Anomalies of retinal development: causes, symptoms, diagnosis, treatment

Anomalies in the development of the eye membranes are detected immediately after birth. The occurrence of anomalies is caused by gene mutations, chromosomal anomalies, and the impact of exogenous and endogenous toxic factors during the intrauterine period of development. A major role in the occurrence of anomalies is played by infectious diseases of the mother during pregnancy and environmental factors such as drugs, toxins, radiation, etc., which affect the embryo. The most severe changes are observed when the fetus is exposed to harmful factors in the first trimester of pregnancy. The most common infections include rubella, toxoplasmosis, syphilis, cytomegalovirus infection, herpes simplex, and AIDS. Medicines and substances that cause the development of anomalies and congenital diseases of the retina include thalidomide, cocaine, and ethanol (embryonic alcohol syndrome).

Anomalies in the development of the retina include retinal coloboma, aplasia, dysplasia and hypoplasia of the retina, albinism, congenital hyperplasia of the pigment epithelium, myelinated nerve fibers, congenital vascular anomalies, and phakomatoses.

Retinal coloboma is the absence of the retina in a limited area. It is usually associated with coloboma of the iris and choroid. Retinal coloboma can be located in the center or on the periphery in the lower half of the eyeball. Its occurrence is associated with incomplete closure of the embryonic fissure. Ophthalmoscopically, coloboma appears as a limited area of white color, oval or round in shape, with smooth edges, located close to or adjacent to the optic disc. Where the retina and choroid are absent, the sclera is exposed. Coloboma can be combined with microphthalmos, skeletal anomalies and other defects.

Dysplasia (from the Greek dis - disorder, plasis - development) is an anomaly of the development of the retina during embryogenesis, expressed in the violation of the normal ratio of cellular elements. This form includes non-adherence of the retina - a rarely observed anomaly, the cause of which is insufficient invagination of the optic vesicle. Dysplasia of the retina is a characteristic sign of trisomy 13 and Walker-Warburg syndrome, combined with other malformations of the eye, cerebellum, muscle tissue.

Albinism is a genetically determined disorder of the visual system formation associated with changes in melanin synthesis.

Patients with albinism are characterized by nystagmus, various refractive errors in combination with astigmatism, decreased vision, weak pigmentation of the fundus, dysplasia of the macular region and disorder of the optic chiasm. The described anomalies correspond to disorders of color vision and brightness sensitivity, as well as supernormal ERG and interhemispheric asymmetry of the VEP. Tyrosinase-negative albinism is caused by the lack of synthesis of the enzyme tyrosinase and the pigment melanin. Such patients have white hair and skin, they are not able to tan. Their iris is light, easily translucent, the reflex from the fundus is bright pink and visible at a distance. Another form of this disease is tyrosinase-positive albinism, in which, on the contrary, the ability to synthesize melanin is preserved, but its normal accumulation is absent. The skin of these patients is poorly pigmented, but is capable of tanning, the hair is light or with a yellow tint, and visual impairment is less pronounced.

There is currently no treatment for albinism. The best approach to helping these patients is corrective eyeglasses with light filters to protect the eyes from the damaging effects of bright light.

Congenital hyperplasia of the retinal pigment epithelium is manifested by focal hyperpigmentation. Grouped pigment spots resemble a bear track. The foci of hyperpigmentation can be single or multiple. The retina around them is not changed. Pigmentation foci rarely increase in size and undergo malignancy.

Myelinated nerve fibers are considered developmental anomalies. In some manuals they are described as developmental anomalies of the retina, in others - of the optic nerve.

Normally, the myelinated coating of the optic nerve fibers usually ends at the posterior edge of the cribriform plate. Sometimes it extends beyond the optic disc and into the nerve fibers of the second-order retinal neurons. Ophthalmoscopically, the myelinated nerve fibers appear as white, shiny, radial bands extending from the optic disc to the periphery. These fibers may not be connected to the optic disc. They are usually asymptomatic, but sometimes scotomas may appear in the visual field.

Congenital vascular anomalies manifest as grape-shaped angioma, von Hippel-Lindau capillary hemangioma, Coats disease, retinopathy of prematurity, cavernous retinal hemangioma, Leber's miliary retinal aneurysms, parafoveal telangiectasias, retinal capillary hemangioma, etc.

Pampiniform angioma is a unilateral anomaly, the characteristic ophthalmoscopic signs of which are significant dilation and tortuosity of arteries, veins and arteriovenous shunts. Its combination with cerebral vascular pathology is called "Waburn-Mazon syndrome", in which central vision is reduced. As a rule, the disease does not progress. Treatment is not carried out.

Coats' disease is a congenital vascular anomaly, including retinal telangiectasias, micro- and macroaneurysms, which lead to exudation and, over time, to retinal detachment. Some authors classify Coats' disease as a vascular disease of the retina. The disease is also called "external hemorrhagic retinitis". Coats' disease is a unilateral disease, manifested in early childhood, more often (90%) in boys.

