Eyesight in the Elderly

Original Editor - Wendy Walker

Top Contributors - Wendy Walker, Lucinda hampton, Scott Buxton, Kim Jackson, Lauren Lopez, 127.0.0.1, Tony Lowe and WikiSysop  

The Aging Eye

As we age, our sensory modalities (including vison) show gradual deterioration.

Older people must adapt to problems such as reduced visual field, decrease in visual acuity, delayed dark adaptation, reduced colour perception and decreased power of accommodation resulting in presbyopia. Taken together, these different visual problems all lead to impairment of visual function.

Then in addition, a large number of older people also suffer from medical conditions affecting function of the eye, such as glaucoma, Age Related Macular Degeneration, diabetic retinopathy and cataracts.

Impairments of visual function

Visual field reductions

With aging there is a decrease in peripheral and upper visual fields. It is thought likely that in the early stages this may be as a result of decreased pupil size and therefore less light admitted to the peripheral retina; later on changes may result from decreased retinal metabolism. 

In addition loss of retrobulbar fat results in the eyes sinking more deeply into the orbits which leads to a mechanical restriction of upper gaze.

Functional effects:

• reduced awareness of the lateral field of view can cause difficulties when driving
• reduced upper visual field vision results in the individual being less aware of high traffic and street signs

Reduced visual acuity

Visual acuity is th ability of the eye to discriminate fine details of objects, and it frequently (but my no means inevitably) declines with age.

An increase in the thickness of the lens combined with its loss of elasticity result in decreased ability to see clearly, and particularly affect near objects. In addition, with increased age the iris no longer changes width and pupil size remains small in both dim and bright light, resulting in detrioration in night vision. It is generally thought that other contributing factors are loss of photoreceptors within the retina and possibly changes in the geniculostriate pathway.

Functional effects:

• need for reading glasses or contact lenses
• may require hand-held magnifiers when doing sewing or craft work

Accommodation difficulties

Accommodation = the ablity of the eye to focus images on the retina independent of object distances.

With age both the cornea and the lens lose transparency, the lens thickens and becomes more rigid and the ciliary muscle weakens. All of which cause the lens to gradually lose its ability to change shape and focus at varyig distances.

This is generally labelled presbyiopia.

Functional effects:

• initially require reading glasses
• later bifocals or varifocals are frequently required as focusing on even distant objects is impaired

Reduced colour perception

With increased age, changes in the retinal cones and the visual pathways, as well as in the lens, lead to the eye becoming less sensitive to colours that have shorter wavelngths, ie. blues, greens and violets (the cooler colours).

References

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