Manifest Refraction Spherical Equivalent Research Articles

Changes in Posterior Cornea and Posterior-To-Anterior Curvature Radii Ratio 1 year After LASIK, PRK, and SMILE Treatment of Myopia.

The purpose of this study was to compare changes in the posterior curvature and the posterior-anterior radii ratio of the cornea, 1 year postoperatively in laser in situ keratomileusis (LASIK), photorefractive keratectomy (PRK), and small incision lenticule extraction (SMILE). This retrospective study was performed at a single surgical center. 199 eyes were included in the study from 119 patients with manifest refraction spherical equivalents from -7.61 to -2.54 D. 67 eyes underwent LASIK, 89 underwent PRK, and 43 underwent SMILE. Both preoperative and 1-year postoperative front and back sagittal keratometry were measured at 4- to 6-mm zones around the corneal vertex. Corneal asphericity (Q-value) was measured at an 8-mm zone around the corneal vertex. The average change in the posterior-anterior radii ratio after LASIK, PRK, and SMILE did not differ between surgery groups at 4 mm (LASIK: -0.075, PRK: -0.073, SMILE: -0.072, P = 0.720), 5 mm (LASIK: -0.072, PRK: -0.068, SMILE: -0.068, P = 0.531), or 6 mm (LASIK: -0.075, PRK: -0.071, SMILE: -0.072, P = 0.456) zones. Anterior Q-value significantly positively increased after all 3 surgeries (P < 0.001). The posterior Q-value also significantly positively increased after LASIK (P < 0.001) and SMILE (P < 0.001), but not after PRK (P = 0.227). Both anterior and posterior keratometric power decreased significantly after LASIK, PRK, and SMILE for all diameters. The change in the posterior-anterior radii ratio was not influenced by the type of refractive surgery performed, as indicated by statistically identical preoperative, postoperative, and delta values. In addition, the posterior cornea exhibited paracentral flattening after LASIK, SMILE, and PRK and increased oblateness after LASIK and SMILE.

Conventional Epithelial-Off Corneal Crosslinking in Patients With Progressive Keratoconus: 10-Year Outcomes.

Corneal crosslinking (CXL) is the standard treatment of progressive keratoconus (KC). We evaluated the safety and 10-year outcomes of conventional "epithelial-off" CXL for progressive KC for the first time in a cohort in France. We conducted a retrospective review of patients undergoing conventional CXL (Dresden protocol) in our tertiary ophthalmology department from 2006 to 2011 with 10-year follow-up. The primary outcome was change in preoperative versus postoperative keratometry measured by maximum keratometry (Kmax), steep keratometry (K2), flat keratometry (K1), mean keratometry (Km), and topographic cylinder. Secondary outcomes were changes in visual and refractive outcomes. We report postoperative complications and adverse events. Eighty-nine eyes from 76 patients (67% male patients, mean age 22.7 ± 7.6 years) were included. Mean Kmax (-2.31 ± 2.98 diopters (D); P < 0.00001), K2 (-2.07 ± 3.15 D; P < 0.00001), K1 (-1.00 ± 2.29 D; P = 0.00008), Km (-1.53 ± 2.47 D; P < 0.00001), and topographic cylinder (-1.15 ± 2.53 D; P = 0.00004) significantly decreased 10 years after CXL compared with preoperative baseline. Significant decreases were still observed between 5 and 10 years after for mean Kmax, mean K2, mean K1, and mean Km. Mean distance best spectacle-corrected visual acuity and mean manifest refraction spherical equivalent were significantly improved after 10 years versus before CXL. The 10-year rate of repeat CXL was n = 3/76 patients (4%) (all younger than 18 years at first CXL) and of loss of >3 lines in best spectacle-corrected visual acuity was n = 1/76 patients (1%). Progressive KC was effectively stabilized with a prolonged flattening and maintenance of functional vision improvements after 10 years. Repeat CXL was rare and only required among younger patients.

Randomized Clinical Trial Comparing Customized Corneal Crosslinking: Epi-on in High Oxygen and Epi-off in Room Air for Keratoconus.

