Diffuse Lamellar Keratitis (DLK)
is a postoperative complication of
All-Laser Lasik that occurs when foreign cells (infiltrates)
are introduced into the interface between the
corneal flap and underlying
stroma. DLK can occur with any flap manipulation including initial
enhancement, removal of
epithelial ingrowth, etc. There is often pain, blurred vision,
foreign body sensation, and sensitivity to light but some patients
have no symptoms other than rapid onset of hazy vision. DLK most
often is present within one to six days after surgery however DLK
has occurred months and years after surgery and can threaten an
otherwise successful visual outcome if not properly treated.
DLK causes the creation of fine white grainy cells that when
viewed through a
slit-lamp appear like waves of sand, hence the nickname Sands
of Sahara. Although the infiltrates are sterile, the cornea attacks
them and if left unchecked will destroy itself causing serious damage
and permanent reduction in visual acuity.
DLK had been a very mysterious problem when it first started
to occur and is still not completely understood. DLK tends to happen
in "runs" of several patients in a row. It appears that there are
several causes or that multiple conditions must exist for DLK to
Surgeons verify that all tools are properly sterilized, but the
problem has persisted in-part because the infiltrates are not alive;
they are actually dead and sterile cells. DLK is not caused by the
infiltrates making trouble. It is caused by the cornea reacting
to the presence of the infiltrates even if they are dead.
The most common used sterilizers utilize steam from distilled
water to cause sterilization. This water would collect in a drain
pan that was difficult to empty completely. If the water was not
drained, the dead infiltrates would collect in the water and then
be readmitted to the next batch of items being sterilized in the
steam. The sterilizer became an efficient method of sterile infiltrate
distribution. Now, doctors empty the sterilizer pans completely,
use new sterile distilled water, and clean the sterilizers often.
Much more than normal protocol. Also, dry sterilizers are used.
DLK is defined in four stages beginning with Stage 1 where DLK
is first present through Stage 4 where the cornea is destroying
Stage 1 consists of infiltrates in the periphery of the flap
without involvement of the central cornea. This stage most commonly
presents on the day after surgery.
Stage 2 occurs as a result of central migration of cells
to involve the
visual axis. Stage 2 most frequently presents on day two
or three. Progression to stage 3 occurs when dense clumps of
cells aggregate in the central visual axis. Relative clearance
of the periphery is also seen.
Stage 3 usually appears 48 to 72 hours after surgery, and
can be associated with a 1- or 2-line loss of visual acuity.
Stage 3 has been referred to as "threshold" DLK because many
of these eyes will develop permanent scarring if not appropriately
Stage 4 is severe lamellar
keratitis resulting in stromal melting and permanent scarring.
Central tissue loss causes a
hyperopic shift. The incidence of Stage 4 is estimated at
one in 5,000 Lasik cases.
Treatment is normally topical and oral medication. Sometimes
it is necessary to lift the flap, remove some of the infiltrates,
irrigate the area, and reposition the flap. Quick diagnosis and
treatment is a must Something important to remember is that DLK
can occur months, even years, after surgery if there is sufficient
trauma or disruption to the Lasik flap. If you ever have trauma
to the eye after having Lasik, it is always good to be evaluated
by a refractive surgeon.
If you are ready to choose a doctor to be evaluated for conventional
RLE, or any
refractive surgery procedure, we highly recommend you consider
a doctor who has been evaluated and certified by the USAEyes
nonprofit organization. Locate a USAEyes Evaluated & Certified
Lasik Laser Eye Surgery Doctor.
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