Dataset Information

Comparison of refractive outcomes after photorefractive keratectomy with different optical zones using Mel 90 excimer laser.

ABSTRACT:

Background

A larger optical zone for photorefractive keratectomy may improve optical quality and stability. However, there is need for limiting ablation diameter in that a larger ablation diameter requires greater ablation depth, and minimizing ablation depth may reduce adverse effects on postoperative wound healing, haze and keratoectasia. In this study, we compared the changes in clinical outcomes and the degree of regression between a 6.0 mm optical zone and 6.5 mm optical zone following PRK.

Methods

The records of 95 eyes that had undergone PRK with a 6.0 OZ (n = 40) and a 6.5 OZ (n = 55) were retrospectively reviewed. We compared data including the spherical equivalent of manifest refraction (SE of MR), simulated K (Sim K), thinnest corneal thickness, change in thinnest corneal thickness (the initial value divided by corrected diopter [ΔTCT/CD]), Q value, corneal higher order aberrations (HOAs) and spherical aberration (SA) pre-operation, at 3 and 6 months postoperative and at the last follow-up visit (Mean; 20.71 ± 10.52, 17.47 ± 6.57 months in the 6.0 and 6.5 OZ group, respectively).

Results

There were no significant differences in the SE of MR, Sim K and UDVA between the 6.0 OZ group and the 6.5 OZ group over 1 year of follow-up after PRK, and the 6.0 OZ group required less ΔTCT/CD than the 6.5 OZ group. The 6.5 OZ group showed better results in terms of post-operative HOAs of RMS, SA and Q value. When comparing that pattern of change in Sim K, there was no significant difference between the 6.0 OZ group and the 6.5 OZ group.

Conclusions

The clinical refractive outcomes and regression after PRK using Mel 90 excimer laser with a 6.0 OZ were comparable to those with a 6.5 OZ.

SUBMITTER: Shin DH

PROVIDER: S-EPMC7346386 | biostudies-literature | 2020 Jul

REPOSITORIES: biostudies-literature

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Publications

Comparison of refractive outcomes after photorefractive keratectomy with different optical zones using Mel 90 excimer laser.

Shin Dae Hwan DH Lee Yong Woo YW Song Ji Eun JE Choi Chul Young CY

BMC ophthalmology 20200709 1

<h4>Background</h4>A larger optical zone for photorefractive keratectomy may improve optical quality and stability. However, there is need for limiting ablation diameter in that a larger ablation diameter requires greater ablation depth, and minimizing ablation depth may reduce adverse effects on postoperative wound healing, haze and keratoectasia. In this study, we compared the changes in clinical outcomes and the degree of regression between a 6.0 mm optical zone and 6.5 mm optical zone follow ...[more]

PMID: 32646401

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Project description:BackgroundHyperopia, or hypermetropia (also known as long-sightedness or far-sightedness), is the condition where the unaccommodating eye brings parallel light to a focus behind the retina instead of on it. Hyperopia can be corrected with both non-surgical and surgical methods, among them photorefractive keratectomy (PRK) and laser assisted In situ keratomileusis (LASIK). There is uncertainty as to whether hyperopic-PRK or hyperopic-LASIK is the better method.ObjectivesThe objectives of this review were to determine whether PRK or LASIK leads to more reliable, stable and safe results when correcting a hyperopic refractive error.Search methodsWe searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (The Cochrane Library 2012, Issue 2), MEDLINE (January 1950 to February 2012), EMBASE (January 1980 to February 2012), Latin American and Caribbean Literature on Health Sciences (LILACS) (January 1982 to February 2012), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov) and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). There were no date or language restrictions in the electronic searches for trials. The electronic databases were last searched on 17 February 2012. When trials are included in the review we will search the reference lists of the studies included in the review for information about further trials. We will use the Science Citation Index to search for papers that cite any studies included in this review. We did not handsearch journals or conference proceedings specifically for this review.Selection criteriaWe planned to include only randomised controlled trials (RCTs) comparing PRK against LASIK for correction of hyperopia and then perform a sensitivity analysis of pre- and post-millennial trials since this is the mid-point in the history of both PRK and LASIK.Data collection and analysisWe did not identify any studies that met the inclusion criteria for this review.Main resultsAs no studies met the inclusion criteria for this review, we discussed the results of non-randomised trials comparing hyperopic-PRK with hyperopic-LASIK.Authors' conclusionsNo robust, reliable conclusions could be reached, but the non-randomised trials reviewed appear to be in agreement that hyperopic-PRK and hyperopic-LASIK are of comparable efficacy. High quality, well-planned open RCTs are needed in order to obtain a robust clinical evidence base.

