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Korean Journal of Ophthalmology : KJO Jun 2024To evaluate the outcomes of wavefront-optimized (WFO) and topography-guided (TG) transepithelial photorefractive keratectomy (transPRK) in the treatment of myopia and...
PURPOSE
To evaluate the outcomes of wavefront-optimized (WFO) and topography-guided (TG) transepithelial photorefractive keratectomy (transPRK) in the treatment of myopia and myopic astigmatism.
METHODS
Patients who underwent transPRK using the WaveLight® EX500 excimer laser for the correction of myopia and myopic astigmatism between January 2022 and March 2023 were divided into the WFO transPRK (77 eyes of 36 patients) or TG transPRK (63 eyes of 31 patients) groups in this retrospective, observational cohort study. The pre- and postoperative 3-month refractive and visual outcomes of the two groups were analyzed.
RESULTS
The uncorrected distance visual acuity was 0.0 logMAR or better in 95% of eyes 3 months postoperatively, and the mean manifest refraction spherical equivalent was within ± 1.0 diopter (D) in 90% of eyes. No significant differences were observed between the groups in terms of the UDVA or astigmatism. A significant induction of higher-order aberrations (HOAs) was observed in both groups. However, the induction of total corneal HOAs (P = .014) and spherical aberrations (P = .000) was significantly lower in the TG group than that in the WFO group.
CONCLUSIONS
WFO and TG transPRK effectively improved the visual and refractive outcomes; however, the induction of total corneal HOAs and spherical aberration was lesser following the TG ablation.
PubMed: 38897594
DOI: 10.3341/kjo.2024.0027 -
International Journal of Ophthalmology 2024
PubMed: 38895670
DOI: 10.18240/ijo.2024.06.25 -
Journal of Clinical Medicine May 2024: To evaluate the safety and efficacy of the transepithelial photorefractive keratectomy (TransPRK) performed using smart pulse technology (SPT) in myopic eyes with...
: To evaluate the safety and efficacy of the transepithelial photorefractive keratectomy (TransPRK) performed using smart pulse technology (SPT) in myopic eyes with refractive error ranging from -5.25 D to -9.75 D. : This retrospective study evaluated the outcomes of SPT-assisted TransPRK in 150 eyes performed using a 1050 Hz AMARIS excimer laser. : At 6 months postoperative, 98% of eyes achieved uncorrected distance visual acuity (UDVA) of 20/25 or better, and postoperative UDVA within one line of preoperative corrected distance visual acuity (CDVA). No eyes lost any line of CDVA. Residual spherical equivalent refraction and cylinder within ±0.50 D of intended correction were achieved in 72% and 67% of eyes, respectively. Ninety-seven percent of eyes reported no halos and glare. : TransPRK using a 1050 Hz excimer laser with SPT showed excellent predictability, safety, and efficacy for moderate to high myopia correction.
PubMed: 38892769
DOI: 10.3390/jcm13113058 -
Cureus May 2024The purpose of this clinical report is to describe a 10-year clinical outcome of advanced surface ablation with photorefractive keratectomy (PRK) in a patient who had...
The purpose of this clinical report is to describe a 10-year clinical outcome of advanced surface ablation with photorefractive keratectomy (PRK) in a patient who had been previously incorrectly diagnosed with keratoconus (KC). Corneal ectasia is a rare but extremely relevant complication of laser vision correction, and KC represents a major contraindication for these procedures. Nonetheless, some surface ablation procedures, such as PRK, might be a valid option for particular patients with atypical corneal topography or subclinical or mild forms of KC. Patient education and complete preoperative refractive multimodal imaging are essential for a more conscious therapeutic decision, minimizing iatrogenic ectasia, as well as decreasing the number of patients who are incorrectly denied refractive surgery, as was the patient presented in this study.
PubMed: 38872649
DOI: 10.7759/cureus.60277 -
Beyoglu Eye Journal 2024The objective of this study was to analyze the changes in the effective optical zones (EOZ) using topographic techniques on the tangential curvature difference map at...
