Results of laser in situ keratomileusis in different degrees of myopia

doi:10.1016/S0161-6420(98)94012-X

Ophthalmology

Volume 105, Issue 4, 1 April 1998, Pages 606-611

Presented in part at the Annual Meeting of the American Academy of Ophthalmology, Chicago, Illinois, October 1996.

https://doi.org/10.1016/S0161-6420(98)94012-X Get rights and content

Abstract

Purpose

This study aimed to analyze the results of laser in situ keratomileusis (LASIK) in different degrees of myopia.

Material and methods

Three hundred consecutive eyes were divided into 4 groups according to their degree of preoperative myopia. Group I was between −3 and −6 diopters (D) (28 eyes), low myopia. Group II was between −6.25 and −10 D (138 eyes), moderate myopia. Group III was between −10.25 and −15 D (91 eyes), high myopia. Group IV was between −15.25 and −25.50 D (43 eyes), extremely high myopia. Patients were observed for 6 to 25 months.

Results

For group I, the preoperative spherical equivalent was −5.12 D ± 0.81 standard deviation (SD), corrected visual acuity was 0.88 ± 0.14 (SD), and keratometry was 44.09 D ± 1.65 (SD). At the last check-up, the spherical equivalent was −0.42 D ± 0.98 (SD), corrected visual acuity was 0.89 ± 0.15 (SD), keratometry was 39.11 D ± 1.61 (SD).

For group II, preoperative spherical equivalent was −8.33 D ± 1.24 (SD), corrected visual acuity was 0.72 ± 0.22 (SD), keratometry was 44.34 D ± 1.64 (SD). At last check-up, the spherical equivalent was −0.19 D ± 1.22 (SD), corrected visual acuity was 0.76 ± 0.17 (SD), keratometry was 37.56 D ± 1.90 (SD).

For group III, the preoperative spherical equivalent was −12.37 D ± 1.49 (SD), corrected visual acuity was 0.58 ± 0.23 (SD), and keratometry was 44.06 D ± 1.63 (SD). At last check-up, spherical equivalent was −0.55 D ± 1.63 (SD), corrected visual acuity was 0.61 ± 0.18 (SD), and keratometry was 35.88 D ± 2.18 (SD).

For group IV, the preoperative spherical equivalent was −19.04 ± 2.82 (SD), corrected visual acuity was 0.37 ± 0.17 (SD), and keratometry was 44.02 D ± 1.30 (SD). At last check-up, spherical equivalent was −1.49 D ± 1.54 (SD), corrected visual acuity was 0.44 ± 0.18 (SD), and keratometry was 33.94 D ± 2.54 (SD).

Conclusion

With some exceptions, LASIK results generally are acceptable and stable. Nevertheless, the scatter of some cases shows that there is room for improvement, even in the most sophisticated excimer software.

The high regression of group I proves the need to sample multizone software to determine whether stability is improved. Although visual results are better in patients with lower myopia, the patients whose eyes had higher ametropia more often showed improvement in their visual acuity. This may be because of the greater postoperative size of the image on the macula.

Section snippets

Materials and methods

The first 300 consecutive eyes underwent myopic LASIK between February 1994 and December 1995. The equipment used was the Automatic Corneal Shaper (Chiron Vision, Irvine, CA) and the Omnimed Excimer Laser (Summit Technology, Inc, Waltham, MA).

Before and after surgery, the patients were examined thoroughly, including undergoing corneal topography and pachymetry. All patients with progressive corneal pathology were excluded as well as those with any other ocular disease except maculopathy or

Group I (28 eyes)

The treated patients with myopia had an average of −5.12 D with a range of −3 to −6 D, standard deviation (SD) of 0.81. At the first postoperative month visit for the 28 eyes, the average residual spherical equivalent was +0.56 with a range of −1.50 to +3.25 D. The SD was 0.96. The obtained correction was therefore 5.68 D (110.94%).

Twenty-seven of the 28 patients were seen at the last 6 months after surgery. The average spherical equivalent was −0.42 within a range of −3 to +1.38 D and an SD of

Discussion

The findings regarding spherical equivalent, corrected visual acuity, uncorrected visual acuity, and keratometry were analyzed for 300 eyes, divided into 4 groups according to the degree of myopia.