To compare clinical outcomes of customized transepithelial (epi-on) corneal crosslinking (CXL) in high oxygen and customized CXL with epithelial removal (epi-off) in room air for keratoconus (KC). Umeå University Hospital, Umeå, Sweden. Prospective, randomized, single-masked, intra-individually comparing study. Thirty-two participants with bilateral progressive KC were treated with bilateral customized topography-guided CXL, 30 mW/cm2; 7.2-15 J/cm2 and were randomized to epi-on in one eye (32 eyes) and epi-off in the fellow eye (32 eyes). Uncorrected (UDVA) and best corrected visual acuities (BCVA), maximal keratometry (Kmax), subjective ocular discomfort, low-contrast visual acuities (LCVA) at 10% and 2.5% contrast, ocular and anterior corneal wavefront aberrations, manifest refractive spherical equivalent (MRSE), endothelial cell count (ECC) and adverse events were assessed through 24 months. Both treatments showed improvements at 24 months in UDVA; -0.16 ± 0.24 (p < 0.001) and -0.13 ± 0.20 logMAR (p = 0.006), respectively, BCVA; -0.10 ± 0.11 (p < 0.001) and -0.10 ± 0.12 (p = 0.001), Kmax; -1.74 ± 1.31 (p < 0.001) and -1.72 ± 1.36 D (p < 0.001). LCVA 10% improved for both protocols (p < 0.001), but LCVA 2.5% improved for epi-on CXL only (p = 0.001). ECC was unaltered and no adverse events occurred. The epi-on eyes had significantly less discomfort symptoms during the whole first week posttreatment (p < 0.05). High-oxygen customized epi-on CXL is a viable alternative to room air customized epi-off CXL, with faster improvements in BCVA and LCVA and less early ocular discomfort.

Long-term Results after Bilateral Implantation of Extended Depth of Focus Intraocular Lenses with Mini-Monovision.

To assess long-term clinical results following bilateral Tecnis Symfony ZXR00 intraocular lens implantation with mini-monovision. The medical records of cataract patients who underwent bilateral implantation of ZXR00 with intended mini-monovision (target refraction of -0.3 diopters [D] in dominant eye and -0.6D in nondominant eye) between April 2019 and March 2021 were assessed. Postoperative uncorrected distance visual acuity (UDVA), corrected distance VA (CDVA), uncorrected intermediate VA (UIVA), uncorrected near VA (UNVA), and rate of spectacle dependence for near distance were investigated at 3 months and 2 years after surgery. This study included 61 patients (122 eyes) with average age of 61.8 ± 7.7 years. At 2 years postoperatively, binocular logarithm of the minimum angle of resolution UDVA, UIVA, UNVA, and CDVA were 0.086 ± 0.094, 0.056 ± 0.041, 0.140 ± 0.045, and 0.012 ± 0.024, respectively. The monocular manifest refraction spherical equivalent was -0.31 ± 0.38 in the dominant eye and -0.53 ± 0.47 in the nondominant eye at 3 months postoperatively, and -0.38 ± 0.43 in the dominant eye and -0.61 ± 0.54 in the nondominant eye at 2 years postoperatively. Eight out of 61 patients (13.1%) needed glasses 3 months after surgery, and nine out of 61 patients (14.8%) needed glasses 2 years after surgery. The bilateral implantation of ZXR00s with mini-monovision allows for a good VA at wide range of distance from far to near, thereby resulting in high rate of spectacle independence. These results have held up well even after 2 years after surgery.

Biomechanical properties of cornea and ocular aberrations in myopic eyes.

To study the correlation of corneal topography, corneal biomechanical properties, and ocular aberrations with the magnitude of refractive error in myopic eyes. All myopic patients attending the clinic for refractive surgery were recruited. Data recorded included visual acuity, axial length (AL), central corneal thickness (CCT), manifest refraction spherical equivalent (MRSE), topography (Pentacam - Oculus), corneal biomechanical factors [ocular response analyzer (ORA)], and optical aberrations (iTrace). They were further categorized into group 1 (suitable for femto-LASIK) and group 2 (unsuitable for femto-LASIK). Sixty eyes (30 myopes) of mean age 22.78 ± 2.71 years were enrolled. A negative correlation of refractive error was noted with AL (ρ = -0.9; P < 0.001), total aberrations (ρ = 0.53; P < 0.001), and lower-order aberrations (LOA) (ρ = 0.54; P < 0.001). A strongly positive correlation was noted between CCT and corneal hysteresis (CH) (ρ = 0.63; P < 0.001), CCT and CRF (ρ = 0.56; P < 0.001), CH and corneal resistance factor (CRF) (ρ = 0.83; P < 0.001), and Goldmann equivalent intraocular pressure (IOPg) and corneal compensated intraocular pressure (IOPcc) (ρ = 0.78; P < 0.001). An increase in higher-order aberrations (HOAs) as well as lower-order aberrations (LOAs) was noted with increasing sim-K [HOA (r = 0.73, P = 0.001); LOA (r = 0.601, P = 0.014)] and increasing CRF [HOA (r = 0.5, P = 0.006); LOA (r = 0.732, P = 0.001)] in group 2. The amount of refractive error, axial length, central corneal thickness, and sim-K were significantly different in the two groups. Increasing degree of myopia is associated with an increase in axial length, total aberrations, and lower-order aberrations. Corneal biomechanical parameters have a strong correlation with each other. Lower corneal biomechanics are noted in high myopes as they have weaker and thinner corneas. Corneal biomechanics and ocular aberrations do not differ significantly between cases suitable for femto-LASIK and cases unsuitable for femto-LASIK.

