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At least 37 records · Page 2Linked to original sources
PubMed2006

The influence of incision-induced astigmatism and axial lens position on the correction of myopic astigmatism with the Artisan toric phakic intraocular lens.

PURPOSE: To evaluate postoperative astigmatism with regard to incision-induced astigmatism and deviation in axial alignment with the use of preoperative limbal marking with the Javal keratometer (Haag Streit, Bern, Switzerland) in eyes implanted with the Artisan toric phakic intraocular lens (IOL) (Ophtec, Groningen, The Netherlands). DESIGN: Prospective nonrandomized trial. PARTICIPANTS: Fifty-four eyes of 33 patients with myopia (mean, -9.67 diopters [D]) and astigmatism (mean, -3.44 D). INTERVENTION: The enclavation site was marked on the limbus using the Javal keratometer. The Artisan toric phakic IOL was implanted according to the axis marked on the limbus. Follow-up was a minimum of 6 months. MAIN OUTCOME MEASURES: Safety index, efficacy index, predictability, safety, and vector analysis of total refractive correction were determined. The effects of axis misalignment and incision-induced astigmatism on the final refractive error were evaluated. RESULTS: At 6 months after surgery, the safety index was 1.29+/-0.29 and the efficacy index was 1.04+/-0.35. Mean spherical equivalent subjective refraction reduced from -11.39+/-4.86 D before surgery to -0.38+/-0.57 D at 6 months. Sixty-seven percent of eyes were within 0.50 D of attempted refraction and 89% were within 1.00 D. Mean preoperative cylinder was 2.92+/-1.60 D at 91.4 degrees . At 6 months, the mean cylinder was 0.28+/-0.54 D at 174.3 degrees . No eyes lost 2 or more lines of best-corrected visual acuity at 6 months. Eighty-three percent of eyes achieved uncorrected visual acuity of 20/40 and 28% achieved 20/20. Vector analysis of total surgically induced astigmatism revealed a mean cylindrical change of 3.21+/-1.71 D. Average axis misalignment was 0.37+/-5.34 degrees . The mean incision-induced astigmatism was 0.74+/-0.61 D at 0.2 degrees . CONCLUSIONS: Implantation of the myopic toric IOL leads to safe, efficacious, and predictable results. The level of unpredictability caused by minor axis IOL misalignment has minimal effects on the residual refractive error. The procedure of axis alignment with the Javal keratometer seems to be an accurate method of marking the eye for toric IOL implantation. Incision-induced astigmatism can result in an overcorrection of the cylinder. A systematic undercorrection of -0.50 D for attempted cylindrical outcome could result in an achieved correction closer to emmetropia.

Adult↗
PubMed2000

A new concept for the correction of astigmatism: full-arc, depth-dependent astigmatic keratotomy.

OBJECTIVE: The purpose of this study is to introduce and evaluate a new concept in astigmatic keratotomy (AK) named full-arc, depth-dependent AK (FDAK). DESIGN: Noncomparative interventional case series. PARTICIPANTS: FDAK was performed on a total of 37 eyes with regular astigmatism; of these, 16 eyes received FDAK alone, and 21 eyes received FDAK combined with cataract surgery. METHODS: Corneal topography was used to divide the cornea into two discreet regions of "steep" and "flat." Then, paired arcuate incisions, 90 degrees in length, were placed along the full arc of the steep area. The level of astigmatic correction was controlled by varying the incision depth from 40% to 80% on the basis of a provisional nomogram developed by the authors. MAIN OUTCOME MEASURES: Keratometries, corneal topographies, and visual acuities were measured. RESULTS: The FDAK alone group showed a significant improvement from a preoperative corneal astigmatism of 2.90 +/- 0.78 diopters (D) to a postoperative value of 0.89 +/- 0.52 D. The "combined" group also showed significant improvement from a preoperative corneal astigmatism of 2.97 +/- 1.01 D, to a postoperative value of 1.02 +/- 0.45 D. The deviation of achieved correction from attempted correction using vector analysis was between 1.37 D of undercorrection and 0.98 D of overcorrection, with 91.9% of cases within the range of +/- 1.0 D. Slight oblique change caused by axis deviation was observed in seven cases. Both uncorrected and corrected visual acuity showed statistically significant improvement. No serious complications were encountered. CONCLUSIONS: Controlling the level of correction by varying the incision depth allowed the surgeon to use long incisions (90 degrees in length in regular astigmatism) covering the entire steep area, minimizing the undesirable changes induced by conventional deep and narrow incision AK and resulting in an ideal corneal sphericity after surgery. FDAK enabled the surgeon to accurately control the level of astigmatic correction with minimal risk of corneal perforation.

