What is Presbyopia?
Presbyopia can be defined as an ocular condition characterized by loss of flexibility in the lens of the eye, causing inability to focus accurately on objects located nearby. It is a condition characterized by a steady loss in the ability of the eyes to focus on objects located nearby. It is a natural side-effect of the aging process and generally begins in the early or mid-forties. The condition continues to aggravate till one attains the age of 65 years.
Patients may realize about the presence of presbyopia when they begin holding newspapers and books at arm’s length so as to be able to read them. Individuals who are nearsighted can briefly manage presbyopia by reading without the corrective glasses.
Presbyopia can be confirmed via a basic eye test. The disorder can be corrective with prescription contact lenses or eye glasses, or non-prescription reading glasses. Patients may also go for surgery to treat presbyopia.
Symptoms of Presbyopia
Presbyopia has a gradual onset. Most of the signs and symptoms occur after the age of 40 years. They include:
- Patients may elicit a tendency to hold reading items farther away so as to ensure that the letters become clearer
- Headaches or eye strain after doing close-up work, or post reading
- Patients may experience blurry vision at normal reading distance
- The symptoms tend to become worse when affected people are in an area with dim light, or after intake of alcohol, or when they are exhausted
Causes of Presbyopia
Presbyopia occurs due to hardening/thickening of the lens in the eye, which typically happens as one becomes older. The decreased flexibility of the lens means that it does not have the ability to alter shape so as to be able to focus on images that are up-close. Hence, such images tend to appear blurred.
The eyes are dependent on the lens and the cornea to focus on the light which is reflected from items. This helps to create an image. It may be noted that the lens is a clear formation about the shape and size of a button, while the cornea is the clear, dome-like front ocular surface. Each of these structures refract or bend the light which enters the eye, so as to be able to focus the image on the retina. The retina is situated on the interior back wall of the eye.
Unlike the cornea, the lens is more flexible and has the ability to alter shape with the aid of a surrounding circular muscle. When people look at an object located close by, then this circular muscle compresses, so as to permit the reasonably elastic lens to curve more acutely and thus alter its focusing strength. Alternatively, when people look at objects located at a distance, then the muscle relaxes, allowing the lens to focus across a wider range.
It may be noted that increasing age is the biggest risk factor for developing presbyopia. A majority of individuals over the age of 40 years get affected by presbyopia.
Premature or early-onset presbyopia: It may be noted that some individuals may develop presbyopia before the age of 40 years, due to intake or certain drugs, or the presence of certain conditions. Premature presbyopia may be a symptom of an underlying disease that the affected individual is not aware of. A few risk factors which can increase the vulnerability to developing early-onset presbyopia are listed below:
- Use of certain medications: Some kinds of non-prescription and prescription medications like diuretics, antidepressants, and antihistamines can reduce the focusing capacity of the eye.
- Pre-existing medical disorders: The presence of far-sightedness or other medical conditions like multiple sclerosis, diabetes, or cardiovascular diseases can also elevate the susceptibility to developing premature presbyopia.
Treatment of Presbyopia
Presbyopia can be treated via use of corrective lenses, having a lens implant, or through refractive surgery.
- Corrective lenses
- Individuals who have not experienced any eye conditions before the onset of presbyopia may use non-prescription reading glasses to correct the disorder. It is important to consult a doctor before going for non-prescription glasses.
- If over the counter corrective lenses are insufficient in resolving presbyopia, then patients may opt for prescription glasses. Such glasses are also required by presbyopia patients who are already using prescription glasses to correct ocular conditions like farsightedness, nearsightedness, or astigmatism. Prescription glasses can be bifocals, trifocals, or bifocal contact lenses.
- Monovision contact lenses which consists of distant vision contact lens in the dominant eye and close-up vision contact lens for the non-dominant eye; and modified monovision which consists of distant vision contact lens in the dominant eye and close-up vision bifocal contact lens for the non-dominant eye, are other corrective options for presbyopia.
- Lens implant:It involves surgical removal of the naturally occurring clear lens and replacing it with synthetic lens. The results are not 100 percent satisfactory. This treatment option also has many side effects.
Refractive surgical methods: CK or conductive keratoplasty, LASIK or laser-assisted in-situ keratomileusis, LASEK or laser epithelial keratomileusis, and PRK or photorefractive keratectomy are some of the refractive surgical treatment options for presbyopia