Journal of refractive surgery最新文献

Purpose: To discuss the technique and outcome of what the authors called the "flap-in-flap" technique and report its safety as a procedure for correction of post-laser in situ keratomileusis (LASIK) myopic regression.

Methods: Seven eyes of 4 patients were included in this study. All patients had previously undergone LASIK for compound myopic astigmatism using the Moria M2 micro-keratome (Moria) 8 to 12 years prior to presentation. All had myopic refractive errors at presentation with a spherical equivalent ranging from -1.25 to -3.30 diopters. A new thinner femtosecond laser flap was created in the old LASIK flap and gently raised, and laser enhancement was performed. All patients were followed up 1 week, 1 month, and 3 months after the procedure. At these visits, the uncorrected distance visual acuity (UDVA), refraction, and corrected distance visual acuity (CDVA) were measured. Pentacam (Oculus Optikgeräte GmbH) and corneal anterior segment optical coherence tomography examinations were obtained on the third visit.

Results: All eyes underwent uneventful enhancement using the flap-in-flap technique. All patients showed an improvement in vision, with 100% of eyes reaching a postoperative UDVA equal to or better than the preoperative CDVA. None of the eyes showed intraoperative complications such as gas breakthroughs or difficult dissections, and no postoperative flap-related complications were seen.

Conclusions: This study describes a technique for post-LASIK enhancement that is surgically safe and shows excellent visual outcomes with the potential to conserve the residual stromal bed and percentage of tissue altered, thus avoiding the risk of post-enhancement ectasia.

Purpose: To analyze stabilization results using various standard and accelerated corneal cross-linking (CXL) protocols in patients younger than 18 years.

Methods: This systematic review was conducted in accordance with the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) 2020 guidelines. A bibliographic search was carried out based on PubMed and Scopus data, with the last being performed in December 2024. Thirty-five articles were eligible for this review. To assess the effectiveness of CXL in children, maximum keratometry measurements were analyzed preoperatively and compared with postoperative values.

Results: A total of 2,186 eyes were included in this review. This review consisted of 15 studies with the standard CXL protocol, 11 with the accelerated CXL protocol, and 9 comparative protocols. Standard and accelerated CXL protocols and comparative studies were analyzed separately. Most studies have shown stabilization rates greater than 80% with different CXL protocols. Factors such as younger age, severity of keratoconus, and cone eccentricity seem to influence the effectiveness of the procedure.

Conclusions: The results indicate that standard and accelerated CXL are effective and safe therapeutic options for treating keratoconus in pediatric population.

Purpose: To assess differences in intraocular lens (IOL) power calculation prediction error (PE) considering the manufacturing tolerance or exact power (EP) versus labeled power (LP), and to compare accuracy using the Barrett formula with optimized constant versus a thick-lens formula.

Methods: The PE and absolute PE were calculated for a random eye of patients implanted with the multifocal Liberty Q-Flex 640PM IOL (Medicontur Ltd) considering the LP and the EP provided by the manufacturer. The outcomes for the Barrett with optimized constant formula and a thick-lens formula personalized for the surgeon, biometer, and IOL were compared.

Results: A total of 155 eyes were included in the analysis. The mean absolute tolerance was 0.12 diopters (D) (range: 15.00 to 25.00 D) and 0.19 D (range: 25.00 to 30.00 D). These mean values corresponded to 0.07 and 0.11 D at the corneal plane, respectively (P = .002). Differences in mean PE considering the LP versus EP were 0.05 D or less (P > .05) for both formulas. No differences were found for absolute PE with a magnitude of 0.01 D or less (P < .05). The percentage of eyes within ±0.375 D ranged between 74.2% and 75.5% (P > .05).

Conclusions: The percentage of eyes within ±0.375 D did not increase using EP in comparison to LP in patients implanted with a multifocal IOL with powers ranging from 18.00 to 27.00 D. If the constant is properly optimized, a thick-lens formula also results in no clinically relevant differences versus the Barrett formula.