Adult↗
PubMed2000

Correction of high astigmatism with astigmatic keratotomy combined with laser in situ keratomileusis.

PURPOSE: To evaluate the efficacy, predictability, and stability of a combined procedure, arcuate keratotomy and laser in situ keratomileusis (LASIK), for the correction of high astigmatism. SETTING: Instituto de Microcirugía Ocular (IMO), Barcelona, Spain. METHODS: Fifteen eyes of 11 patients with naturally occurring astigmatism (NOA) (86. 66%) or surgically induced astigmatism (SIA) (13.34%) between -3.00 and -8.00 diopters (D) who had astigmatic keratotomy were studied. The patients had a secondary procedure, LASIK, to correct the residual refractive error. RESULTS: Mean baseline spherical equivalent refraction was -2.47 D +/- 3.69 (SD) and mean refractive cylinder, -4.59 +/- 1.66 D. Twelve months after LASIK, mean spherical equivalent was -0.09 +/- 1.50 D and the mean refractive cylinder, -1. 21 +/- 1.07 D. The mean cylindrical correction attempted in the NOA group was -4.05 +/- 1.19 D and in the SIA group, -7.00 +/- 1.41 D. Postoperatively, the values were -1.50 +/- 1.17 D and -1.62 +/- 0.17 D, respectively. Twelve months after LASIK, the uncorrected visual acuity (UCVA) was 0.5 +/- 0.1. The UCVA in the NOA group (0.50 +/- 0. 08) was better than in the SIA group (0.32 +/- 0.10). The efficacy index was 0.96 overall. Best corrected visual acuity deteriorated by 1 Snellen line in 1 case (6.6%) but improved by 1 and 2 Snellen lines in 4 cases (26.6%) and 2 cases (13.3%), respectively. All procedures were completed without adverse reactions intraoperatively or postoperatively. CONCLUSION: This combined technique was effective in the treatment of high astigmatism, with excellent results compared with the results of each procedure alone. Because of its high predictability, we strongly recommend the technique in cases with astigmatism higher than 3.0 D, particularly in those with astigmatism higher than 5.0 D.

Adult↗
PubMed2004

LASIK for hyperopia, hyperopic astigmatism, and mixed astigmatism: a report by the American Academy of Ophthalmology.

OBJECTIVE: To describe LASIK for hyperopia, hyperopia with astigmatism, and mixed astigmatism and to examine the evidence to answer questions about the safety and efficacy of the procedure. METHODS: A literature search conducted for the years 1968 to 2002 retrieved 118 citations. During review and preparation of this article, an additional 2 articles were included. The panel members selected 36 articles for the panel methodologist to review and rate according to the strength of evidence. A level I rating is assigned to properly conducted, well-designed, randomized clinical trials; a level II rating to well-designed cohort and case-control studies; and a level III rating to case series, case reports, and poorly designed prospective and retrospective studies. RESULTS: This assessment describes 5 nonrandomized interventional trials (level II), 3 nonrandomized comparative trials (level III), and 20 noncomparative case series (level III). Additionally, 6 single-case reports (level III) were included because they reported relevant complications, and 2 theoretical analyses (level III) were also considered. This assessment does not compare studies because many variables such as range of hyperopia, follow-up periods, lasers, microkeratomes, techniques, and surgeon experience have not been controlled. CONCLUSIONS: For low (<3 diopters [D]) to moderate (3-5 D) hyperopia, results from published studies (levels II and III evidence) have shown that LASIK is effective and predictable in achieving very good to excellent uncorrected visual acuity, achieving postoperative refractions within 1 D of emmetropia, and is safe in terms of minimal loss of best-corrected spectacle vision. Although there are fewer data for hyperopic astigmatism, the results available seem to mirror the data for low to moderate hyperopia (levels II and III evidence). The postoperative results for both uncorrected vision and safety are less compelling, as greater amounts of hyperopia are treated (>4 to 5 D). Utilizing hyperopic LASIK for the treatment of consecutive hyperopia and astigmatism is also effective, although the ability to reduce hyperopic astigmatism after radial keratotomy is limited. Although a variety of ablation profiles can be used to treat mixed astigmatism, very good visual results have been reported (levels II and III evidence). Serious adverse complications leading to permanent visual loss are possible but, fortunately, very rare. There are insufficient data to compare one laser system with another or one ablation profile with another.

