Common eyesight problems are not limited to the elderly. Nearsightedness (myopia), farsightedness (hyperopia or hypermetropia) and astigmatism are common earlier in life and tend to either be present from birth or develop in early childhood. All of these conditions may worsen with age and particularly in the senior years. However, there are three vision problems that the elderly in particular need to be aware of and these are presbyopia, cataracts, glaucoma and macular degeneration. These conditions arise due to different mechanisms but share common features like blurred vision, halos and eyestrain symptoms. Conditions like glaucoma can lead to blindness if left untreated. It is therefore important to recognize the difference between these vision problems and seek medical attention.
Light rays entering the eyeball needs to be bent to different angles so that it meets at a single point (focal point). This should fall on the most sensitive part of the retina – a small area known as the fovea. By doing so, a person can see with clarity. Most light is bent (refracted) by the outer clear portion of the eye known as the cornea. The remaining refraction needed for visual acuity is completed by the lens of the eye. Whereas the cornea’s ability to refract light is constant, the lens can alter its shape as necessary to alter its refractive index. With age, however, the lens becomes stiff and this rapid change is hampered. This condition is known as presbyopia. It is just one type of refractive error, the others being myopia (nearsightedness), hyperopia (farsightedness) and astigmatism.
Presbyopia is unavoidable – in fact almost every person over the age of 40 years has some degree of presbyopia. It tends to continue worsening until the age of about 65 years old. The ability of the eye to focus on nearby objects is impaired and presbyopia is essentially a form of farsightedness. Most people notice this change in vision when they are unable to read print that is close to the eye. They therefore have to hold the material at about an arm’s length to read clearly or the print is blurred. There may also be symptoms of eyestrain like headaches, eye discomfort or pain and redness of the eye.
A cataract is not an inevitable consequence of aging as is the case with presbyopia. However, it is more common in the elderly and advancing age is considered to be one of the risk factors. In order to see clearly, light has to pass unobstructed through the structures of the eye until it strikes the retina at the back of the eyeball. Therefore the eye structures lying in the path of the incoming light are clear. With age and certain diseases, however, the lens of the eye can become slight cloudy. The light is therefore diffused and this leads to blurred vision.
The extent of the symptoms, however, depends on the type of cataract – sometimes the cloudiness in at the center of the lens, on the edges or at back of the lens. Apart from blurring of the vision, a person may also experience a clouding or dimming of the normal vision. Sometimes this dullness can be tainted with with yellow tint or objects may appear faded which is more noticeable when viewing bright colors. Intolerance to light develops with time and a person may also find great difficulty in seeing in very dim light. Other symptoms may include, halos, glare or in rare cases, even double vision.
The macula is the most sensitive part of the inner lining of the eye known as the retina. It is responsible for the most clear and sharp vision. There are two types of macular degeneration – wet and dry. Most people have the dry type but blindness is more common in the wet type. Degeneration of the retinal tissue, particularly of the macula, occurs for various reasons but is common with advancing age. It is the most common cause of permanent blindness.
Macular degeneration affects the central vision. There is gradual dimming of the vision requiring bright light to see objects clearly. The eyes do not adapt as quickly when entering indoors after being outside in the bright sun. Colors do not appear as bright and there may be haziness. Blurred vision is also present but often cannot be distinguished between other eyesight problems. Inability to identify faces, seeing objects particularly geometric shapes that are not present (similar to a hallucination) are considered to be more conclusive symptoms of macular degeneration.
Glaucoma is a serious eye disorder and is among the most common causes of blindness. It can occur in any age group but advancing age is known to be one of the risk factors. However, it is not a very common eye disorder in the elderly but is nevertheless worth noting. Glaucoma arises as a consequences of increased pressure within the eyeball (raised intra-ocular pressure). This gradually causes damage to the neural components of the eye which are responsible for converting light to nerve impulses and then carrying it to the brain where the images are deciphered to yield the sense of vision in humans.
There are two major types of glaucoma – open-angle and angle-closure. Glaucoma develops gradually and initially seems fairly harmless. It may not differ significantly from the symptoms of other eye disorders, particularly angle-closure glaucoma which presents with blurred vision, eye pain, halos around lights, eye redness and discomfort. Open-angle glaucoma has more specific symptoms like gradual loss of peripheral vision in both eyes – meaning the ability to see to the sides when looking straight ahead is reduced. As the condition advances, open-angle glaucoma presents with tunnel vision.
Although these three age-related eyesight problems are not the only vision disorders seen in the elderly, they are among the more common that is almost exclusively seen in older age groups. It is advisable that the elderly have bi-annual eyesight examinations and immediately report any change in vision, even when minor, to a medical doctor.