Loss of vision can occur suddenly or develop gradually over time.
Loss of vision can occur as follows:
- bilateral (right and left),
- occur unilaterally (affecting one eye),
- affect only certain areas of the visual field.
There may also be loss of vision that cannot be corrected by glasses or contact lenses.
- Partial blindness means that vision is severely impaired.
- Complete blindness means not seeing anything, not even the light.
(Most people use the term “blindness” for complete blindness.)
Causes of painless loss of visual acuity
Cataract – the patient reports:
- to be blinded in the dark (he therefore has difficulty driving at night),
- blurred vision,
- Colors appear duller and lifeless to him than before.
In advanced cases, cataracts are visible to the naked eye (which is becoming increasingly rare nowadays because early intervention is taken).
Age-related macular degeneration (AMD) – macular degeneration is expected when the patient is over 50 years of age and presents with one of the following symptoms, affecting only one eye at a time:
- Visual disturbances in which straight lines appear crooked or wavy.
- Vision loss or blurred vision in or around the center.
- The patient describes a black or gray spot in the central field of vision (scotoma).
- Other visual symptoms may occur or AMD may be randomly detected by an optician.
- Visual acuity may be normal or reduced in a Snellen eye test.
During an eye examination in the Amsler grid, patients can perceive interrupted, wavy or partially not continuously visible lines.
Open-angle glaucoma (primary) chronic – it is usually detected during a check-up.
Once it has progressed so far that the patient is already observing a loss of vision, there is little left to do. Glaucoma is characterized by:
- progressive peripheral (or lateral) vision loss,
- Changes in the papillae: the central papillae area becomes larger and the edges shrink.
Diabetic retinopathy – the problem can be caused by:
- diabetic microvasculation disorders (these are exudations and hemorrhages),
- related diseases (e.g. diabetic cataracts)
- independent diseases (e.g. glaucoma).
You should consult an ophthalmologist immediately (within a week), because early treatment of diabetic retinopathy can prevent further vision loss.
Pressure on the optic nerve or the course of the optic nerve – is rare, but must be considered if there is a history of headache and if any neurological or endocrinological abnormalities (for example, acromegaly) appear.
During the examination, the ophthalmologist is looking for:
- after an afferent pupillary defect (but is not present in the above disorders),
- a pale or swollen lens (the edges are then not well defined),
- Visual field defects.
Medicines, toxins or nutrient deficiencies – for example:
- amiodarone – causes various effects on the eye;
- drugs for tuberculosis – ethambutol and isoniazid (cause inflammation of the optic nerve);
- hydroxychloroquine (causes maculopathies);
- corticosteroids by systemic route (cataracts and glaucoma);
- phosphodiesterase inhibitors (for example, sildenafil or Viagra);
- Contraceptive pill;
- other drugs – tetracyclines (benign intracranial hypertension), isotretinoin, tamoxifen (various possible effects on vision);
- alcohol, smoking and nutritional deficiencies (for example, toxic amblyopia on tobacco and alcohol); methanol poisoning; Vitamin A deficiency (usually causes night blindness).
Inherited retinal dystrophies – these are rare and, according to the underlying problem, they can occur from childhood.
Characteristics are poor night vision and light sensitivity. It is possible not to perceive movements in the lateral field of vision well.
Children should be screened for genetic causes.
Cerebrovascular diseases (stroke and transient ischemic attack, TIA for short) – the interrupted oxygen supply causes damage to the brain cells.
The TIA, in which vision is lost, is called Amaurosis fugax.
Low blood pressure – is a disorder characterized by low pressure of blood against the artery walls.
Among the symptoms of low blood pressure is a loss of vision, the affected person has blurred vision.
Papilledema – swelling of the eye disc (where the optic nerve enters the eye), caused by endocranial hypertension.
The initial stage may be asymptomatic (the patient has no symptoms).
Possible consequences for the eye:
- double vision (in case of paralysis of the abducens nerve, which controls the eye muscles that perform the outward movement),
- Blurred vision
- Restriction of the field of vision with the appearance of shadows or colored spots.
Causes of sudden painless vision loss:
1. Retinal detachment
2. Vitreous hemorrhage
3. Retinal vein occlusion
4. Retinal artery occlusion
5. Wet macular degeneration
6. Anterior ischemic optic neuropathy
7. Optic neuritis
8. Cerebrovascular attack
Gradual and slow loss of vision
Causes of slow and gradual vision decline include:
- Refraction error
- Retinal edema
Painful vision loss
This disorder is much less common and must make you think of a more serious condition, such as:
- Narrow-angle glaucoma attack – Glaucoma is an eye condition associated with increasing internal eye pressure. The main symptoms include:
– severe eye pain, – reddened eyes, – deterioration of visual acuity, – opacity of the gaze, – sensitivity to light,
– halos around the lights.