At the first month after postoperative check-up, the spherical equivalent of the first three groups showed an overcorrection that improved with time. Group I achieved 110.94%, group II achieved 105.40%, group III achieved 101.53%, and group IV (myopia >15 D) achieved 94.75% of the attempted

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A new refractive surgical approachin situ keratomileusis for myopia and lamellar keratoplasty for hyperopia
Ophthalmology
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J.I. Barraquer

There are more references available in the full text version of this article.

Cited by (82)

Laser in situ keratomileusis for -6.00 to -18.00 diopters of myopia and up to -5.00 diopters of astigmatism: 15-year follow-up
2015, Journal of Cataract and Refractive Surgery
Citation Excerpt :
The most statistically significant correlation was between the RSB and the refractive status at the end of the follow-up. The retreatment rate was 30.77%, which is similar that in previous studies of laser refractive surgery for different grades of ametropia.18–23 These studies found a retreatment rate of between 20% and 30% after LASIK.
To evaluate the long-term outcomes of laser in situ keratomileusis (LASIK) for high myopia with or without astigmatism.
Vissum Instituto Oftalmologico de Alicante and Miguel Hernandez University, Alicante, Spain.
Retrospective–prospective case series.
Laser in situ keratomileusis was performed using the Visx 20/20 excimer laser. The minimum follow-up was 15 years. The main outcome measures were uncorrected (UDVA) and corrected (CDVA) distance visual acuities, manifest refraction, and corneal topography.
This study included 40 patients (40 eyes) with a mean age of 51.08 years ± 6.67 (SD) (range 41 to 60 years) with high myopia (−6.00 to −18.00 diopters [D]). At 15 years, the safety index was 1.23 and the efficacy index, 0.95. During the follow-up, a significant increase in the dioptric power of all keratometric variables was detected (P≤.028, Friedman test), the most notable increase occurring between 3 months and 1 year (P≤.005). At 15 years, 46.15% of the eyes were within ±1.00 D of the attempted spherical equivalent and 64.10% were within ±2.00 D. The UDVA at 15 years was 20/25 or better in 43.59% of eyes and 20/40 or better in 64.10% of eyes. The postoperative CDVA was significantly better than preoperatively (P<.001). The postoperative complications were minor except in 1 eye in which ectasia occurred.
Laser in situ keratomileusis for high myopia was safe over the long term. However, significant myopic regression with time was detected. Low preoperative pachymetry and low residual stromal bed were predictors of keratometric regression.
No author has a financial or proprietary interest in any material or method mentioned.
Outcome of a 10-year follow-up of laser in situ laser keratomileusis for myopia and myopic astigmatism
2014, Taiwan Journal of Ophthalmology
Citation Excerpt :
The efficacy results of this study were inferior to those of the study based on the data submitted to the Food and Drug Administration (FDA),25 which reported that 97% achieved a postoperative UCVA of 20/40, and 62% of the eyes achieved 20/20 UCVA (86.1% for 20/40 and 52.0% for 20/20 at 10 years in our study). However, our results are comparable to previous studies of LASIK for high myopia, which show that 46–78% of eyes achieved UCVA of 20/40 or better after 6 months of follow-up.2,5,8,15–22 Regarding the visual outcomes, the safety index was good (0.99), which is comparable with the safety index of 1.08 in a large, long-term study.11
To evaluate the results of laser in situ laser keratomileusis (LASIK) for myopia/myopic astigmatism over a 10-year period.
We examined LASIK patients who received regular postoperative assessments over 10 years. We evaluated uncorrected visual acuity (UCVA), manifest refraction, best-corrected visual acuity, intraocular pressure, retreatment rate, safety, efficacy, and complications.
We studied 5423 eyes between December 1997 and February 2002. The study criteria were met by 346 eyes. A UCVA of 20/40 was achieved in 86.1% of the patients, with 52.0% achieving 20/20 at 10 years. Refraction within 1.00 σ of target was achieved in 76.3% of the patients, and 95.7% were within 2.00 σ at 10 years. Retreatment was required in 124 eyes (35.8%). The preoperative logMAR UCVA of 1.24 improved to −0.08 at 1 month, and slightly decreased to 0.06 at 10 years. The safety and efficacy indices were 1.0 and 0.89 at 1 month, and 0.99 and 0.71 at 10 years.
