hemianopia

Hemianopia: Types, causes, symptoms, diagnosis, and treatment

Hemianopia, also referred to as hemianopsia, comes from a culmination of three different Greek words: “hemi” translates to “half,” “an” translates to “without,” and “opsia” translates to “vision.” Hence, it literally means “being without half of your vision.”

This is a condition where half of your visual field can either be completely blind or partially diminished as a result of head trauma, a tumor, or suffering a stroke.

People who suffer from migraine headaches may sometimes experience temporary hemianopia or other visual disturbances, but this typically subsides on its own after a migraine goes away.

Homonymous hemianopia occurs when you lose part of your visual field on the same side of both eyes. This happens frequently to stroke patients or people who’ve suffered traumatic brain injuries. Visual images that are captured on the left side of the brain are communicated to the right side and vice versa, which is why hemianopia typically affects the same side of each eye equally.

The opposing posterior sides of the brain correspond to the opposite eye, which means that if an injury occurs on the left side of the brain, the visual field defects occur in the right eye.

What are the types of hemianopia?

As an umbrella medical term, there are actually five types of hemianopia and two subcategories in total. In fact, the hemianopia type that a patient suffers from is typically correlated with the exact site of the visual field defect.

Homonymous hemianopia

Visual field is lost on the same side in both eyes, depending on which side of the brain is affected by a stroke or injury. The left optic nerve controls the right visual field and the right optic nerve controls the left visual field. The diminished vision is instrumental in helping doctors locate the exact area of the brain that’s been injured or where the stroke occurred.

Heteronymous hemianopia

Loss of vision occurs in different fields of the eyes. Heteronymous hemianopia is separated into two different categories:

Binasal hemianopia: Blindness or vision loss occurs in the field of vision that’s within the closest proximity to the nose. This is caused by lateral damage to the retinal nerve fibers that don’t cross in the optic chiasm. They’re also responsible for registering information and sending it to the temporal retina.

Bitemporal hemianopia: As the name suggests, bitemporal hemianopia is a loss of vision that happens on the side of the eyes that’s closest to the temple. Lesions and damage to the optic chiasm can cause bitemporal hemianopia. The optic chiasm is located near the pituitary gland where the nerves from the left and right eyeballs meet and cross over one another to reach the opposite side of the brain.

Quadrantanopia

Loss of vision occurs in one quadrant or portion of the visual field, and this usually depends on the part of the brain that’s damaged. The area that’s connected to the damaged portion of the brain will suffer either partial or complete hemianopia.

Superior hemianopia: Superior hemianopia is when loss of vision occurs in the upper visual field of either the left or right eye or both.

Inferior hemianopia: Inferior hemianopia is when loss of vision occurs in the lower visual field of either the left, right, or both eyes.

What causes hemianopia?

There are several different factors or injuries that can cause hemianopia including brain injuries, strokes that occur in certain parts of the brain, and physical head trauma.

As mentioned, while severe migraines can cause temporary hemianopia and adversely affect the patient’s vision, this symptom typically subsides on its own once the migraine pain is relieved.

However, there are more permanent and hazardous causes of permanent hemianopia.

Brain injuries

Damage to certain parts of the brain such as blunt force trauma due to an accident or sports injuries accumulated over an extended period of time can lead to hemianopia in the visual fields of the eyes. These injuries can incur the growth of lesions or contusions on the brain over long periods of time, which can cause hemianopia in old age or even earlier on in life depending on the severity and frequency of the injuries.

Brain tumors

As brain tumors begin to form and continue to grow over time, they can have the same effects as traumatic brain injuries. Eventually, the pressure and damage caused by the tumor can directly result in hemianopia in either one or both of the eyes.

Stroke

Strokes typically occur as a result of insufficient supply of oxygen reaching the brain. Oxygen is important because it promotes healthy and stable cranial functions. The blockages happen for a number of reasons, the most common one being the formation of blood clots. Depending on the severity of the stroke, it could be fatal for the person who endures it. While survival is certainly preferable, it also means enduring various physical and mental ailments, including hemianopia.

What are the symptoms of hemianopia?

