Higher-order Aberrations Research Articles

Higher order aberrations according to spherical, and astigmatic refractive errors in children

ABSTRACT Clinical relevance The results of this study present novel insights into the impact of spherical and astigmatic refractive errors on overall, corneal and internal aberrations and may provide a clear understanding of the emmetropisation process and the development of visual function. Background This study aimed to assess the association between overall, corneal and internal higher-order aberrations and the spherical and astigmatic components (magnitude and angle) of refractive error in a large sample of children. Methods A total of 311 children aged 7 – 8 years old were classified based on spherical equivalent refraction (myopic, emmetropic and hyperopic); magnitude of astigmatism (none, low and moderate); and angle of astigmatism (with-the-rule, against-the-rule and oblique). Refractive error and overall, corneal and internal higher-order aberrations were measured using the OPD-Scan III workstation. Results Regarding spherical equivalent refraction, myopic eyes had greater root mean square (RMS) overall higher-order values, total spherical, tetrafoil and secondary astigmatism aberrations, and internal higher-order, total spherical and tetrafoil aberrations in comparison to emmetropic eyes. The magnitude of astigmatism was positively associated with all overall RMS aberrations and with internal higher order, coma, total coma, total spherical and tetrafoil aberrations. Eyes with with-the-rule astigmatism showed higher RMS values of coma and total coma compared to eyes with against-the-rule and oblique astigmatism. Conclusions Higher-order aberrations are dependent on the spherical as well as astigmatic components of refractive error. These findings enhance the current understanding of the emmetropisation process and visual function development.

Low Rate of Postoperative Pterygium Recurrence in Patients under Treatment with Low-Dose Oral Doxycycline for Chronic Blepharitis: A First Report.

Low doses of systemic doxycycline (LD-SD) inhibit angiogenesis and the expression of matrix metalloproteases, which are determinants of pterygium progression. This study aimed to compare the recurrence rate and visual outcome of pterygium excision in patients undergoing chronic treatment with LD-SD for chronic refractory blepharitis and LD-SD-naive patients. A retrospective analysis of patients that underwent surgical excision and conjunctival graft apposition was conducted. Patients were divided in a TETRA group (under LD-SD treatment at the moment of surgery) and a control group. The main outcome was the rate of recurrence at 1 year postoperatively. Secondary outcomes were the comparisons of surface regularity, visual quality, and dry-eye symptoms at 6-week, 6-month, and 1-year follow-up in the two groups. The TETRA group showed a significantly lower rate of 1-year recurrence both in primary (p = 0.034) and recurrent (p < 0.001) pterygia. The best corrected visual acuity (BCVA), astigmatic error, corneal total root mean square (RMS), and ocular surface disease index (OSDI) significantly reduced during the follow-up in both groups. The surface asymmetry index and high-order aberrations (HOAs) significantly reduced only in the TETRA group. The final BCVA was significantly higher, while the OSDI score and total RMS and HOAs were significantly lower in the TETRA group compared to the control. Patients under treatment with LD-SD showed a lower rate of recurrence at 1-year follow-up compared to controls. These patients also experienced higher BCVA and surface regularity and less dry-eye symptoms.

Comparative Analysis of Corneal Higher-Order Aberrations after Laser-Assisted In Situ Keratomileusis, Photorefractive Keratectomy, and Small Incision Lenticule Extraction with Correlations to Change in Myopic Q-Value and Spherical Equivalent with and without Astigmatism.

Background: This retrospective chart review compared the higher-order aberrations (HOAs) among photorefractive keratectomy (PRK), laser-assisted in situ keratomileusis (LASIK), and small incision lenticule extraction (SMILE) alongside changes in spherical equivalent (SEQ) and corneal shape (Q-value). Methods: Analyzing 371 myopic eyes, including 154 LASIK, 173 PRK, and 44 SMILE cases, Pentacam imaging was utilized pre-operatively and at one-year post-operative visits. Results: All procedures resulted in 100% of patients achieving an uncorrected distance visual acuity (UDVA) of 20/40 or better, with 87% of LASIK and PRK, and 91% of SMILE patients having 20/20 or better. Significant increases in HOAs were observed across all procedures (p < 0.05), correlating positively with SEQ and Q-value changes (LASIK (0.686, p < 0.05), followed by PRK (0.4503, p < 0.05), and SMILE (0.386, p < 0.05)). Vertical coma and spherical aberration (SA) were the primary factors for heightened aberration magnitude among the procedures (p < 0.05), with the largest contribution in SMILE, which is likely attributed to the centration at the corneal apex. Notably, PRK showed insignificant changes in vertical coma (-0.197 µm ± 0.0168 to -0.192 µm ± 0.0198, p = 0.78), with an increase in oblique trefoil (p < 0.05). Conclusions: These findings underscore differences in HOAs among PRK, LASIK, and SMILE, helping to guide clinicians.

