Regular eye tests are crucial to maintaining good eye health and detecting any potential vision problems early. Several different tests are performed to evaluate various aspects of vision, providing valuable information about the overall condition of your eyes. These tests are administered by ophthalmologists or optometrists and help determine the need for corrective measures or further medical intervention.
The Snellen Chart Test: The Snellen chart is a widely recognized tool for measuring visual acuity. Patients are asked to stand at a certain distance from the table, usually 6 meters, and read aloud the letters or symbols that appear on it. Each row in the table represents a different level of visual clarity, with the top row consisting of large, easily identifiable characters, and subsequent rows of decreasing size. The results of this test are usually recorded using the fraction format, in which the numerator indicates the distance the patient is from the chart and the denominator represents the distance at which a person with normal vision can read the line withsuccess. For example, if a patient reads the line 20/40, it means that she can read at 6 meters what a person with normal vision would read at 12 meters.
Did she know? The Snellen chart owes its name to Dutch ophthalmologist Hermann Snellen, who developed it in 1862. It is one of the oldest and most widely used ophthalmological tests in the world.
Tonometer test: Also known as the “eye pressure” test, the tonometer measures the intraocular pressure (IOP) inside the eye. Elevated IOP is often associated with glaucoma, a disease characterized by damage to the optic nerve that can cause vision loss if left untreated. During the tonometry test, anesthetic drops are instilled and a small device or probe is gently touched to the cornea to measure the pressure. There are different types of tonometers available, including the applanation tonometer, air puff tonometer, and indentation tonometer, each with its own specific method of measuring IOP.
| Tonometer | Method | Advantages | Disadvantages |
|---|---|---|---|
| Applanation Tonometer | Touch the cornea with a small probe | – Provides accurate and reliable measurements – Commonly used in clinical settings |
– Requires anesthetic eye drops for greater patient comfort – Requires skill to handle |
| air puff tonometer | Measurement of the response of the cornea to a puff of air | – Contactless method – Fast and does not require anesthesia |
– Less accurate than applanation tonometry – May cause mild discomfort to some patients |
| Indentation Tonometer | Applying pressure to the cornea with a small device | – Less affected by the properties of the cornea – Can be used in various positions (sitting, lying down) |
– Requires calibration before each use – Results may be influenced by operator technique |
Tests for Eyes
Visual acuity test: It is one of the most common tests performed during an ophthalmological examination. It measures a person’s visual ability and consists of reading letters or numbers from a distance. The Snellen chart is usually used for this test, in which each row of letters represents a specific level of visual acuity. The results are recorded using the system of fractions, in which the upper number is the distance the person is from the chart, and the lower number indicates the line they were able to read accurately. This test helps determine if corrective lenses are necessary.
Useful tip:
Regular ophthalmological examinations allow vision problems to be detected early, allowing for prompt treatment and prevention of any further deterioration.
- Refraction test: This test determines the exact prescription needed for glasses or contact lenses. The optometrist uses a phoropter to present different lens options and asks the patient to choose the clearest one. By evaluating how the patient’s eyes focus light, the optometrist can determine the appropriate lens power for optimal vision correction.
- Intraocular pressure test: This test measures the pressure inside the eye and helps detect glaucoma, a disease characterized by increased pressure that can cause vision loss. Tonometry testing is often used, in which a small device is gently touched to the surface of the eye or a puff of air is directed over the ocular surface. Results are recorded in millimeters of mercury (mmHg).
It is recommended to schedule regular eye checkups every one to two years, or more frequently if advised by an eye care professional. These tests, along with others, help ensure early detection and proper treatment of any eye condition, contributing to long-term eye health and well-being.
| Proof | Function |
|---|---|
| Visual acuity test | It measures how well a person sees and identifies the need for corrective lenses. |
| Refraction test | Determine the right graduation for glasses or contact lenses. |
| Intraocular pressure test | It measures the pressure inside the eye and helps detect glaucoma. |
Understanding Vision Problems
One of the most frequent vision problems is myopia. This condition causes distant objects to appear blurred, while nearby objects remain crisp. Myopia is usually diagnosed during childhood and can progressively worsen over time. To determine the severity of myopia, the ophthalmologist can perform a visual acuity test in which the patient reads the letters of a table at a certain distance.