Academies and Institutes↗
PubMed1999

Effect of astigmatic keratotomy on spherical equivalent: results of the Astigmatism Reduction Clinical Trial.

PURPOSE: To determine the effect of astigmatic keratotomy on spherical equivalent, as measured by the coupling ratio and a new quantity, coupling constant. METHODS: In a prospective multicenter study, subjects underwent arcuate keratotomy at a 7-mm optical zone by means of the Lindstrom nomogram for correction of astigmatism. One hundred fifty-seven eyes of 95 patients who had a follow-up examination 1 month postoperatively were studied. Mean preoperative refractive cylinder +/- SEM was 2.82 +/- 1.17 diopters. Coupling ratio was defined as the ratio of the flattening of the incised meridian to the steepening of the opposite meridian. Coupling constant was defined as the ratio of the change in spherical equivalent to the magnitude of the vector change in astigmatism. Coupling ratio, coupling constant, and change in spherical equivalent were calculated on the basis of change in refraction and keratometry. RESULTS: On the basis of change in refraction, coupling ratio was 0.95 +/- 0.10 (mean +/- SEM) and coupling constant was -0.01 +/- 0.03, consistent with a minor shift in the spherical equivalent of -0.03 +/- 0.07 diopter. On the basis of change in keratometry, coupling ratio was 0.84 +/- 0.05 and coupling constant was -0.04 +/- 0.02, consistent with minor postoperative keratometric steepening of -0.10 +/- 0.04 diopter. Coupling ratio based on change in refraction was not statistically different from the coupling ratio predicted by the Gauss' law for inelastic domes (P = .370). Incision length and number, amount of achieved cylinder correction, age, and sex had no statistically significant effect on coupling ratio, coupling constant, and change in spherical equivalent. CONCLUSIONS: Cornea behaved as an inelastic surface in response to arcuate keratotomy performed with the Astigmatism Reduction Clinical Trial study nomogram. On average, astigmatic keratotomy had a minimal effect on spherical equivalent refraction. There was variability, however, in coupling ratio, coupling constant, and change in spherical equivalent from eye to eye after astigmatic keratotomy. Caution is therefore advised when simultaneous correction of cylinder and spherical equivalent is planned.

Adolescent↗
PubMed1998

Relationship between preoperative axis of astigmatism and postoperative astigmatic change after superior scleral incision phacoemulsification.

PURPOSE: To evaluate the effect of the preoperative axis of astigmatism on the outcome of corneal astigmatism after sutured 5.2 to 5.7 mm superior incision phacoemulsification. SETTING: Departments of Opthalmology, Odense and Vejle Hospitals, Denmark. METHODS: Seventy-three consecutive patients with preoperative corneal astigmatism of 2.0 diopters (D) or less, axial length between 20.0 and 25.5 mm, and no eye disease except cataract were grouped according to preoperative with-the-rule (WTR) or against-the-rule (ATR) astigmatism. The keratometric cylinder, induced keratometric cylinder (subtraction), and induced cylinder (Jaffe) were measured and calculated 10 to 12 months postoperatively. RESULTS: The postoperative keratometric cylinder and induced keratometric cylinder were significantly higher in the ATR group (P < .00001; mean difference [95% confidence limits]: 0.76 D [0.54; 0.98] and 0.69 D [0.46; 0.92], respectively). There was no significant difference between groups in induced cylinder (Jaffe). CONCLUSION: The estimated differences were significantly in favor of patients with preoperative WTR astigmatism. The findings support using temporal incision in cases with a preoperative ATR axis of astigmatism.

Aged↗
PubMed2002

An assessment of the orthogonal astigmatism test for the subjective measurement of astigmatism.

The orthogonal astigmatism test (OAT) is a newly developed method for assessing ocular astigmatism. This study compares the OAT with the Jackson crossed-cylinder (JCC), Raubitschek arrow (RA) and the fan and block (FB) (fan chart). Fifty emmetropes or corrected spherical ametropes (<0.25 DC of astigmatism) were recruited, with a visual acuity of at least 6/5 in both eyes. Pseudo-astigmatism was induced by placing a +0.75 DC lens in front of the right eye at a random axis. With the left eye occluded, each subjective test was performed in a random order and the correcting lens power and axis noted. No significant difference was found in the ability of the OAT to locate the power and axis of the induced astigmatism over the JCC, RA and FB. In conclusion, the OAT offers the clinician an alternative method for locating and correcting ocular astigmatism. It has a similar but not superior accuracy to the other three subjective tests assessed.