Purpose: To analyze the effects of ablation interruption on ablation depths and clinical refractive outcomes to characterize the impact of ambient temperature changes and ablation interruption on ocular surface temperature (OST) during excimer laser ablation.

Methods: This prospective study was conducted on laser ablations in polymethylmethacrylate (PMMA) plates and porcine corneas to simulate laser in situ keratomileusis (LASIK) treatments using the EX500 laser (Alcon Laboratories, Inc) at ambient temperatures of 18, 20, and 22 °C. Ablation interruption was performed for 1, 2, 3, 4, and 5 seconds at the 10th second of the treatment of -9.00 diopters (D) of myopia. OST changes were recorded using infrared thermography, and the ablation depth of each PMMA plate was measured using a high-precision contact micrometer. Postoperative outcomes of patients were evaluated based on the refractive results under varying ablation interruption durations.

Results: Both the PMMA plates and porcine corneas exhibited significant photothermal effects. Under -9.00 D excimer laser ablation at 18, 20, and 22 °C, the OST reached 80.10 ± 0.22, 82.26 ± 0.99, and 84.01 ± 1.46 °C for PMMA plates and 28.3 ± 0.40, 29.0 ± 0.59, and 30.8 ± 0.43 °C for porcine corneas, respectively. Laser ablation interruption significantly reduced the photothermal peak in PMMA plates and porcine corneas. The ablation depth of PMMA decreased as the ambient temperature increased. The ablation depths of the PMMA plates were less stable with ablation interruptions of 3 and 4 seconds, and the sphere and spherical equivalent (SEQ) refraction was significantly higher than that without ablation interruption.

Conclusions: Changes in the ambient temperature can affect the thermal load during excimer laser ablation. Ablation interruptions reduce the thermal load and increase the ablation depth, which in turn influences clinical refractive outcomes.

Purpose: To present a case of synthetic intrastromal corneal ring segment (ICRS) intrusion secondary to necrosis and migration, managed by implantation of corneal allogenic intrastromal ring segments (CAIRS) within the preexisting tunnel.

Methods: A 24-year-old man with known keratoconus underwent bilateral ICRS implantation. He presented with blurred vision in the right eye 6 weeks after the procedure. The patient developed segment intrusion secondary to migration and necrosis. The synthetic ring was subsequently explanted, and a CAIRS was inserted into the same corneal tunnel.

Results: Postoperative assessment showed significant visual improvement. The patient's spectacle corrected distance visual acuity (CDVA) improved from 20/60 to 20/25, his astigmatism reduced from -6.50 to -4.00 diopters (D), and his keratometry readings decreased from 49.00 to 45.00 D. The CAIRS remained stable, fully filling the stromal defect and covering the area of intrusion, with no signs of necrosis or migration at the 6-month follow-up visit.

Conclusions: CAIRS are a safe and effective alternative for addressing complications arising from synthetic ICRS in patients with keratoconus, offering improved visual and topographic outcomes while minimizing risks. Furthermore, it is possible to implant CAIRS within an existing tunnel.

Purpose: To evaluate visual and refractive outcomes, visual quality, patient satisfaction, and spectacle independence 3 months after phacoemulsification with bilateral non-diffractive enhanced depth of focus (EDOF) lens implantation.

Methods: This study included 68 eyes of 34 consecutive patients, with 51.5% undergoing refractive lens exchange and 48.5% undergoing cataract surgery. Exclusion criteria included previous ocular surgery, corneal higher order aberrations greater than 0.6 μm, and corneal astigmatism greater than 1.50 diopters (D). Mini-monovision of -0.50 D was targeted. Uncorrected and corrected distance visual acuity was measured at 4 m and 66 and 40 cm. Patient satisfaction was assessed using subjective questionnaires. Modulation transfer function, Strehl ratio, and objective depth of focus were measured with ray-tracing.

