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'''Original Editor '''- Wendy Walker
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== The Aging Eye ==
<div>As we age, our sensory modalities (including vison) show gradual deterioration.</div><div>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.</div><div>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, [[Diabetes Mellitus Type 2|diabetic]] retinopathy and cataracts.</div>
== 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<ref>Melore GG: Visual function changes in the geriatric patient and environmental modifications. In Melore GG, editor: Treating vision problems in the older adult, St. Louis, MO, 1997, Mosby</ref>.
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<ref>Spear PD: Neural basis of visual deficits during aging. Vision Res 33:2589–260, 1993</ref>.
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<ref>Linton AD: Age-related changes in the special senses. In Linton AD, Lach HW, editors: Matteson &amp;amp; McConnell’s Gerontological nursing: concepts and practice, ed 3, Philadelphia, PA, 2007, Saunders/Elsevier</ref>.
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<br> ===
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).
In addition, pale pastel colours may become more difficult to distinguish, as may varying shades of grey.
Functional effects:
*may struggle to see furniture if not brightly coloured or in bright light, so can bump into it leading to falls
=== Slower dark adaptation ===
The ability of the eye to become more visually sensitive after remaining in darkness for a period of time is delayed in older people.
Metabolic changes in the retina result in reduced oxygen supply to the rod-dense area of the retina and the reduction in pupil size both contribute to this problem<ref>Melore GG: Visual function changes in the geriatric patient and environmental modifications. In Melore GG, editor: Treating vision problems in the older adult, St. Louis, MO, 1997, Mosby</ref>.
Functional effects:
*difficulty adapting to darkness, especially abrupt and extreme changes in light levels
*risk of falls at night or in low light situations
== Medical eye conditions affecting older people ==
=== Macular Degeneration ===
=== Glaucoma ===
=== Cataracts ===
== Recent Related Research (from [http://www.ncbi.nlm.nih.gov/pubmed/ Pubmed]) ==
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== References ==
References will automatically be added here, see [[Adding References|adding references tutorial]].
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[[Category:Older_People/Geriatrics|Geriatrics]]