Medical Terminology: Vision Tests and Procedures

1. What are Vision Tests and Procedures?
Light rays pass through the cornea, the pupil, and lenses, which focus the ray of light onto the retina located at the back of the eye. When light rays are not properly focused on the retina, the patient is unable to see clearly.
Light rays focused in front of the retina causes myopia (nearsightedness), enabling patients to better see things near them than at a distance. Light rays focused behind the retina causes hyperopia (farsightedness), enabling patients to see things at a distance better than up close. When light rays are irregularly bent, images are blurred, resulting in astigmatism.
A standard vision test is used to assess the patient’s ability to see close up and at a distance. It also determines if the patient is experiencing peripheral vision difficulty or might have macular degeneration. In addition, the test determines the refractive error of the patient’s eye, which determines the corrective lenses needed to restore the patient’s eyesight.
Patients who have myopia might be able to have this condition fixed by having corneal ring implants or by reshaping the cornea using photorefractive keratectomy.
A trabeculectomy or a trabeculotomy can be performed to drain aqueous humor that might be backing up because of a blockage in the trabecular meshwork. Seton glaucoma surgery might be performed to insert a drainage tube in the eye to drain the aqueous humor.
Blood flow in the eye can be assessed by performing an eye angiogram, which detects a vitreous hemorrhage. A vitreous hemorrhage is treated by performing a vitrectomy.
A detached retina occurs when the retina is detached from the back wall of the eye. When this occurs, the health care provider can repair the problem by performing a sclera buckling to relieve traction on the retina. A pneumatic retinopexy might be performed to push the retina back into position, using a gas bubble.

2. Vision Tests
Vision tests are performed to correct the patient’s vision with glasses or contact lenses and to determine if the patient is color blind or losing peripheral vision, or to determine if the patient has macular degeneration. Vision tests determine the refractive error of the patient’s eye, which determines the proper corrective lenses needed to restore the patient’s eyesight.

Understanding Vision Tests
The health care provider examines the patient’s peripheral vision and ability to see near and far distances along with the patient’s ability to distinguish colors by performing nine vision tests:
. Confrontation: This test assesses the patient’s peripheral vision by gazing at the health care provider’s nose.
. Amsler Grid: This test assesses for macular degeneration.
. Perimetry: This test assesses the patient’s peripheral vision by flashing lights randomly in a perimeter.
. Tangent Screen: This test assesses the patient’s peripheral vision by gazing at a concentric circle image.
. Snellen: This test assesses the patient’s ability to see distances.
. E Chart: This chart is used to assess the patient’s ability to see distances when the patient is unable to read.
. Near: This test assesses the patient’s ability to see near distances.
. Color Vision: This test assesses the patient’s ability to distinguish colors.
. Refraction: This test measures the refractive error of the patient’s eyes to determine the lens that will correct the patient’s eyesight.

3. Tonometry Test
The tonometry test is a test to screen for glaucoma.

Understanding the Tonometry Test
Tonometry measures the intraocular pressure of the patient’s eye by assessing the amount of pressure necessary to flatten the cornea. There are four methods used to perform tonometry:
- Pneumotonometry: This method uses a puff of air to measure intraocular pressure. No direct contact is made with the eye.
- Applanation: This method uses a tonometer to measure intraocular pressure based on the force required to flatten (applanate) a constant area of the cornea.
- Electronic Indentation: This method uses a tonometer that is connected to a computer to measure intraocular pressure.
- Schiotz: This method uses a plunger to measure intraocular pressure.

4. Electronystagmogram (ENG)
Electronystagmogram (ENG) assesses the underlying cause of loss of balance and vertigo.

Understanding the Electronystagmogram
The electronystagmogram is a test that measures eye movement (both voluntary eye movement and nystagmus) to assess the patient’s balance and the underlying cause of vertigo.

Basic Questions
Vision Tests and Procedures

1. What is a common reason for a patient to not see clearly?
Light rays pass through the cornea, the pupil, and lenses, which focus the ray of light onto the retina located at the back of the eye. When light rays are not properly focused on the retina, the patient is unable to see clearly.

2. What is myopia?
Light rays focused in front of the retina cause myopia (nearsightedness), enabling patients to better see things near them than at a distance.

3. What is hyperopia?
Light rays focused behind the retina cause hyperopia (farsightedness), enabling patients to see things at a distance better than up close.

4. What is astigmatism?
When light rays are irregularly bent, images are blurred, resulting in astigmatism.

5. What is a detached retina?
A detached retina occurs when the retina is detached from the back wall of the eye.

6. How might a health care provider repair a detached retina?
When a detached retina occurs, the health care provider can repair the problem by performing a sclera buckling to relieve traction on the retina. A pneumatic retinopexy might be performed to push the retina back into position, using a gas bubble.

7. Why are vision tests performed?
Vision tests are performed to correct the patient’s vision with glasses or contact lenses and to determine if the patient is color blind or losing peripheral vision, or to determine if the patient has macular degeneration.

8. How does the health care provider know what corrective lenses are needed to restore the patient’s eyesight?
Vision tests determine the refractive error of the patient’s eye, which determines the proper corrective lenses needed to restore the patient’s eye sight.

9. What is a confrontation test?
A confrontation test assesses the patient’s peripheral vision by gazing at the health care provider’s nose.

10. What is the Amsler grid test?
The Amsler grid test assesses for macular degeneration.

11. What is a perimetry test?
A perimetry test assesses the patient’s peripheral vision by flashing lights randomly in a perimeter.

12. What is the tangent screen test?
The tangent screen test assesses the patient’s peripheral vision by gazing at a concentric circle image.

13. What is a Snellen test?
A Snellen test assesses the patient’s ability to see distances.

14. What is the E chart?
The E chart assesses the patient’s ability to see distances when the patient is unable to read.

15. What is the near test?
The near test assesses the patient’s ability to see near distances.

16. What is the color vision test?
The color vision test assesses the patient’s ability to distinguish colors.

17. What is the refraction test?
The refraction test measures the refractive error of the patient’s eyes to determine the lens that will correct the patient’s eyesight.

18. Why is the tonometry test performed?
The tonometry test is performed to screen for glaucoma.

19. What is measured by the tonometry test?
The tonometry test measures the intraocular pressure of the patient’s eye.

20. What is pneumotonometry?
Pneumotonometry uses a puff of air to measure intraocular pressure. No direct contact is made with the eye.

21. What is applanation tonometry?
Applanation tonometry uses a tonometer to measure intraocular pressure based on the force required to flatten (applanate) a constant area of the cornea.

22. What is electronic indentation tonometry?
Electronic indentation tonometry uses a tonometer that is connected to a computer to measure intraocular pressure.

23. What is Schiotz tonometry?
Schiotz tonometry uses a plunger to measure intraocular pressure.

24. Why is an electronystagmogram (ENG) ENG?
An ENG assesses the underlying cause of loss of balance and vertigo.

25. What is measured in an ENG?
An ENG is a test that measures both voluntary eye movement and nystagmus to assess the patient’s balance and evaluate the underlying cause of vertigo.