Associated Problems Corneal Hypoxia

Corneal hypoxia (lack of oxygen) in rigid lenses often causes an area of edema that is central, rather than diffuse as in soft lenses. This central area is round or oval (in the case of astigmatism), about 2.00 to 4.00 mm across, and grayish white. Draw or describe and grade any edema that is present. The edema becomes more dense as the condition worsens and may eventually be visible without the slit lamp. The problem may also be accompanied by superficial punctate corneal staining (see Corneal Staining below).

Corneal Infiltrates

Corneal infiltrates are congregations of white blood cells and lymphocytes that form in response to a viral infection, chemical sensitivity, or lack of oxygen. They look like little dots under the epithelium and may be surrounded by a tiny fuzzy border of edema. You may draw or describe them.

Corneal Staining

Our concern here is the corneal staining patterns that present when the lens has been removed. Consult Figure 9-12 and use it to draw or describe any corneal staining that you observe. In addition to the patterns shown, another possible cause of staining is a phenomenon known as dimple veiling (Figure 9-13). In this situation, bubbles form under the lens. The bubbles put pressure on the cornea and cause tiny depressions in the corneal epithelium. These depressions, which usually occur centrally or superiorly, will stain with the dye.

OptA

Contact Lens Staining Patterns

Figure 9-12. Common types of rigid lens staining. Top left: Diffuse punctate staining. Usually chemical or environmental in origin. Often related to solution sensitivity. Top center: Apical staining. Often due to poor lens/cornea relationship. Common in keratoconus patients. Top right: Overwear stain (epithelial erosion). Middle left: 3:00 and 9:00 staining. Attributed to lid gap, poor blink pattern, mechanical trauma. Desiccation occurs in areas adjacent to lens edge at approximately 3:00 and 9:00. Middle center: Arcuate stain. Usually due to edge defect, poor edge design, or dried mucus on lens. Middle right: Recentering stain. Can also occur from faulty insertion technique. Bottom left: Swirl-like stain. Seen with poor lens/cornea relationship and in keratoconus patients with apical touch. Bottom center: Foreign body stain. Bottom right: Mucus deposits or scratched lens stain. (Adapted with permission from Koch et al. Adverse Effects of Contact Lens Wear. SLACK Incorporated.)

Figure 9-12. Common types of rigid lens staining. Top left: Diffuse punctate staining. Usually chemical or environmental in origin. Often related to solution sensitivity. Top center: Apical staining. Often due to poor lens/cornea relationship. Common in keratoconus patients. Top right: Overwear stain (epithelial erosion). Middle left: 3:00 and 9:00 staining. Attributed to lid gap, poor blink pattern, mechanical trauma. Desiccation occurs in areas adjacent to lens edge at approximately 3:00 and 9:00. Middle center: Arcuate stain. Usually due to edge defect, poor edge design, or dried mucus on lens. Middle right: Recentering stain. Can also occur from faulty insertion technique. Bottom left: Swirl-like stain. Seen with poor lens/cornea relationship and in keratoconus patients with apical touch. Bottom center: Foreign body stain. Bottom right: Mucus deposits or scratched lens stain. (Adapted with permission from Koch et al. Adverse Effects of Contact Lens Wear. SLACK Incorporated.)

Figure 9-13. Dimple veiling. Note collection of small bubbles under lens. (Photo courtesy Bausch and Lomb/Polymer Technology.)

Reverse Testicular Atrophy

References

Was this article helpful?

0 0

Post a comment