Glaucoma

Excerpt

Glaucoma is a complex eye condition characterized by elevated intraocular pressure (IOP) that may progress to vision loss over time. Glaucoma is the second leading cause of permanent blindness in the United States and occurs most often in older adults. Glaucoma can be categorized into either primary or secondary types and further into open-angle or closed-angle variants within each type of glaucoma. Adult glaucoma includes primary open-angle glaucoma (POAG) and angle-closure glaucoma, as well as secondary open and angle-closure glaucoma, with a specific focus on the most prevalent type, POAG.

Glaucoma is an acquired loss of retinal ganglion cells and axons within the optic nerve or optic neuropathy that results in a characteristic optic nerve head appearance and a corresponding progressive loss of vision. This unique pattern of peripheral vision loss serves as a distinguishing feature from other types of vision impairment.

Patients with POAG are often asymptomatic until significant optic nerve damage occurs unless early signs of glaucoma are identified during routine eye examinations. On the other hand, acute angle-closure glaucoma can develop suddenly and lead to a rapid decline in vision, accompanied by symptoms such as corneal edema, eye pain, headache, nausea, and emesis. Secondary glaucoma often arises due to a previous eye injury or underlying medical conditions, resulting in elevated IOP and subsequent optic neuropathy. This category encompasses various subtypes, including congenital, pigmentary, neovascular, exfoliative, traumatic, and uveitic glaucoma. Normal or low-tension type of glaucoma presents as an optic neuropathy with glaucomatous visual loss despite normal or unremarkable IOP readings.

Although congenital, infantile, and developmental glaucoma, along with a juvenile variant of POAG, primarily affect younger individuals, most types of glaucoma are commonly diagnosed in individuals aged 40 and older. While IOP is often associated with glaucoma, a direct causal relationship has not been definitively established. Researchers are investigating genetic and environmental factors contributing to glaucoma development. Evidence from studies involving monozygotic twin pairs, who exhibit a higher concordance rate compared to dizygotic pairs, suggests that environmental factors also have a significant role in the disease's development.

Although the available treatments cannot cure existing optic nerve damage or reverse visual field loss, they can help control the disease progression through medication, laser treatment, or incisional glaucoma surgeries to prevent further vision loss. All therapeutic interventions are focused on lowering IOP and minimizing the impact of this vision-threatening condition. This approach aims to prevent the onset of glaucoma in patients with risk factors and to manage the condition effectively to limit its progression in affected individuals.