title: The effect of optic asphericity on visual rehabilitation of corneal ectasia with a prosthetic device.
abstract: OBJECTIVE
  To study the effect of optic asphericity on visual rehabilitation of corneal ectasia with a prosthetic device.
  
  
  METHODS
  Subjects with corneal ectasia treated with a fluid-ventilated gas-permeable prosthetic device of diameter 18.0-19.0 mm, who had subjective improvement of good Snellen vision with introduction of optic asphericity, were studied. Best corrected Snellen visual acuity (BCVA) under standard illumination, high contrast visual acuity (HCVA), low contrast visual acuity (LCVA), and wavefront aberrations were measured in a sequence of devices that varied per patient only in presence or amount of ellipsoidal front surface optical eccentricity (FSE).
  
  
  RESULTS
  Five eyes of 5 subjects were studied. (M:F = 3:2; Age: 20-76). Mean steepest SimK was 57.72±8.30 D. BCVA was ≥20/30 in all eyes in all prosthetic devices, regardless of FSE. Although FSE improved BCVA, HCVA, and LCVA in each patient, no optimal amount could be identified in this small series. Asphericity in the form of 0.6 or 0.8 FSE improved HCVA, LCVA, or both in each patient. FSE was associated with a trend toward reduction of higher-order aberrations, particularly coma.
  
  
  CONCLUSIONS
  Optic asphericity shows promise for optimization of vision in the rehabilitation of corneal ectasia with a prosthetic device.
authors.affiliation: Boston Foundation for Sight, Needham, MA 02494, USA.
authors.forename: Trisha
authors.initials: T
authors.lastname: Hussoin
authors.forename: Hong-Gam
authors.initials: HG
authors.lastname: Le
authors.forename: Karen G
authors.initials: KG
authors.lastname: Carrasquillo
authors.forename: Lynette
authors.initials: L
authors.lastname: Johns
authors.forename: Perry
authors.initials: P
authors.lastname: Rosenthal
authors.forename: Deborah S
authors.initials: DS
authors.lastname: Jacobs
mesh_terms: D000328:Adult; D000368:Aged; D004108:Dilatation, Pathologic / Q000628:therapy; D005260:Female; D006801:Humans; D007640:Keratoconus / Q000503:physiopathology / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D019736:Prostheses and Implants / Q000592:standards; D011474:Prosthesis Design; D014792:Visual Acuity / Q000502:physiology; D055815:Young Adult