Biomedical subjects

Maria Regina Chalita

Publications and source records attributed to Maria Regina Chalita.

At least 19 recordsLinked to original sources

PubMed2006

Visual performance of AcrySof ReSTOR apodized diffractive IOL: a prospective comparative trial.

PURPOSE: Evaluate the visual performance of the AcrySof ReSTOR intraocular lens (IOL) and compare it with the monofocal SA60AT IOL. DESIGN: Prospective, nonrandomized, clinical trial. METHODS: Forty patients (80 eyes) from the Federal University of São Paulo were enrolled in two groups. Twenty-five patients were assigned to the ReSTOR group and 15 patients to the monofocal group. Inclusion criteria were corneal astigmatism <1.0 diopter, potential acuity meter >0.2 logMAR units, and no associated ocular diseases. Parameters analyzed included distance uncorrected and best-corrected visual acuity, near uncorrected and distance corrected visual acuity, intermediate visual acuity, contrast sensitivity (Pelli-Robson chart), stereopsis (Titmus test), reading speed, wavefront measurement (LADARWave aberrometer), and a quality-of-life questionnaire. main outcome measure: Distance and near uncorrected and best distance corrected visual acuity, contrast sensitivity, and reading speed. RESULTS: Distance uncorrected and best-corrected visual acuity in the ReSTOR group were not statistically different from the monofocal group (P = .66). Near uncorrected and distance corrected visual acuity were statistically better in the ReSTOR group than the monofocal group (0.16 +/- 0.13 vs 0.62 +/- 0.09, P < .001, and 0.14 +/- 0.12 vs 0.62 +/- 0.07, P < .001, respectively). The ReSTOR group demonstrated less spherical aberrations compared with the monofocal group (P < .001). Monocular photopic contrast sensitivity was statistically lower in the ReSTOR group (P < .001). Stereopsis and reading speed were not statistically different between the groups. CONCLUSION: The AcrySof ReSTOR IOL provides a satisfactory full range of vision and achieves a more satisfactory quality of life when compared with the monofocal SA60AT IOL, but with lower contrast sensitivity.

Acrylic Resins↗

PubMed2006

Wavefront analysis and contrast sensitivity of aspheric and spherical intraocular lenses: a randomized prospective study.

PURPOSE: To compare visual performance, total and high order wavefront aberrations (coma, spherical aberration, and other terms), and contrast sensitivity in 120 eyes implanted with one monofocal aspheric intraocular lens (IOL) and two spherical IOLs. DESIGN: Randomized prospective study. METHODS: Sixty patients were randomized to receive three IOL types: Alcon AcrySofIQ (40 eyes), AcrySofNatural (40 eyes), and advanced medical optic (AMO)Sensar (40 eyes). Complete ophthalmologic examination including uncorrected visual acuity (UCVA), best-spectacle corrected visual acuity (BSCVA), corneal topography, and wavefront analysis were performed preoperatively, 30 days, and 90 days postoperatively. Pelli-Robson chart test and functional acuity contrast testing (FACT-Optec6500) were performed approximately 50 days after surgery. Statistical analyses were performed using analysis chi(2), analysis of variance (ANOVA), and multiple comparisons Tukey test. RESULTS: After 90 days, all eyes had postoperative BSCVA > or =20/32. The AcrySofIQ IOL showed statistically significant less induction of spherical aberration (P < .001) when compared with the AMOSensar and the AcrySofNatural IOLs. The AMOSensar presented significantly less spherical aberration then the AcrySofNatural (P < .05). The AcrySofIQ also had lower values of total and high-order aberration (HOA) (P < .05) when compared with the AMOSensar and the AcrySofNatural. The mean values of trefoil 9, coma, and HOA root mean square (RMS) decreased between one and three months (P < .001, P < .001, P = .023, P < .001, respectively) in all groups. Mean Pelli-Robson contrast sensitivity values in photopic condition were similar between the groups. The AcrySofIQ showed better results in 3cpd spatial frequency in mesopic condition using FACT-Optec 6500 (P = .008), although there were no statistical differences in photopic and mesopic with glare conditions.