Adult↗
PubMedDate not supplied

Arcuate transverse keratotomy for astigmatism followed by subsequent radial or transverse keratotomy. ARC-T Study Group. Astigmatism Reduction Clinical Trial.

BACKGROUND: We studied the safety and efficacy of arcuate transverse keratotomy performed for the primary correction of naturally occurring corneal astigmatism. METHODS: A multicenter, prospective evaluation of one-stage arcuate transverse keratotomy was conducted in 160 eyes with 1.00 to 6.00 diopters (D) of naturally occurring astigmatism. Vector analysis was used. After 1 month, those eyes that needed further refractive surgery received radial keratotomy for myopia and second-stage arcuate transverse keratotomy for residual astigmatism. RESULTS: Mean preoperative refractive cylinder was 2.80 D. At 1 month, the vector-corrected change was 2.30 D. Eighty-eight (61%) eyes had at least 1.00 D of residual refractive cylinder and 24 (17%) had at least 2.00 D. Eyes undergoing a second surgery averaged 1.60 D of vector-corrected effect, for a total effect of 2.90 D from both surgeries, indicating the astigmatic refractive effects were not additive. Eyes that had radial keratotomy alone as the second surgery demonstrated a similar change in refractive cylinder as eyes that had both radial and transverse keratotomies. Two eyes lost two lines of spectacle-corrected visual acuity, 29 eyes lost one line, 84 showed no change, and 26 eyes improved one line. CONCLUSION: Arcuate transverse keratotomy reduced refractive astigmatism. Both overcorrection and undercorrection were common. Complications were infrequent but occasionally caused significant irregular astigmatism. Arcuate transverse keratotomy appears to be a safe procedure with few complications.

Adolescent↗
PubMedDate not supplied

[Correction of high astigmatism and astigmatic anisometropia by intrastromal photokerato-ablation in children and adolescents].

A total of 151 photorefraction operations for correction of medium and high astigmatism in 38 children (9-15 years) and 47 adolescents (16-17 years) carried out by LASIK method are analyzed. The operations were performed under local anesthesia with EC-5000 eximer laser (Nidek) and Hansatome microkeratome (B & L). Complicated and common myopic astigmatism (2.07 +/- 0.89 to 2.91 +/- 0.63 diopters) was decreased by 61.2% in children and by 62.2% in adolescents. Visual acuity without correction increased by 0.58 +/- 01.2. Correction of astigmatic anisometropia resulted in its decrease to 0.75-1.5 diopters in 77.9% children and 62.8% adolescents. Hypermetropic astigmatism decreased by 64.9% of its initial value in children and by 56.9% in adolescents. Mixed astigmatism decreased by 62.7% of its initial value. The resultant visual acuity without correction was 0.39 +/- 0.13 in children and 0.47 +/- 0.17 in adolescents. According to questionnaires distributed among parents, 13.5% patients studied better at school after the operation and 19.2% went in for sports in athletic sections. The main causes for the intervention were limitations in choice of profession (for 49.6%) and desire to practice modern athletics (in 13.8%). Photorefraction correction of astigmatism in children and adolescents brings about an effective stable result decreasing refraction amblyopia and improving the quality of life.

Adolescent↗
PubMed1995

Fourier analysis of video-keratographic data. A tool for separation of spherical, regular astigmatic and irregular astigmatic corneal power components.

Topographic analysis of the cornea and computation of changes in corneal topography is difficult because of the lack of a standardized concept for analysing topographic information. We have used Fourier series harmonic analysis to decompose the often very complex information given in topographic images (TMS-1 video-keratograph). The polar data values arising from each mire were separated into spherical (average power), regular astigmatic (2' harmonic) and non-regular astigmatic components. The non-regular astigmatic components were further divided into a decentration component (1' harmonic) and a higher order irregular refractive component (root mean square (r.m.s.) of the residual between original data and the sum of spherical, 1' and 2' order components). Algorithms for utilizing the Fourier analysis technique on subjective refractive and on keratometric changes in regular astigmatism were also derived. Averages of the separate refractive components were calculated for groups of normal (right and left eye of 25 patients), keratoconic (13 eyes), and transplanted eyes (20 eyes), and average topographic maps were reconstructed and imaged. Changes in the separate topographic refractive components were compared with subjective refractive changes in eyes that had undergone combined myopic-astigmatic excimer laser ablation (8 eyes). Fourier series analysis was found superior to conventional keratometry in predicting spherical and regular astigmatic changes in subjective refraction. Fourier series analysis seems to be a powerful tool to decompose the information of complex topographic corneal images into rational optical components.

