Visual field test
Visual field test
The visual field test aims to identify the safety and correctness of vision. That helps discover physiological dysfunctions in the eye, which arise from a group of diseases, and there are many methods used to examine the visual field. Be it in simple ways, or through advanced technical means.
What is the optical field?
The optical field is defined as the maximum vision a person can see in the center on both sides without moving the eyes, meaning that the visual field is seeing the thing and what is around it.
For example, in the case of driving a car, this requires looking at the road and the mirror and forward at the same time, and man can do so through the visual field, and the same is true for those who work in security jobs, where it takes them a good visual field to carry out their work tasks, as well as for mothers who do their jobs in the kitchen. At the same time, they must look to their children to avoid any harm to them.
What diseases cause defects in the visual field?
There are a variety of diseases that cause negatives in the visual field, including:
The general feature of cataracts is the presence of turbidity in the eye's lens, which leads to a feeling of lack of light, or the inability to distinguish dim colors, as well as the presence of blurring of vision. Patients feel as if they are seen behind a curtain; the images become blurry, resulting in visual field defects.
The leading causes of cataracts include aging, the negative effect of taking some medications, developing diabetes, stopping the sun's rays for long periods, genetic factors, or exposure to trauma and accidents.
Eye tumors are among the causes of defects in the visual field and affect one or more parts of the eye. These tumors may be primary, meaning that arises in the eye. Or transitional, meaning it is formed in other parts of the body, such as kidney, breast, lung, prostate or thyroid, transmitted to the eye in later stages of tumor disease.
Among the most prominent types of eye, tumors are eyelid tumors, eye socket tumors, retinal tumors, and conjunctival tumors. These tumors may be benign or cancerous.
There are various methods for diagnosing eye tumors, including examining a biopsy of the affected tissue, angiography by furacin, and ultrasound.
There are different methods for treating eye tumors, depending on the diagnosis of the patient's condition. The most prominent of these methods are surgical removal of the tumor, chemotherapy, radiotherapy, and laser treatment.
Glaucoma is one of the diseases that lead to the occurrence of defects in the visual field. Often, this disease affects the eyes, where a high level of intraocular pressure occurs. This disease is one of the diseases that lead to the occurrence of blindness in people over the age of sixty years.
Symptoms of glaucoma appear gradually, and are as follows: Halos appear around a light, eye pain, severe headache, blurred vision, and vomiting.
The reasons for the disease's occurrence are the optic nerve damage, and therefore dark points appear in the field of vision. That disease is associated with a high level of intraocular pressure due to the accumulation of fluids. Genetic factors play an essential role in the inheritance of the disease. The visual field can be examined, and blood pressure is identified to explore the extent of infection with glaucoma.
There are many types of glaucoma, including open-angle glaucoma, closed-angle glaucoma, pigmented glaucoma, normal-pressure glaucoma, and pigmented glaucoma.
Macular degeneration is among the common eye diseases that lead to an imbalance in the visual field. Macular degeneration often occurs in the group over the age of fifty. It leads to foggy vision or defects in the central vision, and the reason for this is the lack of thickness the yellow spot behind the retina, helps to see details of objects, read and distinguish colors.
Among the main symptoms of macular degeneration are difficulty in perception, blurred vision, and an inability to distinguish images. The disease can develop into more severe stages due to an expansion in the blood vessels that feed the retina, and deterioration in vision.
The risk factors that cause macular degeneration are:
Ethnicity: The chance of developing macular degeneration is higher in Caucasians than in other human races.
Age: Macular degeneration most commonly affects those over 50 years of age.
Tobacco smoking: Excessive tobacco smoking causes macular degeneration, as well as the location of smokers.
Overweight: Excess weight or obesity leads to mild macular degeneration, and this develops to a more severe stage of treatment is neglected.
Family history: If a family member has macular degeneration, this may lead to infection as a result of genetic transmission.