We analyzed 6.3% of patients who regularly returned for postoperative examinations. Despite the relatively low 10-year-visit rate and the inclusion of single- and multiple-treatment cases, our results may represent the real-world picture of LASIK; furthermore, our study shows that LASIK is an effective and safe procedure.
A 10-Year Prospective Audit of LASIK Outcomes for Myopia in 37 932 Eyes at a Single Institution in Asia
2010, Ophthalmology
This study evaluates the efficacy, predictability and safety of LASIK surgery as a treatment for myopia performed as part of a large-scale, prospective clinical audit spanning 10 years in an Asian study population and to evaluate the outcomes and trends.
Prospective, nonrandomized, single-center, multisurgeon study.
We included 37 932 eyes of 19 753 patients that underwent myopic LASIK at the Singapore National Eye Centre between 1998 and 2007.
All eyes underwent LASIK as a treatment for myopia. Pre- and postoperative refractions, uncorrected visual acuity (UCVA), and best-corrected visual acuity (BCVA) were documented.
Safety, efficacy, refractive predictability, treatment trends, retreatment rates, and complications for mild, moderate, and high myopia according to spherical equivalence (SE) of less than −5.00 diopters (D), −5.00 D or more to less than −10.0 D, and −10.00 D or more, respectively.
Patients' median age was 32 years (mean, 33.0±7.9 years); there were 6832 males (34.6%) and 12 921 females included. Patients were predominantly ethnic Chinese (90.5%). Mean follow-up time was 68.8 days. The mean spherical error corrected was −5.90±2.57 D (median, −5.625 D), and outcomes were categorized into low, moderate, or high myopia. The UCVA achieving ≥20/40 has been consistently above 90% since 2000, with 72.8% achieving ≥20/20. More than 93.0% of eyes achieved within ±1.00 D target in the last 4 years. An improvement in safety was observed since the start of the study, with the best outcomes observed in 2007; loss of 1 and 2 Snellen line BCVA postoperatively was 2.4% and 0.1%, respectively. The overall retreatment rate was 3.8%; 91% of retreated eyes achieved UCVA of ≥20/30. Between 1998 and 2007, there was a significant improvement in postoperative UCVA and BCVA (P<0.001).
Myopic LASIK performed in Asian eyes within a comprehensive LASIK clinical program with appropriate clinical audit governance can be safe and effective, with high refractive predictability. Improvements in the nomograms to prevent undercorrection and to compensate for myopic regression have led to better efficacy after LASIK, with an increasing percentage of patients achieving 20/15 visual acuity postoperatively.
Proprietary or commercial disclosure may be found after the references.
Control-matched analysis of laser in situ keratomileusis outcomes in high myopia
2008, Journal of Cataract and Refractive Surgery
To evaluate the outcomes of laser in situ keratomileusis (LASIK) for high myopia.
Massachusetts Eye and Ear Infirmary, Boston, Massachusetts, USA.
The refractive and visual outcomes in 320 eyes (227 patients) that had LASIK for high myopia (spherical equivalent [SE] −6.00 to −10.00 diopters [D]) were analyzed. Two hundred fifty-eight eyes that had LASIK for low myopia were reviewed, and a subsequent control-matched comparative analysis of visual outcomes in highly myopic eyes (SE −7.54 ± 1.43 D) versus low myopic eyes (SE −2.26 ± 0.51 D) was performed after controlling for preoperative and surgical parameters. Descriptive and control-matched analyses of eyes with thick corneal pachymetry (≥570 μm) versus eyes with thinner corneal pachymetry (≤530 μm) were performed to evaluate the influence of corneal pachymetry on visual outcomes of LASIK for high myopia.
The postoperative uncorrected visual acuity (Snellen; mean −logMAR ± SD) in the low myopia group (20/22; 0.04 ± 0.11) was statistically significantly better than in the high myopia group (20/26; 0.11 ± 0.18) (P = .006). More eyes in the low myopia group (84.7%) than in the high myopia group (56.9%) achieved an SE within ±0.5 D (P<.001). There were no significant differences in visual and refractive outcomes between the thin and thick cornea groups.
Laser in situ keratomileusis for high myopia was safe, although the efficacy and predictability was slightly lower than for low myopia. There was no relationship between preoperative pachymetry and visual and refractive outcomes.
Ten-year Follow-up of Laser In Situ Keratomileusis for High Myopia
2008, American Journal of Ophthalmology
Citation Excerpt :
These observations may infer that regression attributable to chronic stromal remodeling leading to corneal ectasia is a less likely event after LASIK for moderate myopia. Our retreatment rate was 30%, which was similar to the previous reports of laser refractive surgery for high myopes that found a retreatment rate between 30% to 40% after PRK or LASIK for high myopia.13,16–23 Although it is not always easy to define a clear cut, the reasons for retreatments were under correction in 37 (68%) of 54 eyes, followed by regression in 14 eyes (26%), and both over correction and regression in three eyes (6%).
