Changes In Higher-order Aberrations Research Articles

Importance of Higher-Order Aberrations on Both Anterior and Posterior Surfaces After Pterygium Surgery.

The purpose of this study was to investigate the changes in higher-order aberrations (HOAs), coma, and spherical aberrations (SAs) on the anterior, posterior, and total corneal surfaces after pterygium excision. In this single-center study, we examined 19 eyes of 15 patients who underwent pterygium excision at Yokohama Minami Kyosai Hospital between January 2017 and December 2017. We also evaluated 25 eyes of 25 age-matched patients with no history of ocular disease as the control group. Corneal topography, total HOAs, coma, and SAs in all regions at 4 and 6 mm diameters were evaluated using anterior segment optical coherence tomography (CASIA SS-1000, Tomey, Japan). The pterygium area and extent were also assessed. Significant improvements in the HOAs, coma, and SAs at both diameters were observed in the total and anterior corneas from the first postoperative month. Notably, the posterior cornea showed significant improvements in HOAs (4 mm: P < 0.001 [log HOAs]; 6 mm: P = 0.001 [log HOAs]) and coma (4 mm: P = 0.003 [log coma], 6 mm: P = 0.002 [log coma]) within both diameters at 1 month postoperatively. A strong correlation was identified among the pterygium area, posterior HOAs, and coma (Spearman correlation = 0.651). Pterygium induced 2 D of astigmatism when extension exceeded 2.1 mm. HOAs in both the anterior and posterior corneas improved after pterygium excision. This finding underscores the importance of considering corneal aberrations on both anterior and posterior surfaces in pterygium management.

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.

Comparative analysis of corneal parameters between DMEK and UT‐DSAEK eyes in 3‐year follow‐up

Aims/Purpose: The aim of the study was to provide a comparative analysis of corneal parameter changes compared to their preoperative values between Descemet membrane endothelial keratoplasty (DMEK) and ultrathin Descemet stripping automated endothelial keratoplasty (UT‐DSAEK) patients.Methods: The study included 27 eyes after UT‐DSAEK and 34 eyes after DMEK. Best corrected visual acuity (BCVA), endothelial cell count (ECC), central corneal thickness (CCT), mean keratometry (MK), mean astigmatism (MA), astigmatism asymmetry (AA) and higher order aberrations (HOAs) were assessed at baseline and 1, 3, 6, 12, 24 and 36 months after the surgery.Results: Patients after DMEK had significantly better BCVA than patients after UT‐DSAEK (mean 0.9 vs. 0.6 at 24th month, respectively, p = 0.002 and 0.9 vs. 0.7 at 36th month of follow‐up, respectively, p = 0.001). From the 3rd month post operation, ECC was higher in the DMEK eyes than in the UT‐DSAEK eyes (p = 0.01). However, the groups did not differ in this parameter at 24th and 36th month of observation. In a bivariate analysis that was adjusted for age, DMEK was associated with a smaller decrease in posterior MK at the 1‐month (β = −0.49, p = 0.002), 3‐month (β = −0.50, p &lt; 0.001), 6‐month (β = −0.58, p &lt; 0.001) and 12‐month (β = −0.49, p &lt; 0.001) follow‐up visits. Significant differences in MK, AA and HOA values of the posterior surface of the cornea at 12th, 24th and 36th month of observation and MA of the posterior surface of the cornea at 24th month of observation were found as well, with no differences in the total values of these parameters. Accordingly, no significant differences in changes in MA, AA or HOAs compared to the baseline values were identified between the eyes after DMEK and UT‐DSAEK at any follow‐up time point.Conclusions: UT‐DSAEK seem to be an easier and safer technique than DMEK while maintaining similar outcomes regarding irregular astigmatism and total keratometry values. Nevertheless, DMEK produces significantly better BCVA outcomes.

Long Term Evaluation of Surgically Induced Astigmatism and Corneal Higher-Order Aberrations After 2.2 Mm Clear Corneal Incisions in Femtosecond Laser-Assisted Cataract Surgery: Temporal versus Superior Approach.

To assess long term changes of the surgically induced astigmatism (SIA) and corneal higher-order aberrations (HOAs) after 2.2 mm clear corneal incisions (CCIs) in femtosecond laser-assisted cataract surgery and compare them between 2 types of CCIs: temporal and superior approach. Patients received the temporal CCIs (Group A) or the superior CCIs (Group B). Outcome measures included visual acuity, manifest refraction, corneal astigmatism, SIA, flattening effect, and corneal HOAs. Correlation between postoperative corneal HOA and SIA at each follow-up were analysed. This study assessed data from 106 eyes, of which 64 in Group A and 42 in Group B. The two groups had similar postoperative visual acuity of distance, intermediate and near (all P > 0.05). SIA and corneal HOAs were significantly lower in Group A than Group B in the early postoperative period, while there was no significant difference in the late postoperative period. At 6 months after surgery, the arithmetic mean of SIA over corneal 4mm zone was 0.33 ± 0.19D for temporal incision, and 0.37 ± 0.25D for superior incision. For Group A, the correlations of HOAs and SIA persisted from 1 week to 6 months after surgery. For Group B, the changes in corneal HOAs were significantly related to the SIA at 1 week and 1 month postoperatively. This study suggested the consistency of increasing and recovering process of corneal HOAs and SIA after surgery. Compared to the superior incisions, temporal incisions might induce quicker corneal recovery and less change in SIA and corneal HOAs.

