Exam CPC topic 11 question 84 discussion

A 32-year-old male has a three-year history of progressive keratoconus in left eye. Glasses and repeated attempts to fit the patient with various types of contact lenses has not helped his vision. Corneal collagen cross-linking is performed to stabilize the cornea in the left eye. Under an operating microscope, corneal epithelium is removed. Riboflavin eye drops are instilled at frequent intervals until the corneal stroma is saturated (approximately 30 minutes). Corneal thickness is assessed using pachymetry, and ultraviolet light is delivered for approximately 30 minutes.
What CPT® coding is reported for this procedure?