Paralysis of accommodation

Paralyzing can only be what should move, and paralysis of eye accommodation is no exception, since accommodation is the process of changing the curvature of the lens, through which the clarity of the projection of images on the retina of the eye is corrected, and we can clearly see what is near.

This sharp change in the refractive power of the eye (refraction) lasts only 350 milliseconds, and it is provided by reflex compression of the special ciliary muscle. When it is violated, paralysis of accommodation (cycloplegia) develops, a pathology in which a person can not clearly view closely located objects.

[1], [2], [3]

Causes of the paralysis of accommodation

In modern ophthalmology, the causes of paralysis of accommodation are associated with ocular diseases (anterior uveitis, glaucoma, iridocyclitis) and common infections (influenza, diphtheria, infectious mononucleosis, tuberculosis, meningitis, encephalitis, syphilis, botulinum toxin or spores).

Also, the etiology may be due to:

• defeat of the oculomotor nerve (3rd pair of cranial nerves) due to hemorrhage or tumor (glioma of the optic nerve);
• edema of the disk of the optic nerve end of the optic nerve (papilloedema), which develops due to a persistent increase in intracranial pressure;
• neuralgia of the trigeminal nerve;
• the syndrome of Ady-Holmes (dysfunction of the ciliary muscle);
• aplasia of the ciliary body;
• rupture of zonal fibers and partial subluxation of the lens;
• Kurshman-Steinert syndrome (myotonic dystrophy);
• tumor structures of the brain (for example, a pineal gland tumor);
• upper acute hemorrhagic polyoencephalitis (Guy-Wernick syndrome);
• intoxication with exogenous poisons (snake bites, insects) and poisoning with organophosphorus compounds, carbamate insecticides and fungicides, lead, arsenic, carbon monoxide.

[4], [5], [6], [7]

Risk factors

Such risk factors for the development of cycloplegia as diabetes mellitus and alcoholism have been noted; general reduced adaptability of the organism; ocular and orbital eye injuries; damage to the brainstem or ciliary node in cases of craniocerebral trauma; multiple sclerosis and Parkinson's disease.

There is a whole list, including pharmacological agents, causing paralysis of accommodation. It included atropine, amphetamine, amitriptyline, antazoline, belladonna, betamethasone, vincristine, dexamethasone, diazepam, dimedrol, diphenylpyroline, dicyclomine, captopril, carbamazepine, clemastin, isoniazid, naproxen, oxazepam, pilocarpine, pentazocine, scopolamine, temazepam, trichloromethiazide, cimetidine, chloramphenicol, and others.

[8], [9], [10]

Pathogenesis

The paralysis of accommodation is a complete blockade of the contractions of the ciliary muscle, which is located in the ciliary body of the eye, and the ciliary body - in the form of a ring - holds the lens and is located under the sclera. From the inner part of the ciliary body towards the lens, the ciliary nerve processes and the finest, radially located muscle fibers-the zonal ones-depart. Their totality is a ciliary bundle.

To clarify the pathogenesis of accommodation paralysis, it should be borne in mind that the process of accommodation of the eyes is provided by nerve impulses transformed in the retina of light - when a person looks at a closely located object. The afferent impulses go to the central nervous system, entering the structures of the visual hillock in the occipital lobes of the brain, more specifically, to the cortical visual centers of the 18th Broadman field (it turned out that they are responsible for the accommodation). From there, along the parasympathetic fibers of the oculomotor nerve - with a switch in the ciliary knot innervated by the trigeminal nerve - the corresponding back signal reaches the ciliary muscle and it shrinks. This relaxes the zonal fibers of the ciliated ligament, which allows the lens of the eye to become more rounded and correctly focus the image of the closely located object.

The next tension (tension) of the zonal fibers and the entire ligament is the result of the next relaxation of the ciliary muscle, and this happens when a person looks at distant objects. With paralysis of accommodation, the condition of the ciliary muscle is relaxed, which reduces the accommodation amplitude almost to zero.

Ophthalmologists distinguish paralysis and spasm of accommodation, which is also called false myopia; With the spasm of accommodation, the ciliary muscle reduces in a stressed state, which reduces the quality of long-range vision.

[11], [12]

Symptoms of the paralysis of accommodation

According to experts and complaints of patients with paralysis of accommodation, the first signs appear in blurriness (blurriness) of the near vision: to read the text printed in a standard font, a person has to increase the distance between the eyes and the page, pulling the hand with a book or magazine forward. And this can continue until even at a distance of a completely extended hand a person can not read a single line in small print.

Other symptoms of accommodation paralysis are described as difficulties in writing (a person does not see his own written text); one-eye reading; screw up if necessary to see something near.

There are also complaints of rapid eye fatigue and slight burning in them (after a load) and headaches. And doctors call also such a symptom as mydriasis, that is, the dilatation of the pupil.

Complications and consequences

The consequences and complications of cycloplegia for initially normal vision and for hyperopia (hypermetropia) are expressed in the often irreversible weakening of clinical refraction of the eyes and the loss of the ability to clearly see near without the help of optics. With the initial myopia (myopia) paralysis of accommodation can pass almost without consequences for visual acuity.

[13], [14], [15], [16], [17], [18]

Diagnostics of the paralysis of accommodation

Comprehensive history and careful ophthalmological and neuro-ophthalmological examination is the basis on which the diagnosis of paralysis of accommodation rests.

Instrumental diagnostics includes hardware refractometry, rheophthalmography, ophthalmoscopy, perimetry, microscopic examination of a slit lamp. If a neurocerebral etiology of the disorder is suspected, an examination of the brain and / or the spine with ultrasound sonography, CT or MRI is required.

[19], [20]

Differential diagnosis

Differential diagnosis - with the involvement of specialized specialists - is designed to detect or exclude optic neuritis or its infiltration in glioma and sarcoidosis; thrombosis of the cavernous sinus or Chiari syndrome; Foster-Kennedy Syndrome; drug intoxication; Lyme disease (with increased intracranial pressure); medulloblastoma or lymphoblastic leukemia.

[21], [22]

Treatment of the paralysis of accommodation

Given the causes of this pathology of vision, the treatment of paralysis of accommodation can go far beyond the scope of actual ophthalmology: it is enough to look once again at the relevant section of this publication.

And as for ophthalmology, doctors say that there is no therapy in cases of drug paralysis of accommodation: the cancellation of the provoked drug will lead to independent restoration of near vision.

If the paralysis remains after the treatment of systemic diseases (which are prescribed and conducted by the doctors of the appropriate profile), the oculists are prescribed lenses (with plus diopters) to correct the farsightedness.

In indications, under which operative treatment is performed - laser correction of vision (by changing the curvature of the cornea with a laser), anomalies of the refraction of the eye are indicated: myopia, hypermetropia, astigmatism and presbyopia (age-long farsightedness). The paralysis of accommodation in the list of indications does not appear.

Prevention

With the current level of medicine and an extremely wide range of etiological factors in the development of accommodation paralysis, its prevention is hardly possible.

[23], [24], [25], [26], [27], [28]

Forecast

And the fact that the real forecast is in absolute dependence on the causes of pathology is obvious. Paralysis of accommodation, as a violation of contractions of the ciliary muscle, can lead to an amblyopia condition - impaired vision that can not be corrected with glasses or contact lenses, as well as accommodative esotropy (adaptive strabismus) or closed-angle glaucoma.

[29]