discovering dry eye
BY BARBARA CAFFERY, OD, MS, FAAO
Since we are all busy practitioners, it is easy to
decide not to stain a patient wearing hydrogel lenses who wishes to wear them out of the office. Flushing the fluorescein out of the eye and the
calls at the end of the day about yellow lenses are all avoided if we just skip this step. But what are we missing when only white light is used to assess a lens problem?
The symptoms of dryness with lens wear occur in up to 50 percent of lens wearing patients, especially if we ask about end-of-
day symptoms. Some of the generalized discomfort associated with lens wear must relate to the condition of the ocular surface. One of the easiest ways to assess the corneal and conjunctival epithelia is to instill fluorescein and use a cobalt blue light and yellow filter on the slit lamp to observe the ocular surface. Classic fluorescein patterns reveal what is going wrong with lens wear.
Figure 1. Mild corneal epithelial
The most common staining pattern is a ring around the
limbus. The hydrogel lens edge indents the limbal tissue, and fluorescein pools in that area. This suggests a tight lens; therefore this pattern will be more commonly observed later in the day. Refitting with a different lens design may solve this problem.
A generalized light corneal staining pattern or SPK is common in solution toxicity. In hydrogel lens wearers, the stain covers most of the cornea. In rigid lens wearers, it remains more central. You can easily solve this problem by changing solutions. Sometimes a preservative-free solution such as Lens Plus
(Allergan) or Softwear (CIBA Vision) saline is needed to insert lenses on very sensitive eyes.
Superior epithelial arcuate lesions
(SEALs) stain brightly with fluorescein. This lesion occurs more often in patients with tight lids and those wearing silicone hydrogel lenses. It is speculated that toxins and waste material from the cornea become trapped under the lens that the lids tightly hold at this position. The mechanism of trapped tear film is proposed for patients with a smile stain in the inferior cornea. Both of these circumstances require creative refitting with different lens sizes and materials.
A new type of dimple veiling stain may appear in certain patients wearing silicone hydrogel materials. Mucin balls become trapped under the lenses and indent the corneal epithelium. Fluorescein then pools in the divots. This staining quickly disappears after lenses are removed.
Corneal staining from abrasions occurs with damaged lenses, those with debris trapped under them or lenses that are hiding a morning abrasion that occurred when makeup was applied.
Finally, do not forget to look under the superior lids and observe the tarsal plate with the cobalt blue filter. Excess mucous and the earliest signs of GPC can be observed with the help of
fluorescein. Lid inflammation can be reduced with new lenses that are more frequently replaced and perhaps a different care system.
Staining and Dry Eye
Not all of these staining patterns relate to symptoms of dryness. However, when patients do have symptoms of dryness and discomfort with lenses, it is important to stain and observe. Without this knowledge of the state of the ocular surface, your decision making simply cannot be as accurate.
Dr. Caffery has practiced optometry in Toronto, Canada, in a group setting dedicated to contact lens and tear film research since
Contact Lens Spectrum, Issue: November 2002