Maintaining eye health and eye care are vital to protecting your eyesight, maximizing your vision, and intervening to treat eye problems early and prevent damage. Knowing what to expect at an eye exam can help relieve some of the anxiety that people have about scheduling this important check up and also help to make an important distinction between an eye exam and a vision screening.
During the eye exam, the patient will have approximately a dozen eye exams performed and perhaps several more if the doctor determines that further investigation is necessary. The exam typically takes about an hour. The majority of the tests are non-intrusive; however some of the tests require slightly more interaction and can involve eye drops, light touching of the eye surface with instruments or puffs of air blown onto the eyeball. Understanding these tests, their necessity and what to expect can help to ease any trepidation that a patient may have about the eye exam.
The following is a list of eye exams that can take place in a routine exam:
Eye Muscle Movement Test
This test will measure both muscle strength and precision of control. The patient tracks a target visually in many different directions while the doctor observes the eye movements.
The cover test determines how effectively your eyes work together. The patient stares at a small target at a given distance (possibly farther away first and then closer) and the doctor will alternately cover each eye to observe eye movement and determine if the eye looks away from the target.
Physical Exam and Papillary Reaction Test
This test involves the reaction of your pupils both to light and to objects with close proximity, as well as, an examination of the eye itself. The physical exam involves the doctor observing the external features of the eye such as the whiteness of the eye, the eyelids, and the tear ducts to check for general wellness or warning signs.
Visual Acuity Test
The visual acuity test will determine the performance level of your vision and usually involves reading letters across a line from an eye chart covering each eye in turn, with each subsequent line of letters getting smaller and smaller. The distance from the eye exam chart and the level of letters that are discernable to your eye determines your performance level. The visual acuity test is where the patient’s relationship to the 20/20 benchmark for eye performance is determined.
Retinoscopy determines the way the light reflects from the eye to determine the prescription that is necessary to correct vision. While looking through a retinoscope, the patient stares at a target as the doctor shines a light in the eyes and rotates a number of lenses in front of the eyes to observe the way light is reflecting. From the Retinoscopy the doctor can get a general sense of the lens prescription that will be necessary.
This test is used to determine the exact prescription. The doctor will often fine tune the prescription by asking the patient to focus on a target while the doctor flips back and forth through a number of lenses and asks the patient to determine which lens provides the most clarity. This is only performed on individuals that need corrective measures.
Slit Lamp Examination (Biomicroscope)
The slit lamp exam magnifies and illuminates the front of the eye and is used to detect eye disease. The split lamp test helps the doctor examine the cornea, iris, lens and anterior chamber magnified under strong light to detect potential problems.
Retinal Exam (Opthalmoscopy)
The retinal exam uses an opthalmoscope and pupil dilation to examine the back of the eyes. The doctor examines the retina, retinal blood vessels, vitreous and optic nerve head for general health and also any warning signs. For example, some form of diabetes can cause retinal detachment and the retinal exam would reveal this condition.
The Humphrey Visual Field Test uses a bowl shaped machine called a perimeter. The patient stares forward into the center of the bowl without moving their eyes, while lights flash in their peripheral visual field. The patient presses a button each time they see a flash and a computer records each time you respond to or miss a flash. The visual field test results produce a comprehensive map of your peripheral vision.
The glaucoma test determines if the fluid pressure in the eye is within a normal range. There are several methods used to determine the fluid pressure. The applanation tonometer test, uses drops to numb the eyes and as the patient stares at a target directly in front of them, the doctor lightly touches the surface of the eye with a glowing, blue light used to measure the pressure. The non-contact tonometer test, uses a brief, puff of air that is directed into the eye as the patient focuses on a target directly in front of them and the resistance to the puff of air determines the fluid pressure in the eye.
During the pachymetry uses an ultrasound instrument called a pachymeter to measure the thickness of the cornea. The doctor will barely and briefly touch the surface of the eye with the instrument as the patient focuses on an object directly in front of them.
The pupil dilation test allows the doctor to examine the inside of the eye with different instruments and lights, because the pupils are fully enlarged. This pupil dilation eye exam requires pupil-enlarging eye drops that take 20-30 minutes to become effective. The pupil dilation causes the eyes to be much more sensitive to light and blur vision. The dilation can last for a few hours after the exam so it is important to bring sunglasses to wear for the ride home.
These are the components of full, routine eye exams that would take place in an Ophthalmologist or Optometrist’s office. Although visual acuity tests often take place in a variety of eye care settings the additional tests that screen for major disease and potential problems are a critical part of a comprehensive eye exam. Finding an eye doctor is an important part of your health care and regularly scheduled eye exams should be part of your health care routine.