Aged↗

PubMed2006

Comatic aberration as a cause of monocular diplopia.

Three patients (5 eyes) presented with complaints of monocular diplopia and no history of ocular trauma or surgery. The patients had comprehensive neuroophthalmic evaluation including manifest refraction, anterior segment and dilated fundus examination, and corneal topography. All patients also had wavefront analysis using the LADARWave system (Alcon). Two patients (4 eyes) also had hard contact lens overrefraction. The patients had a normal initial examination including corneal topography. One patient (2 eyes) did not experience resolution of diplopia with pinhole. No eye improved with manifest refraction or hard contact lens overrefraction. However, each patient had a significant amount of coma on wavefront analysis. Moreover, eyes with horizontal diplopia had horizontal coma and eyes with vertical diplopia had vertical coma as measured with the wavefront device. Higher-order optical aberrations such as coma may be associated with monocular diplopia. Wavefront technology may be useful in the workup of monocular diplopia.

Corneal Topography↗

PubMed2006

Visual acuity, contrast sensitivity, reading speed, and wavefront analysis: pseudophakic eye with multifocal IOL (ReSTOR) versus fellow phakic eye in non-presbyopic patients.

PURPOSE: To compare the visual performance in the pseudophakic eye and the phakic eye in four patients who underwent unilateral intraocular lens (IOL) implantation. METHODS: Four patients presenting with unilateral cataract underwent ReSTOR (Alcon Laboratories, Ft Worth, Tex) IOL implantation in their nondominant eye, targeting emmetropia. RESULTS: Uncorrected near visual acuity was >20/32 in all operated eyes and best spectacle-corrected distance visual acuity was 20/16 for two eyes, 20/25 for one eye, and 20/32 for one eye. Reading speed was similar between the eyes, but not for critical print size. Contrast sensitivity was lower in the pseudophakic eyes. Wavefront analysis showed no considerable difference in total high order aberrations, coma, and spherical aberration between eyes for all patients. CONCLUSIONS: In young patients with unilateral cataract surgery, unilateral multifocal IOL implantation provides satisfactory visual acuity and may be considered an alternative treatment option in this patient population.

Adult↗

PubMed2005

[Corneal wound healing response following different modalities of refractive surgical procedures].

The corneal wound healing response following refractive procedures represents a subject of high relevance, due to its direct influence on the postoperative results. Technical modifications of current refractive procedures, like the automated flap creation with the femtosecond laser, LASEK, PRK with mitomycin C and Epi-LASIK have been proposed as alternatives to traditional LASIK and PRK. Several theoretical advantages have encouraged the diffusion of these new techniques; however, a better understanding of the corneal wound healing response following these procedures is required. The present text proposes a review of the corneal wound healing characteristics following different modalities of refractive surgical procedures.

Corneal Surgery, Laser↗

PubMed2005

High-speed optical coherence tomography of laser iridotomy.

PURPOSE: To describe high-speed (4000 axial scans/s) optical coherence tomography (OCT) findings in a patient with narrow angles. DESIGN: Interventional case report. METHODS: A 56-year-old woman was found to have occludable narrow angles on OCT screening. This was confirmed by gonioscopy. Bilateral iridotomy was performed. Imaging of the angles was performed with a high-speed OCT prototype before and after iridotomy. RESULTS: OCT showed narrow angle bilaterally. Cornea, sclera, scleral spur, trabecula, iris, and iris recess were visualized. After iridotomy, the OCT showed reduction of iris concavity and patent iridotomies. Quantitative measurements of trabecula-iris space area on the OCT images showed widening of the angles to nonoccludable values. CONCLUSIONS: A 1.3-microm wavelength OCT allows noncontact quantitative assessment of the angle and may be useful in the management of narrow-angle glaucoma.

