Optical Coherence Tomography Guided Transepithelial Phototherapeutic Keratectomy

Optical Coherence Tomography Guided Transepithelial Phototherapeutic Keratectomy

Optical Coherence Tomography (OCT) machines are non-contact instruments that can measure the depth of scars and other causes of cloudiness in the front of the cornea. The purpose of this study is to determine whether OCT-guided settings for the lasers used for removal of corneal scars and other partial-thickness corneal defects result in improved vision in patients receiving these procedures.

The long-term goal of this project is to utilize newly available very high-speed OCT technology to guide surgical treatments of corneas with superficial opacities and irregularities. OCT is well known for its exquisite resolution, but until recently it has not had sufficient speed to capture the shape of the cornea because of eye motion during OCT scanning. The development of Fourier-domain OCT (FD-OCT) technology has made the requisite speed possible.

Eyes with superficial opacities (corneal scars and stromal dystrophies) can be treated by phototherapeutic keratectomy (PTK). Currently, many surgeons rely on subjective slit-lamp impression of opacity depth to guide PTK and repeat slit-lamp examinations during surgery to determine if the opacity has been sufficiently reduced. Unpredictable hyperopic shifts can occur after PTK. The aim of this project is to develop methods for imaging the cornea with an FD-OCT system that will precisely measure corneal shape and use this information to guide surgery. Patients with irregularly shaped corneas could have their vision restored by reshaping the corneas with a procedure that combines the precision of OCT and lasers.

Inclusion Criteria:

• Patients with vision primarily limited by superficial opacities and irregularities that could be removed by PTK while leaving at least 250 µm.

Exclusion Criteria:

• Inability to give informed consent
• Inability to maintain stable fixation for OCT imaging
• Inability to commit to required visits to complete the study
• Deep corneal opacities and irregularities
• Cataracts, retinal disease, glaucoma, or other eye conditions that may limit the visual outcome after surgery