Presbyopia is a medical condition of the eye where the affected person gradually loses the ability to keenly focus on close objects. It's a natural, part of aging and becomes obvious in the 40s and continues to worsen till the 60s.
An eye exam helps in confirming the diagnosis of presbyopia. Nonprescription / prescription reading glasses or contact lenses help in correcting this condition. Surgery can also be done for presbyopia.
Causes of Presbyopia
The cause of presbyopia is hardening of lens due to aging. With age, the eye lens loses it flexibility and is no longer able to adapt to focus on nearby objects resulting in these objects appearing out of focus.
The eye lens is flexible and has the ability to change shape using the circular muscle surrounding it. This muscle relaxes when a person looks at distant objects and constricts when looking at nearby objects and permits relatively flexible lens to curve more in order to adjust its focusing ability. With age, the lens loses this ability and flexibility and this causes presbyopia.
Risk Factors for Presbyopia
Age is the major risk factor and people after age 40, more often than not, experience presbyopia. Although there are some people who can develop presbyopia before reaching age 40 due to some diseases or drugs. This condition is known as premature presbyopia and indicates some other medical condition which the patient is not aware of.
Risk Factors for Premature Presbyopia
- Other medical diseases, such as farsightedness, diabetes, cardiovascular disease, multiple sclerosis increase the risk of premature presbyopia.
- There are some prescriptions and nonprescription drugs which affect the eye's ability to focus such as antihistamines, antidepressants and diuretics.
Signs and Symptoms of Presbyopia
- Patient holds his/her reading material at a distance so that the letters appear clearer.
- Blurry/hazy vision at a standard reading distance.
- Patient suffers from headaches after working on a computer or reading.
- Patient suffers from eye strain after working on a computer or reading.
- Symptoms tend to worsen when tired, in decreased light and upon alcohol consumption.
- Serious symptoms for which the patient should seek immediate medical attention are: Difficulty doing close work or reading, hazy nearby vision affecting quality of life.
Investigations for Presbyopia
A complete eye exam helps in confirming the diagnosis. There are a series of tests involved where the ophthalmologist will instill eye drops in order to dilate the pupils. This makes the eyes more sensitive to light for some hours and helps the doctor to easily assess the interior region of the eyes. The ophthalmologist may also use different instruments and focus bright light at the eyes. The patient is told to look through a variety of lenses to test close vision as well as distant vision. These different tests help the doctor to assess the various sides of the patient's vision.
Treatment for Presbyopia
The aim of treatment is to counteract the loss of ability of the eyes to focus on close images. Treatment comprises of wearing corrective lenses and surgery comprising of refractive surgery or lens implantation.
- Corrective Lenses: With doctor's advice you can use over-the-counter nonprescription reading glasses if you had uncorrected, good vision before presbyopia.
- Prescription Reading Glasses can be used only for reading and if the patient doesn't have other vision issues.
- Bifocals are available in two styles. One is with a horizontal line which is visible and another is progressive bifocals which are without the line.
- Trifocals: These glasses can correct vision during close work and medium distance vision, e.g. T.V. and computer screens. Trifocals are available as progressive lenses or visible lines.
- Bifocal Contact Lenses are like bifocal glasses and are able to correct distance and as well as close vision problems.
- Mono-Vision Contact Lenses for distant vision are worn in the dominant eye and for close-up vision are worn in the non-dominant eye. Dominant eye is usually the eye which we use to aim a camera when taking a picture.
- Modified Mono-Vision: In this, you can wear a bifocal contact lens in the non-dominant eye and a contact lens for distant vision in the dominant eye. Both the eyes are used for distant vision and only one eye is used for reading.
Refractive Surgery for Presbyopia
Refractive surgery is done to change the corneal shape. In presbyopia, refractive surgery is same as wearing mono-vision contact lenses and helps in improving close vision in the non-dominant eye. It is recommended that patients first try mono-vision contact lenses to decide whether they are able to adapt to this type of correction before deciding upon refractive surgery.
Refractive Surgery Comprises of the Following Procedures
- Conductive Keratoplasty (CK) comprises of radiofrequency energy for applying heat to minute spots surrounding the cornea. The results vary and depend on the amount of change in the curvature of the cornea as well as the distance between the spots. The results may not last long for quite a few people.
- Laser-Assisted In-Situ Keratomileusis (LASIK) comprises of using special laser or keratome, which is an instrument used to make a very thin and joined flap in the cornea. The inner layers of the cornea are removed with the help of an excimer laser to define make the dome shape more steep. Unlike other lasers, an excimer laser does not generate heat.
- Epithelial Laser in Situ Keratomileusis is a new procedure which is thought to prevent some of the risks related with LASIK.
- Laser Epithelial Keratomileusis (LASEK): In this a flap is created only in the epithelium and excimer laser is used to reshape the outer layers of the cornea and to increase the curvature. The epithelial flap is repositioned later.
- Photorefractive Keratectomy (PRK) resembles LASEK with the difference being that the surgeon removes the epithelium which later on grows back adapting to the new shape of the cornea.
- Lens Implantation: This procedure involves removing the clear natural lens and replacing it with a synthetic lens inside the eye, also known as intraocular lens implant. Latest lens implants helps in seeing distant as well as near objects; however, these special lens haven't proved to be completely satisfactory. Also, this surgery has the same risks that are associated with a traditional cataract surgery, e.g. infection, inflammation, glaucoma, bleeding and retinal detachment. It is believed with advanced technologies, these implants can be improved in the future.
- Small-Diameter Corneal Inlays: This is a new surgical procedure which comprises inserting small plastic rings at the cornea's edge. However, expected results are not yet seen and this procedure is still considered new and experimental.
Lifestyle Changes for Presbyopia
Presbyopia cannot be prevented, but the following measures help in protecting the eyes and vision:
- Get regular eye checkups.
- Conditions which are chronic in nature like hypertension and diabetes should be closely monitored and controlled.
- Always keep your eyes protected from the sun by wearing sunglasses with UVA and UVB protection.
- Always use protective eyewear when doing activities such as playing sports, painting, mowing and using products containing toxic fumes.
- Follow a healthy diet full of fruits and green leafy vegetables.
- Always wear right glasses to optimize your vision.
- Work or read using good and appropriate lighting.
- If you experience symptoms such as sudden vision loss, sudden hazy vision, light flashes, halos or rainbows or black spots, then visit ER immediately as they may indicate serious medical conditions such as stroke, acute glaucoma, retinal tear or retinal detachment.