Did you know what?
Myopia affects approximately 30% of the world’s population and is expected to increase its prevalence in the coming years due to factors such as the increase in time against the screen and the decrease in time that is passed outdoors.
Another frequent vision problem is farsightedness. This condition makes vision difficult, while distant objects may seem clear. Freemetropia can cause visual fatigue and headaches, especially during activities that need to focus on close objects for prolonged periods. A complete ophthalmological examination, which includes a refraction test, can help diagnose the farsightedness and determine the proper prescription of corrective lenses if necessary.
- Myopia
- Farsightedness
- Astigmatism
- Presbyopia
Astigmatism is another frequent vision problem characterized by a cornea or crystalline irregularly, which causes blurred or distorted vision at any distance. It can be diagnosed by a complete ophthalmological examination and is usually corrected with graduated glasses or contact lenses specifically designed for astigmatism.
With age, people can also suffer from Presbyce, a disorder that affects the ability to focus close objects. The presbyopy is caused by the natural process of aging of the lens, which makes it difficult to read small prints or the realization of tasks that require a close vision. Graduated reading glasses or multifocal lenses can help people with presound to recover a clear vision for activities closely.
- Myopia
- Farsightedness
- Astigmatism
- Presbyopia
| Vision problem | Characteristics | Diagnostic test |
|---|---|---|
| Myopia | Negid close objects, blurred distant objects | Visual acuity test |
| Farsightedness | Clear distant objects, blurred nearby objects | Refraction test |
| Astigmatism | Blurred or distorted vision at any distance | Complete ophthalmological examination |
| Presbyopia | Difficulty focusing close objects | Complete ophthalmological examination |
Common Types of Eye Tests
1. Visual Acuity Test
A visual acuity test measures the clarity and sharpness of a person’s vision. It is usually done with an optometric table, known as Snellen table. During this test, the person must remain standing or sitting at a certain distance from the table and reading aloud the letters or symbols of the smallest row that can see precisely. The results are usually documented in the form of fractions, considering 20/20 as a normal or medium vision. A result of 20/40, for example, means that the person can see at 20 feet what people with normal vision can clearly see 40 feet.
2. Visual Field Test
A visual field test, also known as perimetry, evaluates the scope and sensitivity of a person’s peripheral vision. It helps identify any anomaly or loss of vision in the external areas of the visual field, which may indicate conditions such as glaucoma or retinal injuries. During this test, the person focuses on a fixed point while small flashes of light appear in different places of their peripheral vision. Next, you are asked to press a button or indicate every time you see the flashes. The results are mapped and recorded to create an image of the person’s visual field.
Important:
- The visual acuity test evaluates the clarity and sharpness of the vision.
- The visual field test evaluates the scope and sensitivity of the peripheral vision.
- These tests help identify eye conditions and control the health of the eyes.
Visual Acuity Tests
1. Snellen diagram test (remote visual acuity test):
The Snellen table test is a widely used screening tool to evaluate a patient’s visual acuity. This test evaluates the ability to recognize letters or symbols from a specific distance (usually 6 meters) in a wel l-lit room. The patient covers an eye every time and reads the letters of the table, starting from top to bottom, until he can no longer discern characters clearly.
2. 2. Table and inverted test (test and illiterate):
The Tumbling E table test is specifically designed for people who have difficulty reading or recognizing letters. Instead of using letters, this test uses several orientations of the letter “E” shown in different directions. The patient is asked to indicate the direction in which the E is oriented (up, down, left or right). By precisely identifying the E orientation, the examiner can evaluate the person’s visual acuity without depending on their reading ability.
3. Close visual acuity test:
The near visual acuity test measures a person’s ability to see clearly at a close distance, typically 35 to 40 centimeters (14 to 16 inches). This test is performed with a hand-held chart containing different font sizes, and the patient is asked to read the smallest lines possible. Helps identify myopia or presbyopia, a condition associated with age-related loss of ability to focus on nearby objects.
Visual acuity testing is essential to evaluate a patient’s visual function and identify potential visual abnormalities. These tests form the basis for prescribing appropriate treatments, such as corrective lenses or additional diagnostic evaluations, ensuring optimal visual performance and eye health.