Diagnostic Techniques, Ophthalmological↗

PubMed2005

Anterior chamber width measurement by high-speed optical coherence tomography.

OBJECTIVE: To measure anterior chamber (AC) width and other dimensions relevant to the sizing of phakic intraocular lenses (IOLs) with a high-speed optical coherence tomography (OCT) system. DESIGN: Cross-sectional observational study. PARTICIPANTS: Both eyes of 20 normal volunteers. METHODS: A novel high-speed (4000 axial scans/second) OCT prototype was developed for anterior segment scanning. The system uses long wavelength (1310 nm) for deeper angle penetration, rectangular scanning for undistorted imaging, and short image acquisition time (0.125 seconds) to reduce motion error. Three horizontal cross-sectional OCT images (15.5 mm wide and 6 mm deep) of the anterior segment were obtained from each eye with real-time image display to guide centration on the corneal apex. Image processing software was developed to correct for image warping resulting from index transitions. Anterior chamber dimensions were measured using computer calipers by 3 expert raters (ophthalmologists). Analysis of variance was used to determine interrater, interimage, right versus left eye, and intersubject standard deviation (SD) of OCT measurements. MAIN OUTCOME MEASURES: Anterior chamber width (recess to recess), AC depth, and crystalline lens vault as measured by OCT; external white-to-white (WTW) corneal diameter (CD) as measured by Holladay-Godwin gauge. RESULTS: The mean AC width was 12.53+/-0.47 mm (intereye SD), and the mean corneal diameter was 11.78+/-0.57 mm. Optical coherence tomography measurement of AC width has good repeatability from image to image (SD, 0.134 mm), but there was significant difference between raters (SD, 0.215 mm). Estimation of AC width from WTW CD by linear regression was relatively inaccurate (residual SD, 0.41 mm). The mean AC depth was 2.99+/-0.323 mm (intereye SD), with repeatability of less than 0.001 mm (interimage SD), and the mean crystalline lens vault was 0.39+/-0.27 mm with 0.023 mm repeatability. CONCLUSIONS: Reproducible OCT AC biometry was demonstrated using a high-speed OCT prototype. Further improvement in reproducibility may be achieved by automating the measurements with a computer. Direct OCT AC width measurement may improve sizing of angle-supported AC IOLs over conventional estimation by WTW CD. The measurement of AC depth and lens vault also may be useful for other types of phakic AC IOLs.

Adult↗

PubMed2004

Thygeson's superficial punctate keratitis recurrence after laser in situ keratomileusis.

PURPOSE: To report a case of recurrent Thygeson's superficial punctate keratitis (SPK) in a patient submitted to photorefractive keratectomy (PRK) in one eye and laser in situ keratomileusis (LASIK) in the fellow eye. DESIGN: Observational case report. METHODS: A 32-year-old woman was diagnosed with Thygeson's SPK 5 years before undergoing PRK on the right eye and LASIK on the left eye to correct -3.00 + 1.50 x 20 and -3.75 sph, respectively. RESULTS: The patient presented with recurrence of Thygeson's SPK in the left eye 10 months after the LASIK procedure and no recurrence on the right eye, which was treated with PRK. CONCLUSIONS: This case report suggests that PRK may be a better option than LASIK in patients with ocular history of Thygeson's SPK. However, no strong conclusion can be established until further studies confirm the hypothesis of a lower recurrence rate of Thygeson's SPK following PRK compared with LASIK.

Adult↗

PubMed2004

Correlation of aberrations with visual acuity and symptoms.

Standard refractive surgery (photorefractive keratectomy and laser in situ keratomileusis)induces optical changes in the wavefront aberrations of the eye. Higher-order optical changes are induced, especially spherical aberration and coma. Wavefront sensing performed after refractive surgery has revealed a decrease in low-contrast acuity and contrast sensitivity, comprising the patient's night vision and leading to symptoms such as halos, starburst, and glare.