Algorithms↗
PubMed2006

Astigmatic keratotomy for post-keratoplasty astigmatism.

PURPOSE: To assess astigmatic keratotomy as a means of managing post-keratoplasty astigmatism in the era of excimer laser refractive surgery. SETTING: Moorfields Eye Hospital, London, England. METHODS: Fifty paired arcuate keratotomies were performed with refractive and topographic guidance. Refraction, uncorrected visual acuity, best corrected visual acuity, and visual acuity with the patient's preferred correction were measured before and after surgery. RESULTS: The median follow-up was 34 months. The mean cylinder was 9.13 diopters (D) preoperatively and 4.85 D postoperatively. The mean spherical equivalent refraction was -4.21 D preoperatively and -4.26 D postoperatively. The amount of cylinder reduction was correlated with the amount of pre-existing cylinder (P<.001). Thirty eyes (60%) gained and 1 eye (2%) lost Snellen acuity with preferred correction. In the remaining 19 eyes (38%), there was no change in acuity with preferred correction. The mean change in visual acuity with preferred correction was a gain of 1.5 Snellen lines. Three patients intolerant of spectacles or contact lenses before surgery became tolerant. Ten patients (20%) previously unsuitable for laser in situ keratomileusis (LASIK) because of high cylindrical error went on to have LASIK. CONCLUSIONS: Astigmatic keratotomy remains a useful, safe, relatively simple surgical procedure for treating post-keratoplasty astigmatism. Reduction in cylinder was correlated with pre-existing cylinder. Vision with preferred correction was improved in 60% of cases. High astigmatism reduced to a level at which more definitive refractive surgery such as LASIK became feasible.

Adult↗
PubMed1998

Combined astigmatic keratotomy with corneal valvular incision in the treatment of high surgical astigmatism.

BACKGROUND: Astigmatic keratotomy is used conventionally to correct moderate surgical astigmatism. However, cases with very high surgical astigmatism due to wound compression can show a dramatic response to relaxing keratotomies made in the steeper meridian. The effect obtained cannot be predicted pre-operatively by using standard nomograms. METHODS: Coupled arcuate keratotomies combined with corneal valvular incisions were performed in a case of high astigmatism post-cataract surgery. RESULTS/CONCLUSION: Coupled arcuate keratotomies were combined with a corneal valvular incision enabled a surgical correction of nearly 9 D of astigmatism.

Astigmatism↗
PubMedDate not supplied

Astigmatic keratotomy followed by photorefractive keratectomy in the treatment of compound myopic astigmatism.

Eleven eyes of 9 patients that had compound myopic astigmatism were treated by astigmatic keratotomy followed 1 month later by photorefractive keratectomy (PRK). In 9 eyes arcuate incisions were performed, in 1 eye a modified Ruiz procedure was performed, and in 1 eye radial T cuts were done. The mean spherical equivalent was -8.26 +/- 2.51 diopters (D) after the astigmatic keratotomy but before photorefractive keratectomy, and -0.36 +/- 0.93 D after photorefractive keratectomy. The mean cylinder was -3.11 +/- 1.16 D preoperatively, and -0.14 +/- 0.9 D postoperatively. Combined astigmatic keratotomy and photorefractive keratectomy are effective treatments for compound myopic astigmatism.

Adult↗
PubMed1989

Astigmatism control for the cataract surgeon: a comprehensive review of surgically tailored astigmatism reduction (STAR).

It is increasingly possible for the cataract surgeon to control astigmatism. Based on a review of 4,000 consecutive patients, three categories of astigmatism and cataract patients are identified. A specific approach to astigmatism control for each category is discussed. Preliminary results on the use of astigmatic keratotomy in conjunction with cataract surgery are presented.

Aged↗
PubMed1981

A longitudinal study of corneal astigmatism and total astigmatism.

Cross-sectional studies indicate that mean total astigmatism changes with age; varying from as much as 0.62 D with-the-rule during youth to as much as 0.37 D against-the-rule in samples of elderly patients. The present study involves the examination of adult patients who were seen regularly for a period of at least 40 years. Data are analyzed to determine whether the change in corneal astigmatism accounts for the total astigmatic change, and the magnitude of change with age at each of the principal corneal meridians. Results indicate that steepening of the cornea in the horizontal meridian accounts for a major portion of the increase in against-the-rule total astigmatism among older patients.