OBJECTIVES
The objective of this study was to analyze the changes in the effective optical zones (EOZ) using topographic techniques on the tangential curvature difference map at post-operative 1-year following transepithelial photorefractive keratectomy (T-PRK) and to identify parameters linked to the EOZ alterations.
METHODS
The study comprised 55 eyes of 55 myopic patients who underwent T-PRK. EOZs were measured using the tangential curvature difference map of the Scheimpflug tomography system. Correlations between the EOZ alterations and relevant parameters were assessed.
RESULTS
The EOZ was significantly lower than the programmed optical zone (p<0.001). The decrease in the EOZ was significantly relevant to the decrease in mean keratometry (p=0.01, B/95% confidence interval [CI]: 0.139/0.033 and 0.244, standardized Beta: 0.346) and the increase in maximum keratometry (p=0.003, B/95% CI: 0.072/0.026 and 0.118, standardized Beta: 0.406).
CONCLUSION
The EOZ decreased in the 1 year after T-PRK in eyes with myopia. The decrease in the EOZ was correlated positively with the decrease in mean and maximum keratometry. T-PRK may be an effective and safe surgery for the correction of mild-to-moderate myopia.
PubMed: 38854896
DOI: 10.14744/bej.2024.93075 -
Journal of Refractive Surgery... May 2024To assess the predictive accuracy of new-generation online intraocular lens (IOL) power formulas in eyes with previous myopic laser refractive surgery (LRS) and to...
PURPOSE
To assess the predictive accuracy of new-generation online intraocular lens (IOL) power formulas in eyes with previous myopic laser refractive surgery (LRS) and to evaluate the influence of corneal asphericity on the predictive accuracy.
METHODS
The authors retrospectively evaluated 52 patients (78 eyes) with a history of laser in situ keratomileusis (LASIK) or photorefractive keratectomy (PRK) who subsequently underwent cataract surgery. Refractive prediction errors were calculated for 12 no-history new online formulas: 8 formulas with post-LRS versions (Barrett True-K, EVO 2.0, Hoffer QST, and Pearl DGS) using keratometry and posterior/total keratometry measured by IOLMaster 700 and 4 formulas without post-LRS versions (Cooke K6 and Kane) using keratometry and total keratometry. The refractive prediction error, mean absolute error (MAE), and percentages of eyes with prediction errors of ±0.25, ±0.50, ±0.75, ±1.00, and ±1.50 diopters (D) were compared.
RESULTS
The MAEs of the 12 formulas were significantly different (F = 83.66, < .001). The MAEs ranged from 0.62 to 0.94 D and from 1.07 to 1.84 D in the formulas with and without post-LRS versions, respectively. The EVO formula produced the lowest MAE (0.60) and MedAE (0.47), followed by the Barrett True-K (0.69 and 0.50, respectively). Each percentage of eyes with refractive prediction error was also significantly different among the 12 formulas ( < .001).
CONCLUSIONS
The EVO and Barrett True-K formulas demonstrate comparable performance to the other existing formulas in eyes with a history of myopic LASIK/PRK. Surgeons should use these formulas with post-LRS versions and input keratometric values whenever possible. .
Topics: Humans; Retrospective Studies; Myopia; Lenses, Intraocular; Female; Male; Refraction, Ocular; Middle Aged; Photorefractive Keratectomy; Keratomileusis, Laser In Situ; Lens Implantation, Intraocular; Adult; Optics and Photonics; Visual Acuity; Lasers, Excimer; Cornea; Reproducibility of Results; Biometry; Phacoemulsification; Aged
PubMed: 38848053
DOI: 10.3928/1081597X-20240422-01 -
Indian Journal of Ophthalmology May 2024This study aimed to report the long-term results of combined topography-guided photorefractive keratectomy (PRK) and accelerated corneal collagen cross-linking (CXL) for...