Adult↗

PubMed2004

Wavefront analysis in post-LASIK eyes and its correlation with visual symptoms, refraction, and topography.

PURPOSE: To evaluate the information assessed with the LADARWave wavefront measurement device and correlate it with visual symptoms, refraction, and corneal topography in previously LASIK-treated eyes. PARTICIPANTS: One hundred five eyes (58 patients) of individuals who underwent LASIK surgery were evaluated. DESIGN: Retrospective, noncomparative case series. MAIN OUTCOME MEASURES: Complete ophthalmologic examination, corneal topography, and wavefront measurements were performed. Correlations were made between the examinations and symptoms. METHODS: Wavefront measurements were assessed with the LADARWave device. Manifest, cycloplegic refraction, and topographic data were compared with wavefront refraction and higher order aberrations. Visual symptoms were correlated to higher order aberrations in 3 different pupil sizes (5-mm, 7-mm, and scotopic pupil size). Pearson's correlation coefficient and generalized estimating equations were used for statistical analysis. RESULTS: In post-LASIK eyes, wavefront refraction components were poorly correlated to manifest and cycloplegic components. The comparison between manifest, cycloplegic, and wavefront refraction with total amount of higher order aberrations showed no strong correlation. The comparison between topography and manifest, cycloplegic, and wavefront refraction did not show strong correlation. Visual symptoms analysis showed correlation of double vision with total coma and with horizontal coma for the 5-mm and 7-mm pupil size; correlation between starburst and total coma for the 7-mm pupil size; and correlation of double vision with horizontal coma, glare with spherical aberrations and with total aberrations, and starburst with spherical aberrations for the scotopic pupil size. Scotopic pupil size had a positive association with starburst and a negative association with double vision. CONCLUSIONS: The LADARWave wavefront measurement device is a valuable diagnostic tool in measuring refractive error with ocular aberrations in post-LASIK eyes. A strong correlation between visual symptoms and ocular aberrations, such as monocular diplopia with coma and starburst and glare with spherical aberration, suggest this device is valuable in diagnosing symptomatic LASIK-induced aberrations. Horizontal coma was correlated with double vision, whereas vertical coma was not.

Adult↗

PubMed2004

Shifting trends in in vitro antibiotic susceptibilities for common ocular isolates during a period of 15 years.

PURPOSE: To assess the in vitro susceptibility of the most common ocular bacterial isolates to several antibiotics and verify changing trends in the antibiotic susceptibility in a 15-year period. DESIGN: Experimental study. METHODS: All cultures positive for Staphylococcus aureus, coagulase-negative Staphylococcus (CNS), Streptococcus sp, and Pseudomonas sp in conjunctival (n = 4,585) and corneal (n = 3,779) samples from patients seen at the Federal University of São Paulo from 1985 to 2000 were evaluated. Cultures were performed in liquid and solid media, and susceptibility tests were done to amikacin, gentamicin, neomycin, tobramycin, ciprofloxacin, norfloxacin, ofloxacin, cephalothin, and chloramphenicol. RESULTS: Amikacin and neomycin showed an improvement of their sensitivity during the study period (88%-95% and 50%-85%, respectively) for corneal and conjunctival samples. Gentamicin and tobramycin revealed a decrease of sensitivity in time, from 95% to less than 80% in corneal and conjunctival samples. Ciprofloxacin, norfloxacin, and ofloxacin had good sensitivity to all evaluated bacteria, better in conjunctiva (95%) than in cornea (90%). Sensitivity of S. aureus to cephalothin decreased during the study but was still 98% for CNS. Chloramphenicol had good sensitivity to S. aureus (85% in corneal and 92%in conjunctival samples), CNS (87% and 88.5%), and Streptococcus sp (95% and 96%). CONCLUSIONS: Gentamicin, tobramycin, and cephalothin decreased their in vitro susceptibility to all tested pathogens. The fluoroquinolones remained a good choice in the treatment of ocular infections, with high suscep-tibility to all pathogens tested. Chloramphenicol also revealed an increase in its susceptibility to all bacteria evaluated.

