Corneal ulcer is a destructive process, that proceeds in the cornea and can cause crater-shaped defects on it's surface.
This pathology is always accompanied by corneal syndrome, that is, by corneal opacity, significant decrease of visual acuity and pain.
The cornea of the human eye has a compound structure. It consists of five layers: epithelial tissue, Bowman's membrane, stroma, Descemet's membrane and endothelium. The epithelial layer is being damaged during the formation of ulcer, that spreads deep into the Bowman's membrane.
Corneal ulcer is considered as one of the most serious eye diseases. It is hardly treated and often causes significant or total vision loss.
In all cases the corneal ulcer defect leads to the formation of corneal spot (scar). Central ulcers are the most dangerous as they always cause vision loss.
Causes of corneal ulcers
Corneal ulcers are divided into infectious and non-infectious, depending on their cause. The germs of the infectious ulcers are:
- Viruses (herpes, chickenpox);
- Bacteria (blue pus bacillus, tubercle bacilli, pneumococcus, streptococcus, diplococcus, staphylococcus);
- Parasites (Chlamydia, Acanthamoeba).
Corneal ulcers of non-infectious origin often appear, because of the corneal dystrophy (primary or secondary), dry eye syndrome or some autoimmune diseases.
Predisposing factors of progression of corneal ulcers are:
- The non-observance of the rules of wearing and disinfection of contact lenses;
- Long-term treatment with the use of antibiotics, corticosteroids and some other medical preparations;
- The use of eye drops and ointments, that were infected by pathogenic organisms;
- The non-observance of the rules of asepsis and antisepsis while realizing various ophthalmologic procedures;
- Some diseases of eyes (keratitis, entropion, trichiasis, dacryocystitis, blepharitis, trachoma, conjunctivitis) and nervous system (lesion of the trigeminal or/and oculomotor cranial nerves);
- A number of systemic diseases (pancreatic diabetes, atopic dermatitis, atrophic arthritis, Sjogren's syndrome, polyarteritis nodosa);
- Avitaminosis and Hypovitaminosis;
Corneal ulcers often form as a result of eye burns, ingress of foreign bodies, mechanical injuries and photoelectric ophthalmia.
Classification of corneal ulcers
Corneal ulcers can be divided by the depth of the lesion and the nature of the clinical course of the disease into perforated and non-perforated, superficial and deep, chronic and acute. Depending on the localization of ulcerous defect, there are central, paracentral and peripheral forms of the disease.
It is also very important to consider direction of the incidence of the pathological process for the classification of corneal ulcers. For example, if the disease increases towards one of the edges and is epithelialized from the opposite side, then it is called as creeping. The lesion usually spreads not only on the surface, but also on the deeper layers of the cornea. It finally leads to the formation of hypopyon. In most cases, the germs of the creeping ulcer are a blue pus bacillus, diplococcus and pneumococcus.
There is also an erosive corneal ulcer. It's etiology, that is, causes, remains unknown to date. In this case, the course of the disease is accompanied by simultaneous formation of several defects on the cornea, that are located along it's edges. They grow in size and flow together to form a single ulcer, that has a crescent shape. The healing process is accompanied by the formation of scar.
Symptoms of corneal ulcer
Corneal ulcer is usually characterized by one-sided lesion. Intense pain in the affected eye is it's first sign. Pain increases with the disease progression and finally becomes unbearable. In addition, the person begins to experience blepharospasm, eyelid edema, photophobia and excessive tearing (epiphora).
The degree of visual impairment depends on the localization of the defect, that gets it's greatest expression in the central ulcers. The formation of scar is always the outcome of the ulcerative process (from small and thin scar to corneal spot).
In the case of creeping ulcer, the person experience unbearable pain in the eye, expressed blepharospasm and epiphora. Due to it's progressive (growing) edge it spreads very quickly not only on the surface of the cornea, but also deep into the eyeball. That is why this pathological process can be complicated by panuveitis and panophthalmitis.
Corneal ulcer of tuberculous etiology is always experienced by those people, who suffer from tuberculosis of different localization (renal tuberculosis, pulmonary tuberculosis, genital tuberculosis, etc.). In this case the corneal infiltration, that has a phlyctenular rim, forms on eye surface. With time it gradually turns into round-shaped ulcerative defect. The course of this disease is quite long and is accompanied by frequent relapses. The formation of rough scar is a common consequence of the healing process.
If eye cornea is affected by herpes simplex virus, it is covered by the tree-shaped infiltrations, that gradually change into vesicles. Finally, these vesicles break and form the ulcer surface.
Hypovitaminosis can also become a reason of corneal ulcers. For example, in the case of deficiency of vitamin A in the body the person begins to suffer from corneal opacity, that is accompanied with painless ulcers. At the same time the conjunctiva is covered by dry xerotic plaques. Hypovitaminosis B2 is accompanied by vascularization of the cornea, dystrophy of it's epithelium and the formation of ulcer defects.
