To evaluate your eye health, an ophthalmologist performs an array of eye tests as follows:
Eye muscle test
This is to look for signs of poor eye coordination or control and weakness of eye muscles. You will look at a moving object such as a pen for evaluation of your eye movements.
Visual acuity test - eyechart
This assessment evaluates how well you see. You will look at rows of alphabets in different sizes on a chart or screen at some distance away. Your ophthalmologist will check each eye separately. You may need to hold and read a card to test your near vision.
Refraction test
This test checks the focal point on the back of your eye. If you have a refractive error, you may need glasses, contact lenses, or refractive surgery to correct your vision.
Your ophthalmologist may use an autorefractor or retinoscopy to measure the refractive error by shining a beam of light into your eye and evaluating the reflected light from the back of the eye. Finally, you will look through a phoropter containing different lenses to fine-tune a proper combination of lenses for your eyesight.
This test helps determine the sharpest and most comfortable lens prescription for you.
Visual field test
A visual field test or perimetry assesses the extent of your peripheral vision while your eyes focus on a central point. Your ophthalmologist may order:
- Automated perimetry: You will look at a screen and press a button whenever you see a blinking light.
- Confrontation exam: You will sit opposite your ophthalmologist. You will be asked to cover one of your eyes, look straight ahead, and notify when you see him/her moving into your view.
- Tangent screen or Goldmann field exams: You will be asked to look at a screen and tell your ophthalmologist whenever an object is moving into or disappearing from your side vision.
Your ophthalmologist can evaluate your peripheral visual field based on your response. If you have difficulty seeing in certain spots, the pattern of visual loss can help diagnose the eye condition you are having.
Color vision test
You will look at several multicolored dot patterns and tell the numbers and shapes you see.
If you do not have color blindness, you can make out the numbers or shapes with no problem. However, if you have congenital color vision deficiency, you will not be able to see red or green colors. If you cannot differentiate between blue and yellow colors, you may have color blindness due to eye diseases, including optic nerve disease or glaucoma.
Slit-lamp examination
Your eyes, including eyelashes, eyelid, conjunctiva, cornea, iris, lens, and fluid chamber between your cornea and iris, will be examined through a slit lamp or a magnifying microscope with beaming light into the front part of your eyes. A dye will be dropped into your eyes to check if the front part of your eye is damaged. The dye will wash away rapidly by your tears.
Retinal examination
Retinal examination or fundoscopy is a test to assess your retina, optic disc, and retinal blood vessels. Before the procedure, eyedrops will be given to dilate your pupils for checking the back of your eye.
- Direct exam: An ophthalmoscope will be used to shine light through your pupil to see the back of the eye. Pupil dilation may not be necessary.
- Indirect exam – The retina and internal eye structure will be thoroughly examined through a condensing lens and a bright light.
Glaucoma screening test
Tonometry is a test to measure intraocular pressure and evaluate if you have glaucoma.
- Applanation tonometry: Eyedrops with fluorescein and anesthetic to numb your eye will be dropped onto your eyes. The tonometer will be used to contact your cornea and check the eye pressure.
- Noncontact tonometry: A puff of air will be blown into your eye to determine your eye pressure. You may startle during the process.
- A pachymeter will be used to measure your corneal thickness by sound waves if you have high eye pressure or abnormal optic nerve. Additional tests may be prescribed, depending on your age, medical history, and risks of developing eye diseases.
Results
Once your ophthalmologist has the result, he/she can explain if you need vision refractive correction or have an eye disease. If you have a vision problem, you will need a prescription glasses or corrective lenses. If you have severe eye disorders, such as macular degeneration, diabetic retinopathy, or glaucoma, your ophthalmologist will discuss and suggest appropriate tests and treatments.
