April 18, 2003
Refractive Challenge : Enlarging the Optical Zone
Cataract & Refractive Syrgery Today April 2003
CASE HISTORY
In 1995, a 50-year-old white female underwent bilateral radial keratotomy that targeted plano for -4.50 D of myopia. She was undercorrected, so the surgeon performed myopic automated lamellar keratomileusis (ALK) on her right and left eyes in 1995 and 1996, respectively. The right eye experienced secondary hyperopia, while the left eye remained myopic. Next, the surgeon performed LASIK on the patient’s left eye using the Chiron ACS (Bausch & Lomb Surgical, San Dimas, CA) in 1998 and on her right eye in 1999 with the Hansatome microkeratome (Bausch & Lomb Surgical).
The patient presented in my office with complaints of poor nighttime vision and halos around lights at night. Glasses had not improved her symptoms. She had a bilateral UCVA of 20/60. The patient had a manifest refraction of +0.75 +0.25 X 35 and a BCVA of 20/25-2 OD. The manifest refraction and BCVA of her left eye were +0.50 +0.75 X 165 and 20/25. The slit lamp examination showed well-healed RK scars, as well as a relatively small but thick ALK flap in both eyes . Each eye’s LASIK flap was larger and thinner than its ALK flap. The steep transition zone was evident on the peripheral topography (blue edge to red edge) corresponding with 38.00 D centrally to 45.00 D peripherally. The patient’s pupils were 7.5 mm, extending beyond the edge of the color topography map and signifying that spherical aberrations factored into the patient’s complaints. Her central pachymetry measurements were 492 µm OD and 539 µm OS. The remainder of the examination was unremarkable.
HOW WOULD YOU PROCEED?
1. Would you perform an enhancement on a patient with two flaps per eye?
2. How would you relift the flap?
3. By what method would you enlarge the optical zone?
Posted by mehdi khanlari at April 18, 2003 10:20 PM