Tracker-assisted photorefractive keratectomy for myopia of -1 to -6 diopters.
BACKGROUND
The Autonomous Technologies T-PRK (Tracker-assisted Photorefractive Keratectomy) excimer laser system uses a small beam scanner that allows flexibility in the ablation pattern that is applied to the cornea and incorporates a sophisticated LADARVision eye tracker that is capable of following saccadic movements. This paper describes the first clinical results on sighted eyes for the correction of low myopia.


METHODS
Forty-two normal sighted eyes of 42 patients were treated for spherical myopia between -1.00 diopters (D) and -6.00 D with 6 mm ablations. Visual acuity, refractive error, contrast sensitivity (with and without glare), corneal haze, endothelial cell density, and patient satisfaction were measured.


RESULTS
Mean manifest refraction was -0.39 D +/- 0.68 D at 1 month with regression to -0.94 D at 3 months and -1.05 D at 6 months. At 6 months, 5 (20%) eyes were +/- 0.50 D and 14 (56%) eyes were +/- 1.00 D. Consistent with this undercorrection and regression, uncorrected visual acuity (UCVA) of 20/20 and 20/40 or better was achieved by 10 (40%) and 34 (85%) eyes at 3 months and 16 (40%) and 17 (68%) eyes at 6 months. None of the eyes lost 2 or more lines of spectacle corrected visual acuity. Corneal haze was graded as 1/2 trace or less in 89% to 100% of eyes at all intervals. There was no loss of endothelial cells (mean +/- SD cell density centrally: preop 3115 +/- 322 and 6 months 3220 +/- 333) and contrast sensitivity recovered to baseline levels at 3 months.


CONCLUSIONS
The Autonomous Technologies T-PRK excimer laser system is safe and effective for the reduction or correction of myopia from -1.00 D or -6.00 D. The refractive results may be improved by adjusting the calibration to reduce the undercorrection and by instituting use of topical corticosteroids on an individual basis for those who regress.
Pallikaris
I
I
University of Crete, Department of Ophthalmology, Heraklion, Greece.
McDonald
M B
MB
Siganos
D
D
Klonos
G
G
Detorakis
S
S
Frey
R
R
Downes
R
R
Gauthier
C A
CA
D002452:Cell Count; D003201:Computers; D004728:Endothelium, Corneal / Q000473:pathology; D004867:Equipment Design; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007091:Image Processing, Computer-Assisted; D054018:Lasers, Excimer; D008297:Male; D009216:Myopia / Q000601:surgery*; D017060:Patient Satisfaction; D018903:Photorefractive Keratectomy / Q000295:instrumentation*; D011183:Postoperative Complications / Q000209:etiology; D012029:Refraction, Ocular; D016896:Treatment Outcome; D014786:Vision Disorders / Q000209:etiology; D014792:Visual Acuity / Q000502:physiology