Anti-Bacterial Agents↗

PubMed2003

Secondary microkeratome-induced flap interference with the pathway of the primary flap.

PURPOSE: To report a flap-related complication that occurs when a secondary microkeratome pass interferes with the pathway of a complicated first microkeratome pass. DESIGN: Small, retrospective, noncomparative, interventional case series. PARTICIPANTS: Three patients. METHODS: In three cases, each patient experienced a different flap-related complication with the original surgery, followed by interference of a secondary flap with the primary. The first patient experienced a free cap, followed by an interference of the secondary flap at the nasal portion of the free cap. The second patient experienced a buttonhole, followed by secondary flap interference in the superior quadrant adjacent to the buttonhole. The third patient experienced a decentered flap originally, followed by secondary flap interference temporally. MAIN OUTCOME MEASURES: Visual result after secondary microkeratome-induced flap-related complications. RESULTS: All three patients had poor best spectacle-corrected visual acuity on the first postoperative day, with subsequent visual recovery. All three patients had induced flattening on keratometry along the axis where stromal tissue was removed. In addition, two patients required multiple enhancements to achieve desired visual outcomes. CONCLUSIONS: Complications related to the primary microkeratome pass add further risk for complications to arise during a second microkeratome pass. A secondary microkeratome pass should be attempted only if the original flap cannot be identified, if it is the result of primary flap complication, or if the desired treatment zone is notably larger than the diameter of the original flap. Intraoperative pachymetry of the residual stromal bed should be performed routinely. It is important to examine the stromal bed closely for loose or displaced slivers of tissue and to remove them before excimer treatment.

Adult↗

PubMedDate not supplied

Laser epithelial keratomileusis: outcome of initial cases performed by an experienced surgeon.

PURPOSE: To evaluate refractive outcome and objective clinical data, and determine efficacy, predictability, and safety of laser epithelial keratomileusis (LASEK) for myopic treatments. METHODS: We performed a retrospective non-comparative single-surgeon case series on the first 20 LASEK procedures (Alcon LADARVision 4000 laser). Mean patient age was 41.2 years (range 21 to 60 yr): 13 men and 7 women. Mean preoperative spherical equivalent refraction was -6.47+/-2.78 D. Corneal haze, uncorrected and spectacle-corrected visual acuity and manifest refraction were evaluated. RESULTS: Of 20 eyes studied, 3 were corrected for monovision. In the non-monovision group, 20/40 or better visual acuity was achieved in 94% (16 eyes) at 1 month, 100% (13 eyes) at 3 months, and 91% (10 eyes) at 6 months after LASEK; 20/20 or better was achieved in 12% (2 eyes) at 1 month, 46% (6 eyes) at 3 months, and 45% (5 eyes) at 6 months. Corneal haze at 1 month was grade 0.5 in 35% (7 eyes), 1 in 20% (4 eyes) and 2 in 10% (2 eyes). At 3 months, 62% (12 eyes) had grade 0.5 and 31% (6 eyes) had grade 1. At 6 months, 58% (12 eyes) had grade 0.5, 25% (5 eyes) had grade 1, and 8% (2 eyes) had grade 2. CONCLUSIONS: LASEK is a challenging procedure. Creating the epithelial flap is not simple and may have contributed to the high haze incidence in our study.

Adult↗

PubMedDate not supplied

Correlation of aberrations with visual symptoms using wavefront analysis in eyes after laser in situ keratomileusis.

