Sensory nerve fibers innervating the ocular anterior surface detect external stimuli producing innocuous and painful sensations. Protons are among the first mediators released by damaged cells during inflammation, tissue injury, or other chronic ophthalmic conditions. We studied whether acid-sensing ion channels (ASICs) are expressed in corneal sensory neurons and their roles in the response to moderate acidifications of the ocular surface and in pathologies producing ocular surface inflammation. Moderate acidic pH (6.6) activated ASIC-like currents in corneal sensory neurons, which were blocked by ASIC1- or ASIC3-specific toxins. Acidic pH depolarizes corneal sensory neurons to fire action potentials, an effect blocked by the ASIC3 inhibitor APETx2. 2-Guanidino-4-methylquinazoline, an ASIC3 agonist, activated a population of corneal polymodal sensory nerve fibers and significantly increased the blinking and tearing rate. The nocifensive behaviors produced by application of either a moderate acidic stimulus or ophthalmic drugs formulated in acidic solution were abolished by ASIC blockers. In a model of allergic keratoconjunctivitis, nocifensive behavior was greatly reduced by ASIC3 blockade, presumably by reducing nociceptor sensitization during the inflammatory process. Our results show that, in addition to the established role of TRPV1, ASICs play a significant role in the detection of acidic insults at the ocular surface. The identification of ASICs in corneal neurons and their alterations during different diseases is critical for the understanding of sensory ocular pathophysiology. They are likely to mediate some of the discomfort sensations accompanying several ophthalmic formulations and may represent novel targets for the development of new therapeutics for ocular pathologies.
This technique is both feasible and effective to manage severe ectopia lentis in children. Lifetime ophthalmic follow-up including cECC measurement, IOL position monitoring and fundus examination is mandatory in these patients.
Purpose:
We herein describe possible intraluminal obstruction because of a hyperreflective material found in anterior segment optical coherence tomography (AS-OCT) in 16 of 46 cases with XEN45 gel stent.
Materials and Methods:
This is a retrospective case series of 46 eyes of 39 patients with noncomplicated XEN45 gel stent surgery, analyzed with AS-OCT and slit-lamp photography after at least 6 postoperative months.
Results:
Possible luminal obstruction in the subconjunctival segment of the implant was observed in 16 eyes of 15 patients, characterized by hyperreflective material on AS-OCT, which was not visible in slit-lamp photography. This was found in 15 eyes following combined procedures and in 1 eye following XEN45 alone. None showed signs of filtering bleb on AS-OCT or slit-lamp photography. In 1 case, the discontinuity between the hyperreflective material and subconjunctival opening of the implant tube was evidenced, and in another case, a focal deposit in the intracameral end of the implant was seen.
Conclusions:
We have successfully described the lumen implant deposit of material as a possible cause of late failure of the implant. AS-OCT allows the identification of such cases and may be useful to plan further postoperative interventions for better patient outcomes.
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