Visual and refractive outcomes after implantation of two models of trifocal intraocular lenses in eyes with previous corneal ablation to treat hyperopia

BackgroundTo assess whether a trifocal intraocular lens (IOL) with neutral spherical aberration (SA) provides better visual and refractive outcomes than a trifocal IOL with negative SA after hyperopic corneal laser ablation.MethodsThis is a retrospective comparative study. Patients were classified according to the IOL implanted after cataract or clear lens phacoemulsification [group 1, PhysIOL FineVision Pod-F (negative SA); group 2, Rayner RayOne Trifocal (neutral SA)]. We evaluated uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), uncorrected intermediate visual acuity (UIVA), uncorrected near visual acuity (UNVA), predictability, safety, efficacy, and satisfaction.Results198 eyes of 119 patients met the inclusion criteria. Group 1 comprised 120 eyes and group 2 comprised 78 eyes. At completion, the refractive and predictability results were significantly better in group 1 than in group 2 for manifest refraction spherical equivalent (MRSE) (P < 0.001). Differences were not significant for UDVA (P = 0.647), CDVA (P = 0.343), UIVA (P = 0.059), UNVA (P = 0.382), binocular UIVA (P = 0.157), or binocular UNVA (P = 0.527). Safety and efficacy indices in refractive lens exchange (RLE) eyes were 0.96 and 0.91, and 0.89 and 0.93 in groups 1 and 2, respectively (P = 0.254 and 0.168). Patient satisfaction was similar in both groups (P > 0.05, all items).ConclusionIn eyes previously treated with hyperopic corneal ablation, implantation of a trifocal IOL with neutral SA provided better efficacy and safety outcomes but worse predictability outcomes than those obtained with a trifocal model with negative SA.

Safety and Effectiveness of Smooth Incision Lenticular Keratomileusis (SILKTM) Using the ELITA(TM) Femtosecond Laser System for Correction of Myopic and Astigmatic Refractive Errors.

To evaluate visual outcomes following the Smooth Incision Lenticular Keratomileusis (SILKTM) procedure for correction of myopic refractive errors with and without astigmatism, using the ELITATM Femtosecond Laser System. A prospective, multicenter, single-arm, open-label clinical study was conducted. Eighty-five myopic subjects (n = 170 eyes), aged 18 years or older, with manifest refractive spherical equivalent (MRSE) up to -12.00 D and astigmatism up to -6.00 D, were treated binocularly using the ELITA femtosecond laser and followed up for 6 months. Intended correction was emmetropia for all eyes. The primary outcome measures included post-operative uncorrected and corrected distance visual acuity (UDVA and CDVA). Secondary outcome measures included surgeon's rating for ease of lenticule extraction, predictability, safety, and stability. A total of 170 eyes of 85 patients underwent SILK. Preoperative mean MRSE was -4.14D ± 1.32 D (range -1.38 D to -8.88D) and the mean cylinder was -0.77 D ± 0.62D. Intraoperative surgeon ease of lenticule dissection was rated as grade 0 or 1 in 85.3% of eyes (no/only mild dissection needed). UDVA at 1 day, 1 week, 1 month, and 6 months was 20/20 or better in 65.9%, 85.4%, 91.5%, and 96% of eyes, respectively. No eyes lost any lines of CDVA at 6 months compared to the preoperative. The postoperative MRSE was stable over time, ranging from -0.34 D ± 0.24 D at 1 month to -0.33 D ± 0.23 D at 6 months. MRSE predictability (± 0.50 D) was 93.5% (129/138) at 3 months and 91.1% (113/124) at 6 months. No serious adverse events were noted. The SILK procedure with the ELITA Femtosecond Laser System is safe and effective for the treatment of myopic refractive errors with and without astigmatism. Fast visual recovery was demonstrated, with stability achieved by 3 months.