Adolescent↗
PubMed1989

Irregular astigmatism after radial and astigmatic keratotomy.

Eleven eyes of six patients, who had been referred for management of irregular astigmatism after receiving crossed incisions for myopic astigmatism, had moderate to marked irregular corneal astigmatism with marked flattening in the meridians of intersecting incisions. All six patients had a decrease in best-corrected visual acuity with spectacles after surgery. Visual acuity with spectacles was 20/40 in five of 11 eyes; with contact lenses it reached 20/40 in ten of 11 eyes. However, two patients could not wear the contact lenses because of lens decentration caused by the marked distortion in corneal topography. Even with contact lenses, visual acuity could only be improved to 20/25 or better in six of 11 eyes.

Astigmatism↗
PubMed2006

Surgically induced astigmatism after phacoemulsification in eyes with mild to moderate corneal astigmatism: temporal versus on-axis clear corneal incisions.

PURPOSE: To determine whether there is a difference in surgically induced astigmatism (SIA) and postoperative uncorrected visual acuity (UCVA) and best corrected visual acuity (BCVA) between 2 types of clear corneal incisions used in phacoemulsification: the temporal and the on-axis (ie, on the steeper corneal meridian) clear corneal incision (CCTI and CCOI, respectively). SETTING: Moorfields Eye Hospital, London, United Kingdom. METHODS: In a prospective randomized controlled trial (pilot study), 61 eyes with cataract and mild to moderate corneal astigmatism (<2.58 diopters [D] on corneal topography) having phacoemulsification (single surgeon, 3.2 mm incision) were randomized to receive CCTI or CCOI. Main outcome measures included postoperative BCVA and corneal astigmatism and SIA (calculated using the Holladay vector analysis formula). Measurements were repeated postoperatively at 3 weeks in all eyes, whereas only 46 eyes made it to the final assessment at 8 weeks. Continuous variables between groups were compared by Student t test. The power of the study was calculated. RESULTS: At the first follow-up, the difference in SIA between the 2 incision types was 0.15 D and it was not statistically significant (0.65 D in CCOI; 0.50 D in CCTI). At the second follow-up, the difference was 0.29 D and it was statistically significant (0.63 D in CCOI; 0.34 D in CCTI; P = .0004). There was no statistically significant difference in the final postoperative visual acuity. The power of the pilot study was 72%. CONCLUSION: Seven weeks after small-incision phacoemulsification, the CCTI induced less SIA than the CCOI; however, there were no significant differences in the final UCVA and BCVA.

Aged↗
PubMed2002

Comparison of photorefractive keratectomy, astigmatic PRK, laser in situ keratomileusis, and astigmatic LASIK in the treatment of myopia.

PURPOSE: To determine factors affecting refractive and visual outcomes in patients treated with astigmatic and spherical photorefractive keratectomy (A-PRK and PRK) and laser in situ keratomileusis (A-LASIK and LASIK). SETTING: University referral refractive surgery clinic. METHODS: Refractive and visual acuity results in 619 eyes of 388 consecutive patients having refractive surgery over a 2-year period by a single surgeon were retrospectively analyzed. Patients were divided into mild-to-moderate myopia (spherical equivalent [SE] less than -6.12 diopters [D]) and high myopia (SE -6.12 D or higher). Multivariate and logistic regression analyses were performed. RESULTS: Refractive results in flap-based and PRK-based procedures were comparable in mild-to-moderate myopia patients but were significantly better in high-myopia patients having flap-based procedures. Refractive stability was greater in flap-based procedures than in PRK-based procedures. Elliptical ablations yielded a marked reduction in the astigmatic cylinder in patients having A-LASIK and A-PRK, while spherical PRK induced small amounts of with-the-rule astigmatism. Complications were uncommon in both groups, consisting primarily of epithelial ingrowth in flap-based procedures and haze in PRK-based procedures. Multivariate regression identified the preoperative SE as a significant determinant of PRK outcomes (with higher success for lower myopia) and intraocular pressure as a minor determinant of outcomes in PRK-based and flap-based procedures. Logistic regression suggested that only the preoperative SE was a significant factor in predicting the likelihood of poor outcomes in PRK patients. CONCLUSIONS: Refractive outcomes were almost identical in patients having elliptical or spherical ablations with flap-based or PRK-based procedures. In eyes with mild-to-moderate myopia, there was little difference in refractive or visual outcomes between flap-based and PRK-based procedures; in eyes with high myopia, flap-based procedures offered more predictable refractive outcomes and better visual outcomes.

Adult↗