Retinal Artery Occlusion
Retinal Artery
Susac Syndrome
Fluorescein Angiography
Fundus Oculi
Glaucoma, Neovascular
Amaurosis Fugax
Sneddon Syndrome
Blindness
Retinal Vein
Ophthalmic Artery
Retinal Diseases
Arterial Occlusive Diseases
Visual Acuity
Paracentesis
Ophthalmodynamometry
Carotid Artery Diseases
Optic Neuropathy, Ischemic
Ciliary Arteries
Infarction, Middle Cerebral Artery
Vision Disorders
Superselective intraarterial fibrinolysis in central retinal artery occlusion. (1/169)
Intraarterial fibrinolysis was performed in three patients with acute central retinal artery occlusion using recombinant tissue plasminogen activator as a fibrinolytic agent. In two cases the ophthalmic artery was selectively catheterized, and in the other a thrombolytic drug was infused into the ophthalmic artery by way of the meningeal collaterals. All patients experienced visual improvement. Fibrinolysis can produce better results than obtained from conservative treatment. A good prognosis can be achieved if the treatment starts within the first 4 to 5 hours after occlusion. (+info)Follow up of focal narrowing of retinal arterioles in glaucoma. (2/169)
AIM: To evaluate whether focal narrowing of retinal arterioles increases with progressive glaucomatous optic neuropathy. METHODS: Focal narrowing of retinal arterioles and area of neuroretinal rim were morphometrically evaluated on colour stereo optic disc photographs of 59 patients with primary open angle glaucoma, 22 patients with normal pressure glaucoma, 11 patients with secondary open angle glaucoma, and 31 patients with ocular hypertension. Minimum follow up was 8 months. Focal arteriolar narrowing was quantified by calculating the ratio of the vessel width in the broadest to the narrowest vessel part. RESULTS: In the subgroup of patients with progressive glaucomatous optic nerve damage (n = 37), focal narrowing of retinal arterioles increased significantly (p < 0.005) with decreasing neuroretinal rim area. In the subgroup of patients with stable appearance of the optic disc (n = 86), focal narrowing of retinal arterioles did not change significantly (p = 0.79). The positive correlation between increasing focal thinning of retinal arterioles and progression of glaucomatous optic neuropathy was present, although not statistically significant, in all the glaucoma subtypes examined. The location of focal thinning of retinal arterioles did not change in the follow up. CONCLUSIONS: Focal narrowing of retinal arterioles increases significantly with progressive glaucomatous optic neuropathy, independent of the type of glaucoma. It is stable in patients with non-progressive glaucoma. The findings agree with previous reports on a higher degree of focal arteriole narrowing in eyes with pronounced optic nerve damage in comparison with those with moderate optic nerve atrophy or normal eyes. In the clinical management of patients with glaucoma, in some eyes, increasing focal arteriole narrowing may suggest progression of disease. (+info)Mechanisms of retinal arterial occlusive disease in African American and Caucasian patients. (3/169)
BACKGROUND AND PURPOSE: The aim of our study was to evaluate the causes of retinal arterial occlusive disease in African American patients and to compare these etiologies with those observed in Caucasian patients with retinal ischemic symptoms. METHODS: We performed a retrospective analysis of a series of consecutive patients evaluated by both the ophthalmology department and the neurology/stroke clinic. Patients had a diagnosis of amaurosis fugax, branch retinal artery occlusion, central retinal artery occlusion, or intra-arterial retinal plaques. RESULTS: Twenty-nine African American patients and 17 Caucasian patients were evaluated. African American patients had a mean age of 61 years (range, 30 to 77 years) and Caucasian patients a mean age of 73 years (range, 56 to 94 years) (P=0.003). There was no statistically significant difference between the 2 groups with respect to visible emboli on funduscopy (P=0.462). After adjusting for age, there was also no difference between the 2 groups with regards to risk factors for arterial occlusive disease such as hypertension, coronary artery disease, hypercholesterolemia, tobacco use, and history of stroke or transient ischemic attacks. Caucasian patients had a 41% incidence (7/17) of high-grade ipsilateral internal carotid artery stenosis, measured by carotid duplex, compared with 3.4% incidence (1/29) in African American patients (P=0.002). CONCLUSIONS: There are racial differences in the causes of retinal arterial occlusion. African American patients have a low prevalence of moderate to severe extracranial carotid stenosis, and a high proportion of African American patients have cryptogenic retinal ischemia. In Caucasian patients there is a stronger association between extracranial carotid artery disease and retinal arterial occlusion. (+info)The influence of randomized trials on the use of anticoagulants for atrial fibrillation. (4/169)
