Contact Lenses-How They Work And How I Fit Them Part III

Once the initial lens design, manufacturer and powers have been chosen, the next step is to have the patient experience the lenses in their “real world”.  I have them wear the lenses for a few days to a couple of weeks, after teaching them how to handle and care for their lenses of course.  At the follow up visit, the comfort and quality of vision is assessed as is the interaction between the lens and the patient’s eye.  I expect the patient to have excellent vision and good lens comfort.  There is a bit of an adaptation period until the lenses “can’t be felt” during wear, but the lenses should not be significantly uncomfortable at any point.

If the patient’s vision is not excellent, the power of the lenses may be the culprit so we perform an “over-refraction” checking to see if the lenses need to be stronger or even weaker than the  initial lenses.  I also look at the positioning and rotation of the lenses, especially if the patient is wearing a “soft toric” lens as rotation will adversely effect the patient’s vision.  For multifocal lens wearers, I evaluate both the distance and near lens powers as a change in either one can effect the other.  Below is an image of a soft toric lens on the eye.  Notice the laser etching marks which are used to determine if the lens is rotating on the surface of the eye.

Things that I’m always looking out for at these visits are lenses that fit too right or too loose, lenses that aren’t centered well on the eye, any disruption of the corneal surface as well as any redness or eye irritation.  Below is a video of an RGP lens that is fitting well.  Notice how the lens moves just a bit when the patient blinks.  There’s a delicate balance between too much and too little movement.

The photo below is of an eye that has a small but significant amount of corneal disruption.  I had to change the fit of this lens just a bit to get rid of this problem and avoid potential long term problems with their ocular health.

Once we know that the patient is doing well with their lenses, we will then create a final Rx and lenses for the patient are ordered.  Periodic follow up visits are indicated based on the type of lenses and wearing schedule as well as each patient’s ocular health status.  As you can see, quite a bit goes into the entire contact lens design, fitting and follow up process.  You can rest assured that I will take the time and use the technology to work with you to determine the proper lens type, lens fit, lens wearing schedule and lens replacement schedule that is right for you.


Dr. Warren

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