Presbyopia (Old Eyes)
Presbyopia or old eye is an age-related loss of vision to see the surroundings clearly without suitable eyeglass correction. Presbyopia is not a disease, but the age-related loss of normal eyes function.
Over time, the lens thickens and loses its elasticity and its ability to focus the viewed images. People in their 40s often notice a blurring of their eyesight when looking at close up objects. They have to move away in order to be able to see well, which can quickly become an irritant.
Vision becomes blurred when you read for example near 40 cm (around 16 inches). The patient will be embarrassed to read or to use his/her cell phone
The process of aging of the lens occurs in everyone, but health and the environment can influence this phenomenon to accelerate.
“Gain” of myopia
Some nearsighted people are able to read easily without reading glasses or contact lenses, even after 40 years of age. However, their myopia does not go away. With presbyopia, nearsighted people with astigmatism often have better near vision without a telescope or lens, but the more pronounced the astigmatism, the worse their near vision.
Some people over 50 years of age can read without the help of glasses, this is generally due to the fact that they have some degree of myopia or myopic astigmatism , or that they are developing a cataract that alters the shape of the lens, which paradoxically allows them to see closely no need for glasses.
People who plan to correct their myopia using lasik, or any other surgical technique, should consider that presbyopia significantly changes the accommodation capacity of the eye and this is disadvantageous from the age of 40: they will need corrective glasses for reading. Eye specialists have developed a surgical technique that partially overcomes this difficulty. They operate one eye for reading and another for far vision. This technique, called monovision, is used by contact lens specialists.
Signs and symptoms
The common signs and symptoms of presbyopia are:
- blurring of near vision;
- headaches and pain around the eyes;
- visual fatigue;
- difficulty working at close range for a long time;
- difficulty seeing clearly in the absence of light sources.
Symptoms begin with the onset of difficulty seeing fine print, especially when waking up, and when the ambient light is low. It may be, for example, an increasing difficulty in reading a low contrast text such as a wine bottle label in a restaurant: in the generally subdued light, certain intrinsic difficulties are added such as the fact that the labels often have a background. colorful, and various unusual calligraphy.
In general, it is strongly recommended to consult an ophthalmologist on a regular basis. Only an ophthalmologist will be able to detect any possible pathology, such as the appearance of glaucoma or cataracts, for example. If you are aware of a family history, it is recommended that you be extra careful.
Mechanism of presbyopia
Presbyopia reflects the gradual reduction in the accommodation capacity of the eye (amplitude of accommodation), which is directly linked to the reduction in the elasticity of the lens and its capsule. The lens is a natural lens, located in the anterior segment of the eye, that allows you to focus for a clear view of close-up objects. This is the equivalent of “autofocus” for a camera. In an emmetropic subject (subject seeing sharp without correction in the distance) becoming presbyopic, near vision such as that used for reading is increasingly blurred, while vision for more distant targets remains normal.
How to detect presbyopia?
If you are in your 40s, you may be affected. Very often the first signs appear when reading. The patient can no longer read closely and holds his book or objects at a distance to see them better. Presbyopia results in a patient with otherwise good vision being discomfort in near vision, especially for the small print or details of an image and in low light.
People with nearsightedness will experience presbyopia later than people with hyperopia. In a myopic individual, the image is projected in front of the retina which allows it to compensate for his presbyopia. In contrast, a hyperopic eye projects the image behind the retina, as in presbyopia, which accentuates the phenomenon. The onset of presbyopia is therefore very badly experienced by an already hyperopic patient, especially since it usually happens earlier. Near vision and distance vision deteriorate rapidly from the age of 40.
Presbyopia is linked to the aging of the lens. The ciliary muscle ( intrinsic muscle of the eye formed as a ring of smooth muscle in the eye’s middle layer or vascular layer) plays its role well by contracting, but the lens is no longer able to bulge to correctly converge the light beams on the retina. Presbyopia is therefore not linked to a muscle on which it is possible to work to strengthen it, but an obsolescence of the lens. Currently, no technique or therapy is effective in preventing or delaying presbyopia.