INTRODUCTION: Anticoagulants and anti-platelet drugs have been shown in randomized trials to reduce the risk of stroke in patients with atrial fibrillation (AF). We therefore investigated their use in patients known to be in AF before a stroke, transient ischaemic attack (either cerebral or ocular) or retinal artery occlusion to assess the influence of trials on clinical practice. METHODS: Inpatients and outpatients with acute stroke, transient ischaemic attack or retinal artery occlusion were prospectively identified by a stroke physician from 1990 to 1997. The presence or absence of AF before the vascular event, and prior use of anticoagulant and anti-platelet drugs were recorded at the time of the assessment and verified using information from general practitioner and hospital case notes. RESULTS: Of 1934 patients with stroke or retinal artery occlusion, 191 (10%) were in AF before their ischaemic event. Anticoagulants had been used in 40 (21%) of these, but only in 32 (2%) of the 1743 patients in sinus rhythm [odds ratio (OR) 14.2, 95% confidence interval (CI) 8.6-23.2]. Anti-platelet drugs had been used in 62 (32%) of those with AF compared with 500 (30%) of those in sinus rhythm (OR 1.2, 95% CI 0.9-1.64). Of the 161 patients in AF without contraindications to anticoagulants, only 36 (22%) were taking them. Although there was a statistically significant increase in anticoagulant use from 8% in 1990 to 23% in 1996, this could be explained solely by a fall in the age of the patients referred to our hospital. CONCLUSION: Anticoagulation is probably under-used in AF. We found no conclusive evidence that anticoagulation trials have influenced clinical practice. This raises issues about the dissemination and implementation of trial results. (+info)Continued lodging of retinal emboli in a patient with internal carotid artery and ophthalmic artery occlusions. (5/169)
Internal carotid artery or ophthalmic artery occlusions are devastating ophthalmological events which lead to severe impairment of vision. A case of multiple branch retinal artery occlusions in a 63-year-old male with internal carotid artery and ophthalmic artery occlusions on brain angiography is presented. Emboli lodging in branches of the retinal arteries were bright, glistening, yellow or orange in appearance. Such a distinctive ophthalmoscopic appearance led to the diagnosis of cholesterol emboli. Fluorescein and indocyanine green angiography disclosed delayed filling of the retinal vessels and choroid, and showed multiple hypofluorescence distal to the vessels in which the emboli were lodged. At the time of initial examination, the number of emboli lodged in retinal arteries was estimated at more than 20. As time passed, a few of the previous emboli disappeared and new emboli appeared in other sites on fundus examination. We think that the lodging of new emboli in other sites is due to the continued break-up of atheromatous tissue through the collateral circulation associated with the occlusion of the internal carotid and ophthalmic arteries. (+info)Central retinal vein occlusion combined with cilioretinal artery occlusion. (6/169)
A healthy 65-year-old man with sudden profound visual loss in his right eye presented with clinical signs of central retinal venous occlusion and retinal whitening, indicative of a cilioretinal arterial obstruction. He had been diagnosed with cilioretinal artery occlusion at a private ophthalmology clinic three days before being referred to our department. On fluorescein angiogram of the affected eye, the proximal portion of the retinal arteries filled with dye 27.3 seconds after injection, indicating a delay in retinal arterial filling. Moreover, the cilioretinal artery did not fill at that phase, but went on to fill 45.1 seconds after injection. Over 63.4 seconds after the filling of the retinal arteries, the laminar flow of the retinal venous vessels appeared. This was not until 90.7 seconds after injection. This patient was elderly, had no systemic diseases, and showed non-ischemic CRVO, prolonged retinal arterial filling on fluorescein angiography, and poor prognosis in visual acuity. His clinical course seemed to favor the pathogenetic hypothesis of a primary arterial affection. (+info)Local intra-arterial fibrinolysis for acute occlusion of the central retinal artery: a meta-analysis of the published data. (7/169)
