orthokeratology
today
Sometimes, Ortho-k Works Too Well
BY JOHN MOUNTFORD,
DIP. APP. SC, FAAO, FCLSA
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Figure
1. The cornea in cross-section. Note the granular haze that extends into the stroma.
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Like
most practitioners, I send annual reminders to my contact lens patients advising
them that it's time for a review. It's disconcerting how relatively poor the compliance
of ortho-k patients is compared
to disposable lens wearers. This is probably because soft lens wearers can't get
a prescription renewal unless they present for review. When ortho-k patients finally
present, it's usually because of the lenses losing effect as a result of surface
deposits.
An Ortho-k Patient Returns
A patient presented for review five years after his last ortho-k
checkup, with the main complaint being discomfort. He was wearing the lenses every
second night and reported excellent vision when not wearing lenses. His original
Rx was OD –1.75D, OS –2.50D.
Vision was OD and OS 20/15 with refraction giving +0.25D OU. The
real shock came with the slit lamp examination. Both corneas exhibited a central
circular area of haze about 3.00mm in diameter. There was a "granular" epitheliopathy,
mild disruption of Bowman's Membrane and stromal haze extending to approximately
25 percent of the corneal thickness (Figure 1). The palpebral conjunctiva showed
grade 3 follicles and hyperemia.
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Figure 2. The lenses were opaque with surface
deposits on both surfaces.
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The presenting complaint was discomfort, with no reference to
decreased vision. Furthermore, the discomfort had occurred only in the last month.
When asked why he hadn't presented for routine review as per the reminder notices,
he replied that there was no need because he wasn't having any problems until the
lenses became uncomfortable. Figure 2 shows the deplorable state of the lenses,
which were opaque with surface deposits.
A build-up of surface deposits, especially on the lens' back surface,
is known to cause a loss of the ortho-k effect and an increase in superficial punctate
keratitis. We advised the patient to cease lens wear and return for weekly follow
up. No medication was indicated or prescribed. The epitheliopathy and haze gradually
resolved over a period of four weeks (Figure 3), leaving the cornea crisp and clear.
We prescribed new lenses and ortho-k recommenced, with the patient vowing to return
annually.
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Figure
3. Cornea after four weeks of no lens wear. The haze has resolved.
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Strong Words
Sometimes
we're too successful, especially with ortho-k. If patients remain problem-free,
they may not see the need for annual reviews. I think I'll reword my reminders and
make them a bit more forceful.
Dr. Mountford is an optometrist
in private practice specializing in advanced contact lenses for keratoconus,
post refractive surgery and pediatric aphakia. He is a visiting contact lens lecturer
to QUT and UNSW, Australia.
Contact Lens Spectrum, Issue: January 2006