Comparison of Patients With Emmetropia and Presbyopia and Different Accommodation Who Undergo Unilateral or Bilateral Implantation of a Trifocal IOL

Purpose: To compare visual outcomes and satisfaction in patients with emmetropia, presbyopia, and greater or lesser residual accommodation who undergo unilateral or bilateral implantation of a trifocal diffractive intraocular lens (IOL). Methods: A multicenter, multisurgeon study was performed to evaluate outcomes in patients with emmetropia and presbyopia who underwent refractive lens exchange followed by implantation of a FineVision trifocal IOL (PhysIOL). The inclusion criteria were as follows: emmetropia, sphere −0.25 to +0.50 diopters (D), cylinder less than 0.75 D, and manifest refractive spherical equivalent (MRSE) of −0.25 to +0.25 D. All patients also had to have an uncorrected distance visual acuity (UDVA) of Snellen 0.9 or better in each eye. The sample was divided into different clusters based on two variables: eyes operated on (monocular or binocular) and age either younger than 55 years or 55 years or older. Thus, four possible groups were created. Visual and refractive performance, patient satisfaction, and spectacle independence were assessed. Results: A total of 690 eyes from 431 patients were evaluated. There was no difference in postoperative uncorrected (UDVA) and corrected (CDVA) distance visual acuity between the groups. Binocular uncorrected near vision (UNVA) was better in patients who underwent surgery on both eyes regardless of age (median [interquartile range]: 0.00 [0.00; 0.10] vs 0.10 [0.00; 0.10] logMAR; P &lt; .001). Binocular uncorrected intermediate vision (UIVA) was better in patients who underwent surgery on both eyes aged younger than 55 years than in those who underwent surgery in one eye aged 55 years or older (median [interquartile range]: 0.18 [0.10; 0.18] vs 0.30 [0.18; 0.30] logMAR; P &lt; .001). The efficacy and safety indexes were 0.98 ± 0.09 and 1.01 ± 0.06, respectively. A total of 93.3% of eyes were within the 0.50 D range in postoperative MRSE. Visual dysphotopsia was worse in patients with both eyes operated on, although the differences were not statistically significant. Conclusions: The study shows that after refractive lens exchange, patients with emmetropia and presbyopia who received a trifocal IOL in one or both eyes achieved good UNVA, UIVA, and UDVA. Regarding near binocular visual acuity, results were better for patients who underwent surgery on both eyes than for those who underwent surgery on one eye. Regarding binocular intermediate visual acuity, patients aged younger than 55 years with both lenses replaced had better results than those 55 years or older with only one lens replaced. However, no significant differences were observed in UDVA or patient satisfaction. [ J Refract Surg . 2023;39(12):817–824.]

Ray-tracing-guided myopic LASIK: real-world clinical outcomes.

To assess effectiveness of individualized ray-trace based laser in situ keratomileusis (LASIK) for correction of myopia in everyday clinical practice. Single-site private practice. Retrospective nonrandomised unmasked chart review. Consecutive, myopic eyes (range ≤-8.25 diopters [D] sphere; astigmatism 0 to -4.25 D) treated with ray-trace based LASIK were included. Patients underwent wavefront, tomography, and biometry assessment using the InnovEyes Sightmap diagnostic device. The ray-trace based algorithm (InnovEyes algorithm) then generated an individualized 3D eye model and calculated a customized LASIK ablation profile. Postoperative visual acuity, refractive error and whole eye higher-order aberrations (HOAs) were evaluated over 3 months. The procedure was performed on 400 eyes (200 patients). Mean preoperative manifest refraction spherical equivalent was -3.39 ± 1.58 D (right eye -3.84 ± 1.63 D, left eye -3.98 ± 1.75 D). At month 3, uncorrected distance visual acuity (UDVA) was ≥20/20 in all eyes, ≥20/16 in 89% (right eye 90%, left eye 89%), ≥20/12 in 51% (54% right eye; 47% left eye), and 20/10 in 8% (right eye 8%; left eye 9%) of eyes respectively. UDVA was within 1 line of preoperative corrected distance visual acuity in 98% of eyes (right eye 98.5%; left eye 98%) and 39% of eyes (right eye 38%; left eye 39%) gained 1 line improvement. There was a statistically but not clinically significant increase in total HOAs (right eye 0.06 ± 0.133 μm; left eye 0.057 ± 0.125 μm; P < .001). The spherical aberration decreased (right eye -0.047 ± 0.095 μm, P < .001; left eye -0.051 ± 0.091 μm, P < .001). Ray-trace based LASIK was safe and effective for correction of myopia with and without astigmatism. Approximately, half the eyes achieved ≥20/12.5 UDVA and 8% achieved 20/10. There was no clinically significant increase in total whole eye HOAs.

IRIS® Registry (Intelligent Research In Sight) Analysis of the Incidence of Monovision in Cataract Patients with Bilateral Monofocal Intraocular Lens Implantation.