BACKGROUND/AIM: Central retinal artery occlusion (CRAO) is typically associated with a poor visual outcome. Several favourable reports of local intra-arterial fibrinolysis (LIF), which involves the superselective administration of a thrombolytic agent directly into the ophthalmic artery, have appeared in the recent literature. The aim of this study was to critically appraise these studies in a collective fashion. METHODS: A meta-analysis was performed of all the published literature germane to LIF in cases of CRAO. RESULTS: Of the 16 studies identified, all were retrospective and non-randomised. After correction for data duplication, the results of LIF in 100 patients can be reported. A final acuity of 6/6 or better was seen in 14% of patients following LIF, and a visual result of 6/12 or better was seen in 27% of subjects. A poor final acuity of 3/60 or worse was seen in 60.6% of eyes treated with local intra-arterial fibrinolysis. These results compare favourably with conventional forms of therapy. Potentially serious complications were seen in four patients, but no patient suffered a permanent neurological deficit. CONCLUSION: The results of this study suggest that there may be a marginal visual benefit associated with LIF compared with conventional management of CRAO. However, the methodology of the cited studies was often unsatisfactory, and a randomised controlled trial of LIF in cases of CRAO is justified. Outside of a randomised clinical trial, the use of superselective fibrinolytic therapy for CRAO cannot be recommended on the basis of current evidence. (+info)Transient ischemic injury in the rat retina caused by thrombotic occlusion-thrombolytic reperfusion. (8/169)
PURPOSE: To establish a clinically relevant model of transient retinal ischemia by thrombotic occlusion-thrombolytic reperfusion of the central retinal artery of the rat. METHODS: Thrombus was photochemically induced in the central retinal artery by the combination of intravenous injection of photo-sensitive dye, rose bengal, and green laser irradiation focused on the artery. Transient retinal ischemia for 60 minutes was achieved by a subsequent systemic administration of tissue-type plasminogen activator to reperfuse the occluded vessel. Samples of retinas were excised from the animals killed 3, 9, 12, 24, 48, and 78 hours after the reperfusion. The experimental data were processed using the TdT-dUTP terminal nick-end labeling (TUNEL) method to detect apoptotic cells. RESULTS: The transient retinal ischemia caused time-sequential apoptotic changes in the retinal cells as evaluated by counting the number of TUNEL-positive cells. The most remarkable changes occurred in the central area of retina, and further on the sections taken 24 hours after reperfusion. The peripheral area was less affected, and the outer nuclear cell layer was almost unaffected throughout the observation period. CONCLUSIONS: The proposed method to cause retinal transient ischemia is highly reproducible, and it is easy to simulate the progress and topographical distribution of retinal changes observed in the clinical cases of central retinal arterial occlusion and its subsequent thrombolytic reperfusion. This may provide a useful tool for constructing the effective thrombolytic strategies against the central retinal arterial occlusion and for evaluating the effects of neuroprotective agents. (+info)Retinal artery occlusion (RAO) is a medical condition characterized by the blockage or obstruction of the retinal artery, which supplies oxygenated blood to the retina. This blockage typically occurs due to embolism (a small clot or debris that travels to the retinal artery), thrombosis (blood clot formation in the artery), or vasculitis (inflammation of the blood vessels).
There are two types of retinal artery occlusions:
1. Central Retinal Artery Occlusion (CRAO): This type occurs when the main retinal artery is obstructed, affecting the entire inner layer of the retina. It can lead to severe and sudden vision loss in the affected eye.
2. Branch Retinal Artery Occlusion (BRAO): This type affects a branch of the retinal artery, causing visual field loss in the corresponding area. Although it is less severe than CRAO, it can still result in noticeable vision impairment.
Immediate medical attention is crucial for both types of RAO to improve the chances of recovery and minimize potential damage to the eye and vision. Treatment options may include medications, laser therapy, or surgery, depending on the underlying cause and the severity of the condition.
A retinal artery is a small branch of the ophthalmic artery that supplies oxygenated blood to the inner layers of the retina, which is the light-sensitive tissue located at the back of the eye. There are two main retinal arteries - the central retinal artery and the cilioretinal artery. The central retinal artery enters the eye through the optic nerve and divides into smaller branches to supply blood to the entire retina, while the cilioretinal artery is a smaller artery that supplies blood to a small portion of the retina near the optic nerve. Any damage or blockage to these arteries can lead to serious vision problems, such as retinal artery occlusion or retinal artery embolism.
Susac syndrome, also known as retinocochleocerebral vasculopathy, is a rare autoimmune disorder characterized by the inflammation and damage to small blood vessels in the brain, retina, and inner ear. It primarily affects young adults, particularly women, and can lead to various neurological, auditory, and visual symptoms.
