Retina and optic disc, visual impairment during their lesions
Most of the pathological condition can cause lesions of the retinal vessels. Vascular lesions of the retina can lead to blindness.
Intensity changes in retinal arteries in hypertensive retinopathy associated with levels of total blood pressure:
- Phase I of hypertensive retinopathy noted moderate narrowing of arterioles and arteries with light reflex of "silver wire" type;
- II stage of hypertensive retinopathy is characterized by the intersection of the arteries and veins, hard exudates and bar hemorrhages;
- For stage III hypertensive retinopathy is characterized by retinal edema, hemorrhage, and foci in the form of lumps of cotton wool, which are formed as a result of local ischemia of the nerve fibers;
- In stage IV hypertensive retinopathy observed the same features as in stage III hypertensive retinopathy, and, in addition, swelling of the optic nerve, often with the accumulation of hard exudates in the macular area in the form of a star.
Lesions in the form of cotton wool lumps during the inspection of the retina are the hallmarks of malignant hypertension. Lesions in the form of cotton wool lumps also found in cases of anemia, leukemia, connective tissue, dysproteinemia, infective endocarditis, diabetes.
Light information collected by retina is transmitted to along the optic nerve to the brain for processing and analysis of the data, followed by the perception of what he saw.
Lesions in the form of cotton wool lumps are also common with acquired immunodeficiency syndrome (AIDS). Other ophthalmic manifestations of AIDS include cytomegalovirus retinitis and periphlebitis retinae vein.
Diabetic retinopathy divided into two types:
- exudative retinopathy - characterized by the formation of microaneurysms, hemorrhages, lesions in the form of cotton wool lumps, hard exudates in retinal microvascular shunt and venous bleeding;
- proliferative retinopathy - characterized by neovascularization and macular edema, which lead to a decrease in visual acuity to 20/200 or more; in such patients to slow the progression of blindness successfully apply panretinal photocoagulation.
In the case of blockage (occlusion) of the central retinal artery (CRA) arises infarction (ischemic stroke) of the retina. This leads to permanent blindness side ischemic retinal injury. In the case of blockage (occlusion) of the central retinal artery (CRA) in the fundus reveals:
- irregular narrowing of the retinal veins;
- the retina itself is a milky-white color;
- macula of the retina appears dark cherry as a result of imaging the choroid.
Occlusion of the central retinal artery (CRA) considered a medical emergency. To enhance blood flow performed paracentesis of intraocular fluid. Paracentesis is lowers an intraocular pressure (IOP). Upon detection of atheromatous changes in the internal carotid artery on the side of the affected eye, aorta or heart suggest the central retinal artery (CRA) embolism. Occlusion (blockage) of the central retinal artery (CRA) can also occur with:
- giant cell (temporal) arteritis;
- diseases accompanied by increased blood viscosity.
Transient monocular vision loss (transient blindness) could herald occlusion of the central retinal artery (CRA) and / or threatening ischemic stroke. Patients with symptoms of transient vision loss (transient blindness) need to be hospitalized and monitored by the neurologist and a vascular neurosurgeon.
When macular lesions is a result of intoxication or degeneration, patients do not distinguish between red and green color, but the white color while normally perceive.
Worsening of patientís vision may also be at venous retinopathies. Occlusion (blockage) of the central retinal vein and its branches (arterial hypertension) and retinopathy with venous outflow obstruction caused by blood pressure reduction due to the decrease in the perfusion of the retina. This pressure reduction facilitated by:
- occlusive lesions of the carotid artery on the side of the same name;
- pulseless disease;
Systemic coagulopathy (thrombocytopenia and disseminated intravascular coagulation) lead to bleeding into the retina or blood clotting in capillaries located in the macular region. Systemic coagulopathy sometimes accompanied by hemorrhage in the choroid with retinal detachment. Patients with complain about blurred images due to loss of local visual field (scotoma).
Retinal vascular anomalies are rare. Retinal vascular anomalies include:
- telangiectasia (Coat's disease);
- retinal angiomatosis (von Hippel's disease);
- arteriovenous cavernous aneurysm (cavernous arteriovenous malformation Wyburn-Mason syndrome).
In addition to vascular lesions (arteries and veins), can impair vision and other changes in the retina. The most significant of them are detachment or retinal tear.
Worsening of patientís vision formed because of retinal detachment.
There are also several types of retinal degeneration. These include such changes in the retina as:
- retinitis pigmentosa,
- degeneration of Bruch's membrane,
- extensive degeneration,
- degeneration of the outer retinal layers,
- degeneration of the inner retinal layers.