Transepithelial Photorefractive Keratectomy-Review.

The type and nature of refractive surgery procedures has greatly increased over the past few decades, allowing for almost all patient populations to be treated to extremely high satisfaction. Conventional photorefractive keratectomy involves the removal of the corneal epithelium through mechanical debridement or dilute alcohol instillation. An improvement to this method utilises laser epithelial removal in a single-step process termed transepithelial photorefractive keratectomy (transPRK). We explore the history of transPRK from its early adoption as a two-step process, identify different transPRK platforms from major manufacturers, and describe the role of transPRK in the refractive surgery armamentarium. This is a narrative review of the literature. This review finds that TransPRK is a safe and effective procedure that works across a variety of patient populations. Though often not seen as a primary treatment option when compared to other corneal-based procedures that offer a faster and more comfortable recovery, there are many scenarios in which these procedures are not possible. These include, but are not limited to, cases of corneal instability, previous refractive surgery, or transplant where higher-order aberrations can impair vision in a manner not amenable to spectacle or contact lens correction. We discuss refinements to the procedure that would help improve outcomes, including optimising patient discomfort after surgery as well as reducing corneal haze and refractive regression.

Effect of Cyclotorsion Compensation in Small Incision Lenticule Extraction Surgery for the Correction of Myopic Astigmatism: A Systematic Review and Meta-Analysis.

Small incision lenticule extraction (SMILE) has made notable advancements in addressing myopic astigmatism. Nevertheless, the potential impact of cyclotorsion on surgical outcomes cannot be overlooked. This study aims to assess the effectiveness of cyclotorsion compensation technology in SMILE surgery for the correction of myopic astigmatism, examining its influence on postoperative visual quality. A systematic review and meta-analysis were conducted. A comprehensive literature search was performed using databases, including PubMed, Web of Science, EMBASE, Cochrane Library, EBSCO, Scopus, CNKI, VIP, and Wan Fang. Studies meeting the criteria were selected and included. Data were independently extracted by three authors. Clinical outcome parameters were analyzed using Review Manager version 5.3. This meta-analysis included ten studies. The results showed that, compared with the control group (cyclotorsion compensation was not performed in SMILE), the following indicators in the cyclotorsion compensation group were: residual astigmatism (RA) [weighted mean difference (MD) = 0.73, 95% confidence interval (CI) + 0.26 to + 1.19, P = 0.002], spherical equivalent (SE) (MD = 1.99, 95% CI + 0.77 to + 3.21, P = 0.001), coma (MD = -0.06, 95% CI -0.08 to -0.04, P < 0.00001), higher-order aberrations (HOAs) (MD = -0.04, 95% CI -0.06 to -0.02, P < 0.0001), follow-up 6-month angle of error (AE) (MD = -2.67, 95% CI -3.71 to -1.63, P < 0.00001), and follow-up 6-month uncorrected distance visual acuity (UDVA) (MD = -0.05, 95% CI -0.08 to -0.01, P = 0.005), and the differences in results were statistically significant. However, the differences among correction index, index of success (IOS), targeted induced astigmatism (TIA), magnitude of error (ME), and spherical aberration (SA) were not statistically significant. Cyclotorsion compensation proves to be effective and predictable for correcting myopic astigmatism. The cyclotorsion compensation group demonstrated advantages over the control group in terms of postoperative residual astigmatism, and it induced fewer coma aberrations. Whether cyclotorsion compensation can lead to better visual quality remains to be seen, and further research on correcting myopic astigmatism through cyclotorsion compensation is warranted.

Ten-year observation of corneal densitometry and associated factors following small incision lenticule extraction.

