Chapter 19: Disorders of Visual Function

Cataracts represent a progressive opacification of the lens that gradually impairs vision, particularly affecting the ability to focus on distant objects, and typically culminates in surgical intervention to restore sight. A central focus is glaucoma, a serious ocular disease characterized by pathologically elevated intraocular pressure that damages the optic nerve and threatens vision loss if left untreated. The regulation of intraocular pressure depends on the balance between aqueous humor production and drainage through the trabecular meshwork and other outflow pathways; when this equilibrium is disrupted and pressure accumulates within the eye, the resulting mechanical stress causes progressive degeneration of retinal ganglion cells and optic nerve fibers. A critical challenge with glaucoma is its insidious nature, as many individuals remain asymptomatic during early stages while irreversible damage to peripheral vision and visual fields occurs silently. The chapter emphasizes the importance of identifying risk factors such as age, family history, elevated baseline intraocular pressure, and ethnic background, which necessitate regular screening and ophthalmologic evaluation to enable early detection and intervention before significant vision loss develops. Both conditions represent common causes of vision impairment in aging populations and illustrate how disruption of normal eye physiology, whether through protein aggregation in the lens or abnormal fluid pressure dynamics, can lead to functional disability and blindness if not properly managed.