PURPOSE: To evaluate the information assessed with the Alcon LADARWave wavefront measurement device and correlate it with visual symptoms in eyes previously treated with laser in situ keratomileusis (LASIK), and to analyze the influence of scotopic pupil size on visual symptoms. METHODS: One hundred and five eyes of 58 patients who underwent LASIK were evaluated. Wavefront measurements were assessed using the Alcon LADARWave device. Visual symptoms were correlated to higher order aberrations in three different pupil sizes (5 mm, 7 mm, and scotopic pupil size). Generalized estimating equations were used for statistical analysis. RESULTS: In eyes after LASIK, visual symptoms analysis showed positive correlation of double vision with total coma and with horizontal coma for the 5-mm and 7-mm pupil sizes, negative correlation between starburst and total coma for the 7-mm pupil size, positive correlation of double vision with horizontal coma, and glare and starburst with spherical aberration and with total aberrations. Scotopic pupil size had a positive association with starburst and negative association with double vision. CONCLUSION: The LADARWave wavefront measurement device is a valuable diagnostic tool in measuring ocular aberrations in eyes after LASIK. A strong correlation between visual symptoms and ocular aberrations, such as monocular diplopia with coma, and starburst and glare with spherical aberration, suggest this device is valuable in diagnosing symptomatic LASIK-induced aberrations. Horizontal coma was correlated with double vision, while vertical coma was not, demonstrating a greater sensitivity with horizontally oriented multifocality.

Adult↗

PubMedDate not supplied

LADARWave wavefront measurement in normal eyes.

PURPOSE: We evaluated the correlation of Alcon LADARWave wavefront measurements with clinical refraction and corneal topography. METHODS: In a retrospective, non-comparative case series, 60 eyes (30 patients) of healthy individuals evaluated by preoperative examination for refractive surgery were enrolled (manifest sphere, -11.00 to +4.50 D; manifest cylinder, 0 to -4.75 D; 45 eyes were myopic, 12 eyes were hyperopic, and 3 had mixed astigmatism). Correlation of manifest refraction, cycloplegic refraction, and topographic data with wavefront refraction and higher order aberration was assessed. Match percentage given by the wavefront was analyzed. This number represents how much of the wavefront refraction is due to sphere and cylinder (high percentage match) or is influenced by higher order aberration (low percentage match), in which case aberrometer refraction will not be close to phoropter refraction. Pearson's correlation coefficient was assessed for two continuous variables, adjusting for repeated measurements. RESULTS: The median match percentage was 91%. Mean values for all higher order aberration components in a 7.0-mm pupil were: coma = 0.35 +/- 0.29 microm, spherical aberrations = 0.36 +/- 0.31 microm, and other terms of higher order aberrations = 0.31 +/- 0.14 microm. Wavefront sphere, cylinder, and axis terms were highly correlated to manifest and cycloplegic measurements. The high match subgroup had a higher correlation coefficient than the low match subgroup for refraction. Topographic cylinder and axis were not strongly correlated to wavefront refraction, but manifest axis was significantly correlated to topographic axis. CONCLUSION: In 60 normal eyes, the Alcon LADARWave wavefront measurement was highly correlated with refraction, but less well with corneal topography.

Adult↗

PubMedDate not supplied

Wavefront-guided surface ablation with prophylactic use of mitomycin C after a buttonhole laser in situ keratomileusis flap.

PURPOSE: To describe the surgical outcome of a patient who had a previous buttonhole after laser in situ keratomileusis (LASIK) and 3 months later, had wavefront-guided photorefractive keratectomy (PRK) with topical mitomycin C 0.02%. METHODS: A 38-year-old man underwent bilateral LASIK for correction of myopic astigmatism. A buttonhole in his right eye LASIK flap occurred, but the surgeon decided to proceed with ablation due to the small size of the buttonhole. After LASIK, the patient complained of monocular diplopia in his right eye with 20/30 best spectacle-corrected visual acuity. Wavefront analysis showed a large amount of higher order aberrations, especially coma. Slit-lamp examination revealed a moderate buttonhole scar. Three months after LASIK, the patient underwent wavefront-guided PRK with application of topical mitomycin C 0.02% on the stromal bed, for a duration of 2 minutes. RESULTS: One month after wavefront-guided PRK, his uncorrected visual acuity was 20/25 in the right eye, with no symptoms. Best spectacle-corrected visual acuity in the right eye was 20/15 with +0.25 -0.50 x 110 degrees. No haze or scar was seen on slit-lamp examination. Wavefront analysis showed a decrease in higher order aberrations, especially coma and spherical aberration. CONCLUSIONS: Wavefront-guided PRK with prophylactic topical mitomycin C was effective in treating a patient with visual symptoms and loss of BSCVA after a LASIK flap buttonhole. No delayed epithelial healing, side effects or complications were noted due to mitomycin C.