To investigate the long-term changes of corneal densitometry (CD) and its contributing elements after small incision lenticule extraction (SMILE). Totally 31 eyes of 31 patients with mean spherical equivalent of -6.46±1.50 D and mean age 28.23±7.38y were enrolled. Full-scale examinations were conducted on all patients preoperatively and during follow-up. Visual acuity, manifest refraction, axial length, corneal thickness, corneal higher-order aberrations, and CD were evaluated. All surgeries were completed successfully without complications or adverse events. Ten-year safety index was 1.17±0.20 and efficacy 1.04±0.28. CD value of 0-6 mm zones in central layer was statistically significantly lower 10y postoperatively, compared with preoperative values (0-2 mmΔ=-1.62, 2-6 mmΔ=-1.24, P<0.01). There were no correlations between CD values and factors evaluated. SMILE is a safe and efficient procedure for myopia on a long-term basis. CD values get lower 10y postoperatively, whose mechanism is to be further discussed.

Repeatability of pyramidal aberrometer measurements in keratoconus and normal eyes.

To evaluate the intrasubject repeatability of pyramidal aberrometer measurements in a sample of keratoconus and normal eyes. American University of Beirut Medical Center, Beirut, Lebanon. Prospective comparative repeatability analysis. Study population: Keratoconus and normal eyes from adult patients. Observation procedures: Each eye was evaluated with 3 consecutive acquisitions using a pyramidal aberrometer. Main outcome measures: The repeatability of different ocular higher-order aberrations and lower-order aberrations (HOAs and LOAs, respectively), and Zernike coefficients down to the fifth order, was evaluated. Repeatability was assessed by within-subject SDs (Sw), repeatability limits ( r ), and intraclass correlation coefficients (ICCs), among other parameters. 72 keratoconus patients (72 eyes) and 76 normal patients (76 eyes) were included. In normal and keratoconus eyes, the ICC of total LOAs and HOAs, as well as each of the Zernike coefficients, was >0.9. The Sw for keratoconus eyes with mean maximal keratometry (Kmax) <50 diopters (D) was 0.1345 for total LOAs, 0.0619 for total HOAs, 0.0292 for horizontal coma, 0.0561 for vertical coma, and 0.0221 for spherical aberration as compared with 0.2696, 0.1486, 0.0972, 0.1497, and 0.0757 for keratoconus eyes with Kmax ≥50 D. Similar trend of better repeatability for grade 1 keratoconus and HOAs <2 D as compared with grades 2 and 3 keratoconus and eyes with HOAs >2 D were also noted. Ocular aberrometer measurements generated by high definition pyramidal aberrometers have high repeatability in both normal and mild keratoconus eyes and moderate repeatability, yet still clinically acceptable, in advanced keratoconus. This is of particular importance in ocular wavefront-guided treatments.

Comparison of visual performance between diffractive bifocal and diffractive trifocal intraocular lenses

To evaluate the visual performance of a diffractive bifocal intraocular lens (IOL) with + 4.0 D near addition (ZMB00) and a diffractive trifocal IOL with + 2.17 D and + 3.25 D near addition (AcrySof IQ PanOptix TFNT00), we investigated the 10-week postoperative parameters after cataract surgery in which ZMB00 or TFNT00 lenses were implanted bilaterally from 2011 to 2020 (with a 3-month interval between implantation of the right and left lenses). The study included 1448 eyes of 724 patients. The diffractive bifocal group comprised 1326 eyes of 663 patients (aged 67.0 ± 7.8 years; females/males, 518/145), and the diffractive trifocal group comprised 122 eyes of 61 patients (aged 66.6 ± 7.3 years; females/males, 35/26). A linear mixed-effects model using data for both eyes, with strict adjustments for sex, age, subjective refraction spherical equivalent, subjective refraction cylinder, corneal astigmatism, axial length, corneal higher-order aberrations, and pupil diameter, ensured statistical validity. Uncorrected near visual acuity and higher-order aberrations (ocular/internal, scaled to a pupil size of 4 mm) (Wavefront_4mm_postoperative_Ocular/Internal_Spherical) were significantly better in the bifocal group (p < 0.00068, Wald test). Uncorrected intermediate visual acuity, contrast sensitivity (6.3/4.0/2.5/1.6/1.0/0.7 degrees), and contrast sensitivity with glare (4.0/1.6/1.0/0.7 degrees) were significantly better in the trifocal group (p < 0.00068, Wald test).

