Remodeling of the Lamina Cribrosa: Mechanisms and Potential Therapeutic Approaches for Glaucoma

Glaucomatous optic neuropathy is the leading cause of irreversible blindness in the world. The chronic disease is characterized by optic nerve degeneration and vision field loss. The reduction of intraocular pressure remains the only proven glaucoma treatment, but it does not prevent further neurodegeneration. There are three major classes of cells in the human optic nerve head (ONH): lamina cribrosa (LC) cells, glial cells, and scleral fibroblasts. These cells provide support for the LC which is essential to maintain healthy retinal ganglion cell (RGC) axons. All these cells demonstrate responses to glaucomatous conditions through extracellular matrix remodeling. Therefore, investigations into alternative therapies that alter the characteristic remodeling response of the ONH to enhance the survival of RGC axons are prevalent. Understanding major remodeling pathways in the ONH may be key to developing targeted therapies that reduce deleterious remodeling.

Evaluation of potential topical and systemic neuroprotective agents for ocular hypertension-induced retinal ischemia-reperfusion injury

OBJECTIVE

To evaluate for drugs with superior neuroprotective efficacy and investigate their underlying mechanisms related to antioxidation.

PROCEDURES

Brinzolamide (1%), timolol (0.5%), minocycline (22 mg/kg), lidocaine (1.5 mg/kg), and methylprednisolone (30 mg/kg) were administered to Sprague-Dawley (SD) rats. The retina was evaluated by electroretinography and histological analysis. The antioxidative capacity of drugs was evaluated to clarify the underlying mechanism. The oxidant/antioxidant profiles of plasma, red blood cells, and retina were analyzed by lipid peroxidation (malondialdehyde) and by measuring the activities of antioxidants. Proteomic analysis was used to investigate the possible protective mechanisms of the drug against ischemia-reperfusion injury.

RESULTS

The results suggested that timolol, methylprednisolone, and minocycline protected retinal function. Methylprednisolone and minocycline possessed good antioxidative activity. Brinzolamide and lidocaine preserved the structural integrity of the retina, but not retinal function.

CONCLUSION

Methylprednisolone, minocycline, and timolol have potential acute or delayed benefit in retinal ischemia-reperfusion injury. Their neuroprotective actions depend at least partially on the ability to alleviate oxidative stress.