Adult↗

PubMedDate not supplied

Wavefront aberrations associated with the Ferrara intrastromal corneal ring in a keratoconic eye.

PURPOSE: To describe the optical implications of the aberration pattern of a keratoconic eye implanted with an intrastromal corneal ring (Ferrara ring). METHODS: A 32-year-old man with bilateral keratoconus had a Ferrara intrastromal corneal ring implanted in his right eye. Surgery was uneventful and both uncorrected (UCVA) and best spectacle-corrected (BSCVA) visual acuity improved. Corneal topography was performed before and after surgery. Wavefront measurements were performed 1 month after the procedure in both eyes for comparison. The point spread function, modulation transfer function (MTF), and convolved acuity chart were analyzed. RESULTS: The right eye--implanted with the intrastromal Ferrara ring--had high root-mean-square (RMS) values for higher order aberrations. The left eye-keratoconus without an intrastromal ring-had moderate values. Point spread function, MTF, and convolution acuity charts are presented for each eye, with the latter two showing improved visual function in the implanted eye, despite a higher aberration value. CONCLUSION: The wavefront measurement device captured aberrations even in a highly aberrated eye. Despite better UCVA and BSCVA, the Ferrara ring notably increased higher order aberrations compared to the fellow eye, but with a more uniform central pattern. In this case, the larger RMS value was a poor predictor of good visual function; other metrics better predicted the patient's subjective response. Metrics other than RMS error may be necessary to better correlate aberration value with visual satisfaction in some eyes.

Adult↗

PubMedDate not supplied

Flap-induced and laser-induced ocular aberrations in a two-step LASIK procedure.

PURPOSE: To identify aberrations created by making a laser in situ keratomileusis (LASIK) flap and treating the refractive error with laser ablation at a later date. METHODS: Twenty-two eyes (11 patients) underwent a two-step LASIK procedure with the Alcon LADAR-Vision laser (Alcon Laboratories, Ft Worth, Tex). In the first step, a flap was created, and 1 month later the flap was lifted and laser ablation performed. Aberrations were measured with the LADARWave wavefront measurement device preoperatively, after making the flap (1 day, 1 week, 1 month) and after laser treatment (1 week and 3 months). Two different microkeratomes were used (Moria M2 [Moria; Antony, France] and SKBM [Alcon]). With the SKBM, all flap hinges were nasal; with the Moria M2, the flap hinge was randomly selected as superior in one eye and nasal in the other. RESULTS: A slight hyperopic shift was seen in the manifest and wavefront refractions at 1 week and 1 month after flap creation for the Moria M2, but not for the SKBM. Statistically significant change in manifest sphere with the Moria M2 showed a mean shift at 1 month of +0.50 +/- 0.08 diopters (D) whereas the SKBM showed no mean shift, but less reproducibility, +0.06 +/- 0.17 D. Higher order aberrations after flap creation were statistically significantly higher for all except coma with both microkeratomes, but with no predictable trends observed. Although higher in magnitude, post flap aberrations were less than one quarter the increase noted in post laser aberrations, except for "other terms." CONCLUSIONS: Creating a LASIK flap induces changes in lower and higher order ocular aberrations. The change in lower order terms is microkeratome dependent. Higher order aberrations increase to a much larger degree after laser than after flap, making a two-step procedure unnecessary in conventional LASIK.

Adult↗