Comparative study of surgical outcomes regarding tear meniscus area and high-order aberrations between two different interventional methods for primary acquired nasolacrimal duct obstruction.

To compare endonasal dacryocystorhinostomy (EN-DCR) with sheath-guided dacryoendoscopic probing and bicanalicular intubation (SG-BCI) by evaluating tear meniscus area (TMA) and total high-order aberrations (HOAs) for primary acquired nasolacrimal duct obstruction (PANDO). We retrospectively reviewed 56 eyes of 42 patients (7 men, 35 women; age, 72.7±13.1 years) who underwent EN-DCR or SG-BCI for PANDO in Toyama University Hospital from February 2020 to June 2022. In the EN-DCR and SG-BCI groups, we measured the patency of the lacrimal passage, preoperative and postoperative TMA, and HOAs of the central 4 mm of the cornea using optical coherence tomography (AS-OCT), six months postoperatively. There was a positive correlation between preoperative TMA and preoperative HOAs in all cases. Postoperative patency of lacrimal passage was 100% in the EN-DCR and 80.8% in the SG-BCI group. There was a significant difference in the number of passages between the two groups (p = 0.01). Preoperative TMA and HOAs showed a significant postoperative decrease in both groups (EN-DCR group: p<0.01, p<0.01, SG-BCI group: p<0.01, p=0.03, respectively). We then calculated the rate of change of preoperative and postoperative TMA and HOAs and compared them between the two groups. The rate of change was significantly higher in the EN-DCR group than that in the SG-BCI group (TMA, p=0.03; HOAs, p=0.02). Although both EN-DCR and SG-BCI are effective for PANDO, our results suggest that EN-DCR is more effective in improving TMA and HOAs.

Optimum pinhole size determination in pinhole pupilloplasty for higher-order aberrations.

To determine optimal pinhole size (OPS) and establish a relationship with visual acuity (VA) and RMS (root mean square) values in cases with higher-order aberrations (HOAs) undergoing pinhole pupilloplasty (PPP). Private practice, India. Prospective, interventional study. RMS value for 6-mm-diameter optical zone was determined by Scheimpflug imaging (Pentacam). Patients with RMS value >0.3 μm were included. Preoperatively, a hand-held pinhole gauge with varied apertures determined the OPS, and single-pass four-throw technique was used to perform pupilloplasty with Purkinje-1 reflex as a marker for centration. VA with OPS, correlation of RMS values with OPS and pupil size, and Strehl ratio were the main outcome measures. 29 eyes with HOAs were analyzed; all patients chose 1.0 or 1.5 mm as OPS. The mean preoperative and postoperative pupil size was 3.25 ± 0.81 mm and 1.8 ± 0.54 mm ( P = .000), respectively. Postoperative mean pupil size when compared with OPS denoted that 14 eyes had a difference of <0.1 mm, 8 eyes ranged from 0.2 to 0.45 mm, and 7 eyes had ≥0.6 mm (range from 0.6 to 1.8 mm) difference from OPS. Eyes with higher RMS values needed smaller pupil gauge to achieve better VA. Preoperatively, vision with OPS correlated well with preoperative 6-mm RMS HOAs ( r = 0.728; P = .00). Postoperative UDVA correlated well with VA measured with OPS ( r = 0.847; P = .00). The preoperative and postoperative mean Strehl ratio was 0.109 ± 0.07 and 0.195 ± 0.11 ( P = .001), respectively. Higher RMS values required a smaller pupil to achieve optimum VA. PPP can help achieve pinhole size in accordance with patient's optimum pinhole requirement.

Fourier analysis of corneal irregular astigmatism after small-incision lenticule extraction and transepithelial photorefractive keratectomy: A comparative study.