The medical definition of Susac syndrome includes:
1. Encephalopathy (brain dysfunction) - This is characterized by headaches, cognitive impairment, behavioral changes, seizures, or psychiatric symptoms due to inflammation in the brain.
2. Branch retinal artery occlusions (BRAO) - These are blockages of small blood vessels in the retina, leading to visual disturbances such as blurry vision, scotomas (blind spots), or even permanent vision loss.
3. Sensorineural hearing loss - This is caused by damage to the inner ear structures responsible for hearing, resulting in difficulties with hearing, tinnitus (ringing in the ears), or vertigo (dizziness).
The triad of these symptoms is necessary for a definitive diagnosis of Susac syndrome. However, not all patients may present with all three components simultaneously. The presence of any two features should raise suspicion for this condition, and further diagnostic workup is required to confirm the diagnosis. Early recognition and treatment are crucial to prevent long-term complications and improve outcomes in patients with Susac syndrome.
Fluorescein angiography is a medical diagnostic procedure used in ophthalmology to examine the blood flow in the retina and choroid, which are the inner layers of the eye. This test involves injecting a fluorescent dye, Fluorescein, into a patient's arm vein. As the dye reaches the blood vessels in the eye, a specialized camera takes rapid sequences of photographs to capture the dye's circulation through the retina and choroid.
The images produced by fluorescein angiography can help doctors identify any damage to the blood vessels, leakage, or abnormal growth of new blood vessels. This information is crucial in diagnosing and managing various eye conditions such as age-related macular degeneration, diabetic retinopathy, retinal vein occlusions, and inflammatory eye diseases.
It's important to note that while fluorescein angiography is a valuable diagnostic tool, it does carry some risks, including temporary side effects like nausea, vomiting, or allergic reactions to the dye. In rare cases, severe adverse reactions can occur, so patients should discuss these potential risks with their healthcare provider before undergoing the procedure.
"Fundus Oculi" is a medical term that refers to the back part of the interior of the eye, including the optic disc, macula, fovea, retinal vasculature, and peripheral retina. It is the area where light is focused and then transmitted to the brain via the optic nerve, forming visual images. Examinations of the fundus oculi are crucial for detecting various eye conditions such as diabetic retinopathy, macular degeneration, glaucoma, and other retinal diseases. The examination is typically performed using an ophthalmoscope or a specialized camera called a retinal camera.
Neovascular glaucoma is a type of glaucoma that is characterized by the growth of new, abnormal blood vessels on the iris (the colored part of the eye) and/or over the drainage channels (trabecular meshwork) in the corner of the eye. These new blood vessels can interfere with the normal flow of fluid out of the eye, leading to an increase in eye pressure (intraocular pressure or IOP). This elevated IOP can cause damage to the optic nerve and result in permanent vision loss if not treated promptly and effectively.
Neovascular glaucoma is often associated with other underlying conditions that affect the blood vessels, such as diabetes, central retinal vein occlusion, or ocular ischemic syndrome. Treatment typically involves addressing the underlying cause, as well as controlling the IOP with medications, laser treatment, or surgery to prevent further vision loss.
Amaurosis fugax is a medical term that describes a temporary loss of vision in one eye, which is often described as a "shade or curtain falling over the field of vision." It's usually caused by a temporary interruption of blood flow to the retina or optic nerve. This condition is often associated with conditions such as giant cell arteritis, carotid artery stenosis, and cardiovascular disease.
It's important to note that Amaurosis fugax can be a warning sign for a more serious medical event, such as a stroke, so it's essential to seek medical attention promptly if you experience any symptoms of this condition.
Sneddon syndrome is a rare medical condition characterized by the concurrence of livedo reticularis (a purplish, net-like discoloration of the skin) and recurrent strokes or transient ischemic attacks (TIAs). It primarily affects young to middle-aged women. The exact cause of Sneddon syndrome remains unknown, but it's thought to be an autoimmune disorder with potential involvement of the coagulation system.
The main diagnostic criteria for Sneddon syndrome are:
1. Livedo reticularis (fixed, persistent form)
2. One or more cerebrovascular events (strokes or TIAs)
Additional features may include cognitive impairment, migraine-like headaches, seizures, and other neurological symptoms. Diagnosis is often challenging due to its rarity and the need to exclude other conditions that can present with similar symptoms. Treatment typically involves anticoagulation therapy, antiplatelet agents, or immunosuppressive medications to manage symptoms and prevent further cerebrovascular events.
