Glare
Decreased visual perception related to glare is a frequent complaint. As the eye ages, changes in the lens and vitreous increase the scattering of light in the ocular media. Lens opacities at the periphery, though not directly interfering with vision, can also increase the scattering of light passing through the lens, especially at night or in dim light, because the pupil is slightly dilated. Thus, it is not unusual for the elderly patient to complain about the glare of oncoming headlights while driving at night. As long as visual acuity is normal, the patient should just be advised to curtail driving at night or avoid looking directly at oncoming headlights.
Decreased visual perception from daytime glare is also common. With aging, opacities may appear in various portions of the lens, such as the nucleus and cortex. Such opacities may interfere little with visual acuity, but opacities in the central cortex region just beneath the posterior lens capsule (posterior subcapsular lens opacities) tend to scatter light to a greater extent. This occurs because these opacities are closer to the focal point of the lens through which all light must pass on the way to the retina. Although these opacities may eventually increase in size or density and interfere with visual acuity (posterior subcapsular cataract), their earliest manifestation is the scattering of light and increased glare, especially in bright light.
Some temporary relief may result from mild dilation of the pupil with mydriatic drops and from sunglasses that allow the patient to see around the opacity. However, these measures should be used only under appropriate ophthalmologic care. Early nuclear opacities may actually improve close vision in the elderly. Cataracts are discussed further below.