To compare changes in the spherical component, regular astigmatism, and irregular astigmatism of the anterior surface of the cornea after small-incision lenticule extraction (SMILE) and transepithelial photorefractive keratectomy (TransPRK). Fifty-six patients underwent SMILE in 56 eyes, and 68 patients underwet TransPRK in 68 eyes. The right eye was chosen to enter the group. Six months after the procedure, Scheimpflug images were acquired, and Fourier analysis of the anterior surface of patients' corneas was performed using the Pentacam built-in software. Fourier parameters encompass various measurements such as the steepest radius of the curvature and average eccentricity of the spherical components (SphRmin and SphEcc), maximum decentration (MaxDec), central and peripheral regular astigmatism (regular astigmatism at the center [AstC] and regular astigmatism at the periphery [AstP]), and irregularity (Irr). At 6 months postoperatively, SphEcc decreased significantly (P < .001), MaxDec increased significantly (P < .001), and Irr increased insignificantly (P = .254) in the SMILE group. SphEcc decreased significantly (P < .001) and MaxDec and Irr increased significantly (P < .001) in the TransPRK group. TransPRK caused greater changes in SphEcc, MaxDec, and Irr on the anterior corneal surface than SMILE (P < .05). The amount of MaxDec-induced changes in SMILE and TransPRK was significantly correlated with the amount of higher-order aberrations and spherical aberration changes (P < .05). SMILE and TransPRK increase overall irregular astigmatism on the anterior surface of the cornea, more so with TransPRK, where changes in decentration are associated with with increased higher-order aberrations.

Effect of Decentration, Rotation, and Tilt on Objective Optical Quality of Plate Haptic Toric Intraocular Lenses in the Early Postoperative Period.

This study aimed to determine the influence of decentration, rotation, and tilt on objective optical quality of plate haptic toric intraocular lenses (tIOLs). The area ratio of modulation transfer function (MTF), strehl ratio of point spread function (PSF), and higher order aberrations (HOAs) for 3 mm and 5 mm pupil diameter (PD) were evaluated at postoperative 1 month. The retroillumination images pictured by OPD-scan III were used to quantify the degree of decentration and rotation, whereas the tIOL tilt was directly obtained by the tilt aberration. Patients were separated into two subgroups based on tIOL misalignment cutoff values. There were 29 eyes (24 patients) in the study. The decentration of more than 0.25 mm did not substantially differ from those less than or equal to 0.25 mm. PSF of 3mm PD and MTF, intraocular HOAs, and trefoil aberration for 3 mm and 5 mm PD significantly deteriorated with a rotation of more than 3 degrees, whereas only intraocular HOAs for 5 mm PD and coma for 3 mm and 5 mm PD were significantly severe with a tilt of more than 0.1 µm and 0.25 µm in corresponding PD. Furthermore, tIOL rotation and tilt were highly correlated with intraocular trefoil aberration and coma, respectively. The decentration of the monofocal bitoric IOLs is more tolerant to optical quality degradation after 1 month of surgery but more sensitive to intraocular trefoil aberration caused by rotation and coma aberration induced by tilt. As far as we know, this is the first study to investigate the relationship between the plate haptic bitoric IOL misalignment and objective optical quality measured by OPD-scan III in the real world, which may provide reference information for IOL selection to improve surgical outcomes.

Refractive results of photorefractive keratectomy comparing trans-PRK and PTK−PRK for correction of myopia and myopic astigmatism

PurposeTo compare refractive outcomes after transepithelial photorefractive keratectomy (tPRK) and combined phototherapeutic keratectomy (PTK−PRK) procedure using two different excimer laser platforms for correction of myopia and myopic astigmatism.MethodsIn this retrospective multicenter study, we compared the results of two different PRK methods. The first group received a tPRK treatment with the Amaris750 excimer laser (Schwind eye-tech solutions). The second group received a combined PTK−PRK treatment with the MEL90 excimer laser (Carl Zeiss). Only healthy eyes with no previous surgery and a spherical equivalent (SE) of −1 to −8 diopters (D) were included. Preoperative spherical equivalent (SE), age, and sex were matched among the two groups. All treatments were performed by the same surgeon in different clinics. This study was approved by the local Ethics Committee (No. 2022–1980).ResultsWe included 154 eyes of 86 patients in our study. There was no difference in predictability of SE between the two groups. Efficacy and safety indices were equally high in both groups. Similarly, no significant differences were seen in change of higher order aberrations (HOA) between the two groups (p > 0.05). No complications occurred.ConclusionBoth investigated methods provide safe and effective refractive results. The combination of PTK with PRK may be a suitable option to the already used one-step tPRK for the correction of myopia.