PURPOSE
This study aimed to report the long-term results of combined topography-guided photorefractive keratectomy (PRK) and accelerated corneal collagen cross-linking (CXL) for keratoconus using the Zeiss refractive coordinated system.
METHODS
A prospective interventional study was conducted in a tertiary eye care hospital in South India. Patients with mild-to-moderate progressive keratoconus and corneal pachymetry greater than 450 μm were included. They underwent customized topography-guided PRK followed by CXL. Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), and keratometry readings and complications were evaluated at 1, 3, 6, 12, and 24 months postoperatively.
RESULTS
Thirty patients (30 eyes) were included in the study. All study parameters showed a statistically significant improvement postoperatively over baseline values. At 24 months, the mean UDVA improved from 0.8 ± 0.180 logarithm of the minimum angle of resolution (logMAR) to 0.38 ± 0.118 logMAR ( P -value <0.001) and CDVA improved from 0.467 ± 0.142 logMAR to 0.227 ± 0.078 logMAR ( P -value <0.001). The mean flat, steep, and maximum keratometry values were significantly reduced by 2.133, 3, and 4.54 diopters, respectively, at the last follow-up examination ( P -value <0.001).
CONCLUSION
The combined topography-guided PRK and accelerated CXL procedure seem to be a promising treatment alternative for early keratoconus. This is the first such study on the Zeiss refractive coordinated system. However, further studies with a larger study population and longer follow-up periods are required to draw final conclusions about the benefits of this procedure in keratoconus.
PubMed: 38767551
DOI: 10.4103/IJO.IJO_791_23 -
International Journal of Ophthalmology 2024To study the effect of mitomycin C (MMC) applied during transepithelial photorefractive keratectomy (TPRK) on the corneal endothelium one week (W1) and three months (M3)...
AIM
To study the effect of mitomycin C (MMC) applied during transepithelial photorefractive keratectomy (TPRK) on the corneal endothelium one week (W1) and three months (M3) after surgery and its determinants.
METHODS
In this two-armed cohort study conducted in 2022, eyes treated with MMC during TPRK (group 1) were compared with eyes not treated with MMC (group 2). The corneal endothelial cell (EC) count, EC density (ECD; cells/mm), average (µm), standard deviation (µm), coefficient of variation (CV%), EC, EC, and EC percentage of hexagonality were estimated at W1 and M3. The postoperative changes in the EC count in the two groups were compared and correlated with the other independent variables.
RESULTS
Group 1 had 26 eyes, and group 2 had 78 eyes. All TPRK indices were significantly higher for the eyes in group 1 than for those in group 2. The MMC usage was not a significant predictor of the change in ECD (=0.644), change in CV (=0.374), and change in the percentage of hexagonality of EC (=0.164) at W1. However, the use of MMC was a significant predictor of changes in CV (=0.014) and the change in the percentage of hexagonality of EC (=0.039) at M3. The duration of laser exposure and the size of the optical zone influenced the correlation of MMC use with the changes in EC indices, postoperatively.
CONCLUSION
The use of MMC doesn't affect ECD, CV, and percentage of hexagonality at W1 if other surgical indices are considered. At M3 after operating myopic eyes by TPRK, MMC significantly influence the CV and percentage of hexagonality. The duration of the laser application and the size of the optical zone should be considered when determining the effect of MMC on the EC indices.
PubMed: 38766343
DOI: 10.18240/ijo.2024.05.16 -
Translational Vision Science &... May 2024Computational models can help clinicians plan surgeries by accounting for factors such as mechanical imbalances or testing different surgical techniques beforehand....
PURPOSE
Computational models can help clinicians plan surgeries by accounting for factors such as mechanical imbalances or testing different surgical techniques beforehand. Different levels of modeling complexity are found in the literature, and it is still not clear what aspects should be included to obtain accurate results in finite-element (FE) corneal models. This work presents a methodology to narrow down minimal requirements of modeling features to report clinical data for a refractive intervention such as PRK.
