What is presbyopia and when does it occur?
This is presbyopia, a visual disturbance “typical” of age, which takes away the sharpness of images that appear in the “near” (ie at a distance of 30 to 40 centimeters).
But what happens to us after 40 years? What are the alarm bells that tell us if we are suffering from presbyopia?
And what options are available today to correct this vision problem?
Presbyopia: a problem of sight and age
The term âpresbyopiaâ comes from the Greek words presbus (old, worthy of respect) and opia (sight) and designates a visual disturbance totally related to age and therefore physiological.
Unlike the more common refractive errors (myopia, hyperopia and astigmatism), which depend on an abnormality in the ocular structure, presbyopia is caused by the loss of flexibility of the lens, the lens inside the eye.
Over the years, the central part of this lens (core) loses water, hardens and cannot change shape to focus on objects near or far.
The lens then loses its ability to “accommodate”, that is to say to maintain a clear vision of objects at different distances.
In the case of presbyopia, near vision is made difficult.
Note that presbyopes use two different corrections for far and near vision.
Indeed, even the slightly short-sighted person who reads without glasses is presbyopic, that is to say, he uses glasses for distance vision and takes them off when looking at objects or writing at about 30 centimeters away. .
The presbyopia alarm bell
From the age of 45, the person notices a certain difficulty in distinguishing the images on the screen of the cell phone, feels the need to move away from books or newspapers to be able to read the text and perceives a certain eyestrain, in particular during of all activities carried out at close range.
These complaints tend to get worse with age.
Rarely, presbyopia can occur as young as 40 years old.
In such cases, diseases such as diabetes, multiple sclerosis, cardiovascular disease or the use of drugs such as diuretics, antihistamines and antidepressants contribute to the accelerated onset of the problem.
Eye exam for the diagnosis of presbyopia
Presbyopia is a clock provided by Mother Nature that should inspire everyone to see an eye doctor, and for many it will be the first eye exam of their lives.
The specialist will assess not only the degree of correction of the glasses, which are often extremely simple to correct, but also the health of the eye.
During this examination, visual acuity with the most reliable dioptric correction, eye pressure and eye fund will be specifically checked, which is especially recommended for people with a family history of diseases such as glaucoma and maculopathy.
To check visual acuity, that is, the ability of the eye to focus properly on objects, the âclassicâ vision measurement is usually performed using the octotype table.
This is a table usually made up of letters of different sizes arranged in several rows on top of each other.
The person looks at the board from a distance, first covering one eye and then the other, and the specialist checks whether the letters are read correctly.
Correct presbyopia: glasses and contact lenses
Presbyopia is usually corrected by the prescription of glasses.
The choice of the most suitable glasses for the correction is suggested by the specialist according to the age of the person, the seriousness of the problem and the possible presence of other associated refractive errors (myopia, astigmatism and hyperopia).
In some cases, multifocal soft contact lenses can be used, which is especially recommended for people who have worn contact lenses for a long time to correct other refractive errors.
In addition to traditional means of correction, glasses and contact lenses, refractive laser surgery has been used to correct presbyopia since 2005.
Surgical options to correct presbyopia
Laser surgery can be an effective solution in cases of presbyopia, because it increases the depth of field and thus offers good comfort in medium vision (the distance at which we typically have a computer screen) and helps in vision. up close (books, newspapers and smartphones) in a well-lit environment.
It is particularly indicated if presbyopia is associated with other refractive errors, such as myopia, astigmatism and hyperopia.
In the field of refractive laser surgery, 2 techniques are most commonly used: the Excimer laser (with PRK technique) and Femtolaser (with Lasik technique).
Excimer laser (PRK technique)
The Excimer laser (PRK, PhotoRefractive-Keratectomy) is the most experienced treatment in the world (since 1990).
It consists in reshaping the anterior aspect of the cornea, the first lens of the eye, after mechanical removal of the superficial epithelium (deepithelialization procedure).
A “natural contact lens” of the desired dioptric power is sculpted for the correction of the refractive error and, in the case of a presbyopic correction, a multifocal zone is modeled on the anterior aspect of the cornea to help the patient in. near vision.
Only the precision of the laser beam makes it possible to eliminate at each “spot” (blow) plates of corneal tissue of a micron (one thousandth of a millimeter).
It is therefore a treatment which has the advantage of taking place on the surface of the cornea, without the surgeon having to manipulate the eye and therefore without intraoperative risks.
It causes pain for 2-3 days after treatment.
Femtolaser (with Lasik technique)
The Lasik technique involves an initial step in which the femtolaser cuts the cornea sagittally.
The flap is then lifted by the surgeon who, with the second instrument, the excimer laser, modifies the curvature of the cornea by excavating it internally according to the required treatment parameters (as in PRK).
This technique, like PRK, corrects not only presbyopia, but also any other refractive error that may be present.
Femtolasik is particularly recommended for correcting high refractive errors, in particular hyperopia and astigmatism.
The femtoLASIK technique is more invasive than PRK, but is painless after the operation.
When the lens becomes cloudy and cataracts occur, as an alternative to refractive laser surgery, cataract surgery with implantation of an intraocular lens or artificial lens can be used to correct presbyopia.
These lenses are accommodative or multifocal, that is, they are able to focus the eye both near and far. They do not become opaque and last a lifetime.
This procedure allows the simultaneous correction of associated refractive errors such as myopia, astigmatism and hyperopia.
It should be noted that the most suitable operation must be evaluated by the surgeon according to the age, the severity of the symptoms and the presence of other refractive errors.
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