Coping With the Six-Month Syndrome
BY JOHN MARK JACKSON, OD, MS, FAAO
Establishing a schedule for follow-up visits is important with any type of contact lens wear, but it's especially important with orthokeratology. You should see ortho-k patients regularly to ensure that complications are minimal and that patients are compliant with their wear and care regimens.
The "six-month syndrome," which I'll explain here, is a perfect example of why you need to schedule regular visits for these patients.
Observing the Phenomenon
When I first started fitting ortho-k lenses, I noted a curious phenomenon that other practitioners later confirmed. Patients would do well until their six-month visit, at which point they would report that their vision had degraded a little during the previous few weeks. Their uncorrected acuity was usually a few letters to a line worse than previously, and sometimes we couldn't achieve a full 20/20 with correction.
Biomicroscopy usually revealed no corneal signs such as staining or edema. Corneal topography, however, usually showed some degree of central irregularity compared to previous maps (see the six-month [lower right] map in Figure 1). What was the cause of this irregularity, and how could we fix it?
Figure 1. Corneal topography reveals central irregularity after six months of ortho-k lens wear.
Clearing Things Up
When I inspected the patients' contact lenses, almost all of them had some back surface deposits visible with the slit lamp. Because I could find no other cause, I assumed that the deposits might be causing the topography irregularity and decreased daytime acuity.
I cleaned each patient's lenses with heavy duty lab cleaners (such as Boston Cleaning Polish [Polymer Technology] and Fluorosolve [Paragon Vision Sciences, Inc.]) to remove the deposits and asked the patients to return for follow up in week or so. The cleaning usually resolved the problem and improved their acuity. If it didn't, then I ordered a clean, new pair of lenses.
Other reasons may cause a patient to experience reduced acuity during treatment, so make sure you explore all possibilities. But a thorough cleaning usually takes care of it.
Let me communicate a note of caution: I don't recommend polishing the back surface of ortho-k lenses. Doing so can alter the parameters, resulting in a change in treatment effect.
Review lens cleaning steps with your patients to make sure that they understand your care instructions, but know that even this may not help -- I've found that even seemingly compliant patients have experienced the "six-month syndrome."
Because of this problem, I generally recommend that patients use a daily cleaner or daily enzyme rather than a multipurpose GP solution alone when caring for their ortho-k lenses.
Dr. Jackson is an assistant professor at Southern College of Optometry where he works in the Advanced Contact Lens Service, teaches courses in contact lenses and performs clinical research.