Fuchs’ syndrome is a form of chronic iridociliary dystrophy characterized by a monocular lesion with the formation of corneal precipitates. The main symptom of stage I is heterochromia of the irises. At stage II-III, patients note a decrease in visual acuity and the appearance of “fog” in front of their eyes. Diagnosis includes external examination, biomicroscopy, gonioscopy, keratoesthesiometry, tonometry, visometry, ultrasound in In-mode. No treatment is required at stage I. At stage II-III, dedystrophic therapy is indicated, consisting of a course of corticosteroids, angioprotectors, vasodilators and nootropic drugs, as well as multivitamin complexes.
H21.8 Other specified diseases of the iris and ciliary body
Fuchs’ syndrome or heterochromic uveopathy is an anterior non–granulomatous uveitis characterized by a chronic slowly progressive course. The classical symptoms of uveal heterochromia were first described in 1906 by the Austrian ophthalmologist Ernst Fuchs. The author believed that the development of the dystrophy is caused by paralysis and exposure to unknown toxic substances on the body. Individual manifestations of this disease were described in 1843 by the English ophthalmologist J. Lawrence.
Fuchs’ syndrome has a slight prevalence in ophthalmology (4% of the total number of all uveitis). In 90-92.2% of cases, the disease develops monocularly. Pathology occurs with the same frequency among men and women. As a rule, uveal heterochromia occurs at the age of 20-60 years, the peak incidence of Fuchs’ syndrome occurs at 40 years.
Causes of Fuchs’ syndrome
Often Fuchs’ syndrome develops sporadically, it is not possible to establish the etiology of the disease. In rare cases, an autosomal dominant type of inheritance is traced. At the same time, the degree of penetrance is poorly expressed, which leads to a rare phenotypic manifestation of the allele in the population. The results of histological examination indicate that the trigger mechanism may be an inflammatory process with intraorbital localization. Confirmation of this theory of the development of Fuchs’ syndrome is a violation of the functions of the visual organ, but the absence of other signs of inflammation and the low effectiveness of anti-inflammatory therapy exclude this variant of pathogenesis in a number of patients.
At the same time, there are clinical cases of Fuchs’ syndrome in patients with neurodystrophic changes in the anterior parts of the vascular membrane of the eyeball. The trigger is disorders of sympathetic innervation provoked by pathology of spinal cord development at the level of the Budge ciliospinal center. In addition, according to the neurovegetative theory of pathogenesis, risk factors for Fuchs’ syndrome include a violation of sympathetic innervation of the cervical spine and abnormalities of the vasomotor center. The congenitally degenerative theory of development has no scientific justification.
Heterochromic uveopathy can occur against the background of the ocular form of toxoplasmosis, since toxoplasma infection provokes the development of chorioretinitis with subsequent involvement of the entire uveal tract in the pathological process. The cause of the symptoms of Fuchs’ syndrome in childhood is prenatal or postnatal iritis. Cases of detection of this pathology in patients with chorioretinitis with Benier-Beck-Schauman disease, iridocyclitis of tuberculous and infectious origin are described.
Symptoms of Fuchs’ syndrome
The main symptom of Fuchs’ syndrome is heterochromia of the iris. At the same time, the iris of the affected eyeball looks lighter. In patients with brown eyes, this clinical sign is less pronounced. Patients with light eyes may develop reverse heterochromia, which is associated with the visualization of the pigment layer of the iris during the destruction of the anterior stroma. The disease progresses slowly and for several years has no other clinical manifestations. Uveitis in Fuchs syndrome is not accompanied by hyperemia, photophobia and pain syndrome. As a rule, patients seek help from a specialist in connection with the development of a clinical picture of complications – cataracts or glaucoma.
The appearance of small translucent precipitates on the cornea is not accompanied by the injection of eyeballs and the closure of the angle of the anterior chamber. There is a stage-by-stage flow. At the initial stage, a small number of small precipitates appear, which do not affect the sensitivity of the cornea. The second stage of Fuchs’ syndrome is characterized by the dissemination of the process. In this case, precipitates of small and medium size lead to the appearance of opacities in front of the eyes with further destruction of the pigment pupillary border. Patients complain of decreased visual acuity and constant pupil dilation.
