Dry eye syndrome (xerophthalmia) is a condition of insufficient moisture on the surface of the cornea and conjunctiva due to a violation of the quality and quantity of tear fluid and instability of the tear film. The manifestations are burning and cutting, a feeling of sand in the eyes, lacrimation, photophobia, rapid fatigue during visual work, intolerance to dry and dusty air. Syndrome is diagnosed by the results of biomicroscopy, Schirmer and Norn tests, fluorescein instillation test, thiascopy, osmometry, crystallography of lacrimal fluid, cytological examination of a smear from the conjunctiva. Artificial tear preparations, tear duct obturation, tarzoraphy, keratoplasty, salivary gland transplantation are indicated as a treatment for dry eye syndrome.
H04.1 Other diseases of the lacrimal gland
Dry eye syndrome is a fairly common condition in ophthalmology, which is characterized by a lack of moisture on the surface of the cornea and conjunctiva of the eye and the development of signs of xerosis. Syndrome occurs in 9-18% of the population, more often in women (almost 70% of cases), the incidence of the disease increases significantly with age: up to 50 years – 12%, after 50 – 67%.
Normally, the anterior surface of the eyeball is covered with a continuous thin (about 10 microns) tear film having a three-layer structure. The outer lipid layer – the oily secret of the meibomian glands ensures that the upper eyelid slides over the surface of the eyeball and slows down the evaporation of the tear film. An aqueous layer with dissolved electrolytes and organic compounds washes out foreign bodies from the eye, provides the cornea with nutrients and oxygen, and creates immune protection. Mucin layer – the mucous secret of goblet-shaped and epithelial cells directly contacts the cornea: it makes its surface smooth and smooth, binding the tear film to it and providing high quality vision.
Approximately every 10 seconds, the tear film ruptures, initiating a blinking movement of the eyelids and the renewal of the tear fluid, restoring its integrity. Violation of the stability of the cornea tear film leads to its frequent ruptures, dryness of the surface of the cornea and conjunctiva, the development of dry eye syndrome.
Dry eye syndrome is caused by insufficient quantity and quality of tear fluid, as well as excessive evaporation of the precorneal tear film, which reduces its preservation time or volume.
The causes of dry eye syndrome may be internal diseases and syndromes associated with a decrease in tear production: autoimmune (Sjogren’s syndrome), diseases of the hematopoietic and reticuloendothelial systems (Felty syndrome, malignant lymphoma), endocrine dysfunction (endocrine ophthalmopathy, menopause), kidney pathology, exhaustion of the body and infectious diseases, skin diseases (pemphigus), pregnancy.
Pathology of the visual organs (chronic conjunctivitis, corneal and conjunctival scars, neuroparalytic keratitis, lagophthalmos, lacrimal gland dysfunction) and surgical ophthalmological interventions that destabilize the tear film (anterior radial keratotomy, corneal photoablation, keratoplasty, conjunctival plastic surgery, correction of ptosis) can lead to dry eye syndrome.
There are arteficial factors that cause a violation of the stability of the tear film – dry air from air conditioners and fan heaters, hard work with a PC, watching TV, errors in the selection and use of contact lenses, environmental problems.
Reduces lacrimal production and causes dry eye syndrome long-term use of ocular drugs containing beta-blockers, cholinolytics, anesthetics; some systemic drugs (hormonal contraceptives, antihistamines, hypotensive).
The appearance is facilitated by too rare blinking movements, vitamin deficiency with a violation of the metabolism of fat-soluble vitamins, genetic predisposition, age after 40 years, belonging to the female sex. The decrease in the frequency of blinking movements may be due to a decrease in the sensitivity of the cornea of a functional or organic nature.
Dry eye syndrome is distinguished by pathogenesis, which developed as a result of a decrease in the volume of lacrimal fluid secretion, increased evaporation of the tear film, as well as their combined effects; according to etiology, dry eye syndrome, symptomatic, and arteficial are distinguished.
Syndrome can be expressed in various clinical forms: recurrent macro- and microerosions of the cornea or conjunctiva of the eyeball; dry keratoconjunctivitis, filamentous keratitis.
According to the severity, there are mild, moderate, severe and especially severe forms of dry eye syndrome.
Clinical manifestations of dry eye syndrome are very diverse and largely determined by the severity of the disease. Subjective symptoms include the sensation of a foreign body (sand) in the conjunctival cavity, redness, burning and pain in the eyes; lacrimation, hypersensitivity to light, fatigue; blurry vision, pain during instillation of eye drops.
Symptoms of dry eye syndrome are usually more pronounced in the evening, as well as when in a dry or polluted room, in the cold, wind, after prolonged or strenuous visual work.
Objective signs are xerotic changes of the cornea and conjunctiva of varying severity (corneal-conjunctival xerosis). With a mild course of corneal-conjunctival xerosis, a compensatory increase in tear production (hyperlacrimia) and an increase in the height of the lower lacrimal meniscus develops. With moderate xerosis, reflex lacrimation decreases, lacrimal menisci decrease or are completely absent, there is a feeling of “dryness” in the eyes, the creeping of the swollen conjunctiva on the free edge of the lower eyelid and its displacement together with the stuck eyelid during blinking movements. Severe corneal-conjunctival xerosis manifests itself in the following clinical forms: filamentous keratitis, dry keratoconjunctivitis and recurrent erosion of the cornea, occurring against the background of existing manifestations of dry eye syndrome.
