Presbyopia

The age-related weakening of the adaptive function of the eyes to change the optical setting and to see close objects clearly is defined in ophthalmology as presbyopia (from Greek presbys - old and ops - eye). This decrease in visual acuity is also referred to as age-related hyperopia, and specifications such as senile presbyopia or age-related presbyopia are considered unnecessary. [1]

Epidemiology

According to statistics, globally, more than 1.04 billion people had presbyopia in 2005, and in 2015m this number increased to 1.85 billion.

According to the American Society of Cataract and Refractive Surgery (ASCRS), nearly 90% of adults experience a gradual decline in vision beginning at age 45. And in North America, the prevalence of age-related hyperopia in 45 to 55 year olds is estimated at 80%. [2]

Causes of the presbyopia

Presbyopia refers to age-related refractive abnormalities - disorders of refraction of light rays by the lens and automatic distance-dependent adjustment of the focal length of the eye lens - decreased amplitude of accommodation.

So the key causes of presbyopia are age-related changes in accommodation, which occur after 40 45 years of age. Most ophthalmologists consider this condition to be part of the natural aging process of the eye, which sooner or later happens to most people, although in ICD 10, under diseases of the eye and its appendage, age-related hyperopia has the code H52.40.

But this vision problem can also develop at a younger age: in people with existing hypermetropia - farsightedness.

As you understand, presbyopia in children is impossible, but due to a shorter anteroposterior axis of the eye or a too flat cornea there can be accommodative insufficiency and congenital hypermetropia (farsightedness) in children. [3]

Risk factors

The main risk factors for the development of presbyopia are age-related changes associated with the inevitable biological process of aging of the body, including vision.

The risk of age-related hyperopia is increased in the presence of visual fatigue syndrome - accommodative eye asthenopia, and in the presence of corneal sphericity disorders - astigmatism.

There is also a risk of premature age-related hyperopia, which may be due to:

• activities involving constant strain on the near vision (including working at a computer);
• by overexposing your eyes to ultraviolet radiation;
• anemia;
• cardiovascular disease;
• with diabetes;
• early onset of menopause;
• alcohol abuse;
• long-term use of sedatives and antidepressants, as well as antihistamines or antispasmodics.

Pathogenesis

Specialists explain the pathogenesis of age-related hyperopia by problems with the accommodative apparatus of the eye, which includes the ciliary body (corpus ciliare); the annular ciliary muscle of the eye (musculus ciliaris). Supporting ligaments - zonular fibers (zonula ciliaris), which branch from the inner wall of the eye and hold the lens. And, of course, the lens crystallin, which is located behind the iris and pupil, consists of epithelial cells and fiber-packed water-soluble proteins α, β and γ crystallins and continues to grow towards the central part throughout life.

By changing its shape, it changes the focal length of the eye, and this change in shape increases the optical power, so that objects at different distances can be seen clearly. As we age - due to the constant formation of concentric layers of secondary fibers - the lens becomes less flexible (elastic) and more ellipsoidal in shape, which affects its ability to change its curvature (refractive power) to focus light rays on the retina.

According to another model of presbyopia, it's not just the lens, but a weakening of the ciliary muscle, which controls the lens of the eye. When the ciliary muscle is relaxed, the supporting ligaments tighten and the lens assumes a shape suitable for seeing distant objects. And positive accommodation, which allows you to see objects up close, occurs due to the contraction of this muscle - when the zonular fibers relax and the anterior surface of the lens becomes more curved. However, the effect of human age on the contractility of the ciliary muscle is controversial due to conflicting findings in some studies.

So, the mechanism of presbyopia development is still being studied by researchers, but the connection of blurred vision at close distances with age-related changes in the flexibility and shape of the crystalline lens is beyond anyone's doubt.

Symptoms of the presbyopia

The first signs of age-related farsightedness become noticeable around the age of 45 and at first often occur only when reading, and it is initial presbyopia - the earliest stage when there is some difficulty in reading small print. The condition (usually presbyopia in both eyes) slowly progresses, and the person already has difficulty reading small print by squinting hard.

Presbyopia symptoms are also manifested by having to hold reading text at a considerable distance from the eyes, and requiring brighter lighting when reading or doing close work.