Complications of corneal ulcer
If you start treatment immediately after detecting the symptoms, it is possible to achieve regression of the ulcer. The surface of the cornea will be cleaned and the defect will be filled up gradually with fibrous tissue, what leads to the formation of corneal spot – stable cicatricial corneal opacity.
The process of rapid progression of the ulcer is accompanied by the deepening of the defect and the formation of evagination (like hernia) of the Descemet's membrane – descemetocele, the corneal perforation. Through the formed opening the pinching of the iris can occur. In most cases, the perforated corneal ulcer continues it's harmful influence in the formation of goniosynechia and front synechia, that create obstacles to the normal outflow of intraocular fluid. This process, in it's turn, creates preconditions for optic nerve atrophy and secondary glaucoma.
If the defect of the cornea, that was caused by perforated ulcer, will not be pluged with an iris, the infection can invade the deeper structures of the eyeball. It can probably become the reson of the development of such serious complications as panophthalmitis and endophthalmitis. But the most dangerous complications of the corneal ulcer are: sepsis, meningitis, brain abscess, cavernous sinus thrombosis and orbital phlegmon.
Diagnostics of corneal ulcer
Diagnostics of corneal ulcer is based on the characteristic clinical symptoms of the disease. The specification of diagnosis requires medical eye inspection with the help of biomicroscope (slit lamp). If necessary, the cornea is applied with fluorescein preparation, that colours ulcerous defect in bright green colour. This method of diagnosis allows to examine even the smallest ulcers and also to estimate the depth and the extensiveness of the lesion.
If there are the suspicions of the involvement of internal structures of the eyeball in the pathological process, it is always recommended to conduct eye ultrasound, ophthalmoscopy, gonioscopy, diaphanoscopy and to measure intraocular pressure. For the estimation of the function of production and removal of intraocular fluid, it is also advised to conduct Schirmer's and Norn's tests or coloured nasolacrimal test.
For the proper treatment of corneal ulcer it is very important to identify the exact reasons of the disease. It necessitates the conduction of bacteriological and cytological analysis of conjunctiva, microscopy of ulcer's scrape, determination of content of immunoglobulins in the lacrimal fluid and in the blood serum.
Medical treatment of corneal ulcer
Corneal ulcer should be treated only in specialized ophthalmologic hospital. To prevent further expansion and deepening of the defect, it is lubricated with iodine tincture or brilliant green solution. Also, the diathermocoagulation of the ulcer surface can be conducted for the same purpose.
If corneal ulcer appeared on the background of dacryocystitis, the doctor irrigates nasolacrimal duct. It allows to eliminate the source of infection. Specific therapy is prescribed depending on the etiology of the ulcer. For it's conduction are used various antifungal, antiparasitic, antiviral or antibacterial agents. In addition, it is prescribed to use hypotensive, antiphlogistic, immunomodulatory, antihistaminic and metabolic preparations and also mydriatics. All of them in most cases are injected topicall - in the form of ointment applications, instillations, parabulbar or subconjunctival injections. But in case of heavy course of the disease, the conduction of systemic therapy may be required. It implies intramuscular and/or intravenous injections of all the medicinal preparations. After the damaged surface of the cornea will begin to clean, it is prescribed to pass through resolve physiotherapy (phonophoresis, electrophoresis, magnetotherapy, etc.), aimed at the stimulation of reparative process and prevention of the formation of rough scar tissue.
In those cases when there is a danger of corneal perforation, the lamellar and penetrating keratoplasty are conducted. After the complete healing of ulcer surface, the formed scar can be removed with the help of excimer technology.
Prognostics and prophylaxis of corneal ulcer
Taking into account that the common outcome of corneal ulcer is in the formation of corneal spot, the chance of saving full visual function is quite poor. That is why the optical keratoplasty may be required after the complete healing of corneal defect.
The prognosis is even more disappointing in the case of development of orbital phlegmon and panophthalmitis, because there is a high probability of loss of the affected eyeball.
The disappointing prognosis is also may be obrserved in the case of herpetic, fungal ulcers. They have chronic course with frequent relapses. For the prophylaxis of corneal ulcers, it is extremely important to take preventive measures to prevent eye injuries. Users of contact lenses should follow thoroughly all the rules of wearing and disinfection. Also, it is important to start antibiotic therapy in proper time and at any danger of infection of eye cornea. Moreover, it is necessary to detect and treat not only ophthalmic, but also systemic diseases.
Well-timed visit of the professional ophthalmologist with health complaints about discomfort or noticeable vision loss can guarantee qualitative and successful treatment.