Hopes for High Myopes in the Future?Key words: orthokeratology,myopia,corneal topography
Our patient is a 29-year-old white female project manager with a 20 year history of (R)GP lens wear. She would like to reduce her dependency on daily wear contact lenses because of sports and environmentally induced comfort issues, but she is not interested in eye surgery. She heard about orthokeratology from her co-workers.
Her prescription is:
OD -8.25D, 20/20 distance and near
OS -8.00D, 20/20 distance and near
After repeated attempts to dissuade the patient, we agreed to try reducing the amount of myopia sufficiently to allow for part-time soft lens wear.
Her keratometry values are:
OD 42.25/43.00 @ 082
OS 42.25/42.75 @ 089
Lenses selected were ShinyEyes GOV XM lenses, a specialty lens for high orthokeratology corrections, in Paragon HDS 100: OU 10.14 / +2.00D / 11.20. The reverse geometry design featured a spherical base curve, 5mm BOZD and an aspheric alignment curve with appropriate edge lift.
Lenses were fitted and observed to center well with appropriate bullseye fluorescein pattern and sufficient movement.
One day later: significant treatment occurred overnight and -1.00D soft lenses were dispensed, but the patient required -4.00D correction by mid afternoon.
By day three the correction was lasting well into the evening, requiring re-application of OK lenses only for driving.
By day 10, all-day full treatment was achieved with excellent daytime vision, but the small treatment zone was causing too much glare in low light conditions.
Oftentimes by loosening the peripheral alignment curves and flattening the base curve radius, the lens will settle in closer to the cornea by a few microns, thereby increasing the treatment zone diameter.
New lenses were ordered and dispensed: OU 10.17/+2.00/11.20. After one week of wear, the treatment zone diameters improved enough to allow for much more comfortable vision in dim illumination.
One month after initial fit: Unaided visual acuities were 20/20 in each eye and 20/15 OU. Refraction as measured by Ophthonix Z-View Aberrometer:
OD: -0.25 -0.25 X 013
OS: +0.25 -0.25 X 173
Good unaided visual acuity
Although full correction was not the goal with this patient, the overrefraction is minimal and the visual acuity very satisfactory.
Aside from high myopia, there were several aspects to this case that made it a bit more challenging. While corneas can be routinely taken to 36.00 diopters (9.38mm), moving on to 34.00 diopters (9.93mm) can sometimes be more tedious. Furthermore, the patient’s unwillingness to discontinue (R)GP wear and return to baseline corneal topography was a handicap. When a successful finish relies on differences of a few microns, it would be good to know where the starting line was. This could certainly explain having to adjust the fit midway through the treatment.
Correcting these levels of high myopia with orthokeratology is an off label use in the United States and should be monitored more closely for possible adverse reactions. That being said, this could be a viable adjuvant to traditional methods of treatment for higher myopia.
Bruce T. Williams
Seattle, Washington USA