To determine the incidence of pseudophakic monovision among patients bilaterally implanted with monofocal intraocular lenses (IOLs) and to characterize the distribution of myopic offsets achieved. This retrospective database study included data on patients receiving care from ophthalmologists who contributed to the Academy IRIS® (Intelligent Research In Sight) Registry. Anonymized data were collected, including patient age, ethnicity, procedure data (CPT code, date, laterality), and postoperative manifest refractive spherical equivalent (MRSE) in both eyes implanted with monofocal or monofocal toric IOLs. No data regarding IOL manufacturer, model, or power were collected. One primary outcome measure was the percentage of patients achieving monovision (defined as emmetropia within ±0.25 diopters [D] in one eye and a myopic offset of ≥0.50 D in the fellow eye) among all patients receiving bilateral monofocal IOLs at the time of cataract surgery between January 1, 2016, and September 1, 2019, with at least 90 days of follow-up. Other primary outcomes included the distribution and frequency of myopic offsets (anisometropia) between eyes. Of the 16,765 people receiving bilateral monofocal IOLs within the study period, 4796 (28.6%) achieved emmetropia in at least one eye, as defined by an MRSE within ± 0.25 D. The incidence of monovision among these patients was 34.2% (1638/4796). One-quarter (24.7%; 405/1638) of patients who achieved monovision had a myopic offset between 0.50 and 0.74 D, with more than one-third (35.2%; 576/1638) falling within 0.75-1.24 D and 18.0% within 1.25-1.74 D. A myopic offset ≥1.75 D was observed in 22.1% (362/1638) of patients who achieved monovision. Pseudophakic monovision for presbyopia correction was achieved in ~34% of patients in the IRIS Registry bilaterally implanted with monofocal IOLs, with myopic offsets typically ranging from 0.5 to 1.24 D.

Comparing clinical outcomes of Optiwave Refractive Analysis, Lenstar, and surgeon’s modified method for intraocular lens power calculation in Asian eyes

The study aimed to compare the accuracy of intraocular lens (IOL) calculation to predict postoperative refraction by Optiwave Refractive Analysis (ORA), Lenstar LS 900, and the surgeon’s Modify method in normal Asian eyes. The IOL power of the Lenstar group was calculated according to Lenstar LS 900, whereas the surgeon's Modify group used topography, axial length (AL) of Lenstar, and Barrett Universal II online formula. Intraoperative aphakic measurements and IOL power calculations were obtained with the ORA system. From the results acquired through Lenstar, Modify, and ORA, the surgeon used his judgment to select the actual IOL power. Postoperative manifest refraction spherical equivalent (MRSE) was obtained 2 months after surgery. The prediction error (PE) was calculated as the difference between the postoperative MRSE and the target refraction proposed by three methods. AL, anterior chamber depth (ACD, measured from corneal endothelium to lens), lens thickness (LT), and ACD + 1/2LT were also included in the survey. In 67 eyes, the average real PE was smaller for the Lenstar (0.06 ± 0.44) and Modify (− 0.05 ± 0.40) than for the ORA group (− 0.25 ± 0.60, p < 0.05). The ORA system demonstrated the best results of IOL power selection in eyes with a normal range of ACD + 0.5 LT (5.2–5.6 mm) in Asian eyes.

Influence of Preoperative Parameters on the Ratio of Keratometric Change per Diopter of Attempted Spherical Equivalent (∆K/∆SEQ) for Myopic Correction Within LASIK, PRK, and SMILE.

To compare 3 of the most common corneal refractive procedures; PRK, LASIK, and SMILE assessing ΔK/ΔSEQ ratio and its correlation with preoperative demographics including age, keratometry, pachymetry, cylinder value, and attempted myopic correction. The goal was to analyze the relative strength of each preoperative parameter in accounting for changes in ∆K/∆SEQ. A total of 370 eyes from 102 male and 97 female patients (173 eyes PRK, 153 LASIK, and 44 SMILE) with ages ranging from 20 to 51 underwent refractive surgery for myopia between -0.25 and -7.71 D manifest refraction spherical equivalent (MRSE). All surgeries were performed at a single surgery center in Draper, Utah. The Pentacam was used for all optical measurements and data were gathered pre-operatively and then again 1-year post-operatively. Only patients who achieved emmetropia at a visual acuity of 20/25 or better were included. The mean ΔK/ΔSEQ ratio for LASIK (0.839 ± 0.020) was significantly greater than that of PRK (0.775 ± 0.022) and SMILE (0.709 ± 0.046). Age was found to negatively correlate with ΔK/ΔSEQ for both LASIK (r = -0.177) and SMILE (r = -0.451) procedures. Pre-op keratometry was found to negatively correlate with ΔK/ΔSEQ for LASIK (r = -0.202) but not for PRK or SMILE. Pre-op pachymetry was not correlated with ΔK/ΔSEQ for any of the procedures. Attempted myopic spherical equivalent (SEQ) correction was positively correlated with ΔK/ΔSEQ for LASIK (r = 0.236), PRK (r = 0.459), and SMILE (r = 0.304). Lastly, pre-op cylinder value was found to be correlated to ΔK/ΔSEQ in SMILE (r = -0.367), but not in LASIK or PRK. The ΔK/ΔSEQ ratio not only differs depending on the procedure being done but also by pre-operative factors such as age, keratometry, attempted correction, and cylinder value. Multiple linear regression analysis revealed that the attempted correction had the greatest effect on ∆K/∆SEQ out of all parameters in LASIK and PRK. For SMILE, age had the greatest predictive value of the change in ∆K/∆SEQ. While the exact effect of these parameters will vary by surgeon, all of these should be factored into a refractive surgeon's nomograms in order to achieve optimal visual outcomes for their patients.