Deposits of hard exudate of bright yellow color are found in the subretinal space in the posterior pole of the eye. In the late stages of the disease, cataracts, neovascular glaucoma, and subatrophy of the eyeball develop. Moderate forms are represented only by teloagiectasias.

It is differentiated from tumor and other processes that can be masked by detached retina and exudate, as well as from retinopathy of prematurity.

The goal of treatment is to obliterate abnormal vessels to prevent exudation: laser photocoagulation and cryotherapy are performed.

In case of widespread exudative retinal detachment, surgical treatment is advisable.

Phacomatoses are congenital malformations. They have characteristic systemic and ocular manifestations: the presence of hemangioma-like formations, hamartomas or nodes. Phacomatoses include Recklinghausen's neurofibromatosis, tuberous sclerosis, von Hippel-Lindau disease, characterized by an autosomal dominant type of inheritance, as well as sporadically detected Sturge-Weber-Krabbe syndrome. The cause of the disease is a mutation of the tumor suppressor gene, which is identified in all dominant types of the disease.

Recklinghausen's neurofibromatosis (NF-1) is characterized by the presence of a tumor of Schwann cells, which often appears on the skin as multiple fibromas (molluscum). The gene responsible for the development of neurofibromatosis type 1 is localized in the 17th chromosome in the 17qll.2 locus. Diffuse neurofibromatous infiltration is the cause of the development of deforming neuromatous elephantiasis. The diagnostic criterion is the presence of more than 6 café-au-lait spots on the skin (more than 1.5 cm in size).

Ocular manifestations of neurofibromatosis type 1 are numerous and include, in various combinations, plexiform neurofibroma of the eyelids and orbit, S-shaped palpebral fissure, congenital glaucoma (if the upper eyelid has neurofibromatous tissue), melanocytic hamartomas on the iris (Lisch nodules), hamartomatous infiltration of the choroid with corpuscle-like bodies, optic nerve glioma, astrocytic hamartoma of the retina, thickening and prominence of the corneal nerves, conjunctival neurofibroma, pulsating exophthalmos, buphthalmos.

Hamartoma is a tumor that develops from embryonic tissue whose differentiation is delayed compared to the differentiation of the host organ. The cells that form the hamartoma have a normal structure, but the density of cell populations and their ratio are abnormal. Melanocytic hamartomas (Lisch nodules) develop to cutaneous manifestations, are observed on the iris of all adult patients and are a diagnostic criterion.

Plexiform neurofibroma is a tangle of intertwined hypertrophic nerves that appear nodular due to the proliferation of Schwann cells and endoneurial fibroblasts in the mucinous interstitial tissue.

Frequent complications of neurofibromatosis type 1 include vascular disorders such as narrowing of the lumen of blood vessels and their occlusion. Perivascular fibroglial proliferation develops later. Characteristic signs of retinal ischemia in neurofibromatosis type 1 are peripheral avascular zones, arteriovenous shunts, preretinal fibroglial membranes, and optic disc atrophy.

Tumors that cause deformation of surrounding tissues and functional impairments are subject to removal.

Neurofibromatosis type 2 is a rare disorder. The characteristic symptom is bilateral schwannoma of the eighth (auditory) cranial nerve. Ocular manifestations include combined hamartomas of the retina and pigment epithelium, glioma or meningioma of the optic nerve.

Hippel-Lindau disease is a hereditary disorder with the gene localization in chromosome 3p25. Often, the changes are discovered accidentally during examination of children for strabismus or during a routine medical examination. Retinal angiomas have a cherry-like appearance with large tortuous feeding and draining vessels. These formations are called retinal hemangioblastomas, since they are histologically similar to hemangioblastomas that develop in the cerebellum. In the retina, hemangioblastomas have endophytic or exophytic growth, the optic disc and optic nerve may be involved in the process; hemangioblastomas are often combined with maculopathies. Other organs are involved in the pathological process. Along with retinal angiomatosis, renal cysts or renal carcinoma, pheochromocytoma, etc. are detected.

Due to impaired capillary wall permeability, sub- and intraretinal exudate containing lipids may accumulate in them. In the late stages of the disease, exudative retinal detachment develops. In the arteriovenous phase of FAG, accumulation of contrast agent in the angioma is noted; in the late phase, increased permeability of fluorescein is determined, due to the inferiority of the tumor vessels.

Treatment: cryotherapy, laser coagulation, surgical removal of the tumor.

Tuberous sclerosis (Bourneville disease) is a rare disease with an autosomal dominant type of inheritance caused by two genes located on chromosomes 9 and 16. The classic triad of tuberous sclerosis is epilepsy, mental retardation, and facial skin lesions (angiofibromas). Whitish tumor-like formations resembling a mulberry are detected on the fundus near the optic disc. Astrocytomas that form on the optic disc are called giant optic nerve drusen. They can be mistaken for retinoblastoma.

Treatment is usually carried out in a neurological clinic. As neurological symptoms increase, patients die early.

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