Blindness is a condition of complete or near-complete vision loss. It can be caused by various factors such as eye diseases, injuries, or birth defects. Total blindness means that a person cannot see anything at all, while near-complete blindness refers to having only light perception or the ability to perceive the direction of light, but not able to discern shapes or forms. Legal blindness is a term used to define a certain level of visual impairment that qualifies an individual for government assistance and benefits; it usually means best corrected visual acuity of 20/200 or worse in the better eye, or a visual field no greater than 20 degrees in diameter.
A Retinal Vein is a vessel that carries oxygen-depleted blood away from the retina, a light-sensitive layer at the back of the eye. The retinal veins originate from a network of smaller vessels called venules and ultimately merge to form the central retinal vein, which exits the eye through the optic nerve.
Retinal veins are crucial for maintaining the health and function of the retina, as they facilitate the removal of waste products and help regulate the ocular environment. However, they can also be susceptible to various pathological conditions such as retinal vein occlusions, which can lead to vision loss or damage to the eye.
The ophthalmic artery is the first branch of the internal carotid artery, which supplies blood to the eye and its adnexa. It divides into several branches that provide oxygenated blood to various structures within the eye, including the retina, optic nerve, choroid, iris, ciliary body, and cornea. Any blockage or damage to the ophthalmic artery can lead to serious vision problems or even blindness.
Retinal diseases refer to a group of conditions that affect the retina, which is the light-sensitive tissue located at the back of the eye. The retina is responsible for converting light into electrical signals that are sent to the brain and interpreted as visual images. Retinal diseases can cause vision loss or even blindness, depending on their severity and location in the retina.
Some common retinal diseases include:
1. Age-related macular degeneration (AMD): A progressive disease that affects the central part of the retina called the macula, causing blurred or distorted vision.
2. Diabetic retinopathy: A complication of diabetes that can damage the blood vessels in the retina, leading to vision loss.
3. Retinal detachment: A serious condition where the retina becomes separated from its underlying tissue, requiring immediate medical attention.
4. Macular edema: Swelling or thickening of the macula due to fluid accumulation, which can cause blurred vision.
5. Retinitis pigmentosa: A group of inherited eye disorders that affect the retina's ability to respond to light, causing progressive vision loss.
6. Macular hole: A small break in the macula that can cause distorted or blurry vision.
7. Retinal vein occlusion: Blockage of the retinal veins that can lead to bleeding, swelling, and potential vision loss.
Treatment for retinal diseases varies depending on the specific condition and its severity. Some treatments include medication, laser therapy, surgery, or a combination of these options. Regular eye exams are essential for early detection and treatment of retinal diseases.
Arterial occlusive diseases are medical conditions characterized by the blockage or narrowing of the arteries, which can lead to a reduction in blood flow to various parts of the body. This reduction in blood flow can cause tissue damage and may result in serious complications such as tissue death (gangrene), organ dysfunction, or even death.
The most common cause of arterial occlusive diseases is atherosclerosis, which is the buildup of plaque made up of fat, cholesterol, calcium, and other substances in the inner lining of the artery walls. Over time, this plaque can harden and narrow the arteries, restricting blood flow. Other causes of arterial occlusive diseases include blood clots, emboli (tiny particles that travel through the bloodstream and lodge in smaller vessels), inflammation, trauma, and certain inherited conditions.
Symptoms of arterial occlusive diseases depend on the location and severity of the blockage. Common symptoms include:
* Pain, cramping, or fatigue in the affected limb, often triggered by exercise and relieved by rest (claudication)
* Numbness, tingling, or weakness in the affected limb
* Coldness or discoloration of the skin in the affected area
* Slow-healing sores or wounds on the toes, feet, or legs
* Erectile dysfunction in men
Treatment for arterial occlusive diseases may include lifestyle changes such as quitting smoking, exercising regularly, and eating a healthy diet. Medications to lower cholesterol, control blood pressure, prevent blood clots, or manage pain may also be prescribed. In severe cases, surgical procedures such as angioplasty, stenting, or bypass surgery may be necessary to restore blood flow.
Visual acuity is a measure of the sharpness or clarity of vision. It is usually tested by reading an eye chart from a specific distance, such as 20 feet (6 meters). The standard eye chart used for this purpose is called the Snellen chart, which contains rows of letters that decrease in size as you read down the chart.