Prediction of Posterior-to-Anterior Corneal Curvature Radii Ratio in Myopic Patients after LASIK, SMILE, and PRK Using Multivariate Regression Analysis.

The ratio of posterior-to-anterior curvature radii of the cornea (P/A ratio) is an important element in determining corneal refractive power. P/A ratio has been well studied in patients prior to undergoing refractive surgery, but its postoperative value remains less so. We aimed to examine the value of preoperative characteristics of refractive surgery patients in predicting the 1-year postoperative P/A ratio in LASIK, PRK, and SMILE using both linear and multivariate regression analyses. This was a retrospective study that included patients with manifest refraction spherical equivalents (MRSE) from -7.71D to -0.25D. In total, 164 eyes underwent LASIK, 183 underwent PRK, and 46 underwent SMILE. All patients had preoperative and 1-year postoperative front sagittal and back sagittal keratometry measurements at 4, 5, and 6 mm around the corneal vertex. Postoperative P/A after LASIK, PRK, and SMILE was found to be significantly correlated with MRSE and preoperative P/A. Stepwise variable selection in multivariate regression revealed that spherical equivalent was the most significant predictor of postoperative P/A. When coupled with other preoperative characteristics, including P/A, age, asphericity, and keratometry, the multivariate regressions were able to produce models with high predictive value in LASIK (adjusted R2: 0.957), PRK (adjusted R2: 0.934), and SMILE (adjusted R2: 0.894).

Long-term results of hyperopic ablations using alcohol-assisted PRK and FS-LASIK: comparative study.

To evaluate the long-term visual and refractive outcomes of hyperopic excimer ablation using alcohol-assisted photorefractive keratectomy (PRK) and femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK). American University of Beirut Medical Center, Beirut, Lebanon. Retrospective, matched comparative study. Eyes that underwent alcohol-assisted PRK were compared to matched eyes that underwent FS-LASIK. All patients were followed up for at least 3 years after surgery. The refractive and visual outcomes of each group were compared at different postoperative time points. The main outcome measures were spherical equivalent deviation from target (SEDT), manifest refraction, and visual acuity. 83 eyes underwent alcohol-assisted PRK and 83 matched eyes underwent FS-LASIK. Preoperative manifest refraction spherical equivalent was 2.44 ± 1.18 diopters (D) and 2.20 ± 0.87 D ( P = .133) in the PRK and FS-LASIK groups, respectively. Preoperative manifest cylinder was -0.77 ± 0.89 D and -0.61 ± 0.59 D ( P = .175) for the PRK and LASIK groups, respectively. 3 years postoperatively, SEDT was 0.28 ± 0.66 D and 0.40 ± 0.56 D for the PRK and LASIK groups, respectively ( P = .222), whereas manifest cylinder was -0.55 ± 0.49 D and -0.30 ± 0.34 D for PRK and LASIK, respectively ( P < .001). The mean difference vector was 0.59 ± 0.46 for PRK and 0.38 ± 0.32 for LASIK ( P < .001). 13.3% of PRK eyes and 0% of LASIK eyes had >1 D of manifest cylinder ( P = .003). Both alcohol-assisted PRK and FS-LASIK are safe and effective for the treatment of hyperopia. PRK induces slightly more postoperative astigmatism than LASIK. Larger optical zones and recently introduced ablation profiles that lead to a smoother ablation surface might improve the clinical results of hyperopic PRK.

Comparison of planned versus achieved central corneal stromal thickness reduction in SMILE versus FS-LASIK: a retrospective study

Accuracy of planned corneal stromal thickness (CST) reduction is essential to the safety of laser vision correction. This study was to compare the accuracy of the planned central CST reduction in small incision lenticule extraction (SMILE) and femtosecond laser-assisted in situ keratomileusis (FS-LASIK). A total of 77 patients (43 for SMILE, 34 for FS-LASIK using Custom-Q algorithm) were included in this retrospective study. At postoperative 6–18 months, the central CST reduction was overestimated by 18.49 ± 6.42 μm in the SMILE group (P < 0.001) and underestimated by 2.56 ± 7.79 μm in the FS-LASIK group (P = 0.064). The planned-achieved difference (PAD) of central CST reduction was positively correlated with preoperative manifest refraction spherical equivalent (MRSE) and with planned central CST reduction in both groups. When calculated by manifest refraction (MR) without nomogram adjustment, the central CST reduction was overestimated by 11.14 ± 6.53 μm in the SMILE group and underestimated by 2.83 ± 7.39 μm in the FS-LASIK group. The PAD of central CST reduction without nomogram was significantly narrowed in SMILE and maintained in FS-LASIK, suggesting estimation using MR without nomogram adjustment may be feasible for SMILE and FS-LASIK in clinical practice.