Results: At 3 months, the follow-up rate was 97.1% and mean corrected distance visual acuity at 4 m and 66 and 40 cm was -0.02 ± 0.10, 0.11 ± 0.11, and 0.36 ± 0.13 logarithm of the minimum angle of resolution (logMAR), respectively. Monocular defocus curve was higher than 0.20 logMAR from +1.50 to -1.50 D. Mean Objective Scatter Index score at 3 months was 1.48 ± 0.72; it decreased significantly in eyes with cataract and increased significantly in eyes that had refractive lens exchange (P < .05). Spectacle independence was achieved by 95%, 100%, and 34% patients for far, intermediate, and near distances, respectively; 90% patients reported no photic phenomena. Patients were satisfied with daily life activities not requiring near vision.

Conclusions: Bilateral implantation of a non-diffractive EDOF lens resulted in good visual performance at far and intermediate distances, with functional near vision at 3 months postoperatively. Patient satisfaction and spectacle independence were high.

Purpose: To analyze the difference in objective and subjective photic phenomena following virtual implantation of three different presbyopia-correcting diffractive intraocular lens (IOL) designs.

Methods: The study was conducted at JENVIS Research Germany. A prospective cross-over and double-masked trial design was used. Seventy-four healthy individuals without cataract (age: 18 to 50 years) were enrolled. All participants assessed photic phenomena with three diffractive IOL designs by virtual implantation using the VirtIOL device (10Lens S.L.U), which allows participants to view through the IOL imaged at the iris plane as if it were implanted: IOL A (Tecnis Synergy ZFR00V; J&J Vision), IOL B (AcrySof IQ PanOptix TFNT00; Alcon Laboratories, Inc), and IOL C (AT ELANA 841P; Carl Zeiss Meditec). The size of the starburst and annular light pattern was measured in degrees, and participants were asked about their preference in terms of quality of night vision when comparing by pairs the IOLs.

Results: The starburst pattern size was significantly larger with IOL A (5.54 ± 0.62º) compared to the IOLs B (3.82 ± 0.90º, P < .001) and C (3.65 ± 0.57º, P < .001). However, there were no significant differences between IOLs B and C (P = .078). Regarding the induced annular light pattern, no significant differences were found between IOLs (P > .05). In a pairwise short-term comparison of the IOLs using a simulated night scene with a glare source, participant preference was in favor of IOL C (P < .001).

Conclusions: IOL A had objectively a significantly larger starburst pattern than the other two. In a short-term comparison, the new trifocal IOL C was significantly preferred in a night driving scene.

Purpose: To evaluate tilt, decentration, and axial stability of the Clareon toric intraocular lens (TIOL) (CNW0T3-9; Alcon Laboratories, Inc) over a 6-month follow-up period.

Methods: A single-center, prospective, interventional clinical trial was conducted with a study population of 130 eyes from 82 patients who received a Clareon TIOL. Tilt, decentration, and the aqueous depth were determined preoperatively and at 1 week and 6 months postoperatively using anterior segment optical coherence tomography (Casia 2; Tomey Corporation). Difference vectors were used to assess changes in individual decentration and tilt. Uncorrected intermediate visual acuity was measured at 66 cm at 6 months postoperatively.

Results: Mean tilt and decentration values were 5.7 ± 1.7° and 0.17 ± 0.1 mm for the crystalline lens, 5.6 ± 1.5° and 0.24 ± 0.13 mm for the TIOL at 1 week, and 5.8° ± 1.6° and 0.24 ± 0.15 mm for the TIOL at 6 months. Mean changes in tilt and decentration from preoperatively to 6 months were 1.01 ± 0.86° and 0.18 ± 0.12 mm. Tilt and decentration correlated between the crystalline lens and TIOL at 6 months (r = 0.92; P < .01, r = 0.29; P < .01). A posterior axial shift of 0.023 ± 0.054 mm was observed between 1 week and 6 months. Mean binocular uncorrected intermediate visual acuity at 66 cm at 6 months postoperatively was 0.18 ± 0.13 logarithm of the minimum angle of resolution (20/30 Snellen).