Hemianopia has a variety of signs and symptoms that are associated with it, including the following:

  • Loss of peripheral vision on one or both sides of the face
  • Loss of visual awareness
  • Constantly bumping into people or objects on a regular basis
  • Failing to notice objects or people on the side of the face where the hemianopia damage has occurred
  • Inability to process entire sentences, phrases, or words when reading due to disturbed or interrupted visual patterns
  • Visual hallucinations, as in seeing things that aren’t necessarily there such as certain lighting effects

In addition to the physical indicators of hemianopia, there are also a few psychological, emotional, cognitive, and even social repercussions. Many patients who suffer from hemianopia can become increasingly frustrated or frightened as their condition worsens because it can make mobility and attending social events extremely difficult. As a result, this loss of field vision can also have a negative effect on a person’s ability to live independently and a lot of patients may become gradually reclusive because they fear the outside world and enduring potential injuries.

Mounting irritation, aggravation, and stress also accompany hemianopia because people who suffer from it constantly think that people are bumping into them or objects are appearing out of nowhere. This can make it virtually impossible to function normally in crowded places. Part of the problem is that a lot of people don’t even realize that they have hemianopia until they’re officially diagnosed with it.

How is hemianopia diagnosed?

In order to accurately diagnose hemianopia, your optometrist will most likely send you to a specialist who will then conduct a series of tests on your vision. They’ll start off by asking you a series of questions with the intent of gaining a thorough and clear understanding of the symptoms you’re experiencing. You’ll also undergo a series of visual tests using a machine called a Humphrey Field Analyzer.

This machine tests the depth of vision in each eye individually. It flashes lights in each possible point of your vision including the upper left, lower left, upper right, lower right, and the center. All you have to do is press a button to indicate when you see the light. If the machine detects that you’ve missed the light multiple times in the same areas, it’ll determine that there may be blank patches within your visual field and this is an indication that you may have hemianopia.

Following this assessment, if it’s determined that you do have hemianopia, your doctor may then order a series of MRI tests to establish the initial cause of this condition, whether it was a brain injury, stroke, or a tumor.

How is hemianopia treated?

It’s important to note that while hemianopia treatments can be highly effective and rehabilitative, there’s no actual cure for this condition and you will have to continuously undergo various relief methods that can only stand to improve the condition and make it more manageable.

That said, the following is a list of treatment options for hemianopia. It’s up to your doctor to determine which one would be the most suitable for you depending on the type and severity of the hemianopia you have. In some cases, it might even be appropriate and useful to incorporate a combination of these treatments. Again, your doctor will typically use their own expertise and discretion in such cases.

Visual restoration therapy

This is provided by NovaVision and uses computerized software to help improve patients’ vision in half-hour increments where the patient is instructed to focus their gazes on a specified point and must move their head whenever they see a flash of light or other stimuli in their field of vision. This information is recorded by the computer and the treatment is adjusted with each session and progress of the patient.

Audio-Visual stimulation training

This is a multi-sensory visual training approach to attempting to improve the visual fields of people who suffer from hemianopia and it’s especially effective for treating homonymous hemianopia. It stimulates both the auditory and visual senses in an attempt to get them to work harmoniously with one another and improve the patient’s quality of life despite having this condition.

Optical visual span expanders

These are specialized sunglasses that are formulated specifically for each individual patient and their level of hemianopia. The sunglasses have prisms embedded in their lenses that can help enhance the patient’s vision and expand their field of vision while wearing them.

Explorative saccade training

Also referred to as scanning therapy, this technique tests the speed and correlation with which both eyes move from one focal point to another. The optometrist will observe as the patient’s eyes jet from one vertical or horizontal focal point to another and examine whether the eyes separate or move in unison. People who suffer from hemianopia are taught to incorporate this visual technique in their everyday lives to help them naturally expand their field of vision in every direction.

How does hemianopia affect everyday life?

Hemianopia can have a detrimental effect on a person’s everyday life if left untreated. Especially as people get older, they tend to become more reclusive due to this condition because they feel like burdens to their loved ones and everyone around them. People with diminished eyesight may have a hard time moving around without bumping into people or objects and because their line of vision is diminished as well, they most likely will have to surrender their driving privileges as well. This can make them feel like an even greater burden on their family and friends if they need to be driven everywhere or require the special assistance of a loved one or caregiver.

Hemianopia will undoubtedly have a strong impact on your everyday life, but that doesn’t mean it has to hold you back from being able to resume your regular activities or from doing the things you enjoy. By learning proper management and adaptation techniques, you can learn to live with and even conquer symptoms associated with hemianopia. If you’ve recently suffered a stroke, brain injury, or tumor and are noticing a vast decline in your vision, express these concerns to your doctor immediately so that they can start taking steps to administer a helpful treatment plan.

Related: How to improve vision: 11 home remedies to improve eye health


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