were recruited. One eye of each patient was included in the study and was randomly assigned to receive intraoperative topical MMC 0.02% for 5 seconds or a balanced salt solution in the same manner (control group). Corneal haze development during the 6 months after the PRK was the main outcome measure. RESULTS: Of the 184 eligible patients (MMC = 93; control = 91), 152 (78 and 74, respectively) completed the follow-up. The postoperative haze grade was significantly lower in the MMC group (P=.01). The mean endothelial cell density was not significantly different between the MMC group and the control group preoperatively (2879.97 cells/mm(2) ± 298.04 [SD] versus 2819.69 ± 303.89 cells/mm(2); P=.22) or 6 months postoperatively (2878.79 ± 283.04 cells/mm(2) versus 2878.79 ± 283.04 cells/mm(2); P=.25). No notable ocular complication occurred throughout the study. CONCLUSION: Short-time application of MMC 0.02% was safe and effective in preventing haze formation in eyes having PRK with an ablation depth of less than 65 µm compared with matched controls up to 6 months. FINANCIAL DISCLOSURE: No author has a financial or proprietary interest in any material or method mentioned.