Filamentous keratitis is a form of chronic inflammation of the cornea that develops against the background of hypofunction of the lacrimal glands and drying of the corneal epithelium. Filamentous keratitis is characterized by a moderately pronounced corneal syndrome (photophobia, burning and eye irritation, etc.), the presence of filamentous discharge from the eyes, dryness of the nasopharynx. Diagnosis is carried out using biomicroscopy, endothelial microscopy, confocal microscopy, determination of corneal sensitivity, tear production studies, microscopic and cytological examination of scraping. Treatment is symptomatic; it includes the use of vitamin eye drops, artificial tear preparations, softening ointments, etc.
Filamentous keratitis (dry keratitis) in ophthalmology is considered as a clinical form of severe corneal-conjunctival xerosis, developing against the background of the so-called dry eye syndrome. With filamentous keratitis, due to hypofunction of the lacrimal glands, drying and inflammatory-dystrophic changes of the conjunctiva and cornea occur. Chronic inflammation and dystrophy of the cornea leads to a decrease in its transparency, deterioration of vision, in some cases – to softening and perforation of the cornea, loss of the membranes of the eyeball.
According to the etiology, there are primary (idiopathic, typical) forms of filamentous keratitis and secondary (atypical).
Primary refers to ophthalmic diseases of unexplained etiology. It is based on a decrease in tear production and a change in the composition of the tear fluid. It is known that filamentous keratitis often develops with Sjogren’s syndrome – an autoimmune lesion of the exocrine (salivary, lacrimal) glands, accompanied by their hypofunction in combination with systemic immune-inflammatory manifestations (myalgia, arthralgia, neuritis, muscle weakness, etc.). Progressive atrophy of the lacrimal glands can also contribute to senile age, hormonal changes in the body in women in the pre-menopausal period and during menopause.
The occurrence of secondary filamentous keratitis is associated with a violation of the flow of tears into the conjunctival cavity. This may be due to scarring of the conjunctival arches due to eye burns, conjunctivitis with diphtheria, trachoma, etc. In some cases, the development of filamentous keratitis is preceded by extirpation of the lacrimal gland.
Typical for most forms of keratitis, including filamentous, is the development of corneal syndrome, manifested by pain, photophobia, constant sensation of a foreign body and burning behind the eyelids, blepharospasm. It is characterized by a decrease in lacrimation or a complete absence of tears when crying.
In the first stage of filamentous keratitis, moderate hyperemia of the conjunctiva, the presence of a viscous filamentous secretion in the conjunctival cavity is objectively determined. In stage II, grayish foci of corneal epithelium desquamation appear within the ocular fissure. In the later, III stage of filamentous keratitis, pinpoint areas of focal hyperkeratosis form on the cornea, which in the form of thin strands stretch from the surface of the cornea into the conjunctival sac. Microscopically, these filamentous formations are represented by degenerated corneal epithelial cells. At the final, IV stage of filamentous keratitis (dry keratoconjunctivitis), extensive keratinization (xerosis) of the cornea develops, areas of opacity are formed, leading to visual impairment. In severe cases, recurrent erosion and corneal ulcers may develop, creating a threat of perforation.
Eye damage in filamentous keratitis is more often bilateral. In Sjogren’s disease, other exocrine glands (salivary, sweat) are affected simultaneously with lacrimal ones, therefore, extra-ocular symptoms are characterized by dryness of the mucous membranes of the mouth and nose, difficulty swallowing, dryness and peeling of the skin. Of the systemic manifestations, patients are concerned about myalgia, arthralgia, muscle weakness, recurrent polyarthritis, digestive disorders, loosening and tooth loss.
The course of filamentous keratitis is chronic, with remissions and exacerbations. The disease mainly occurs among women aged 45-60 years.
To correctly assess the causes of filamentous keratitis, an examination of the patient by an ophthalmologist, rheumatologist, gynecologist-endocrinologist is required.
Characteristic changes in the eye with this disease are clearly determined during biomicroscopy: spot opacities, infiltrates, foci of hyperkeratosis, filamentous strands are visible in the lower half of the cornea. The nature of morphological changes in the cornea is clarified by endothelial and confocal microscopy of the cornea.
Epithelial defects are detected during an instillation test with fluorescein. Microscopic and cytological examination of the scraping reveals degenerated corneal epithelial cells. The sensitivity of the cornea in filamentous keratitis persists. In order to study tear production in filamentous keratitis, the Schirmer test and the Norn test are used.
With this disease pathogenetic and local symptomatic treatment is carried out. Pathogenetic therapy is aimed at mitigating or eliminating the causes leading to filamentous keratitis. General therapy is prescribed and carried out under the supervision of a rheumatologist.
Topical treatment is aimed at preserving the precorneal film and cornea moisture, protecting the cornea from epithelial metaplasia. Patients with filamentous keratitis are prescribed instillation of eye drops with vitamins (riboflavin, ascorbic acid), taurine solution, artificial tears, corticosteroids (hydrocortisone, prednisone, dexamethasone), irrigation of the eyes with sodium chloride solution 2-3 times a day. Ointment preparations are laid behind the eyelids: synthomycin emulsion, thiamine ointment, gels based on dialysate from the blood of dairy calves, etc.
With multiple filamentous cords of the cornea, they are carefully removed, followed by extinguishing the attachment site with solutions of brilliant green, silver nitrate or zinc sulfite.
With a persistent course of filamentous keratitis, surgical ophthalmology methods are resorted to – obturation (filling) of the lacrimal tubules with collagen or silicone implants, plasty of lacrimal points (closure of lacrimal points with a flap of the patient’s conjunctiva). Sometimes the compensation state can be achieved by using low-hydrophilic contact lenses.
Prognosis and prevention
Usually disease is difficult to cure – this is due to systemic pathological processes in the body. Drying and clouding of the cornea leads to a progressive decrease in vision.
Due to the ambiguity of the etiology of filamentous keratitis, no specific methods of preventing the disease have been developed. Patients with Sjogren’s syndrome are shown the observation of an ophthalmologist, preventive therapy. It is necessary to protect the eyes from injuries, treat inflammatory diseases of the visual organ in a timely manner.