To evaluate the long-term outcomes of laser in situ keratomileusis (LASIK) for high myopia.
A long-term (10 years) follow-up retrospective interventional case series study.
The study included 196 myopic eyes of 118 patients with a mean preoperative spherical equivalent of −13.95 ± 2.79 diopter (D) treated with myopic LASIK at the Instituto Oftalmológico de Alicante, Spain using the VISX 20/20 excimer laser (VISX Inc, Santa Monica, California, USA) and the Automated Corneal Shaper microkeratome (Chiron Vision, Irvine, California, USA). All patients were evaluated three months, one year, two years, five years, and 10 years postoperatively. The main outcome measures were refractive predictability and stability, mean corneal keratometry, topographical cylinder, safety, efficacy, stability of visual acuity, and postoperative complications.
At 10 years, 82 (42%) of 196 eyes were within ±1.00 D and 119 (61%) were within ±2.00 D. Fifty-four (27.5%) eyes underwent retreatments attributable to under correction and/or regression. The myopic regression decreases with time in eyes that did not undergo retreatment with a mean rate of −0.25 ± 0.18 D per year. Eleven eyes (5%) lost more than 2 lines of best spectacle-corrected visual acuity (BSCVA) and 78 eyes (40%) showed a postoperatively uncorrected visual acuity of 20/40 or better. Two eyes (1%) with more than 15 D myopic correction developed corneal ectasia.
LASIK for myopia over −10 D is a safe procedure with myopic regression that slows down with time and a high rate of BSCVA increase in the long-term.
Ten-Year Follow-up of Laser In Situ Keratomileusis for Myopia of up to -10 Diopters
2008, American Journal of Ophthalmology
Citation Excerpt :
We found that 73% (64% for the no retreatment group and 75% for the retreatment group) of eyes were within ± 1.00 D and 92% were within ± 2.00 D 10 years after LASIK. These results are similar to those of previous short-term follow-up studies of LASIK for moderate myopia: O’Doherty and associates and Pallikaris and Siganos, with a long-term follow-up of six years, found that between 33% and 66% of eyes were within ± 1.00 D after myopic LASIK9,10; other authors,11,15–19 in studies of LASIK for moderate myopia with shorter than 12 months of follow-up, found that between 40% and 85% of eyes were within ± 1.00 D after surgery. Some previous studies suggested that myopic ablations were accompanied by a hyperopic shift and that the magnitude of the hyperopic shift increased with the magnitude of attempted correction.20,21
To evaluate the long-term outcomes of laser in situ keratomileusis (LASIK) for myopia of up to −10 diopters (D).
A long-term (10-year) follow-up retrospective, interventional case series.
The study included 97 eyes of 70 patients with a preoperative spherical equivalent (SE) of up to −10 D treated with myopic LASIK at the Instituto Oftalmológico de Alicante, Alicante, Spain, using the VISX 20/20 excimer laser (Santa Clara, California, USA) and the Automated Corneal Shaper microkeratome (Chiron Vision, Irvine, California, USA). All patients were evaluated three months, one year, two years, five years, and 10 years after surgery. The main outcome measures were refractive predictability and stability, mean corneal keratometry, topographical cylinder, safety, efficacy, stability of visual acuity, and postoperative complications.
At 10 years, 71 (73%) of 97 eyes were within ± 1.00 D and 89 (92%) were within ± 2.00 D. Twenty eyes (20.8%) underwent retreatments because of overcorrection, undercorrection, regression, or both. The mean SE slightly decreased (myopic regression) over 10 years, with a mean myopic regression of −0.12 ± 0.16 D per year. Fifty-four (54.6%) of 97 eyes demonstrated an increase in best spectacle-corrected visual acuity (BSCVA) after 10 years. No eye developed corneal ectasia in the long-term, and only three eyes lost more than two lines of BSCVA because of complications that were not attributable to the LASIK procedure.
LASIK for myopia of up to −10 D is a safe and effective procedure with slight myopic regression that slows down with time and a high rate of BSCVA increase in the long-term.

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¹: The authors have no proprietary interest in any of the materials used in this study.

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Results of laser in situ keratomileusis in different degrees of myopia1