Diseases pituitary gland:
Pituitary diseases lead to a disorder in the secretion of many hormones that help in performing various functions in the body. Including growth-stimulating hormone, adrenal stimulating hormone, milk-stimulating hormone (prolactin), luteinizing hormone, thyroid-stimulating hormone, and Anti hormone diuresis. And from the symptom of the pituitary gland is the impairment in the visual field.
A stroke occurs due to a lack of oxidized blood flow to the parts of the brain, which causes cell death. Among the causes of stroke are high blood pressure, obesity, smoking, diabetes, and atrial fibrillation.
Symptoms of a stroke include severe sudden headache, speech disorder, problems in the field of vision, numbness tingling in the face, leg, or arm, with difficulty walking and balance.
Retinal detachment is an emergency that leads to complete visual impairment. That occurs as a result of a portion of the retinal tissue moving in the background of the eye from its normal position, which leads to the separation of the retinal wall from the blood vessels supplying the cells with blood loaded with oxygen and other nutrients. In the event of a prolonged period of retinal detachment without treatment, this may cause vision loss.
Among the main signs of retinal detachment are flashes, disturbances in the peripheral vision, and shadow blocking vision.
Among the most prominent factors that increase the chances of retinal detachment disease are aging, genetic factors, eye injuries, eye surgery, and separation in previous periods, infections, and acute myopia.
Retinal detachment can be treated by fixing the retina by freezing it in the eyewall, or by using lasers and destroying the damaged part. Then fusion occurs between the torn part and the tissues below it.
Multiple sclerosis affects the outer covering surrounding nerve cells in the brain and spinal cord, and this prevents contact between the brain and the rest of the body. Among the most prominent symptoms of the disease: defects in the visual field or total loss of vision, and this often occurs in one eye, and also can Numbness in the extremities, permanent fatigue, speech problems, sexual function defects, and tingling sensation in different parts of the body.
The retina is a slender layer consisting of light-sensitive tissues located in the back of the eye in the form of a semi-circular disk. The retina converts the light refracted to the cornea of the eye, and transmits it to the brain through the optic nerve, and, accordingly, what people see is translated in detail. Mostly retinal bleeding due to disturbed blood sugar level, high blood pressure, or occlusion of blood vessels in the eye causes various complications, including defects of the visual field (field of view).
Benign and malignant brain tumors:
Brain tumors are defined as an abnormal growth of cells that make up brain tissue, and these tumors may be benign or malignant. The tumor may arise primarily in the brain, or it may arise secondary as a result of tumors occurring elsewhere in the body and its transmission to the brain.
The main types of brain tumors include choroid plexus cancer, auditory nerve tumor, Craniopharyngioma, meningioma, glioblastoma, oligodendroglioma, and astrocytoma.
Symptoms of benign and malignant brain tumors include unexplained nausea, difficulty in balance, changes in motor coordination, negatives in hearing, feeling distorted in the field of vision, and frequent headaches.
Brain infection (brain abscess):
A cerebral abscess occurs in the brain tissue, and the cause is the infection of germs that reach the brain through contaminated blood, teeth, nose, or ears. The symptoms of this disease are varied, including high body temperature, an inability to walk, weakness in the extremities, problems with speech, Blurred vision.
What are the ways to examine the visual field?
There are many ways to examine the visual field, and we will explain it as follows:
Tactile screen inspection:
The tangential screen test is among the tests used to examine the visual field, where the examiner sits in front of the screen and focuses the eyesight on one of the targets in the center. Inform the doctor if the object sees an object toward the examined field of vision and when it disappears.
This examination helps to detect defects in the areas of the eye and is called another "endoscopy," and ophthalmologists resort to this examination. To evaluate the posterior parts of the eye, including the retina, the vascular layer, and the hard disk, doctors use a drop to expand the pupil of the eye, so that the doctor can see accurately, and the retina examination is divided into:
Direct examination of the retina: the doctor uses the endoscope and shines light rays toward the pupil; So that he can see the back parts.
Indirect retinal examination: In this type of test, the doctor uses a lens attached to his forehead with a bright light projected, which helps see the eye's internal structure.
