LASIK with an inferior hinge.

PURPOSE: To investigate the refractive results and corneal pachymetric changes after laser in situ keratomileusis (LASIK) with an inferior hinge. METHODS: Forty-six eyes of 23 patients who underwent LASIK with an inferior hinge were involved in this prospective study. All patients had a complete ophthalmic examination including uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), manifest refraction, computerized corneal topography (Orbscan II Corneal Topography System; Orbscan Inc, Salt Lake City, Utah), air-puff tonometry, slit-lamp examination of the anterior segment, and fundus examination. RESULTS: Preoperatively, mean sphere was -4.09+/-0.27 diopters (D) (range: -8.00 to -0.25 D), mean cylinder was -0.60+/-0.11 D (range: -3.25 to 0.00 D), and mean spherical equivalent refraction was -4.39+/-0.27 D (range: -8.63 to -1.50 D). At 1 month postoperatively, mean sphere was -0.04+/-0.01 D (range: -0.25 to 0.00 D), mean cylinder was -0.01+/-0.01 D (range: -0.50 to 0.00 D), and mean spherical equivalent refraction was -0.04+/-0.02 D (range: -0.00 to -0.50 D). At 1 month postoperatively, no eyes lost any lines of BSCVA. CONCLUSIONS: Laser in situ keratomileusis with an inferior hinge is an alternative technique, which was safe and effective in our series. Further studies with long-term follow-up comparing the incidence of corneal ectasia in eyes with a superior hinge to that in eyes with an inferior hinge are recommended.

The efficacy of hourly prophylactic steroids in diffuse lamellar keratitis epidemic.

PURPOSE: To investigate the inciting agent, clinical features, and the efficacy of hourly steroids in the prophylaxis in a diffuse lamellar keratitis (DLK) epidemic. METHODS: One hundred and five eyes of 58 patients that had DLK after LASIK were included in the study. To identify the cause of the epidemic, some interventions were made: irrigation solution was changed from BSS to Ringer lactate (week 5), wiping of the interface with a sponge was discontinued (week 6), the air conditioner in the LASIK room was checked (week 6), the routine postoperative topical regimen was changed from fluoromethalone and fluoroquinolones 4 times a day to hourly prednisolone acetate or dexamethasone sodium and fluoroquinolones (week 7), and the trademark of the drape used was changed (week 12). RESULTS: There was no statistical difference in any of the attack rates associated with variables including BSS versus Ringer lactate (9.9 vs. 14%, p = 0.4), and air conditioner check with wiping versus not wiping the interface with the microsurgical sponge (14.0 vs. 18.2%, p = 0.6). There was a significant decrease in the attack rate from 18.2 to 5.3% with use of the hourly prophylactic topical steroids (p = 0.012). After introduction of a new trademark of the drape, the incidence of DLK was further reduced from 5.3 to 0.7% (p = 0.016). CONCLUSION: The cause in a particular DLK epidemic should be identified and eliminated adopting a scientific approach. Hourly steroid use for prophylaxis is recommended until the etiologic agent responsible has been identified.

Wavefront-guided laser in situ keratomileusis with the Bausch & Lomb Zyoptix system.

PURPOSE: To evaluate the clinical results of wavefront-guided laser in situ keratomileusis (LASIK) with the Zyoptix system. METHODS: Twelve patients (24 eyes) underwent wavefront-guided LASIK with the Bausch & Lomb Zyoptix system. Uncorrected and best spectacle-corrected visual acuity and manifest refraction were measured at postoperative day 1, week 1, and months 1 and 3. A subjective vision quality questionnaire evaluated light sensitivity, dryness, tearing, glare, halos, ghost images, and difficulties in night driving, preoperatively and 3 months postoperatively. RESULTS: Preoperatively, mean sphere was -3.70 +/- 2.33 D (range -0.50 to -8.00 D), mean cylinder was -0.90 +/- 0.98 D (range 0 to -3.00 D), and mean spherical equivalent refraction was -4.15 +/- 2.16 D (range -1.38 to -8.25 D). Three-month postoperative spherical equivalent refraction was within +/- 0.50 D of emmetropia in 17 eyes (70.8%) and within +/- 1.00 D in 22 eyes (91.7%). At 3 months postoperatively, no eyes lost any lines of BSCVA and eight eyes (33.3%) gained 2 lines. The ratio of postoperative BSCVA to preoperative BSCVA (safety) was 1.05 +/- 0.09 (range 1.00 to 1.20) at 1 month and 1.07 +/- 0.10 (range 1.00 to 1.29) at 3 months. The ratio of postoperative UCVA to preoperative BSCVA (efficacy) was 0.96 +/- 0.12 (range 0.80 to 1.20) at 1 month and 0.95 +/- 0.12 (range 0.8 to 1.2) at 3 months. The subjective vision quality questionnaire revealed less tearing, fewer halos, and less difficulty in night driving after wavefront-guided LASIK. Comparison of higher order optical aberrations before and after surgery was not done. CONCLUSIONS: Wavefront-guided LASIK with the Bausch & Lomb Zyoptix system was safe and effective in correcting low to moderate myopic refractive error.

Orbscan corneal topography system in evaluating the anterior structures of the human eye.

PURPOSE: To investigate the relationship among horizontal corneal diameter, corneal thickness, anterior chamber depth, pupil size, and spherical equivalent and to evaluate the variation in these parameters attributable to age, sex, iris color, and refractive state of the eye. METHODS: One thousand three hundred forty-one eyes of 688 consecutive patients who had a LASIK evaluation at World Eye Hospital were involved in the study. The information that was reviewed included age and sex of the patient, horizontal corneal diameter, corneal thickness, anterior chamber depth, iris color, pupil size (scotopic and photopic), and spherical equivalent. RESULTS: The mean corneal thickness was 537.6 +/- 37.5 microm (range, 334-702). The mean anterior chamber depth was 3.5 +/- 0.38 mm (range, 1.99-4.75). The iris color was dark in 829 (61.8%) eyes and light in 512 (38.2%). The mean scotopic pupil size was 6.1 +/- 0.9 mm (range, 3.5-9.0) and the mean photopic pupil size was 4.0 +/- 0.7 mm (range, 2.1-7.4). The mean spherical equivalent was -3.4 +/- 3.7 D (range, -16.00-+7.50 D). Age was correlated with corneal thickness (r = 0.069, p = 0.012), spherical equivalent (r = 0.080, p = 0.003), and inversely correlated with corneal diameter (r = -0.367, p< 0.001), anterior chamber depth (r = -0.335, p< 0.001), scotopic pupil size (r = -0.309, p< 0.001), and photopic pupil size (r = -0.367, p< 0.001). Males had larger corneas (p< 0.001) and deeper anterior chambers (p< 0.001) than females. The eyes with a dark iris color had thicker corneas (p< 0.001), deeper anterior chambers (p< 0.001), and more minus spherical equivalents (p = 0.017) than the eyes with a light iris color. CONCLUSIONS: There is a substantial range of dimensions of anterior structures of the human eye. These dimensions are related to each other and are influenced by age, sex, iris color, and refractive state of the eye.