Phasing segmented telescopes via deep learning methods: application to a deployable CubeSat.

Capturing high-resolution imagery of the Earth's surface often calls for a telescope of considerable size, even from low Earth orbits (LEOs). A large aperture often requires large and expensive platforms. For instance, achieving a resolution of 1m at visible wavelengths from LEO typically requires an aperture diameter of at least 30cm. Additionally, ensuring high revisit times often prompts the use of multiple satellites. In light of these challenges, a small, segmented, deployable CubeSat telescope was recently proposed creating the additional need of phasing the telescope's mirrors. Phasing methods on compact platforms are constrained by the limited volume and power available, excluding solutions that rely on dedicated hardware or demand substantial computational resources. Neural networks (NNs) are known for their computationally efficient inference and reduced onboard requirements. Therefore, we developed a NN-based method to measure co-phasing errors inherent to a deployable telescope. The proposed technique demonstrates its ability to detect phasing errors at the targeted performance level [typically a wavefront error (WFE) below 15nm RMS for a visible imager operating at the diffraction limit] using a point source. The robustness of the NN method is verified in presence of high-order aberrations or noise and the results are compared against existing state-of-the-art techniques. The developed NN model ensures its feasibility and provides a realistic pathway towards achieving diffraction-limited images.

One-year results for myopia control of orthokeratology with different back optic zone diameters: a randomized trial using a novel multispectral-based topographer.

To present the 1-year results of a prospective cohort study investigating the efficacy, potential mechanism, and safety of orthokeratology (ortho-k) with different back optic zone diameters (BOZD) for myopia control in children. This randomized clinical study was performed between Dec. 2020 and Dec. 2021. Participants were randomly assigned to three groups wearing ortho-k: 5 mm BOZD (5-MM group), 5.5 mm BOZD (5.5-MM group), and 6 mm BOZD (6-MM group). The 1-year data were recorded, including axial length, relative peripheral refraction (RPR, measured by multispectral refractive topography, MRT), and visual quality. The contrast sensitivity (CS) was evaluated by CSV-1000 instrument with spatial frequencies of 3, 6, 12, and 18 cycles/degree (c/d); the corneal higher-order aberrations (HOAs) were measured by iTrace aberration analyzer. The one-way ANOVA was performed to assess the differences between the three groups. The correlation between the change in AL and RPR was calculated by Pearson's correlation coefficient. The 1-year results of 20, 21, and 21 subjects in the 5-MM, 5.5-MM, and 6-MM groups, respectively, were presented. There were no statistical differences in baseline age, sex, or ocular parameters between the three groups (all P>0.05). At the 1-year visit, the 5-MM group had lower axial elongation than the 6-MM group (0.07±0.09 vs 0.18±0.11 mm, P=0.001). The 5-MM group had more myopic total RPR (TRPR, P=0.014), with RPR in the 15°-30° (RPR 15-30, P=0.015), 30°-45° (RPR 30-45, P=0.011), temporal (RPR-T, P=0.008), and nasal area (RPR-N, P<0.001) than the 6-MM group. RPR 15-30 in the 5.5-MM group was more myopic than that in the 6-MM group (P=0.002), and RPR-N in the 5-MM group was more myopic than that in the 5.5-MM group (P<0.001). There were positive correlations between the axial elongation and the change in TRPR (r=0.756, P<0.001), RPR 15-30 (r=0.364, P=0.004), RPR 30-45 (r=0.306, P=0.016), and RPR-N (r=0.253, P=0.047). The CS decreased at 3 c/d (P<0.001), and the corneal HOAs increased in the 5-MM group (P=0.030). Ortho-k with 5 mm BOZD can control myopia progression more effectively. The mechanism may be associated with greater myopic shifts in RPR.

The visual impact of higher-order aberrations in patients with pediatric blepharokeratoconjunctivitis.