Effect of preoperative pupil offset on corneal higher-order aberrations after femtosecond laser-assisted in situ keratomileusis

BackgroundThis study aimed to investigate the relationship between multiple higher-order aberrations (HOAs) subgroups and pupil offset, as well as to analyze the factors affecting postoperative corneal HOAs in patients with different degrees of refractive errors.MethodsWe enrolled 160 patients (316 eyes) aged ≥ 18 years who had undergone femtosecond laser-assisted in situ keratomileusis (FS-LASIK) treatment. Based on the relationship between the preoperative pupil offset and the postoperative ΔHOAs, all patients were divided into two groups: group I (pupil offset ≤ 0.20 mm) and group II (pupil offset > 0.20 mm). All of the eyes had low to high myopia with or without astigmatism (manifest refraction spherical equivalent (MRSE) < -10.00 D). Uncorrected distance visual acuity, corrected distance visual acuity, MRSE, pupil offset, central corneal thickness, corneal HOAs, vertical coma (Z3−1), horizontal coma (Z31), spherical aberration (Z40), trefoil 0° (Z33), and trefoil 30° (Z3−3) over a 6 mm diameter central corneal zone diameter were evaluated preoperatively and at 1 and 3 months postoperatively.ResultsOur result revealed significant differences in postoperative corneal total root mean square (RMS) HOAs, RMS vertical coma, RMS horizontal coma, RMS spherical aberration, and RMS trefoil 30° between group I and group II. ΔMRSE was found to be an effective factor for ΔRMS HOAs (R2 = 0.383), ΔRMS horizontal coma (R2 = 0.205), and ΔRMS spherical aberration (R2 = 0.397). In group II, multiple linear regression analysis revealed a significant correlation between preoperative pupillary offset and Δtotal RMS HOAs (R2 = 0.461), ΔRMS horizontal coma (R2 = 0.040), and ΔRMS trefoil 30°(R2 = 0.089). The ΔRMS vertical coma effect factor is the Y-component, and the factor influencing ΔRMS spherical aberration was ΔMRSE (R2 = 0.256).ConclusionA small pupil offset was associated with a lower induction of postoperative corneal HOAs. Efforts to optimize centration are critical for improving surgical outcomes in patients with FS-LASIK.

Network meta-analysis comparing efficacy and safety of different protocols of corneal cross-linking for the treatment of progressive keratoconus.

This study aimed to determine the preferred protocol of corneal collagen cross-linking (CXL) in the treatment of progressive keratoconus. Relevant studies were retrieved in PubMed, EMBASE and Cochrane Central Register of Controlled Trials (CENTRAL). Maximum keratometry value (Kmax), best spectacle-corrected visual acuity (BSCVA), manifest refraction spherical equivalent (MRSE), and endothelial cell density (ECD) were evaluated in network meta-analysis. Eight randomized controlled trials (RCTs) were included. Low-level evidence suggested that aCXL with 30mW/cm2 for 3min (aCXL-3) might be the best protocol for reducing BSCVA (65.22%) but worst protocol for reducing MRSE (51.53%). aCXL with 18mW/cm2 for 5min (aCXL-5) might be the best protocol for reducing Kmax (39.58%) and MRSE (77.85%) but might be the worst for preserving ECD (50.98%). aCXL with 9mW/cm2 for 10min (aCXL-10) might be the best protocol for preserving ECD (31.53%). Overall, three protocols of aCXL are comparable in therapeutic efficacy and safety for treating progressive keratoconus. Despite no direct data comparing the efficacy of each technique according to different patients' profiles, it is reasonable to state that aCXL-5 may be the best for patients at early-stage to reduce Kmax and MRSE, aCXL-3 may be the best for patients at mid-stage to improve BSCVA, and aCXL-10 may be the best for patients at late-stage to preserve DEC.

Wavefront-guided PRK treatment of myopia using a refractive aberrometer.

