Pigmentary glaucoma is more often a binocular pathology of the visual organ, the development of which is based on the degeneration of the pigment epithelium. Symptoms of this pathology are the appearance of “rainbow circles” or “fog” in front of the eyes, a violation of accommodation, headache spreading to the eye socket and brow arches. Diagnostics includes anamnesis collection, biomicroscopy, ophthalmoscopy, tonometry, visiometry, gonioscopy and perimetry. Conservative therapy is reduced to taking myotics. Depending on the severity of pigmentary glaucoma, laser trabeculoplasty, iridotomy, iridectomy or trabeculectomy may be performed.
Pigmentary glaucoma is one of the forms of open–angle glaucoma, in which an increase in IOP is a consequence of the deposition of melanin granules in the anterior segment of the eye. The first description of pigmentary glaucoma was presented in 1949 by the scientist S. Sugar. The prevalence among other forms is 1-1.4%. Males are more at risk of developing this pathology (about 85% of cases) than women. As a rule, pigmentary glaucoma affects people of working age (from 16 to 65 years). The peak incidence among men is observed at the age of 35, among women – at the age of 50. The disease is more common among people with fair skin than among the dark-skinned population. Patients with myopic refraction predominate among the patients.
The trigger of pigmentary glaucoma is the degeneration of the pigment epithelium of the iris and the ciliary body. At the same time, the increase in intraocular pressure (IOP) is based on the deposition of melanin granules in the anterior segment of the eyeball (angle of the anterior chamber, stroma of the iris and the posterior surface of the cornea, trabecular apparatus). The defeat of the trabecular apparatus aggravates the progression of pathology, since a violation of the outflow of watery moisture stimulates the growth of IOP. In addition, against the background of degenerative processes, the pigment epithelium is repaired, which is subsequently rejected.
The mechanism of development of pigmentary glaucoma in some cases is inextricably linked with the syndrome of pigment dispersion (PDS). Initially, PDS proceeds as an asymptomatic stage of glaucoma. There is no increase in IOP, because the available amount of pigment is insufficient to provoke pathological changes in the trabecular apparatus. While degenerative processes affect a small area of the pigment layer, the hydrodynamics of the visual organ is within normal limits, glaucoma neuroopticopathy does not occur. With severe degeneration, the clinical picture of pigmentary glaucoma develops. At the same time, in a number of patients with a history of PDS, IOP indicators do not exceed tolerant values, decompensation of this condition is not observed.
Young people with PDS with a history of myopia are at a higher risk of developing pigmentary glaucoma. With mechanical prerequisites for a violation of the structure of the iris (sports, mydriasis, overstrain), the pigment layer of the iris contacts the ligamentous apparatus of the visual organ, which leads to the rejection of melanin granules. Pigment granules enter the anterior chamber and stimulate the excess of IOP tolerant values.
Pigmentary glaucoma in most cases affects both eyes simultaneously. In the early stages, the disease is asymptomatic. Subsequently, patients complain of a decrease in visual acuity, the appearance of “fog”, “shroud” or “flies” in front of their eyes. The symptom of exceeding IOP tolerant indicators is the development of headache. Pain can radiate to the area of the eye socket or brow arches. A specific symptom of pigmentary glaucoma is the frequent appearance of “rainbow” circles when looking at bright light. This is due to the deposition of melanin granules on the posterior surface of the cornea. In this regard, patients note the appearance of circles regardless of the IOP level.
A sharp increase in intraocular pressure in pigmentary glaucoma is manifested by the clinical symptoms of a short-term crisis. At the same time, patients complain of blurred vision, accompanied by a pronounced increase in all symptoms of the disease. A crisis can provoke pupil dilation, physical exertion, because these conditions lead to rejection of the pigment with its subsequent accumulation in the anterior chamber. A significant part of patients with different frequencies feel the trembling of the iris during pupil movements.