With filamentous keratitis on the cornea, multiple epithelial growths are observed, manifestations of a moderately pronounced corneal syndrome without inflammatory changes in the conjunctiva.
With dry keratoconjunctivitis, pronounced corneal-conjunctival changes of an inflammatory and degenerative nature are noted: subepithelial opacities, dullness and roughness of the cornea, saucer-shaped epithelized or non-epithelized depressions on its surface, sluggish hyperemia, swelling and loss of luster of the conjunctiva of the eye, more pronounced adhesion of the eyeball with the conjunctiva of the eyelids.
With recurrent erosion of the cornea, surface microdefects of its epithelium periodically appear, which persist for up to 3-5 or more days, after their epithelization, prolonged discomfort is noted.
Particularly severe corneal-conjunctival xerosis usually develops with complete or partial non-closure of the eye slit. Dry eye syndrome on the background of a pronounced lack of vitamin A is manifested by scaly metaplasia of the epithelium and keratinization of the conjunctiva.
Dry eye syndrome is often combined with blepharitis. Dry eye syndrome can lead to severe and irreversible xerotic changes and even corneal perforation.
Diagnostic examination of a patient with dry eye syndrome begins with the collection of complaints, assessment of anamnesis and clinical symptoms of the disease, in order to identify pathognomonic and indirect signs of corneal conjunctival xerosis.
During a physical examination for dry eye syndrome, an external examination is performed, during which an ophthalmologist determines the condition of the eyelid skin, the sufficiency of their closure, the nature and frequency of blinking movements. Biomicroscopy of the eye analyzes the condition of the tear film, cornea, conjunctiva of the eyeball and eyelids, the height of the lacrimal menisci.
If dry eye syndrome is suspected, a fluorescein instillation test is performed using a staining solution that allows determining the tear film rupture time and detecting the presence of dry foci – areas of the cornea devoid of epithelium. With the help of special samples, the rate of formation of tear fluid is investigated – the total tear production (Schirmer test), the quality and rate of evaporation of the tear film (Norn test). A noninvasive assessment of the strength of the pre-corneal tear film is carried out using thiascopy (inspection in polarized light) and measurement of the thickness of the lipid layer.
A complete ophthalmological examination also includes a laboratory examination of osmolarity and crystallography of lacrimal fluid, cytological examination of a smear from the conjunctiva (including impression). In case of systemic or endocrine diseases in the anamnesis of a patient with dry eye syndrome, appropriate immunological and endocrinological studies are carried out.
Treatment of dry eye syndrome is focused on the elimination of etiological factors of xerosis; full-fledged moistening of the ocular surface and increasing the stability of the pre-corneal tear film; relief of pathological changes in the cornea and conjunctiva and prevention of complications.
The most widely used for dry eye syndrome are regular instillations of artificial tear preparations (natural tear, gels with carbomer and dexpanthenol), which allow restoring a sufficiently stable tear film on the surface of the eyeball. With a mild course of dry eye syndrome, low viscosity drugs are prescribed, with moderate and severe forms – medium and high viscosity (gels), in particularly severe cases of xerosis – low viscosity drugs without preservatives.
Also, with dry eye syndrome, instillations of anti–inflammatory and immunotropic agents are indicated, in the presence of degenerative xerotic corneal changes, metabolic drugs are indicated. Additionally, antihistamines, stabilizers of mast cell membranes, stabilizers of lysosomal macrophage membranes are prescribed.
Surgical treatment of dry eye syndrome is carried out if necessary to limit the outflow and evaporation of native or artificial tears from the conjunctival cavity, increase the flow of tear fluid, eliminate complications (xerotic ulcer, corneal perforation). The closure of the lacrimal pathways of the eye is performed by the following methods: obturation of lacrimal points with special plugs; plasty of lacrimal points with conjunctiva or skin; diathermocoagulation, laser coagulation or surgical suturing.
Obturation of the lacrimal tubule with miniature silicone plugs and conjunctival covering of the lacrimal point in dry eye syndrome are more preferable because they are minimally invasive, more effective and do not cause irreversible changes.
With severe corneal xerosis (xerotic ulcer, keratomalacia) and no effect from drug therapy and obstruction of the tear ducts, keratoplasty is performed with dry eye syndrome. Patients with incomplete eyelid closure, wide eye slit and rare blinking are shown lateral tarzoraphy.
Innovative ways of treating are the transplantation of salivary glands from the oral cavity into the conjunctival cavity, implantation of dacryoreservoirs into the soft tissues of the patient with the removal of special tubes into the conjunctival cavity.
Prognosis and prevention
Even with a mild course, dry eye syndrome requires full and adequate treatment in order to avoid the development of severe conjunctival and corneal diseases with possible loss of vision.
It is possible to prevent dry eye syndrome by reducing the impact of artificial factors on the eyes, conducting preventive treatment of internal diseases, including pathology of the organs of vision, consuming a sufficient amount of fluid, eating rationally, more often making blinking movements with visual load.