The primary function of the presynaptic nerve terminal is to release transmitter quanta and thus activate the postsynaptic target cell. In almost every step leading to the release of transmitter quanta, there is a substantial involvement of ion channels. In this review, the multitude of ion channels in the presynaptic terminal are surveyed. There are at least 12 different major categories of ion channels representing several tens of different ion channel types; the number of different ion channel molecules at presynaptic nerve terminals is many hundreds. We describe the different ion channel molecules at the surface membrane and inside the nerve terminal in the context of their possible role in the process of transmitter release. Frequently, a number of different ion channel molecules, with the same basic function, are present at the same nerve terminal. This is especially evident in the cases of calcium channels and potassium channels. This abundance of ion channels allows for a physiological and pharmacological fine tuning of the process of transmitter release and thus of synaptic transmission.

Purpose: To report on the clinical use of subconjunctival bevacizumab in patients with corneal neovascularization. Methods: The charts of 10 consecutive patients with corneal neovascularization who received subconjunctival injections of bevacizumab (2.5 mg/0.1 mL) were reviewed. Digital photographs of the cornea were graded by 2 masked observers for density, extent, and centricity of corneal vascularization. Image analysis was used to determine the area of cornea covered by neovascularization as a percentage of the total corneal area. Results: No significant ocular or systemic adverse events were observed during 3.5 ± 1.1 months of follow-up. Seven patients showed partial regression of vessels. The extent decreased from 6.0 ± 1.2 (SD) clock hours before the injection to 4.6 ± 1.0 clock hours after bevacizumab injection (P = 0.008). Density decreased from 2.7 ± 0.2 to 1.9 ± 0.3, respectively. (P = 0.007). No change was noticed in the centricity of corneal vessels. Corneal neovascularization covered, on average, 14.8% ± 2.5% (SD) of the corneal surface before the injections, compared with 10.5% ± 2.8% (P = 0.36, t test) after bevacizumab injection. Therefore, bevacizumab decreased corneal neovascularization by 29%. Conclusions: Short-term results suggest that subconjunctival bevacizumab is well tolerated and associated with a partial regression of corneal neovascularization.

To compare the visual outcomes and complications rate after penetrating keratoplasty (PKP) and Descemet stripping automated endothelial keratoplasty (DSAEK), in the fellow eye of the same subjects, and to evaluate the patient's perspective on these operations. A retrospective cohort study was undertaken in the Cornea Clinic at the Toronto Western Hospital. We reviewed the records of 12 patients (24 eyes) who underwent PKP in one eye and DSAEK surgery in their fellow eye. Patient's satisfaction for both procedures was evaluated using a subjective questionnaire. These techniques were compared for intraoperative and postoperative complications and visual and refractive outcomes including contrast acuity, contrast threshold, and high-order ocular aberrations (HOA). All the patients in this study preferred the DSAEK operation. They reported faster recovery time [1.5 week in the DSAEK vs 5.3 weeks in the PKP operation (P = 0.01)], significantly less pain, and better visual outcomes with the DSAEK operation. Uncorrected visual acuity and best-corrected visual acuity were significantly better in the DSAEK operated eyes. The DSAEK surgery was associated with significantly less astigmatism (P = 0.0003) and ametropia. Contrast acuity was significantly better in the eye that underwent DSAEK procedure (P < 0.05), whereas contrast threshold was better in the PKP eye. The PKP operated eyes demonstrated increased level of HOA. Patients preferred the DSAEK operation compared with PKP. Better uncorrected visual acuity, best-corrected visual acuity, and contrast acuity together with avoidance of surgery-induced astigmatism and HOA are the main benefits of the DSAEK technique.