To evaluate the safety, effectiveness, and patient-reported outcomes of wavefront-guided photorefractive keratectomy (PRK) for the correction of myopic refractive errors with and without astigmatism. U.S. multicenter study. Prospective, nonrandomized clinical investigation. 334 eyes (167 patients) underwent wavefront-guided PRK with the STAR S4 IR Excimer Laser System. Patients had preoperative myopic refractive errors with sphere up to -8.00 diopters (D) and cylinder up to -4.00 D with a maximum spherical equivalent (SE) of -10.00 D. All eyes were targeted for emmetropia, and treatment plans were derived from the iDESIGN system wavefront measurements. At 6 months, the point of refractive stability, 99.4% of eyes achieved 20/20 or better uncorrected distance visual acuity (UDVA), 92% of eyes achieved 20/16 or better UDVA, 85.5% of eyes achieved manifest refraction SE (MRSE) within 0.50 D of target, mean SE was -0.06, and less than 1% of eyes lost more than 2 lines of corrected distance visual acuity. Glare and halos occurred with similar or lower frequencies at 6 months vs preoperative. Results from the National Eye Institute Refractive Error Quality of life questionnaire showed statistically significant improvements at 6 months vs preoperative across most measures of vision-related functioning and well-being. Approximately 98% of patients reported high satisfaction with their overall vision at 6 months. Wavefront-guided PRK with the iDESIGN aberrometer was safe, effective, and predictable for the correction of low to moderate myopia with and without astigmatism and led to high patient satisfaction.

Supracor Multifocal Corneal Laser-Assisted In Situ Keratomileusis Procedure for the Correction of Presbyopia in Hyperopic Eyes.

To investigate the outcomes of unilateral Supracor treatment to enhance near vision while maintaining good distance vision in hyperopic eyes. This prospective interventional study includes consecutive hyperopic patients with presbyopia. All eyes underwent femtosecond laser-assisted in situ keratomileusis treatment for hyperopia with an additional Supracor multifocal treatment algorithm in nondominant eyes. Monocular and binocular uncorrected and spectacle-corrected distance visual acuity (UCDVA and SCDVA), monocular and binocular uncorrected near visual acuity (UNVA), and distance-corrected near visual acuity at 40 cm and high-order aberration changes and complications were evaluated for 6 months. Sixty-four patients with a mean age of 51.91 ± 3.64 were enrolled. After 6-month follow-up, the mean binocular UCDVA and UNVA were 0.03 ± 0.05 and 0.04 ± 0.06 logMAR, respectively. UCDVA (logMAR) of nondominant and dominant eyes was 0.30 ± 0.18 and 0.03 ± 0.05, respectively. Preoperative and postoperative mean ± standard deviation manifest refraction spherical equivalent was +1.84 ± 0.75 and -0.48 ± 0.57, respectively, in nondominant eyes and +1.77 ± 0.69 and +0.12 ± 0.33, respectively, in dominant eyes. No complications were observed. Supracor procedure in nondominant eyes may improve functional near, intermediate, and distance vision without significant photic phenomena in presbyopic patients with low and moderate hyperopia.

Outcomes of LASIK vs PRK enhancement in eyes with prior cataract surgery.

To compare postenhancement visual acuity between patients who underwent postcataract laser in situ keratomileusis (LASIK) or photorefractive keratectomy (PRK). A private, tertiary referral practice in Sioux Falls, South Dakota. 3-year, retrospective chart review. Patients who underwent postcataract extraction excimer laser enhancement surgery targeted for emmetropia (±0.50 diopter). Postenhancement uncorrected distance visual acuity (UDVA) and manifest refraction spherical equivalent (MRSE) was recorded for all available follow-ups and compared for both groups. 822 postcataract enhanced eyes (491 LASIK; 331 PRK). For patients with at least 6-month follow-up, mean UDVA was 0.05 ± 0.13 logMAR in LASIK-enhanced patients and 0.15 ± 0.20 in PRK-enhanced patients ( P < .001). Mean absolute value MRSE was 0.22 ± 0.36 and 0.48 ± 0.62 for LASIK-enhanced and PRK-enhanced patients at or beyond 6 months, respectively ( P < .001). 330 (67%) LASIK-enhanced patients achieved 20/20 or better postenhancement UDVA, compared with 142 (43%) PRK-enhanced patients ( P < .001). Controlling for pre-enhancement UDVA, LASIK-enhanced patients showed significantly better postenhancement UDVA than PRK-enhanced patients, except in those with pre-enhancement vision of 20/20 or better, or those worse than 20/50. LASIK-enhanced virgin corneas had mean postenhancement of 0.05 ± 0.14 UDVA compared with 0.13 ± 0.19 UDVA in PRK-enhanced virgin cornea patients ( P < .001). LASIK provides better and more predictable outcomes in UDVA than PRK in postcataract enhancement patients, even when controlling for pre-enhancement visual acuity and prior ocular procedures.