- Multiple sclerosis – Loss of visual acuity is one of the initial and most common symptoms of multiple sclerosis.
This disease causes damage to the optic nerve, which conducts the optical signals from the retina to the brain.
Multiple sclerosis causes the loss of myelin (insulation layer around the nerves), resulting in retrobulbar neuritis (NNO): inflammation of the optic nerve.
Normally, the visual disturbance is temporary and can cause visual field defects (scotomas) and retrobulbar pain.
- Progressive neoplasia (for example, choroidal melanoma) or an inflammatory process (for example, chorioretinitis).
- Corneal ulcer: open and painful wound of the cornea.
- systemic disease (e.g. sarcoidosis or vascular collagenosis).
- Lesions of the optic nerve (optic neuritis, granuloma or neuroma).
- Intracranial disease or tumor masses, a pituitary tumor can cause the following symptoms:
– headache – restriction of the field of vision, you can see only half of the field of vision (hemianopsia)
- Endocranic hypertension (may cause headache).
- Concussion. Cranial trauma can lead to vision loss or temporary blurred vision. Based on the medical history:
– neurological tests – blood tests
All patients should be presented to a specialist within a few days.
Transient vision loss (Amaurosis fugax)
What is Amaurosis fugax?
Amaurosis fugax is a short-lasting visual disturbance caused by lack of blood flow in the eye. Vision loss usually occurs in only one eye and lasts from a few seconds to a few minutes, up to about half an hour.
These disorders can occur repeatedly.
Once the cause has been resolved, temporary vision loss can be prevented.What is the cause?
The most common causes of temporary vision loss are:
- Narrowing of the carotid artery (called stenosis). It can slow blood flow to the eye.
This is the most common cause of a transient episode of blindness.
There are two carotid arteries, one on each side of the neck.
They carry the blood from the heart to the eyes and brain.
Some smaller arteries branching off from the carotid arteries carry blood to the eyes.
- Arterial thrombosis. Along the inner artery walls, atherosclerotic plaques can form and slow blood flow.
These plaques can peel off and block blood flow to the eyes.
- Diabetes, smoking, high blood pressure and high cholesterol can cause problems in the carotid arteries and lead to temporary blindness.
- Migraines can cause spasms and narrowing of the arteries that carry blood to the eyes.
- Stress causes numerous symptoms, including insomnia and temporary loss of vision; in severe cases, the patient sees everything black.
Loss of vision during pregnancy
In pregnancy, the woman’s vision may be temporarily reduced; the causes are:
- hormone fluctuations,
- Iron deficiency
- high blood sugar levels, which can lead to gestational diabetes,
- High blood pressure, can provoke preeclampsia.
- Dry eyes due to reduced production of,
- tired eyes,
- Occurrence of flashes of light in the field of vision.
Loss of near and far vision
Farsightedness. Blurred vision in farsightedness makes objects appear clear in the distance, but the eyes cannot focus objects in the foreground correctly or unusual tiredness and exhaustion of the eyes is observed.
In severe cases of farsightedness, the objects in the distance also appear blurred.
Myopia. This disorder leads to impaired vision in the distance.
Astigmatism. Loss of visual acuity for near and far is often a symptom of astigmatism. In particular, the view is blurred and clouded. These refractive errors are usually caused by an unevenness of the cornea or lens.
In astigmatism, the light rays do not reach specific points on the retina to create a clear view, regardless of the distance between the eye and the object.
Presbyopia. If you are older than 40 years and your visual acuity decreases nearby, for example when reading the newspaper, it is likely that you suffer from so-called presbyopia.
It is a visual defect that occurs in adults from the age of 45 and in the elderly.
The symptoms of presbyopia are similar to those caused by farsightedness (blurred vision near and eye strain when reading).
The difference is that presbyopia is a decrease in the ability to see objects up close due to hardening of the lens inside the eye, while farsightedness is a visual defect due to the shape of the eyeball.
A person who has lost their vision may have trouble driving, reading, or doing small jobs such as sewing or other crafts.
One can make changes to the house and customs that will help you stay independent and feel safe.
There are health services that provide further education and support to be able to live independently.
Computers for people with visual impairments
PCs have operating systems (software such as Windows, Mac, etc.) with accessibility features that allow the computer to be used by those who have vision problems or a red-green visual impairment.
For the blind, Windows allows you to get information about sounds or “touch” technology.
Listening to the text through a screen reader A screen reader is an application that reads aloud the text that appears on the screen and describes events such as error messages.
A blind person who has partially lost his vision or is visually impaired is thus able to use the Windows operating system from the first start of the computer.
Using Speech Recognition to Use Programs
Speech Recognition in Windows is a technology that allows you to control your PC and dictate in almost any application.
You can dictate documents and mails and navigate the web.
A simple installation and interactive tutorial are available to familiarize yourself with voice commands and train the computer to better understand the person who has lost their eyesight.
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