To analyze higher-order aberrations (HOAs) and their visual impact in a pediatric blepharokeratoconjunctivitis (PBKC) cohort compared with healthy controls. Prospective case-control study of pediatric patients (≤ 16 years old). Subjects underwent wavefront aberrometry analysis to compare HOAs and their impact on visual quality. A total of 150 eyes from 76 patients were included in the analysis. The PBKC group consisted of 50 eyes and the control group of 100 healthy eyes. Mean age was 10.39 ± 3.81 years for the PBKC group and 10.80 ± 3.61 years for the controls. Mean corrected-distance visual acuity (CDVA) was 0.24 ± 0.21 logMAR in the PBKC group and 0.07 ± 0.1 in the controls (P < 0.001). Mean astigmatism was 1.6 ± 1.98D in the PBKC group vs. 0.67 ± 0.76D in the control group (P = 0.01). Mean RMS of HOAs was 1.05 ± 1.7mm in the PBKC group and 0.41 ± 0.18mm in the controls (P < 0.001). The mean modulation transfer function (MTF) in the PBKC group was significantly lower (16.37 ± 16.32) than controls (30.3 ± 23.57) (P < 0.001). Corneal leukomas, stromal vascularization, peripheral nummular subepithelial scars, and pannus formation are associated with increased HOAs. There was a significant increase in total HOAs of eyes with PBKC compared to healthy controls. Corneal opacity, vascularization, and scarring are associated with increased HOAs. The PBKC eye aberration profile: coma, secondary astigmatism, quadrafoil, and pentafoil, were associated with decreased CDVA and visual quality (PSF and MTF).

Enhanced Monofocal Intraocular Lenses in Fuchs' Endothelial Dystrophy Patients: Results from Triple Descemet Membrane Endothelial Keratoplasty Procedure.

Descemet membrane endothelial keratoplasty (DMEK) is currently regarded as the most effective surgical procedure for addressing Fuchs Endothelial Corneal Dystrophy (FECD), frequently performed in conjunction with cataract surgery. In this retrospective study, we present a comparison of visual performance, clinical outcomes, and optical quality between two types of monofocal Intraocular Lenses (IOLs): one standard and one enhanced intermediate vision model, implanted in patients who underwent combined phacoemulsification and DMEK surgery. This single center comparative retrospective study was conducted at the Eye Clinic of the University of Florence (Italy) and included a total of 48 eyes of 48 patients affected by FECD and cataract. All patients underwent combined DMEK with phacoemulsification procedures. The patients' data were analyzed and divided into two groups: one group (standard group) consisted of 24 eyes that underwent phaco-DMEK with implantation of a monofocal IOL, and the second group (enhanced monofocal group) included 24 eyes that underwent phaco-DMEK with implantation of an enhanced monofocal IOL. In both groups, the following monocular visual outcomes were evaluated 6 months after surgery: Uncorrected Distance Visual Acuity (UDVA) and Best-Corrected Distance Visual Acuity (BCDVA) at 4 mts; Uncorrected Intermediate Visual Acuity (UIVA), Distance-Corrected Intermediate Visual Acuity (DCIVA) at 66 cm; Uncorrected Near Visual Acuity (UNVA) and Best Corrected Near Visual Acuity (BCNVA). Monocular defocus curves were also assessed. Furthermore, optical quality in terms of Contrast Sensitivity (CS) in photopic conditions, Higher-Order Aberrations (HOAs) at a pupil size of 5 mm. Modulation Transfer Function (MTF), Objective Scatter Index (OSI), and Strehl ratio, were also analyzed. A Patient-Reported Spectacle Independence Questionnaire was revised to evaluate spectacle independence outcomes. the two groups did not exhibit statistically significant differences in terms of UDVA, BCDVA, UNVA and BCNVA, photopic CS, HOAs, OSI, Strehl ratio, and MTF. However, in the phaco-DMEK enhanced monofocal IOL group, significantly better results were observed in terms of UIVA and DCIVA as well as a different defocus curve profile at 1.50 D, providing better defocus results at intermediate distance compared with the ZCB00 IOL. In our study, we found that enhanced monofocal lens performed favorable visual outcomes, even in cases of FECD, compared to standard monofocal IOLs. Comparable optical quality observed in the Eyhance group could allow surgeons to consider these lenses as a viable option for selected patients with FECD.

Meta-analysis of efficacy, safety, stability and predictability of Small Incision Lenticule Extraction (SMILE) for myopia.

