Laser thermal keratoplasty for the treatment of photorefractive keratectomy overcorrections: A 1-year follow-up

doi:10.1016/S0161-6420(98)95039-4

Ophthalmology

Volume 105, Issue 5, 1 May 1998, Pages 926-931

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

https://doi.org/10.1016/S0161-6420(98)95039-4 Get rights and content

Abstract

Objective

To evaluate the results of holmium:YAG laser thermal keratoplasty (LTK) treatment for overcorrection of myopia after a photorefractive keratectomy (PRK) treatment.

Participants

Thirty-six eyes (33 patients) were treated with a nontouch holmium:YAG laser (Sunrise Technologies, Model LTK, Freemont, CA) because of hyperopia (mean ± standard deviation of +2.06 diopter [D] ± 0.75, ranging from +1.0 to +3.5 D) following a PRK treatment. A control LTK group treated for primary hyperopia, who had preoperative refraction values not statistically different from the PRK + LTK group, was used for comparison.

Intervention

The number of spots applied varied from 8 to 24, and the energy used was 200 to 240 mJ. A maximum of three rings of four to eight spots were placed between 6 and 8 mm from the visual axis.

Results

Twelve months after the LTK retreatment for PRK patients, mean refraction was +1.14 D ± 1.09. Regression from 1 to 12 months was 0.5 D ± 1.1. At 12 months, 50% of eyes were within 1 D of emmetropia; 93% of eyes had uncorrected visual acuity (UCVA) of 20/40 or better; and 24% of eyes had UCVA of 20/20 or better. Refraction was not stable for 11 eyes (34%) that regained original sphere values or higher. Best-corrected visual acuity was not affected, and haze was not increased nor decreased by the procedure.

Conclusions

Twelve months after an LTK retreatment for an initial PRK, two thirds of the retreated eyes did not need further retreatments. However, clinical data showed that LTK should be kept for +1 to +2 D of hyperopia for PRK overcorrection retreatments.

Section snippets

Patients and methods

Laser thermokeratoplasty, using a nontouch holmium:YAG laser (Sunrise Technologies, Freemont, CA), was proposed to and accepted by 33 patients (36 eyes) who had become hyperopes after myopic PRK treatment. The LTK post-PRK group was compared with a natural hyperopia population of 40 eyes (27 patients) with a comparable level of refraction error. This population had no PRK treatment prior to the LTK.

Preoperatively, manifest refraction, best spectacle-corrected Snellen visual acuity (BSCVA),

Results

Mean age ± SD of the PRK + LTK group was 39.4 years ± 8.0, ranging from 19 to 54 years. Forty-five percent of the patients were female and 55% were male. Mean refraction ± SD before treatment was +2.07 D ± 0.75, ranging from +1 to +3.50 D. Astigmatism varied between 0 and −3.5, with a mean ± SD of −0.78 D ± 0.95. Eleven eyes (30.5%) were retreated after the study for further enhancement. Before LTK, 29 (88%) eyes in the PRK + LTK group had 20/40 or better BSCVA. The remaining four eyes that

Discussion

Among all of the complications from myopic PRK corrections, over- and undercorrections generally rank first. However, not all eyes need a retreatment because of the accommodation factor. One study reported that retreatments for undercorrections had resulted in acceptable final refractions for at least 50% of the cases that were missed in the first instance.5 In another study on myopia retreatments with the Visx 20/20B excimer laser (Visx Co., Santa Clara, CA), 84% of eyes had acceptable final

Acknowledgements

The author thanks Julian Stevens, MD, FRCOphth, for the Refract Tools 1.38 software, and Yves Payette, MSc, for his suggestions, contributions, and analysis of data.

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Cited by (17)

