Presbyopia is an age–related decrease in the accommodative ability of the eye associated with the natural aging process of the lens. Presbyopia is manifested by a deterioration in the ability to see at close range: blurring and blurring of vision near, asthenopic symptoms (headaches, eye fatigue, poor general well-being). Diagnosis includes vision testing, assessment of refraction and accommodation, ophthalmoscopy. Treatment may consist in the selection of the necessary glasses, laser vision correction (LASIK), refractive lens replacement (lensectomy).
Presbyopia or senile hyperopia is an inevitable process associated with the natural aging of the eye. It is known that with normal refraction (emmetropia) presbyopia develops at the age of 40-45 years, with farsightedness – a little earlier, and with myopia – later. With age, there is a progressive decrease in accommodation, which leads to a gradual loss of the ability of the visual organ to focus on nearby objects. According to ophthalmology, presbyopia occurs in 25-30% of the population.
Causes of presbyopia
Presbyopia is based on natural involutional processes occurring in the organ of vision and leading to a physiological weakening of accommodation. The development of presbyopia is an inevitable age–related process: for example, by the age of 30, the accommodative ability of the eye is reduced by half, by the age of 40 – by two–thirds, and by 60 it is almost completely lost.
Accommodation is the ability of the eye to adapt to the vision of objects located at different distances. The accommodative mechanism is provided due to the property of the lens to change its refractive power depending on the degree of remoteness of the object and focus its image on the retina.
The main pathogenetic link of presbyopia is sclerotic changes of the lens (phacosclerosis), characterized by its dehydration, compaction of the capsule and nucleus, loss of elasticity. In addition, with age, the adaptive capabilities of other structures of the eye are also lost. In particular, dystrophic changes develop in the ciliary (ciliary) muscle of the eye that holds the lens. The degeneration of the ciliary muscle is expressed by the cessation of the formation of new muscle fibers, their replacement by connective tissue, which leads to a weakening of its contractility.
As a result of these changes, the lens loses the ability to increase the radius of curvature when viewing objects located close to the eye. With presbyopia, the point of clear vision gradually moves away from the eye, which is manifested by the difficulty of performing any work near.
Age-related changes in the optical apparatus of the eye are associated with metabolic disorders through the vessels of the retina and conjunctiva and develop faster in people suffering from diabetes mellitus, atherosclerosis, hypertension, hypovitaminosis, chronic intoxication (nicotine, alcohol). Hypermetropia, astigmatism, frequent eye inflammations (conjunctivitis, uveitis, blepharitis, keratitis), eye surgeries, eye injuries, as well as professional activities associated with intense and prolonged visual load at close range (laboratory assistants, engravers, programmers, etc.) contribute to the earlier development of presbyopia. In turn, early presbyopia is a risk factor for the development of glaucoma.
In people with emmetropia, the first signs of presbyopia develop at the age of 40-45 years. When working at close range (writing, reading, sewing, classes with small details), rapid visual fatigue (accommodative asthenopia) occurs: eye fatigue, headaches, dull pain in the eyeballs, bridge of the nose and brows, lacrimation and mild photophobia. With presbyopia, objects located nearby become blurry, indistinct, which is manifested by the desire to move the object of study away from the eyes, turn on brighter lighting.
Subjective manifestations of presbyopia develop when the nearest point of clear vision moves away from the eye by 30-33 cm, i.e. on average after 40 years. Changes in accommodation progress up to 65 years – approximately at this age, the nearest point of clear vision moves away to the same distance where the next point is located. Thus, accommodation becomes zero.
Presbyopia in hypermetropics (persons with hyperopia) usually manifests earlier – at the age of 30-35 years. At the same time, not only near vision deteriorates, but also in the distance. Thus, farsightedness not only contributes to the early development of presbyopia, but also enhances it.
In people with nearsightedness (myopia), presbyopia may go unnoticed. Thus, with small degrees of myopia (-1-2 dpt), the age-related loss of accommodation is compensated for a long time, and therefore the manifestations of presbyopia develop later. Persons with myopia -3-5 dpt often do not need to correct near vision at all: in this case, it is enough for them to simply remove the glasses in which they look into the distance.
If the manifestations of presbyopia are detected earlier than 40 years, a thorough examination by an ophthalmologist is necessary, aimed at detecting hyperopia and immediate, properly organized correction.
When diagnosing presbyopia, age characteristics, asthenopic complaints, as well as objective diagnostic data are taken into account.
To identify and evaluate presbyopia, visual acuity is checked with a refraction test, refraction (skiascopy, computer refractometry) and accommodation volume are determined, the study of finding the nearest point of clear vision for each eye.
Additionally, the structures of the eye are examined using ophthalmoscopy and biomicroscopy under magnification. To exclude concomitant presbyopia of glaucoma, gonioscopy and tonometry are performed.
During the diagnostic appointment, the ophthalmologist, if necessary, selects glasses or contact lenses to correct presbyopia.
Correction and treatment
Presbyopia correction can be performed by optical, microsurgical and laser methods.
Most often they resort to eyeglass correction of presbyopia, which is carried out with the help of collective “plus” lenses. In ophthalmology, specially calculated parameters of the strength of glasses are used, which are necessary for the correction of presbyopia at every age. So, for the emmetropic eye, lenses +0.75 +1 dptr are assigned at the age of 40, in the future +0.5 dptr is added every 5 years (i.e., at 45, the strength of the glasses will be +1.5 dptr; at 50 + 2 dptr; at 55 +2.5; at 60 + 3 dptr and As a rule, after 65 years of age, strengthening of presbyopia correction is not required.
In hypermetropics, to calculate the optical strength of glasses, it is necessary to add the degree of farsightedness to the value of the age correction of presbyopia. To determine the strength of the lenses in myopes, the degree of myopia should be subtracted from the value corresponding to the age of the presbyopic lens. It should be borne in mind that these data are indicative and necessarily require clarification by directly placing glasses to the eye.
Taking into account the need, simple glasses are selected for working at close range, complex glasses (bifocals) with two foci for distant and near vision, progressive, multifocal lenses or other options for optical correction of presbyopia.
In the complex correction of presbyopia, vitamin therapy, gymnastics for the eyes, massage of the cervical-collar zone, magnetolaser therapy, reflexotherapy, hydrotherapy, electro-oculostimulation, training on an accommodotrener (the “Trickle” apparatus) is used.
Surgical treatment of presbyopia can also be variable. In the field of laser surgery for the correction of presbyopia, the PresbyLASIK technique is successfully used, with the help of which a multifocal surface is formed on the cornea, which allows both far and near focus to be obtained on the retina. Other methods of laser correction of presbyopia include PRK (photorefractive keratectomy), Femto LASIK, LASEK, EPI-LASIK, Super LASIK, etc.
Intraocular correction of presbyopia involves the replacement of the lens, which has lost its physico-chemical properties and elasticity, the ability to accommodate an artificial intraocular lens (IOL). To correct presbyopia, special accommodating monofocal IOLs or multifocal IOLs are used, which are implanted immediately after cataract phacoemulsification.
It is not possible to completely exclude the development of presbyopia – with age, the lens inevitably loses its original properties. In order to delay the onset of presbyopia and slow down the progressive deterioration of vision, it is necessary to avoid excessive visual loads, choose the right lighting, perform gymnastics for the eyes, take vitamin preparations (A, B1, B2, B6, B12, C) and trace elements (Cr, Cu, Mn, Zn, etc.).
It is important annually visit an ophthalmologist, carry out timely correction of refractive errors, treat eye diseases and vascular pathology.