Color Vision Tests
The most used color vision tests
- Ishihara color plate test
- Farnsworth-Munsell 100-tone test
- anomaloscope test
The Ishihara color plate test is a widely recognized screening tool for detecting defects in red and green color vision. It consists of a series of plates, each with a pattern of dots of different colors and sizes. People with normal color vision can perceive numbers or shapes within the patterns, while those with color vision deficiency may have difficulty identifying them. This test is especially useful for detecting the most common types of color blindness.
Important note: The Ishihara color plate test should not be the sole criterion for diagnosing color vision deficit. Other tests may be necessary to confirm the results.
The Farnsworth-Munsell 100 Shade Test is a comprehensive assessment that assesses a person’s ability to arrange color caps in a specific order based on their shades. This test is more sophisticated and can detect subtle deficiencies in color vision. It provides a detailed analysis of a person’s color perception and helps identify specific color deficiencies or variations.
The anomaloscope test consists of comparing the perception of a mixture of red and green with a fixed yellow color. People with different types of color vision deficiencies may perceive the mixture differently. This test helps determine the type and severity of color vision deficiency by evaluating the trichromatic nature of color vision.
| Test name | Evaluation mode | Strengths |
|---|---|---|
| Ishihara color plate test | Perception of numbers/shapes in colored patterns | Quick and easy screening tool, widely available |
| Farnsworth-Munsell 100-tone test | Sorting colored caps by shade | Thorough analysis, detects subtle deficiencies |
| anomaloscope test | Relates the perception of red-green mixture with yellow | Determine the type and severity of chromatic vision deficiency |
Eye Movement Tests
A widely used ocular movement test is the s o-called soft monitoring test. During this evaluation, patients are told to follow a moving target, normally a pen or a finger, only with the eyes. This test evaluates the ability of the eyes to gently follow an object in motion and helps detect any problem of coordination of the eye muscles. The soft follo w-up test is especially useful for diagnosing disorders such as strabismus (crossed eyes) or nystagmus (involuntary eyes movements).
Types of Eye Movement Tests:
- Prefixed test: This test measures the speed and precision of volunteer eye movements. Patients are asked to look at a series of predetermined points in different directions, evaluating both the speed and the accuracy of eye movements.
- Caloric reflex test: This test consists in stimulating the internal ear with a warm or cold stimulus and observing the resulting eye movements. The caloric reflex test is useful to evaluate the integrity of the vestibular system and detect any anomaly related to it.
- Stability test of the gaze: This test evaluates the patient’s ability to maintain fixed and stable positions of the eyes. Evaluate both the precision and the duration of the fixation of the look, which can provide valuable information on the vestibular function and the oculomotor control.
Ocular movements tests play a crucial role in the diagnosis and monitoring of conditions such as strabismus, nystagmus and vestibular disorders. These evaluations help identify both neurological and muscle anomalies, allowing health professionals to develop specific treatment plans. Ocular movements tests are safe and no n-invasive procedures that provide valuable information on visual health and the general welfare of the patient.
Tonometry: A Test for Glaucoma
1. What is tonometry?
Vision plays a fundamental role in our daily lives, since it allows us to move around the world easily. However, several vision disorders, such as glaucoma, can threaten the health of our eyes. Tonometry is a no n-invasive test that measures pressure inside the eye, providing valuable information about the health of the optical nerve and the risk of developing glaucoma.
2. Tonometry types:
- Applanation Tonometry: This is the most common type of tonometry performed in clinical settings. During the test, the ophthalmologist or optometrist administers numbing drops and then lightly touches the surface of the eye with a small probe called a tonometer. The device measures the amount of force needed to flatten a small area of the cornea, providing an accurate measurement of IOP.
- Air puff tonometry: This type of tonometry is quick and painless. A gentle puff of air is directed over the surface of the eye and a sensor measures the response, providing an estimate of IOP.
“Tonometry is a crucial tool for identifying people at risk of glaucoma. By measuring intraocular pressure, it helps doctors make informed decisions about monitoring and managing the disease to preserve vision.”
Regular check-ups using tonometry are essential, especially for people with a family history of glaucoma, as early detection and treatment can significantly slow the progression of the disease. By providing valuable information about intraocular pressure, tonometry plays a critical role in identifying people at risk of glaucoma and taking the necessary steps to protect their vision.
