- 1). Calculate the proper power of the contact lenses. The prescription's power is different from a spectacle prescription's power because the contact lenses sit right on the eye and spectacle lenses sit away from the eye. The power is based on vertex distance, which is between the back surface of a lens and the front surface of the eye.
- 2). Measure and record the K-readings with a keratometer, an ophthalmic instrument that measures the curves of the cornea, the front surface of the eye.
- 3). Determine the curvature of the lenses based on the K-readings. Called a base curve, this measurement determines if the lenses follow the shape of the cornea and do not curve too flat or steep. Improper curvature in a contact lens fit can cause discomfort and damage.
- 4). Use the slit lamp, an ophthalmic microscope, to evaluate the health of the cornea and dryness of the eye. Certain kinds of contact lenses work better for dry eyes. A cornea with any damage, even little nicks or tears, cannot be fitted with a contact lens until it heals.
- 5). Do a trial fit of potential lenses based on all your previous testing. Trial fitting is done to see how a lens fits on the eye after predetermining base curve, lens power and the type of lens. Allow the lenses to sit on the eyes for at least 20 minutes. Then check the fit under the slit lamp, and check visual acuity with a Snellen chart and reading chart.
- 6). Continue to monitor the lens fit for several weeks. Check how the lenses fit, as well as distance and near visual acuity, until a final determination for a contact lens prescription is made.
SHARE
