title: Effect of lens design on peripheral corneal desiccation.
abstract: BACKGROUND
  Management of peripheral corneal desiccation (PCD; also known as 3 and 9 o'clock staining) has challenged rigid-lens fitters since the early days of corneal contact lenses. This study investigated effects of changing diameter and edge lift on severity of staining in two groups of rigid extended wear patients: stainers and nonstainers.
  
  
  METHODS
  Five different lens designs, representing three diameters (9.0, 9.6, and 10.2 mm) and three edge lifts (low, moderate, and high), were worn by 12 subjects who exhibited significant levels of PCO (stainers) and a matched group that had shown no significant staining (nonstainers) after a period of wear with the same standard tricurve design.
  
  
  RESULTS
  The study demonstrated that larger lens diameters (10.2 and 9.6 mm) and moderate-edge lifts outperformed the small-diameter (9.0 mm) and low-edge lift designs. However, these effects were demonstrated in the group of stainers only. Significant lens performance variables affecting the degree of staining in known stainers included low-vertical centration, narrow or shallow edges observed with fluorescein, erratic or insufficient lens movement, and smaller lens diameters.
  
  
  CONCLUSIONS
  In patients who demonstrate a significant amount of peripheral corneal desiccation with rigid lenses, careful attention should be paid to the peripheral lens design. Larger lenses are preferred, as long as a moderately wide tear reservoir can be maintained under the lens edge.
authors.affiliation: Manicon USA, Inc., Clovia, California 93612, USA.
authors.forename: C M
authors.initials: CM
authors.lastname: Schnider
authors.forename: R L
authors.initials: RL
authors.lastname: Terry
authors.forename: B A
authors.initials: BA
authors.lastname: Holden
mesh_terms: D000328:Adult; D003262:Contact Lenses, Extended-Wear / Q000009:adverse effects*; D003315:Cornea / Q000473:pathology*; D003316:Corneal Diseases / Q000209:etiology* / Q000473:pathology / Q000503:physiopathology; D003890:Desiccation; D005260:Female; D006801:Humans; D008297:Male; D011474:Prosthesis Design; D012029:Refraction, Ocular; D014792:Visual Acuity