METHODS
A pipeline to create FE models of a refractive surgery is presented: It tests different geometries, boundary conditions, loading, and mesh size on the optomechanical simulation output. The mechanical model for the corneal tissue accounts for the collagen fiber distribution in human corneas. Both mechanical and optical outcome are analyzed for the different models. Finally, the methodology is applied to five patient-specific models to ensure accuracy.
RESULTS
To simulate the postsurgical corneal optomechanics, our results suggest that the most precise outcome is obtained with patient-specific models with a 100 µm mesh size, sliding boundary condition at the limbus, and intraocular pressure enforced as a distributed load.
CONCLUSIONS
A methodology for laser surgery simulation has been developed that is able to reproduce the optical target of the laser intervention while also analyzing the mechanical outcome.
TRANSLATIONAL RELEVANCE
The lack of standardization in modeling refractive interventions leads to different simulation strategies, making difficult to compare them against other publications. This work establishes the standardization guidelines to be followed when performing optomechanical simulations of refractive interventions.
Topics: Humans; Finite Element Analysis; Cornea; Photorefractive Keratectomy; Computer Simulation; Lasers, Excimer; Models, Biological
PubMed: 38748408
DOI: 10.1167/tvst.13.5.11 -
Journal of Refractive Surgery... May 2024To compare the effects of three common refractive surgeries on corneal biomechanics. (Comparative Study)
Comparative Study
PURPOSE
To compare the effects of three common refractive surgeries on corneal biomechanics.
METHODS
Two hundred seven patients who had refractive surgery were included in this study, of whom 65 received transepithelial photorefractive keratectomy (tPRK), 73 received femtosecond laser-assisted laser in situ keratomileusis (FSLASIK), and 69 received small incision lenticule extraction (SMILE). Each patient had biomechanical measurements using the Corvis ST (Oculus Optikgeräte GmbH) preoperatively and at 3 and 6 months postoperatively. The measurements included five parameters expected to be associated with corneal biomechanics: deformation amplitude ratio at 2 mm (DAR2), integrated inverse radius (IIR), stiffness parameter at first applanation (SP-A1), highest concavity time (HCT), and the updated stress-strain index (SSIv2). The variations in these parameters postoperatively among the three surgeries, and their relationship with corneal thickness (CCT) and intraocular pressure measured by the Dynamic Contour Tonometer (DCT-IOP) were analyzed.
RESULTS
SP-A1 decreased significantly from preoperatively to 3 months postoperatively in all three groups, whereas DAR2 and IIR increased significantly, all indicating stiffness losses. Between 3 and 6 months postoperatively, the results were inconsistent, with DAR2 decreasing (indicating stiffness increases) and IIR increasing (denoting stiffness decreases) in the FS-LASIK and SMILE groups. The decrease in SSIv2 (the only measure of corneal material stiffness) postoperatively was comparatively less pronounced at both 3 and 6 months postoperatively. On the other hand, HCT remained generally stable after all three surgeries. Unlike DAR2, IIR, and SP-A1, the changes postoperatively in stiffness parameters HCT and SSIv2 were independent of the corresponding changes in both DCT-IOP and CCT.
CONCLUSIONS
Among the stiffness parameters considered, SSIv2 was not correlated with CCT or DCT-IOP, and holds promise for representing the corneal material stiffness and how it remains largely unaffected by refractive surgeries. Overall, FS-LASIK had the most significant impact on corneal stiffness, followed by SMILE, and finally tPRK. .
Topics: Humans; Cornea; Adult; Female; Male; Biomechanical Phenomena; Lasers, Excimer; Keratomileusis, Laser In Situ; Young Adult; Elasticity; Myopia; Intraocular Pressure; Photorefractive Keratectomy; Visual Acuity; Refraction, Ocular; Middle Aged; Prospective Studies; Corneal Surgery, Laser; Corneal Topography
PubMed: 38717086
DOI: 10.3928/1081597X-20240322-01