Phototherapeutic keratectomy (PTK)
Since late 1980s and early 1990s the excimer laser has been used to reshape the anterior corneal curvature in a procedure known as photorefractive keratectomy (PRK) or keratomileusis in situ (LASIK). Excimer laser phototherapeutic keratectomy (PTK) was approved by the U.S. Food and Drug Administration (FDA) in 1995 to treat a variety of anterior corneal pathologies and nowadays is a technique very used for many surgeons around the world.
The main goals of performing PTK are to remove or decrease the opacities affecting the visual acuity, to smooth the corneal surface, to improve the adherence of the corneal epithelium, or a combination thereof to help with painful symptoms.
This procedure is potentially applicable to a large number of patients but including:
- Corneal scars and opacity (from trauma and inactive infections)
- Dystrophies (Reis-Buckler’s, granular and lattice)
- Salzmann’s nodular degeneration
- Band keratopathy
- Painful bullous keratopathy
Patients with deep lesions are not good candidates for this technique. (lesions in the posterior two-thirds of the cornea)
The procedure is generally done under topical anaesthesia and with strict sterile technique; general anaesthesia may be required in pediatric patients. After applying the wire speculum, the epithelium is removed manually with a hockey stick knife or with a cellulose sponge after using alcohol 20% (5-10 seconds). Some surgeons prefer to remove the epithelium with the excimer laser (Trans-PTK: 50 um depth). After the epithelium is removed, the ablation is performed according to the depth, size and shape of the lesions. Antibiotic eye drops are given and a bandage contact lens is placed until re-epithelialization. Postoperative treatment consists of topical antibiotics, corticosteroids and anti-inflammatory eye drops, all for about 1–2 weeks.
- Deep stromal lesions, dense band keratopathy
- Significant corneal thinning
- Neurotrophic cornea, lagophthalmos
- Severe keratoconjunctivitis sicca
- Severe blepharitis
- Any corneal infection
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