Mah et al: "The incidence of DLK after LASIK surgery (0.75% to 32%) has increased worldwide since it was first described in 1998, paralleling the increase in the number of patients who have had this popular form of refractive surgery."
Source: J Cataract Refract Surg. 2006 Feb;32(2):264-8.
One of the most common complications of LASIK is inflammation known as diffuse lamellar keratitis (DLK) or Sands of the Sahara. Diffuse lamellar keratitis is characterized by a diffuse white, granular infiltrate occurring within a few days after LASIK. DLK is a potentially serious, sight-threatening complication.
DLK is classified by four stages depending on the severity and location of the inflammation. DLK should be immediately treated with topical steriods. If DLK progresses it may require surgical intervention. Severe cases of DLK may progress to flap melt with associated vision loss.
Proposed causes of DLK include deposits from microkeratome blades, particles from the eye drape, epithelial defects, meibomian secretions, surgical glove talc, debris from surgical sponges, and contamination of reservoir sterilizers by gram-negative endotoxins.
Click here for more information and medical studies: DLK after LASIK
Journal of Refractive Surgery Volume 17 May/June 2001
Complications of Laser in situ Keratomileusis: Etiology, Prevention, and Treatment
Renato Ambrósio Jr, MD; Steven E. Wilson, MD
Excerpts:
Smith and Maloney thoroughly described diffuse lamellar keratitis (DLK) (American Academy of
Ophthalmology, San Francisco, CA, November, 1997).71 Other reports have appeared since that
time (Linebarger EJ. Diffuse lamellar keratitis: trouble in paradise? ASCRS Film Festival, Grand
Prize Winner, 1999).20,41,72-78 It has also been called sands of the Sahara syndrome (Bobby Maddox, MD,
El Paso, TX, coined the phrase), because of the characteristic wavy appearance at slit-lamp examination.
In severe cases, it is associated with stromal necrosis and irregular astigmatism.
However, we have seen two cases of infectious keratitis in which treatment was inappropriately delayed because of erroneous diagnosis of DLK. Both cases had severe vision loss.
The incidence of DLK is highly variable. One report noted an incidence of approximately 1 in 500.74 Some high volume LASIK surgeons have reported never seeing a case in their own practice. We have seen only two mild cases in 3000 LASIK procedures. Others have experienced focal outbreaks of DLK that have included dozens of patients.
Another grading system has been proposed by Linebarger (Linebarger, 1999, cited above).75 Stage 1 DLK is typically seen on day 1 postoperatively as white, granular cells in the periphery with sparing of the visual axis. Stage 2 Typically seen on postoperative day 2 or 3, shows white cells in the visual axis.
Stage 3 DLK involves an aggregation of cells clumped in the visual axis and associated with haze
and reduced vision. Stage 4 Involves central stromal necrosis, melt, and secondary hyperopia with irregular astigmatism.
At the other extreme, severe (grade 4) cases typically have decreased vision and severe pain associated with marked interface inflammation and necrosis that results in topographic flattening of the corneal contour, secondary irregular astigmatism, and poor vision.
Many potential etiologies for DLK have been proposed (Linebarger, 1999, cited above).75-77 Most of
these are based on speculation without supporting data. These have included betadine from surgical
preps, impure balanced salt solution, retained meibomian secretions and other tear film components,
metallic debris, use of improper detergents, talc from gloves, thermal effects from the excimer laser,
lubricants on the microkeratome or blades, topical medications such as anesthetics, bacterial cell wall
hypersensitivity, and biofilms from inadequate sterilization protocols.
The bacterial cell wall hypersensitivity mechanism could have been the underlying factor in a recent epidemic of DLK.77 The authors suggested that the microkeratome or irrigating cannula became contaminated by bacteria. These bacteria may reside in water left standing in the sterilizer. If the contaminated instruments are cleaned and left to dry, bacteria could proliferate on residual trace protein and the bacterial cell count could increase significantly.
These data suggest that injury to the surface epithelium or epithelial debris left within the LASIK interface triggers production of factors that are chemotactic for inflammatory cells via interleukin-1 release. This mechanism could account for many DLK cases.
Surgical technique may limit DLK, whatever the underlying mechanism.
Eyes with severe DLK are at high risk for stromal necrosis that may be focal and result in haze, irregular
astigmatism, and hyperopic shift.
Disclaimer: The information contained on this web site is presented for the purpose of warning people about LASIK complications prior to surgery. LASIK patients experiencing problems should seek the advice of a physician.