Clear lens replacement surgery.
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Humans↗
Biomedical subjects
David M Choi
Publications and source records attributed to David M Choi.
Incisional refractive surgery.
The use of incisional refractive surgery has become limited due to the widespread use of the excimer laser to correct myopia, hyperopia and astigmatism. Laser in situ keratomileusis and photorefractive keratectomy have proven to be much more accurate and predictable in correcting refractive error. This has made some forms of incisional refractive surgery practically obsolete. Radial keratotomy should not be considered a primary refractive procedure in the modern world, as RK has become "RKhaic". There are still indications for incisional refractive surgery in cataract and post-surgical patients for the treatment of astigmatism. However, with the advent of the toric intraocular lens and the use of LASIK in such aforementioned patients, these indications for incisional surgery will likely become more limited. In this review, we go over the past history of incisional refractive surgery and also report the current uses and advancements of this technique in today's practice environment.
Astigmatism↗
Noncontact optical coherence tomography for measurement of corneal flap and residual stromal bed thickness after laser in situ keratomileusis.
PURPOSE: Studies show significant variability in the thickness of laser in situ keratomileusis (LASIK) corneal flaps cut by various microkeratomes. Most studies of corneal flap thickness are based on contact ultrasonic pachymetry measurements taken during the surgical procedure. This study reports a technique to obtain reproducible corneal flap thickness and residual stromal bed thickness measurements using noncontact optical coherence tomography (OCT) following LASIK. METHODS: The corneal flap thicknesses of 26 eyes of 15 patients were measured following LASIK in which the flap was created using the Amadeus microkeratome: 160-microm head, 9.5-mm ring, 4.0-mm/s translation speed, 8000 oscillations/m, and full vacuum. Zeiss Humphrey OCT-2 line scans were performed on postoperative days 1 and 7. The raw data from three scans for each eye and day were exported to Microsoft Excel for processing, averaging, and analysis. RESULTS: The OCT corneal flap thickness and residual stromal bed thickness measurements correlated well with ultrasonic pachymetry measurements performed during surgery (R2 = .92). The OCT technique yielded reproducible results, as the variance for repeated scans was only 2.5% of the variance between eyes. In bilateral cases a single blade was used for both eyes. The mean flap thickness of 15 first eyes was significantly greater than that of the 10 second eyes: 181 +/- 31 microm vs. 143 +/- 41 microm (P < .01). A positive correlation was found between the preoperative pachymetry and corneal flap thickness. CONCLUSIONS: The OCT scan averaging technique is a reproducible, noncontact postoperative method for measuring corneal flap and residual stromal bed thicknesses following LASIK.
Adult↗