This main goal of this study is to improve the detection, classification, monitoring, and treatment of irregular corneas due to keratoconus, warpage, dry eye, scar, stromal dystrophies, and other corneal conditions.

The primary goal will be achieved by using optical coherence tomography (OCT) to:

1. Develop an OCT-based system to classify and evaluate corneal-shape irregularities.
2. Develop OCT metrics for more sensitive detection of keratoconus progression.
3. Develop OCT-and-topography guided phototherapeutic keratectomy (PTK) for irregular corneas.

Inclusion Criteria:

GROUP A:

• Keratoconus:

  1. CDVA ≥ 20/25 in the better eye; and both of the following in the worse eye
  2. Topography characteristic of keratoconus or pellucid marginal degeneration

• Contact lens-related corneal warpage:

  1. Contact lens use; and
  2. Topography irregularities

• Dry eye:

  1. Symptoms of dry eye documented by Ocular Surface Disease Index (OSDI) questionnaire score ≥ 30; and
  2. Topography irregularities
  3. Presence of punctate epithelial erosion on exam with surface staining
  4. Aqueous deficiency or evaporative dry eye

• Epithelial basement membrane dystrophy (EBMD):

  1. Negative corneal fluorescein staining; and
  2. Corneal opacities; and
  3. Topography irregularities

• Stromal addition or subtraction:

  1. Scars; or
  2. Salzmann's degeneration; or
  3. Stromal dystrophies; or
  4. Complication (visual complaints) after LASIK or photorefractive keratectomy (PRK)

• Stromal distortion:

  1. Radial keratectomy (RK); or
  2. Corneal transplants.

• Normal controls:

  1. Healthy eyes with no previous eye procedures/surgeries.

GROUP B:

Participants will be selected from the keratoconus population in Group A based on topography findings.

GROUP C:

Participants will be selected from the stromal addition/subtraction and stromal distortion populations of Group A if they have vision primarily limited by scars, dystrophy, or high astigmatism that could benefit from PTK.

Exclusion Criteria (all groups):

• Inability to give informed consent.
• Inability to maintain fixation for OCT imaging.
• Inability to commit to required study visits.
• Eyes with concurrent cataract, retinal disease, glaucoma, or other eye conditions that may limit the visual outcome after surgery.
• Previous corneal surgeries if considered as a keratoconus participant.
• Pregnancy or breastfeeding.

A total of 445 participants ages 14 or older will be recruited for the 3 clinical studies. All 3 studies will be performed at the Casey Eye Institute at Oregon Health & Science University.

Group A:

• Keratoconus: 150 participants
• Epithelial deformation: 105 participants; This category includes contact lens-related corneal warpage, dry eye, and EBMD.
• Primary stromal changes: 100 participants; This category includes corneal scars, Salzmann's degeneration, stromal dystrophies, complicated LASIK/PRK cases with visual complaints, RK cases, and corneal transplants.
• Healthy Controls: 90 participants