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Perimetry is an ophthalmological examination performed by the ophthalmologist to assess the ability to perceive the central and peripheral visual field, being mainly indicated for diagnosis and monitoring of glaucoma treatment.
Perimetry, which is also known as visual field examination, can also be done to identify visual field changes and retinal diseases, such as diabetic retinopathy, macular degeneration or edema, retinitis pigmentosa, tumors, or retinitis, for example. example.
The perimetry exam can be performed free of charge by SUS, as long as it has a medical indication, but it is also performed in private exam clinics, and the results must be analyzed by the ophthalmologist, who may also indicate the performance of other exams complementary tools to assess the structures of the eyes, such as the OTC test or corneal topography, for example.See other eye exams that can be done by the ophthalmologist.
When is indicated
Perimetry is mainly indicated for diagnosing and monitoring the evolution and response to glaucoma treatment, but it can also be used to diagnose and monitor other situations such as:
- Macular Degeneration;
- Macular edema;
- Pigmentary retinitis;
- Alterations in the optic nerve, such as papilledema and papillitis;
- Neurological problems such as stroke or brain tumors;
- Eye pain;
- Medication poisoning;
- Changes in field of view.
Furthermore, perimetry should be performed when there is a diagnosis of hyperthyroidism, multiple sclerosis, diabetes, high blood pressure, or pituitary diseases, as it allows checking for changes in the visual field.
Types of campimetry
According to the way the exam is performed, perimetry can be classified into three main types:
1. Computerized Perimeter
Computerized perimetry, also called computerized perimetry, is performed using an electronic device, with no operator interference, and generally provides a more accurate diagnosis, and can be performed on one or both eyes.
2. Kinetic Campimetry
Kinetic perimetry that uses equipment with a light source that is in motion, being moved at different angles, which is perceived by the person.
3. Static perimeter
In static perimetry, the equipment with the light source is stationary, without moving, emitting different light stimuli, and the person must click on a button on the device, each time it identifies the brightness.
4. Manual Campimetry
Manual perimeter monitoring includes kinetic and static perimeter monitoring, as it is performed using the commands of a trained professional.
In general, manual perimetry is indicated to identify problems in the more peripheral vision and to evaluate people with great loss of visual acuity, the elderly, children or debilitated people, who have difficulty following the device's commands.
How the perimeter is made
Visual campimetry is performed with the person seated and with the face glued to the measuring device, called a campimeter, which emits points of light in different places and with different intensities in the patient's field of vision.
During the test, a light on the back of the device is emitted so that the person keeps the vision focused on it. Thus, he will have to ring a bell as he manages to identify the new points of light that appear, but without moving his eyes to the sides, finding the lights only with his peripheral vision.
The perimetry exam is simple and painless, lasting about 10 to 20 minutes, depending on the person's collaboration. No preparation is required to perform this exam, it is only indicated that people who are being treated for glaucoma discontinue the drug pilocarpine about 3 days before the exam, according to the doctor's guidance.
Also, people who wear contact lenses do not need to remove them to take the exam, but they should always remember to bring the last prescription for the prescription of the glasses.