Eye Diseases

Pathophysiological Visual Changes with Age

The human eye undergoes significant changes with time, resulting in progressive visual loss. The vitreous gel slowly loses its attachment to the retina, leading to periodic “floaters.” The lens hardens, becomes sclerotic, and progresses to impairment in near-vision accommodation, resulting in presbyopia. The lens also clouds with time, leading to cataracts.

The eyelids lose elasticity and become loosely adherent to the orbit. Fascial plane atrophy may lead to fat herniation into the lid tissue, leading to the common phenomenon of “bags” under the eyes. As people age, lacrimal gland secretion declines, resulting in dry eyes. Saline drops are usually effective for symptomatic treatment. Ectropion is seen when the lower lid has laxity and rotates away from the orbit. This can interfere with the transport of tears into the lacrimal sac, resulting in epiphora (persistent tearing). Entropion can be more concerning. Here, tissue planes within the bottom eyelid lose adhesion, allowing the eyelid margin to rotate medially. Lashes often rub directly against the conjunctiva and cornea, resulting in irritation and scarring. Ectropion and entropion can be treated with excision of redundant tissue if symptomatic therapy is unsuccessful.

Eyelid tumors usually result from chronic sun exposure. They are typically basal cell carcinomas and are treated with local excision. Metastasis is rare.

Subconjunctival hemorrhage is frequently noted in the elderly population. It usually occurs spontaneously or secondary to trauma and usually does not require treatment, resolving without complications. Chronic sunlight may cause a connective tissue degeneration between the eyelids, leading to conjunctival thickening (pingueculum). If the thickening progresses over the cornea and medially to the pupil, pterygium results. These conditions most commonly occur in dry, dusty, or smoky environments. Surgical intervention is needed only if the visual axis is obstructed.

Because the cornea is inherently required to be transparent for sharp vision, it must nourish itself without the use of cell-containing fluids such as blood vessels to maintain its transparency. To eliminate any cloudy residue accumulation over the cornea, a metabolic pump in corneal endothelial cells is present to dehydrate the cornea. From adulthood, the corneal endothelial cells cease to divide and cell density begins to decline. As a result, the cornea may become cloudy and fluid may collect. Hypertonic saline drops can be [Page 217]used to manage mild cases; corneal grafts may be needed to replace the endothelial cells for severe cases. Bacterial corneal ulcers are common in the elderly, due primarily to impaired tear secretion, diminished epithelial structure, and immunity. Antibiotic therapy is usually indicated.

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