Can we delay presbyopia?
Presbyopia is not related to the reduction in the strength of the ciliary muscle (which is brought into play during the accommodative effort to see up close), but to the loss of elasticity of the lens (understanding the mechanism of the accommodation makes it possible to apprehend that of presbyopia). The ciliary muscle contracts, the zonule (the ligament of the lens) relaxes, but the lens itself does not bulge enough (a young lens naturally bombs when the tension of the zonule is released).
If presbyopia were linked to a reduction in the intensity of ciliary muscle contraction, one could imagine treatments aimed at “re-muscle” the eye to maintain accommodation. Unfortunately, during the onset of presbyopia, the ciliary muscle contracts well, but the lens, which tends to increase in size and lose its flexibility during life, no longer bulges enough. Currently, we do not know any effective therapy to restore its lost elasticity to the lens.
Therapeutic trials have been carried out using the femtosecond laser to make incisions directly into the lens, in the hope of restoring some flexibility to the lens. The results of these techniques do not seem sufficient, and the risk of induced cataracts is however real. The answer to the question of a possible prevention of presbyopia is therefore negative, and it is also remarkable how consistently presbyopia sets in over time in humans (between 42 and 44 years of age most often).
The solutions to correct presbyopia are:
1. Wearing an optical correction system
Progressive lens glasses (of which near or mid-distance lenses are a subtype);
Multifocal lens glasses (double and triple focus);
2. Contact lenses (progressive, multifocal or single vision)
For some particular presbyopic needs, single vision glasses or unique “homemade” fixtures may be offered.
Excimer laser (Presby-Lasik, Laser Excimer, or Femtosecond IntraCOR, SupraCor, Isovision …) either to make the corneas of the two eyes multifocal, or to give the cornea of one eye the correction for near vision and for the other eye a far vision;
Classic surgery, to replace the lens with a multifocal implant.
There are three principles for correcting presbyopia:
1. Monovision, like a monocle
One eye will be corrected to see correctly up close and the other far away. This method of correction is found in patients who have undergone a surgical operation to replace the lens with a monofocal implant, patients fitted with monofocal contact lenses, and presbyopes who have undergone a corneal operation by Laser in order to put in place monofocal correction.
2. Multifocal vision
Where the correcting system sends several images of the scene seen on the retina of the eye, each image being corrected for a precise distance, the brain being responsible for filtering the images to keep only the correct one. This mode of correction is found in patients who have undergone a surgical operation to replace the lens with a multifocal implant, patients equipped with multifocal contact lenses, and presbyopes who have undergone a corneal operation by Laser in order to put in place multifocal correction.
3. Progressive vision
Where the system provides the eye with the necessary correction for each viewing distance, in the case of glasses with progressive lenses, aiming through the correct zone of the glasses; in the case of progressive lenses, these lenses move over the eye, with contact with the eyelids, along its axis of vision, which places the adequate vision zone in front of the lens.
4. Several multifocal laser surgery techniques grouped under the name PresbyLasik
Such as Isovision4 or Supracor5,6, have the advantage of being able to correct presbyopia and all refractive errors in both eyes at the same time and at all distances and this regardless of the patient’s age. They respect the dominant eye-dominated eye pair and allow patients to regain good vision at any distance on each eye. Vision fatigue is therefore less and headaches are limited during activities such as working on the computer or driving.
Types of Presbyopia
Presbyopia can be divided into some types, having as a dividing element the period and intensity that manifests itself, namely:
incipient, functional, absolute, premature and nocturnal.
The first of them encompasses the initial cases in which individuals feel some difficulty in seeing what is closest, mentioning an extra effort to read reduced letters.
The functional, or second phase, refers to those individuals whose visual impairment is clinically proven.
As the name implies, absolute presbyopia is the culmination of the person’s visional difficulty, the third stage of the disease.
The others are separate phases, with early presbyopia being that which appears before the estimated age of 35 to 40 years of age, and nocturnal presbyopia, which is the difficulty in seeing in poor light environments.
Photo description: you can’t see small prints without eyeglasses. Illustrative of the problems with presbyopia.