In order to investigate the postoperative efficacy, safety, stability, and predictability of SMILE surgery as a treatment for myopia, a comprehensive search was conducted in April 2023 across prominent databases, including PubMed, EMBASE, Web of Science, and Cochrane Library. The search aimed to select relevant studies of randomized controlled trials (RCTs) comparing clinical outcomes between SMILE and other corneal refractive surgeries for myopia. Upon conducting the initial search, a total of 324 records were retrieved from the aforementioned databases. These records were subjected to a meticulous selection process, adhering to predetermined inclusion criteria, resulting in 17 studies being ultimately included for analysis. By pooling the results of these studies, the comparison between SMILE surgery and alternative corneal refractive surgeries demonstrated similar outcomes in terms of efficacy, safety, stability, predictability, and higher-order aberrations (HOAs) concerning the correction of myopia. Furthermore, it was observed that the SMILE procedure exhibited a lesser impact on corneal sensation and corneal nerve density compared to other corneal refractive surgeries. Based on these findings, SMILE surgery may be considered as a treatment option with a slight superiority over conventional corneal surgery for myopia.

Aberration change after scleral lens wear in eyes with pellucid marginal degenerations.

To investigate the impact of scleral lenses (SLs) on higher-order aberrations (HOAs), corrected distance visual acuity (CDVA), and contrast sensitivity (CS) in pellucid marginal degeneration (PMD) eyes. SLs were fitted in 24 eyes diagnosed with PMD. CDVA, CS, and HOAs were measured at baseline and with the lens on the eye. The HOAs were measured using an i-Trace aberrometer. A statistically significant improvement was noted in CDVA ( P < 0.001) with BSS lenses (0.05 ± 0.04) compared to baseline (0.42 ± 0.06). Front surface eccentricity 1 (FSE1) lens provided the best CDVA in most of the eyes. The baseline CS of 1.24 ± 0.74 improved to 1.58 ± 0.48 with SL and reported a statistically significant improvement ( P < 0.001) and a gain of 6 letters. The baseline higher order-root mean square (HO-RMS) was 0.89 ± 0.53 µm, which reduced to 0.38 ± 0.24 µm ( P < 0.001), and RMS coma of 0.45 ± 0.29 µm improved to 0.20 ± 0.12 µm ( P < 0.001). Though there was a marginal reduction from 0.04 ± 0.14 to 0.03 ± 0.07, RMS spherical aberration did not show any statistically significant difference ( P = 0.37). RMS secondary astigmatism reduced from 0.17 ± 0.15 µm to 0.08 ± 0.12 µm ( P = 0.007), and RMS trefoil reduced to 0.13 ± 0.09 µm from 0.64 ± 0.36 µm ( P < 0.001) with SLs and showed statistically significant improvement. SLs can be considered an effective option that corrects a significant amount of HOAs and enhances visual performances in PMD eyes.

Characterization the corneal transparency profile in SMILE-treated myopic patients with densitometry: A 7-year cohort study.

To investigate 7-year changes in corneal densitometry (CD) and its influencing factors following small incision lenticule extraction (SMILE) for moderate to high myopia. A total of 32 patients (52 eyes) with a mean spherical equivalent (SE) refraction of -6.30 ± 1.30 D who underwent SMILE were recruited for this prospective study. Pre- and postoperative CD and corneal aberrations were measured by an oculus Pentacam system, and patients were followed up to 7 years. The CD evolution over time and its influencing factors were explored. No complications were observed after SMILE. There was a significant time effect on postoperative CD ( P < 0.05). The CD values at the 0-to-2 and 2-to-6 mm of the anterior layer increased at the first day ( P < 0.05) and declined to baselines at 1 year postoperatively; after that, CD values at any zone and any corneal layer presented a decreasing trend over time (all P < 0.05). Multivariate analysis showed that postoperative CD was positively correlated with age and optical zone (OZ), whereas negatively correlated with SE, corrected distance visual acuity (CDVA), and corneal aberrations (higher-order aberrations, Coma0 and Coma90) (all P < 0.05). Generalized estimating equation revealed that age, SE, CDVA, OZ, and Coma0 were the main factors influencing postoperative CD values (all P < 0.05). CD manifested a long-term decreasing trend in moderate to high myopia treated with SMILE. Its main influencing factors are age, SE, CDVA, OZ, and Coma0.