For millions, contact lenses provide a safe and effective alternative to eyeglasses. Like the proper fit of shoes, contacts must be expertly fitted for cornea health and comfort with a Contact Lens Exam. One contact lens size doesn't fit all. If the curvature of a contact lens is too flat or too steep for your eye's shape, you could experience discomfort or even eye damage. Here’s what to expect during a comprehensive Contact Lens Exam at Eye Health Northwest:
You will be asked general questions about your lifestyle and preferences regarding contact lenses, such as whether you're involved in sports or if you're interested in options such as daily disposable lenses or overnight (extended) wear. Your eye doctor may also discuss the option of rigid gas permeable (RGP or GP) contact lenses. Although most people today are fitted with soft lenses, some patients with high amounts of astigmatism or other irregular corneal conditions benefit from the high degree of vision correction offered by GP lenses.
Your eye doctor may ask you about how you might want to correct vision problems related to aging. At about age 40 or maybe older, you will develop a condition known as presbyopia that decreases your ability to see clearly at close distances. To correct presbyopia, your eye doctor may offer you the choice of multifocal or bifocal contact lenses or monovision. With monovision one contact lens corrects for near vision and the other contact lens corrects for distance vision.
The doctor or contact lens technician will use an instrument called a keratometer to measure the curvature of your eye's clear front surface called the cornea. These measurements or K-readings help your eye doctor determine the proper curve and size for your contact lenses. Because the keratometer measures only a small, limited section of the cornea, additional computerized measurements of your cornea (corneal topography) may be done. Corneal topography provides extremely precise details about surface characteristics of the cornea. A computer creates and prints out a surface "map" of your eye with different contours in much the same way as a steepness of a hillside can be illustrated by a topographical map.
Some types of contact lens fitting require that your doctor knows the size of your pupils in different lighting conditions as well as the diameter of your cornea. Pupil and iris measurements help achieve a proper sizing and orientation of your contact lens.
Contact lens fittings may also include a tear film evaluation (epithelium) with these methods.
Your eye's moisture content may be evaluated through use of small strip of paper inserted underneath the lower eyelid. You close your eyes for about five minutes, and then the paper is removed to determine how much moisture your eye has produced.
Process of detecting dry eye involves placing fluorescein dye in your eye through eye drops and then evaluating how long it takes for the dye to be washed away by your eye's tears. If your eyes don't produce enough moisture and you have severe dry eye, contact lenses may not be right for you. However, new contact lens materials have allowed many patients with mild to moderate dry to wear contact lenses successfully.
The health of your cornea will be evaluated using a biomicroscope or slit lamp. This information is critical for determining the type of contact lens & wear schedule, as well as establish a baseline for your doctor to evaluate any future changes to your eyes related to contact lens wear. The biomicroscope is used to evaluate the fit of a trial pair of lenses; it allows the doctor to observe the alignment of the lens as it rests on the surface of your eye, ensuring the lens is not too tight or too loose and that it positions on the center of your cornea after each blink. You'll typically need to wear these trial lenses for at least 15 minutes so that initial tearing of the eye stabilizes and so that the lens settles into place on the cornea.
Maintaining your eye health with contacts. Your eye doctor may place a special dye (fluorescein staining) on your eye to check for defects and make sure your contact lenses are not damaging your eye's surface.
It typically takes about two office visits to complete the contact lens fitting. After finding a contact lens that fits properly, is comfortable for you, and provides good vision, your eye doctor will write a contact lens prescription. This prescription will designate the type of contact lens or contact lens material, contact lens power, a shape matching the curvature of your eye (base curve), and diameter.
Once you are successfully fitted for contact lenses, keep in mind that your eyes will need to be examined once annually so that your eye doctor can monitor the health of your eyes. Some patients may need contact lens progress evaluations prior to the annual visit.