Patient History
A patient history helps to determine any symptoms the individual is experiencing, when they began, the presence of any general health problems, medications taken and occupational or environmental conditions that may be affecting vision. Dr. Miller will ask about any eye or vision problems you may be having and about your overall health, and about any previous eye or health conditions you or your family members may have.
Visual Acuity
Visual acuity measurements evaluate how clearly each eye is seeing. As part of the testing, you are asked to read letters on distance and near reading charts. If the patient cannot read, we will use shapes. The results of visual acuity testing are written as a fraction such as 20/40.
When testing distance vision, the top number in the fraction is the standard distance at which testing is done, twenty feet. The bottom number is the smallest letter size you were able to read. A person with 20/40 visual acuity would have to get within 20 feet of a letter that should be seen at 40 feet in order to see it clearly. Normal distance visual acuity is 20/20.
Preliminary Tests
Preliminary testing may include evaluation of specific aspects of visual function and eye health such as depth perception, color vision, eye muscle movements, peripheral or side vision, and the way your pupils respond to light. We will also evaluate the vision and fit of contact lenses.
Keratometry
This test measures the curvature of the cornea, the clear outer surface of the eye, by focusing a circle of light on the cornea and measuring its reflection. This measurement is particularly critical in determining the proper fit for contact lenses.
Refraction
Refraction is conducted to determine the appropriate lens power needed to compensate for any refractive error (nearsightedness, farsightedness, or astigmatism). Using an instrument called a phoropter, we will place a series of lenses in front of your eyes and measures how they focus light using a hand held lighted instrument called a retinoscope.
It can be stressful to answer, “which is better, one or two.” With the use of the phoropter, we can limit how many times you are asked, and achieve an accurate prescription. Depending on your eyes, Dr. Miller may choose to use an automated instrument that automatically evaluates the focusing power of the eye. The power is then refined by patient’s responses to determine the lenses that allow the clearest vision.
This testing may be done without the use of eye drops to determine how the eyes respond under normal seeing conditions. In some cases, such as for patients who can’t respond verbally or when some of the eyes focusing power may be hidden, eye drops are used. The drops temporarily keep the eyes from changing focus while testing is done.