Confrontation Examination (Donder Test):
The confrontational examination is among the simple tests performed to examine the visual field, where the doctor is facing the patient with a distance of one meter. Then the doctor requests the patient to cover one eye and to use the other eye. The doctor moves his hand in the area outside the examiner's visual field of the examiner, he slowly restores his hand, and the doctor asks the patient to tell him when he sees his hand, which is repeated concerning the other eye.
Goldman lens examination:
One of the most common ways to examine the optical field is a Goldmann lens examination. This lens consists of a central part, in addition to three mirrors, and each mirror has a different angle. That helps in testing peripheral vision, and then follows the changes in vision in glaucoma patients.
The slit-lamp device is one of the devices used in examining the visual field, where the specialist enlarges the eye through a microscope and highlights. Sometimes the doctor puts drops to expand the pupil of the eye before the test, which helps to examine the iris, cilia, cornea, eyelids, and lens, and accurate images can be obtained three dimensional.
Automated field of view measurement:
One of the critical methods used in examining the visual field is measuring an automatic field of vision. The way the device works depends on the use of light stimuli or images moving on a screen. If the patient sees the light, one of the buttons is pressed, and in this light, the extent of the examiner's visual field is tested. This method is suitable for blind-spot detection.
Glaucoma is one of the tests that aim to identify the level of pressure of the fluid inside the eye, then the discovery of glaucoma that causes nerve damage inside the scientific, and among the methods of measurement:
Flattening pressure gauge: The measurement of eye tension by flattening is one of the methods used to recognize eye pressure, and anesthetic drops are used in it with fluorescein, and the doctor moves the device on the cornea, and then measures the level of pressure inside the eye.
Non-contact pressure gauge: The doctor uses a puff of air toward the eye, which helps to measure eye pressure without touching any parts of the eye. It doesn't require anesthesia, and all that the patient feels is an instantaneous air impulse.
Thickness meter: in case the eye pressure is high or if there are defects in the optic nerve; the doctor can turn to the thickness meter, where this device works through ultrasound to identify the thickness or thickness of the cornea.
Color vision test:
This type of visual field test helps to demonstrate the ability to distinguish between colors. Where the specialist displays a set of raster models with multiple colors, and in the absence of any defects in the color vision, the examiner will know the raster patterns, on the contrary in the case of a color deficiency; the subject will find it difficult to distinguish the specific patterns.
What kinds of eye exams are there other than the visual field examination?
There are various eye examinations other than those related to examining the visual field, including the following:
Light refraction test (evaluation of eye refraction errors):
This examination measures whether or not light is directed toward the focus of the eye inside. If refraction doesn't occur; this is among the disadvantages that require correction through the use of eyeglasses, refractive surgery, or contact lenses, to restore vision. This examination helps determine the specifications of the needed lenses accurately.
Visual acuity examination:
This test measures the sharpness of vision and clarity of vision, as the doctor uses a (Snelline diagram) that includes a set of alphabets printed on a plate, and is displayed at a distance from the examiner. The letters' size ranges from the largest to the smallest, and each eye is examined separately, and the examiner must determine every letter.
Eye muscle tests:
This test helps identify the efficiency of the eye muscle, helps it to control and coordinate, where the doctor notes the eye movement during the follow-up of one of the moving objects directed by the doctor, and then diagnoses the patient's condition.
What are the natural results after completing the visual field examination?
Often, the visual field examination results appear within three days from the date of the test and include various details that determine the extent of the presence of damage or not in the vision through mathematical measurements. The report also includes pictures of the retina, the base of the eye, the cornea and the iris, and they are printed on the computer. In patients with glaucoma (glaucoma), cataracts, some neurological diseases, brain tumors, eye tumors, people with optic nerve damage, or who have suffered strokes, the possibility of finding defects in the visual field increases. If the examined person is normal and doesn't suffer from any symptoms, the results are as follows:
Excellent field of vision - 20/20 vision power - no blue water, lens darkening, macular degeneration, or retinal disturbances - Examined can distinguish between colors - the external makeup of the eye is standard.
If any abnormal results appear, the ophthalmologist approves the appropriate treatment protocol according to the examined case.