Many people have complaints of eye strain and fatigue, and in some cases may experience headaches after reading or working with near vision.

By the way, ordinary hyperopia or hyperopia and presbyopia have similar symptoms: a person sees distant objects clearly, but closer objects seem blurred. But in terms of etiology, these are two different disorders.

There can be presbyopia with myopia (myopia), and in such cases age-related hyperopia comes later, and with correctable "minus" glasses mild myopia a person can take them off when reading.

If at the same time there is a refractive anomaly due to irregularly curved cornea astigmatism and presbyopia, there is blurred contours of close objects.

Degrees of presbyopia are determined by the amount of additive - the addition of plus diopters to correct vision. A mild degree means the need to add +0.5 to +1.25 dptr; a medium degree means +1.25 to +2.25 dptr; a high degree means +2.25 dptr and above. [4]

Complications and consequences

As ophthalmologists point out, complications of presbyopia - the gradual deterioration of near vision that affects lifestyle and professional activities - occur if it is undiagnosed or uncorrected.

In addition, age-related farsightedness can lead to a problem with eye movement coordination and a deviation of one eye from the other, resulting in constant double vision - diplopia.

Diagnostics of the presbyopia

Diagnosing presbyopia involves examining the eye, which uses:

• tests for visual acuity;
• Instrumental diagnostics, including ocular ultrasound, slit lamp biomicroscopy and retinal examination, ophthalmoscopy and methods of accommodation testing.

Differential diagnosis

Differential diagnosis is designed to verify the diagnosis and exclude: nuclear cataract development, senile degeneration of the yellow spot (macula), retinal degeneration, diabetes-related retinopathy, CNS disorders and ocular nerve damage.

Differentiation is also required:

• presbyopia and retinal angiopathy, in which a shroud appears in front of the eyes and nearsightedness develops;
• Hypertensive angiopathy and presbyopia.

Treatment of the presbyopia

Age-related farsightedness correction improves near vision with glasses, contact lenses, or surgery. [5]

Improving your eyesight helps:

• presbyopia glasses (with monofocal lenses with plus diopters) - for reading;
• Bifocal contact lenses for presbyopia;
• Progressive presbyopia glasses with multifocal lenses that provide smooth magnification from the top of the lens to the bottom, allowing you to see clearly at any distance with just one pair of glasses.

Also read:

• Correction of poor vision
• Vision correction with spectacle lenses

Corneal refractive surgery for presbyopia is the treatment of presbyopia eyes with laser, that is, the correction of age-related hyperopia by reshaping the cornea using laser in situ keratomileusis (LASIK).

See also - Excimerlaser correction of refractive anomalies

Presbyopia lens replacement (PRELEX) is the replacement of the removed lens with an intraocular multifocal lens that can restore normal vision. The main risks of this surgery are the development of inflammation of the inner membranes of the eyeball (endophthalmitis) and retinal detachment. [6]

Drug treatment of age-related hyperopia has become possible: the FDA recently approved Vuity presbyopia drops, which are a 1.25% solution of pilocarpine hydrochloride (used to treat glaucoma). Pilocarpine stimulates the cholinergic receptors of the smooth muscle cells of the ciliary muscle and iris sphincter, resulting in pupil constriction and a temporary increase in depth of field and improvement in near visual acuity. The effect begins a quarter of an hour after the application of drops and lasts for six hours. However, prolonged use of pilocarpine can cause side effects in the form of redness and itching of the eyes, spasm of accommodation, pain in the ocular orbits and temporal region, allergic or follicular conjunctivitis, photophobia, corneal edema and erosion, dizziness, arterial hypo or hypertension. [7]

Gymnastics for presbyopia see - Eye exercises for farsightedness

What eye vitamins are needed for presbyopia, read in the publications:

• How to improve vision with vitamins?

Prevention

There is no proven method for preventing presbyopia, and ophthalmologists offer general recommendations of protecting the eyes from UV light, eating a healthy diet, drinking enough water, and limiting alcohol.

Forecast

There is no way to stop or reverse the aging process that causes presbyopia, and the eyes of every person who lives to age 50-55 will gradually lose the ability to change optical setting and see close objects clearly.

But thanks to vision correction, the prognosis is considered favorable because presbyopic changes usually stabilize by age 65.