Visual acuity is typically expressed as a fraction, with the numerator representing the testing distance and the denominator indicating the smallest line of type that can be read clearly. For example, if a person can read the line on the eye chart that corresponds to a visual acuity of 20/20, it means they have normal vision at 20 feet. If their visual acuity is 20/40, it means they must be as close as 20 feet to see what someone with normal vision can see at 40 feet.
It's important to note that visual acuity is just one aspect of overall vision and does not necessarily reflect other important factors such as peripheral vision, depth perception, color vision, or contrast sensitivity.
Paracentesis is a medical procedure in which a thin needle or catheter is inserted through the abdominal wall to remove excess fluid from the peritoneal cavity. This procedure is also known as abdominal tap or paracentesis aspiration. The fluid removed, called ascites, can be analyzed for infection, malignant cells, or other signs of disease. Paracentesis may be performed to relieve symptoms caused by the buildup of excess fluid in the abdomen, such as pain, difficulty breathing, or loss of appetite. It is commonly used to diagnose and manage conditions such as liver cirrhosis, cancer, heart failure, and kidney failure.
Ophthalmodynamometry is a medical technique used to measure the amount of pressure or force required to flatten the cornea, which can help in the diagnosis and evaluation of various eye conditions, particularly glaucoma. It involves using a handheld device called an ophthalmodynamometer to apply gentle pressure to the eyelid while observing changes in the optic nerve head and retinal vessels through an ophthalmoscope. The test provides information about the resistance of the eyeball to external pressure, which can be useful in assessing the functioning of the eye's aqueous humor drainage system and identifying any abnormalities that may contribute to increased intraocular pressure (IOP).
The procedure typically involves several steps:
1. The patient is asked to look in different directions while the examiner observes the optic nerve head and retinal vessels through an ophthalmoscope.
2. The examiner then applies gentle pressure to the eyelid using the ophthalmodynamometer, gradually increasing the force until the cornea begins to flatten.
3. The amount of pressure required to achieve this is recorded as the ophthalmodynamometric value.
4. The examiner may repeat the process several times to ensure accurate and consistent results.
5. The results are then compared with normative data to determine whether the patient's IOP is within normal limits or if there are any signs of glaucoma or other eye conditions.
It is important to note that ophthalmodynamometry should only be performed by trained healthcare professionals, as improper technique can lead to inaccurate results and potential harm to the patient's eyes.
Carotid artery diseases refer to conditions that affect the carotid arteries, which are the major blood vessels that supply oxygen-rich blood to the head and neck. The most common type of carotid artery disease is atherosclerosis, which occurs when fatty deposits called plaques build up in the inner lining of the arteries.
These plaques can cause the arteries to narrow or become blocked, reducing blood flow to the brain and increasing the risk of stroke. Other carotid artery diseases include carotid artery dissection, which occurs when there is a tear in the inner lining of the artery, and fibromuscular dysplasia, which is a condition that affects the muscle and tissue in the walls of the artery.
Symptoms of carotid artery disease may include neck pain or pulsations, transient ischemic attacks (TIAs) or "mini-strokes," and strokes. Treatment options for carotid artery disease depend on the severity and type of the condition but may include lifestyle changes, medications, endarterectomy (a surgical procedure to remove plaque from the artery), or angioplasty and stenting (procedures to open blocked arteries using a balloon and stent).
Ischemic optic neuropathy (ION) is a medical condition that refers to the damage or death of the optic nerve due to insufficient blood supply. The optic nerve is responsible for transmitting visual information from the eye to the brain.
In ION, the blood vessels that supply the optic nerve become blocked or narrowed, leading to decreased blood flow and oxygen delivery to the nerve fibers. This results in inflammation, swelling, and ultimately, damage to the optic nerve. The damage can cause sudden, painless vision loss, often noticed upon waking up in the morning.
There are two types of ION: anterior ischemic optic neuropathy (AION) and posterior ischemic optic neuropathy (PION). AION affects the front part of the optic nerve, while PION affects the back part of the nerve. AION is further classified into arteritic and non-arteritic types, depending on whether it is caused by giant cell arteritis or not.
Risk factors for ION include age (most commonly occurring in people over 50), hypertension, diabetes, smoking, sleep apnea, and other cardiovascular diseases. Treatment options depend on the type and cause of ION and may include controlling underlying medical conditions, administering corticosteroids, or undergoing surgical procedures to improve blood flow.