Conclusions: Tilt and decentration of the Clareon TIOL were generally low and a strong correlation was found between crystalline lens tilt and TIOL tilt at 6 months.

Purpose: To report the refractive outcome of femtosecond laser-assisted lenticule intrastromal keratoplasty (LIKE) in correcting moderate to high hyperopia. Intraoperative effective optical zone (EOZ), centration offset, and postoperative higher order aberrations (HOAs) were analyzed to better understand factors affecting postoperative outcomes.

Methods: This was a prospective, consecutive case series study of LIKE for correcting hyperopia in one department from 2018 to 2023. Refraction, tomography, uncorrected and corrected distance visual acuity (UDVA/CDVA), EOZ, and decentration offset by an innovated method using semi-automated software (ImageJ; National Institutes of Health) were analyzed. Tomography measured the preoperative and postoperative refractive tomographic changes.

Results: In the 18 eyes (9 participants) that underwent LIKE for correcting moderate to high hyperopia, the attempted spherical equivalent (SEQ) was +6.22 ± 0.85 diopters (D). One year postoperatively, 61% of all eyes had UDVA better than or equal to preoperative CDVA. In 78% of all eyes, the SEQ was less than 1.00 D from the attempted value. Compared to the programmed optical zone, the EOZ obtained after LIKE was significantly smaller (6.42 ± 0.15 vs 5.24 ± 0.23, P < .001). This was comparable to mild to moderate hyperopic LASIK treatment. The percentage of optical zone reduction was 18 ± 3%. The centration offset of the EOZ generated by LIKE was 0.27 ± 0.15 mm, and 94% of eyes had decentration within 0.5 mm. The induction of vertical coma and spherical aberration after LIKE were significantly higher.

Conclusions: LIKE is a promising procedure to maintain stable refraction and keratometry in correcting moderate to high hyperopia with sufficient EOZ, and acceptable decentration and corneal HOAs.

Purpose: To use parametric numerical simulation to characterize and compare the differences in corneal biomechanical responses to laser in situ keratomileusis (LASIK) and keratorefractive lenticule extraction (KLEx) under various surgical settings.

Methods: The Finite Element Model was used in a parametric study to evaluate corneal biomechanical responses to LASIK and KLEx, considering variations in preoperative corneal thickness, corneal flap/cap thickness and diameter, refractive correction, and optical zone diameter. Surgery-induced stress, displacement, and interface contact pressure were compared between LASIK and KLEx using the Wilcoxon signed-rank test. Spearman correlation analysis explored the correlation of the biomechanical response differences between surgeries with various parameters.

Results: LASIK induced more stress reductions and displacements than KLEx in corneal flap/cap (P < .001). Both surgeries introduced a centralizing redistribution of stress and displacement in the stroma (ie, stress increased with outward stromal displacement at the center), and stress decreased with inward displacement in the periphery. Stromal stress and displacement were higher after LASIK than after KLEx (P < .001). Corneas after KLEx exhibited higher contact pressure than those after LASIK (P < .001). With the significant increase in preoperative corneal thickness, refractive correction, optical zone diameter, and decreased flap/cap thickness, the biomechanical differences between surgeries were notably reduced, with most Spearman correlation coefficients (|r|) being greater than 0.3 (eg, stress and displacement differences at the stromal center reduced by 36.69% and 82.17% from refractive correction of -1.00 to -9.00 diopters).

Conclusions: Finite element simulations indicate that KLEx may provide improved corneal stability compared to LASIK under comparable surgical conditions. However, this biomechanical advantage is not absolute and depends on multiple factors, including refractive correction magnitude, central corneal thickness, and flap or cap thickness. These findings suggest that as refractive correction increases, cap or flap thickness decreases, or central corneal thickness increases, the biomechanical differences between KLEx and LASIK diminish. In certain cases, KLEx may exhibit biomechanical risks comparable to LASIK. These results highlight the need for a personalized approach in refractive surgery planning, considering both biomechanical and surgical complexity factors.