In the case of retinitis pigmentosa degeneration of the outer receptor's layer and the adjacent pigment epithelium is hereditary. Degeneration of the retina is accompanied by a loss of night vision followed by impairment of the peripheral and, ultimately, central vision. Retinal degeneration may develop because of some systemic diseases:
- abetalipoproteinemia (Bassen-Kornzweig syndrome);
- neuronal ceroid lipofuscinosis (NCLs, or Batten disease);
- Refsum disease;
- Kearns-Sayre syndrome.
Bruch's membrane protects the pigment epithelium adjacent to the rods and cones. Degeneration of Bruch's membrane leads to the formation of angioid bands (gaps), which are located on the disc to the equator.
Angioid bands are often a sign of extensive degenerative changes in the elastic connective tissue of any location. Extensive degeneration occur when:
- elastic pseudoxanthoma;
- Paget's disease;
- lead poisoning;
- familial hyperphosphatemia.
Degeneration of the outer retinal layers may occur as a complication in the background reception of drugs phenothiazine series. These drugs have the ability to bind to melanin in the pigment layer, and therefore used in minimum therapeutic doses. Patients taking these drugs for a long time, it is necessary every three months to examine the color perimetry with objects red and white color to avoid occurrence of degeneration of outer retinal layers.
Degeneration of the inner retinal layers can be a side effect when taking chingaminum and hydroxychloroquine.
Elevation or edema of the optic disc caused by the following factors:
- optic disc edema,
- optic disc papillitis,
- optic disc drusen,
- optic disc infiltration with malignant cells, etc.
True optic disc edema caused by swelling of the axons and axoplasm stasis, developed with increased intracranial pressure. Increased intracranial pressure will transmitted by cerebrospinal fluid (CSF) in the subarachnoid space, which surrounds the optic nerve on the way of its passage from the cranial cavity into the orbit. Visual acuity at the beginning of the optic disc edema accompanied by increased intracranial pressure will reduced slightly. The patient have transient sensation of darkness, visual field loss and increased blind spots. Vascular changes in the form of hyperemia venous stasis and hemorrhage with the optic disc edema are secondary. The presence of spontaneous venous pulse on the disk indicates the absence of increased intracranial pressure.
Increased intraocular pressure in glaucoma leads to damage of the optic nerve entering into the eyeball from the fundus.
Pseudo-edema of the optic nerve will called congenital disc swelling because of the formation of vitreous tissue (drusen) or farsightedness.
Papillitis - a swelling disc in conjunction with optic neuritis. Papillitis in patients leads to early loss of vision. Papillitis may develop in the following cases:
- optic disc inflammatory processes;
- optic nerve demyelination (multiple sclerosis, neuromyelitis optica);
- optic nerve's disc degeneration (Leber's hereditary optic neuropathy);
- optic disc infiltration by malignant cells;
- optic disc's vascular lesions.
It is important to distinguish between papillitis from optic neuritis. Optic neuritis is characterized by foci of demyelination in optic nerve (seen at high field MRI), which at the beginning of the disease is not accompanied by changes in the fundus and optic disc. Optic neuritis causes loss of vision and pupil's loss reaction on the light. Comparison of the pupil's direct reaction on light with indirect (an involuntary reaction) is important for the afferent level lesion's localization. Test for the detection of this reflex sometimes called a test with flickering flash. Marcus Gunn's pupil called the pupil who is an indirect reaction to light expressed well than direct.
Slitlamp used to explore of the patient's eye internal structure features.
Optic neuritis differentiated from loss of vision that occurs in some patients with hysteria. Binocular vision in these patients do not suffer, there is a defect afferent pupil reaction to light. For the diagnosis of optic neuritis is essential to have a history of trauma, abuse of drugs, effects of toxic substances or alcohol. Young people with idiopathic optic neuritis (an inflammatory or retrobulbar) the risk of multiple sclerosis of developing is approximately 30-40%. In the elderly, the main reason for the decrease in visual acuity and visual field loss is optic nerve infarction (anterior ischemic optic neuropathy). Optic nerve infarction (anterior ischemic optic neuropathy) occurs in elderly patients with giant cell arteritis (temporal arteritis), no arteritis arteriosclerosis or posterior ciliary arteries embolism.
Most lesions of the optic nerve accompanied by blanching of his disc. There are three reasons for optic disc blanching:
- hereditary optic nerve atrophy;
- primary optic nerve atrophy, which develops as a result of the necrosis of retinal ganglion cells and axons;
- secondary optic nerve atrophy with papillitis and chronic optic disc edema.
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