Arteries are blood vessels that carry oxygenated blood away from the heart to the rest of the body. They have thick, muscular walls that can withstand the high pressure of blood being pumped out of the heart. Arteries branch off into smaller vessels called arterioles, which further divide into a vast network of tiny capillaries where the exchange of oxygen, nutrients, and waste occurs between the blood and the body's cells. After passing through the capillary network, deoxygenated blood collects in venules, then merges into veins, which return the blood back to the heart.
Ciliary arteries are a type of ocular (eye) artery that originate from the posterior ciliary and muscular arteries. They supply blood to the ciliary body, choroid, and iris of the eye. The ciliary body is a part of the eye that contains muscles responsible for accommodation (the ability to focus on objects at different distances). The choroid is a layer of blood vessels that provides oxygen and nutrients to the outer layers of the retina. The iris is the colored part of the eye that controls the amount of light reaching the retina by adjusting the size of the pupil.
Middle Cerebral Artery (MCA) infarction is a type of ischemic stroke that occurs when there is an obstruction in the blood supply to the middle cerebral artery, which is one of the major blood vessels that supplies oxygenated blood to the brain. The MCA supplies blood to a large portion of the brain, including the motor and sensory cortex, parts of the temporal and parietal lobes, and the basal ganglia.
An infarction is the death of tissue due to the lack of blood supply, which can lead to damage or loss of function in the affected areas of the brain. Symptoms of MCA infarction may include weakness or numbness on one side of the body, difficulty speaking or understanding speech, vision problems, and altered levels of consciousness.
MCA infarctions can be caused by various factors, including embolism (a blood clot that travels to the brain from another part of the body), thrombosis (a blood clot that forms in the MCA itself), or stenosis (narrowing of the artery due to atherosclerosis or other conditions). Treatment for MCA infarction may include medications to dissolve blood clots, surgery to remove the obstruction, or rehabilitation to help regain lost function.
Fibrinolytic agents are medications that dissolve or break down blood clots by activating plasminogen, which is converted into plasmin. Plasmin is a proteolytic enzyme that degrades fibrin, the structural protein in blood clots. Fibrinolytic agents are used medically to treat conditions such as acute ischemic stroke, deep vein thrombosis, pulmonary embolism, and myocardial infarction (heart attack) by restoring blood flow in occluded vessels. Examples of fibrinolytic agents include alteplase, reteplase, and tenecteplase. It is important to note that these medications carry a risk of bleeding complications and should be administered with caution.
Vision disorders refer to a wide range of conditions that affect the visual system and result in various symptoms, such as blurry vision, double vision, distorted vision, impaired depth perception, and difficulty with visual tracking or focusing. These disorders can be categorized into several types, including:
1. Refractive errors: These occur when the shape of the eye prevents light from focusing directly on the retina, resulting in blurry vision. Examples include myopia (nearsightedness), hyperopia (farsightedness), astigmatism, and presbyopia (age-related loss of near vision).
2. Strabismus: Also known as crossed eyes or walleye, strabismus is a misalignment of the eyes where they point in different directions, which can lead to double vision or loss of depth perception.
3. Amblyopia: Often called lazy eye, amblyopia is a condition where one eye has reduced vision due to lack of proper visual development during childhood. It may be caused by strabismus, refractive errors, or other factors that interfere with normal visual development.
4. Accommodative disorders: These involve problems with the focusing ability of the eyes, such as convergence insufficiency (difficulty focusing on close objects) and accommodative dysfunction (inability to maintain clear vision at different distances).
5. Binocular vision disorders: These affect how the eyes work together as a team, leading to issues like poor depth perception, eye strain, and headaches. Examples include convergence insufficiency, divergence excess, and suppression.
6. Ocular motility disorders: These involve problems with eye movement, such as nystagmus (involuntary eye movements), strabismus, or restricted extraocular muscle function.
7. Visual processing disorders: These affect the brain's ability to interpret and make sense of visual information, even when the eyes themselves are healthy. Symptoms may include difficulty with reading, recognizing shapes and objects, and understanding spatial relationships.
8. Low vision: This term refers to significant visual impairment that cannot be fully corrected with glasses, contact lenses, medication, or surgery. It includes conditions like macular degeneration, diabetic retinopathy, glaucoma, and cataracts.
9. Blindness: Complete loss of sight in both eyes, which can be caused by various factors such as injury, disease, or genetic conditions.