Project description:Purpose: To evaluate the change in corneal biomechanics in patients with postoperative ectasia risk when combining two common laser vision correction procedures (tPRK and FS-LASIK) with cross-linking (in tPRK Xtra and FS-LASIK Xtra). Methods: The study included 143 eyes of 143 myopic, astigmatic patients that were divided into non-cross-linked refractive surgery groups (non-Xtra groups, tPRK and FS-LASIK) and cross-linked groups (Xtra groups, tPRK Xtra and FS-LASIK Xtra) according to an ectasia risk scoring system. The eyes were subjected to measurements including the stress-strain index (SSI), the stiffness parameter at first applanation (SP-A1), the integrated inverse radius (IIR), the deformation amplitude at apex (DA), and the ratio of deformation amplitude between apex and 2 mm from apex (DARatio2mm). The measurements were taken preoperatively and at 1, 3, and 6 months postoperatively (pos1m, pos3m, and pos6m). Posterior demarcation line depth from the endothelium (PDLD) and from the ablation surface (DLA) were recorded at pos1m. Results: SP-A1 significantly decreased, while IIR, deformation amplitude, and DARatio2mm increased significantly postoperatively in all four groups (p < 0.01)-all denoting stiffness decreases. In the FS-LASIK group, the changes in IIR, DA, and DARatio2mm were 32.7 ± 15.1%, 12.9 ± 7.1%, and 27.2 ± 12.0% respectively, which were significantly higher (p < 0.05) compared to 20.1 ± 12.8%, 6.4 ± 8.2%, and 19.7 ± 10.4% in the FS-LASIK Xtra group. In the tPRK group, the change in IIR was 27.3 ± 15.5%, significantly larger than 16.9 ± 13.4% in the tPRK Xtra group. The changes of SSI were minimal in the tPRK (-1.5 ± 21.7%, p = 1.000), tPRK Xtra (8.4 ± 17.9%, p = 0.053), and FS-LASIK Xtra (5.6 ± 12.7%, p = 0.634) groups, but was significant in the FS-LASIK group (-12.1 ± 7.9%, p < 0.01). After correcting for baseline biomechanical metrics, preoperative bIOP and the change in central corneal thickness (△CCT) from pre to pos6m, the changes in the IIR in both FS-LASIK and tPRK groups, as well as DA, DARatio2mm and SSI in the FS-LASIK group remained statistically greater than their corresponding Xtra groups (all p < 0.05). Most importantly, after correcting for these covariates, the changes in DARatio2mm in the FS-LASIK Xtra became statistically smaller than in the tPRK Xtra (p = 0.017). Conclusion: The statistical analysis results indicate that tPRK Xtra and FS-LASIK Xtra effectively reduced the biomechanical losses caused by refractive surgery (tPRK and FS-LASIK). The decrease in corneal overall stiffness was greater in FS-LASIK than in tPRK, and the biomechanical enhancement of CXL was also higher following LASIK than after tPRK.

Dataset Information

Comparison of refractive outcomes after photorefractive keratectomy with different optical zones using Mel 90 excimer laser.

Background

Methods

Results

Conclusions

Publications

Comparison of refractive outcomes after photorefractive keratectomy with different optical zones using Mel 90 excimer laser.

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