At the third stage of Fuchs’ syndrome, corneal sensitivity is significantly reduced. A large number of precipitates of different sizes leads to dystrophy of the iris and pronounced pigmentation in the area of the angle of the anterior chamber of the eye. On the anterior surface of the iris, small formations appear – Russell corpuscles, the occurrence of which is associated with the aggregation of immunoglobulins. The most common complications of Fuchs syndrome are glaucoma, posterior subcapsular cataract, ophthalmic hypertension.
Diagnosis of Fuchs’ syndrome is based on the results of external examination, biomicroscopy, gonioscopy, keratoesthesiometry, tonometry, visometry, ultrasound examination in In-mode. During an external examination, the degree of severity of the heterochromia of the iris is determined, which varies from doubtful to clearly pronounced. As a rule, questionable results or the absence of heterochromia are observed in patients with binocular lesions.
The biomicroscopy method allows to identify corneal precipitates, the size of which depends on the stage of Fuchs’ syndrome. They have the appearance of delicate translucent formations, which in rare cases contain pigment inclusions. In 20-30% of patients, mesodermal Boussac nodules are detected on the surface of the iris, and Keppe nodules are detected along the edge of the pupil. Conducting an ultrasound of the eye in B-mode indicates a focal or diffuse change in the structure of the iris. Precipitates in Fuchs syndrome are visualized as hypoechoic formations.
With keratoesthesiometry (algesimetry of the cornea), a decrease in its sensitivity is determined. When diagnosing the angle of the anterior chamber of the eye by gonioscopy, as a rule, it is open, has an average width, in rare cases it is already normal. The development of secondary (dystrophic) glaucoma in Fuchs syndrome leads to a gradual narrowing of its lumen with further closure.
Intraocular pressure (IOP) during tonometry is normal or slightly increased. The addition of secondary glaucoma is accompanied by an increase in IOP above 20 mmHg. Invasive interventions (gonioscopy, surgery, contact tonometry) may be accompanied by the development of filamentous hemorrhage from the angle of the anterior chamber, which is associated with a sharp decrease in IOP. The occurrence of complications of Fuchs’ syndrome (cataract, glaucoma) leads to a decrease in visual acuity, which is revealed during visometry.
Treatment of Fuchs’ syndrome
The tactics of treatment of Fuchs’ syndrome depends on the stage of the disease and the severity of secondary complications. At the initial stage, specific treatment is not indicated. Eye color correction is carried out with the help of cosmetic colored contact lenses. At the second and third stages of the disease, local and systemic dedystrophic therapy aimed at improving trophic processes is recommended. The complex of treatment of Fuchs’ syndrome includes angioprotectors, nootropics, vasodilators and vitamins. In case of formation of a large number of precipitates, the course of therapeutic measures should be supplemented with corticosteroids for topical use in the form of drops and enzyme therapy should be performed.
With the development of secondary posterior subcapsular cataract in the initial stages against the background of Fuchs’ syndrome, drug treatment is indicated. In the absence of an effect, microsurgical intervention is recommended, consisting in phacoemulsification of cataracts with subsequent implantation of an intraocular lens. The occurrence of secondary glaucoma is an indication for the appointment of local hypotensive therapy in parallel with the main course of treatment of Fuchs dystrophy.
Prognosis and prevention
Specific prevention of Fuchs’ syndrome has not been developed. Patients with this pathology need to be examined by an ophthalmologist twice a year with mandatory biomicroscopy, gonioscopy, visometry and tonometry for the purpose of early prevention and diagnosis of secondary complications in the form of cataracts and glaucoma. It is also recommended to correct the diet with the inclusion of a large amount of vitamins, normalization of sleep and rest. The prognosis for Fuchs’ syndrome for life and working capacity is more often favorable. For a long period of time, the disease has a latent course, but in the case of secondary cataract or glaucoma, complete loss of vision with subsequent disability is possible.