Ten-year Follow-up of Photorefractive Keratectomy for Myopia of Less Than -6 Diopters
2008, American Journal of Ophthalmology
Citation Excerpt :
Similar to the previous studies,28,29 LASIK retreatments (five eyes) after PRK in our study were safe and effective without significant complications and without the need for further retreatments. Previously, a high rate of regression was reported after holmium laser thermoplasty for hyperopia correction.30,31 Given that two eyes that underwent retreatment with holmium laser thermoplasty required further retreatments for residual refractive errors or regression in the present study, holmium laser thermoplasty retreatments for hyperopia (overcorrection) did not seem to be effective.
To evaluate the long-term outcomes of excimer laser myopic photorefractive keratectomy (PRK) for myopia of less than −6 diopters (D).
Long-term (10-year) follow-up retrospective, interventional case series.
The study included 225 eyes of 138 myopic patients with spherical equivalent (SE) between 0 and −6 D treated with myopic PRK at the Instituto Oftalmológico de Alicante, Alicante, Spain, using the VISX 20/20 excimer laser (Santa Clara, California, USA). 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, 169 (75%) of 225 eyes were within ± 1.00 D and 207 (92%) were within ± 2.00 D. Ninety-five (42%) eyes underwent retreatments because of overcorrection, regression, or both. The mean SE slightly decreased (myopic regression) with a mean magnitude of −0.10 ± 1.08 D over 10 years (−0.01 ± 0.11 D per year). Forty-one (58%) of 225 eyes demonstrated increase in best spectacle-corrected visual acuity after 10 years. Only one eye lost eight lines because of significant cataract, and two eyes lost vision (one lost seven lines and the other lost four lines) because of posterior segment-related complications. The mean corneal haze score gradually decreased from 0.22 ± 0.39 at three months to 0.01 ± 0.09 at 10 years.
Photorefractive keratectomy for myopia of less than −6 D is a safe and effective procedure in the long-term.
Surgical Correction of Hyperopia
2006, Survey of Ophthalmology
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At 1 year, both patterns were effective; however, the radial pattern achieved a faster return of preoperative BSCVA and better stability over time. Attempts to correct hyperopia with non-contact Ho: YAG after lamellar refractive procedures12,148,168,303 or following cataract extraction115 have also been reported. However, Hill showed better outcomes using LASIK when compared to LTK.159
Surgical attempts to correct hyperopia have yielded varying results over the last 130 years. These techniques include the reshaping of the cornea through incisions, burns, or lamellar cuts with removal of peripheral tissue; the addition of central inlays; laser ablations; and the replacement of the crystalline lens. By examining the success of each surgical technique, the refractive surgeon may be able to make an informed decision on its indications and limitations, based on the specific patient's characteristics. Reporting the outcomes and complications of hyperopic surgery will help refine our approach to the management of an increasingly hyperopic and presbyopic population.
Laser thermokeratoplasty for hyperopia and astigmatism
2006, Refractive Surgery, Second Edition
Long-term results of conductive keratoplasty for low to moderate hyperopia
2005, Journal of Cataract and Refractive Surgery
Citation Excerpt :
Alió and coauthors7 reported UCVA of 20/20 or better in 47% of eyes and 20/40 or better in 72% at 15 months; Koch et al.2 reported a mean value of 20/63. Pop33 reported a UCVA of 20/20 or better in 24% of the treated eyes. A recent study of noncontact LTK for hyperopia with a 2-year follow-up34 described better efficacy results than other LTK reports.
To assess the long-term safety, efficacy, predictability, and stability of conductive keratoplasty (CK) for the treatment of low to moderate hyperopia and to evaluate the impact of the procedure on the quality of vision.
University of Crete, Medical School, Vardinoyannion Eye Institute of Crete, Crete, Greece.
In this prospective nonrandomized noncontrolled single-center study, 38 eyes of 26 patients (13 women and 13 men) were treated for hyperopia with a Refractec ViewPoint CK system and followed for 30 months. Preoperatively, the mean manifest refraction spherical equivalent (MRSE) was +1.89 diopters (D) ± 0.6 (SD) (range +1.00 to +3.25 D), and the mean follow-up was 30.9 ± 1.1 months. All eyes were treated with the regular CK nomogram for the treatment of spherical hyperopia. The treatment consisted of 8 to 32 spots applied to the periphery of the cornea. Mean age was 50.3 ± 8.8 years (range 31 to 71 years). All treated eyes were analyzed for safety, efficacy, predictability, and stability.
At 12 months, the MRSE was −0.06 ± 0.8 D and at 30 months was −0.02 ± 0.7 D. At 30 months, the mean MRSE was within ±0.50 D in 68%, within ±1.00 D in 92%, and within ±2.00 D in all eyes. At 30 months, uncorrected visual acuity was 20/20 or better in 52.5% and 20/40 or better in 89% of eyes. No eye lost 2 or more Snellen lines or had an induced cylinder of 2.00 D or greater. The procedure did not cause statistically significant changes in contrast sensitivity.
Results show that CK for low to moderate hyperopia is a safe, effective, predictable, and stable procedure.
Conductive keratoplasty to correct residual hyperopia after corneal surgery
2003, Journal of Cataract and Refractive Surgery
Conductive keratoplasty (CK) is an electrical-current-based technique for steepening the central cornea to reduce low to moderate hyperopia. We report 4 patients who had CK to correct hyperopia after laser in situ keratomileusis (LASIK) and were followed for at least 6 months. An overcorrection was noted after the CK procedure in all patients, but no sight-threatening complications arose. Conductive keratoplasty appears to be safe and well tolerated after LASIK. However, the algorithms should be modified to increase the predictability of the CK procedure in previously treated eyes.
Refractive surgical problem
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¹: The author has no proprietary interest in any of the materials used in this study.

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Laser thermal keratoplasty for the treatment of photorefractive keratectomy overcorrections: A 1-year follow-up1

Abstract

Objective

Participants

Intervention

Results

Conclusions

Section snippets

Patients and methods

Results

Discussion

Acknowledgements

Clinical study with two-year follow-up. Ophthalmology

J Cataract Refract Surg

Ophthalmology

Classification of variable clinical response after photorefractive keratectomy for myopia

J Refract Surg

Computerized corneal topography of surface ablations with the EyeSys System

Noncontact Holmium:YAG laser thermal keratoplasty

Holmium:YAG laser thermokeratoplasty for hyperopia and astigmatisman overview

Refract Corneal Surg

Holmium:YAG laser thermokeratoplasty to correct hyperopiatwo years follow-up

Ophthalmic Surg Lasers

Laser thermal keratoplasty for the treatment of photorefractive keratectomy overcorrections: A 1-year follow-up¹