Phototherapeutic keratectomy, or PTK, is a procedure where the excimer laser (that is also used to correct spectacle power in LASIK) is used to remove very thin layers of the cornea to treat a medical problem of the cornea.
Problems that can be treated this way
- Recurrent erosions
This is a troublesome condition where the surface epithelial ('skin') cells of the cornea do not attach firmly to the cornea, and regularly break open again causing pain and tearing of the eye. This can arise after injuries such as scratches to the cornea with paper or a fingernail, or sometimes it is due to an inherited/genetic condition called epithelial basement membrane dystrophy.
Figure 1 - A patient with recurrent erosions who could benefit from laser PTK.
Figure 2A - Before PTK, note the loose folds of corneal epithelium below.
Figure 2B - After PTK the corneal epithelium is much smoother with slight irregularity remaining.
- Superficial scars and irregularity of the cornea
PTK is done in a very similar way to photorefractive keratectomy, or PRK. After the abnormal surface cells are removed under topical (eyedrop) anaesthesia, pulses of laser are applied to the corneal surface. As little as 5-10 microns of tissue are ablated/removed with the laser. After the procedure, a contact lens is applied as a bandage over the treated cornea, and antibiotic drops are instilled. The bandage lens is left in the eye for 5-7 days while the corneal surface heals.