[Clinical investigation of epipolis laser in situ keratomileusis on high myopia]

To investigate the surgical characteristics and clinical results of Epi-LASIK on high myopia.

Epi-LASIK was performed with a rotational epikeratome, which features a blunt oscillating blade. Corneal epithelial separation was achieved mechanically without the use of alcohol. Laser ablation was performed with Zeiss Mel-80 excimer laser. After ablation, epithelial sheet was repositioned and a therapeutic contact lens was applied to the eye for 3 to 5 days. The postoperative symptom, epithelial flap, contrast sensitivity, wavefront aberration and haze formation were investigated. The period of follow-up ranged from 3 to 6 months.

52 eyes of 30 patients with a mean spherical equivalent (SE) of (-12.82 +/- 4.38) D were included in the clinical trial. Among which 36 eyes were pathologic myopia and 16 eyes were simple high myopia. Patient age ranged from 20 to 50 years. Integrated epithelial flap with a diameter of 8 to 9 mm was made in 49 eyes leaving an about 3 mm superior hinge. Epithelial flap contained part of stroma tissue was seen in one eye. Free epithelial flap was made in 2 eyes. 4 eyes had moderate photophobia, tearing and foreign body sensation. Other patients only had mild discomfort. No patient reported other subjective symptom after 2 days with the exception of mild foreign body sensation. In 3 months after surgery, spherical equivalent of 44 eyes (84.61) were within +/- 1.00 D of attempted refraction. No eye lost more than one line of best spectacle-corrected visual acuity (BSCVA), whereas 10 eyes (19.23%) gained one or two lines of BSCVA. Grade 0.5 haze was found in 8 eyes (15.38%) and grade 1 haze was found in 2 eyes (3.84%). In 6 months after surgery, Grade 0.5 haze was found in 3 eyes. Contrast sensitivity decreased 1 month postoperatively and recovered to preoperative lever gradually 3 months postoperatively. Higher order aberration was increased postoperatively.

Epi-LASIK is a safe and efficient method to correct high myopia with the advantages of having mild irritating symptom and haze. Larger series with adequate follow-up are needed to observe the long term clinical results and haze.