The diagnosis of pigmentary glaucoma is based on anamnestic data, the results of biomicroscopy, ophthalmoscopy, tonometry, visiometry, gonioscopy and perimetry. The tonometry method determines the increase in IOP (above 20 mmHg). However, at normal IOP values, in the case of a single measurement in patients with clinical manifestations of the disease, the diagnosis of pigmentary glaucoma cannot be excluded. When conducting visiometry, a decrease in visual acuity is detected in most patients. Perimetry allows you to diagnose a slight narrowing of the visual fields.
Biomicroscopy using a slit lamp reveals a sprayed pigment in the area of the endothelial layer of the cornea in the form of a Krukenberg spindle, melanin deposits in the area of the anterior surface of the iris and on the back wall of the lens. In the vitreous body, the pigment is determined in the zone of the hyaloid canal. During ophthalmoscopy on the fundus, pigment deposits have a peripapillary localization. Gonioscopy in pigmentary glaucoma allows you to determine the degree of increase in the depth of the anterior chamber of the eye (more than 3.5 mm), diagnose iris prolapse, manifestations of iridodonesis, extensive pigmentation in the area of the anterior chamber angle.
Auxiliary methods for the study of pigmentary glaucoma are ultrasound biomicroscopy, optical coherence tomography, and a sample with mydriatics. The method of ultrasonic biomicroscopy makes it possible to detect iridosonular contact. When conducting a drug test with drugs that dilate the pupil, a positive result is noted. The coefficient of ease of outflow is below normal (0.28-0.45 mm3/min). In ophthalmology, with the help of optical coherence tomography, structural anomalies of the visual organ can be visualized in more detail.
Differential diagnosis of pigmentary glaucoma should be carried out with diseases of the visual organ, which are accompanied by hyperpigmentation and increased IOP. In pseudoexfoliative glaucoma, the pigment can accumulate only in the trabecular apparatus, and the defects of the iris are localized along the pupillary edge. In elderly patients, pathology often affects one eye. With artifacia, contact of eye structures with the surface of the intraocular lens is possible, which can lead to degeneration of the pigment layer and disrupt the outflow of watery moisture. A similar clinical picture is characteristic of anterior uveitis. In the case of subacute angle-closure glaucoma, an increase in IOP stimulates hyperpigmentation of the trabecular network. For differential diagnosis, it is necessary to perform gonioscopy, which in the case of angle-closure glaucoma will allow diagnosing the closed angle of the anterior chamber of the eye, unlike pigmentary glaucoma.
The tactics of treatment of pigmentary glaucoma depends on the severity of the disease. Patients at an early stage of pathology without concomitant myopia in the anamnesis are indicated for drug therapy, which consists in taking myotics (cholinomimetics and anticholinesterase drugs). Preparations of this group reduce the degree of iridozonal contact and, thereby, contribute to the outflow of watery moisture. In the absence of the effect of conservative therapy, surgical intervention is recommended. Laser trabeculoplasty is performed at a young age. The power of laser exposure is determined depending on the severity of pigmentary glaucoma. Laser iridotomy is performed to prevent the destruction of the pigment layer and eliminate the clinical symptoms of iris displacement.
Laser iridectomy is performed in patients with pigmentary glaucoma on the background of pigment dispersion syndrome, provided that the pupillary block develops. This surgical intervention can be performed at the onset of the disease. When used at the stage of the appearance of the first symptoms, the operation is indicated for preventive purposes. Trabeculectomy is performed in patients with a history of trabeculoplasty and resistance to all methods of surgical and drug treatment. In the postoperative period, the use of neuroprotectors (vitamin E, flavonoids) is recommended.
Prognosis and prevention
Specific measures for the prevention of pigmentary glaucoma have not been developed. With the development of the first clinical manifestations of the disease in patients with PDS, preventive iridectomy is recommended. All patients with suspected pigmentary glaucoma should be examined by an ophthalmologist 2 times a year with mandatory tonometry, visiometry, gonioscopy, ophthalmoscopy. All persons with pigment dispersion syndrome should also undergo a timely examination for early detection and treatment of this pathology.
The prognosis of pigmentary glaucoma with timely diagnosis and treatment is favorable for life and work capacity. In the absence of therapeutic measures, total loss of vision with subsequent disability is possible.