Aberracje wyższego rzędu jako coraz istotniejszy parametr podczas kwalifikacji pacjenta do operacji usunięcia zaćmy

Higher order aberrations are complex optical errors that affect the quality of vision, especially in low light conditions. The article discusses the impact of higher order aberrations on the choice of intraocular lens during cataract removal surgery. These aberrations affect the patient’s vision quality after the surgery, and their analysis allows for a more precise selection of intraocular lens, increasing the chances of achieving better clinical outcomes. The article covers the main types of higher order aberrations and their impact on the choice of intraocular lens. The number of higher order aberrations changes with the patient’s age and can be the cause of suboptimal outcomes after the implantation of multifocal IOLs. Preoperative examination of the patient, taking into account higher order aberrations, is crucial for obtaining satisfactory postoperative results. Further research on higher order aberrations is essential for the development of technologically advanced intraocular lenses.

Change in Corneal Epithelial Thickness After Photo Refractive Keratectomy (PRK)

Purpose: The study of change of the epithelium of the cornea in two points after Photo Refractive Keratectomy (PRK): at the peak of the cornea (ETpeak) and in the middle of the cornea (ETcenter). The study of the change of Lower Order Aberrations (LOAs) and Higher Order Aberrations (HOAs), Contrast Sensitivity (CS) and Corrected Distance Visual Acuity (CDVA) and the relationship of these parameters with the change of ETpeak and ETcenter after PRK. Materials and Methods: Twenty-seven patients (5 women and 22 men) with an average age of 27 years (age range 23-36) underwent PRK. For two years all 27 patients had stable refraction. The refractive objective was emmetropia. Results: After PRK, a statistically significant difference was found between pre-surgery and post-surgery measurements of ETpeak and ETcenter with in relation to LOAs, HOAs, CS and CDVA. As well as between CS and HOA (Z33). Conclusion: In conclusion, after PRK, the change in ETcenter and ETpeak is associated with the change in CDVA and the changes in LOAs and HOAs. Also, the change in CDVA is related to SC, LOAs and HOAS. Finally, the change in the ETcenter appears to be related to the change in the CS.

One-year clinical efficacy evaluation of selective corneal wavefront aberration-guided FS-LASIK correction in patients with high myopia.

To evaluate the effectiveness, safety, predictability, precision and changes of higher-order aberrations (HOAs) on corneal front surface of selective corneal wavefront aberration-guided femtosecond laser-assisted in situ keratomileusis (CW-FS-LASIK) in patients with high myopia 1-year postoperatively. Totally 74 eyes of 37 patients with high myopia or myopic astigmatism in both the eyes who underwent the CW-FS-LASIK procedure in Xi'an Gaoxin Hospital from January 2021 to June 2021 were included. The changes of uncorrected distance visual acuity (UDVA), best corrected visual acuity (BCVA), spherical equivalent refraction (SER), astigmatism, HOAs and Strehl ratio (SR) on the anterior surface of the cornea after 1y of the surgery were analyzed. At postoperative 1y, the UDVA (logMAR) of 74 eyes (100%) reached 0 or better, including 0 in 8 eyes (10.81%), -0.1 in 45 eyes (60.81%), and -0.2 in 21 eyes (28.38%). The effectiveness index was 1.29±0.134. There was no decrease in postoperative BCVA compared with preoperative BCVA in all patients. Postoperative BCVA was the same in 44 eyes (59.46%) as preoperative BCVA, increased by 1 line in 23 eyes (31.08%) and increased by 2 lines in 7 eyes (9.46%) compared with preoperative BCVA. The safety index was 1.11±0.159. The estimated corrected SER before surgery was (-7.76±1.21) D, and the actual corrected SER was (-7.83±1.25) D (Y=0.9811X+0.2156, R2=0.9084). There was a high correlation between the estimated corrected SER and the actual corrected SER. The postoperative SER in 74 eyes (100%) was within ±0.75 D. The postoperative astigmatism of all was within -0.75 D to 0. Root mean square (RMS) HOAs of spherical aberration and SR within 5 mm of the corneal front surface were all increased compared with those before operation (P<0.01). The total coma, horizontal coma and vertical coma were all decreased compared with those before operation (P<0.01). There was no statistically significant difference in horizontal trefoil and vertical trefoil compared with preoperative ones (P>0.05). Selective CW-FS-LASIK for correction of high myopia is effective, safe, predictive, and accurate. For patients with preoperative RMS HOAs over 0.25 defocus equivalent, postoperative coma aberration can be significantly reduced, and SR value can be increased, thus corneal imaging quality can be improved.

Optical changes and association with axial elongation in children wearing orthokeratology lenses of different back optic zone diameter

PurposeTo compare changes in ocular aberrations in children wearing orthokeratology (ortho-k) lenses with a back optic zone diameter (BOZD) of 6 mm (6-MM group) or 5 mm (5-MM group) and their associations with axial elongation (AE) over two years.MethodsSeventy Chinese children, aged 6 to < 11 years, with myopia between − 4.00 to − 0.75 D, were randomly allocated to 5-MM and 6-MM groups. Ocular aberrations were measured, rescaled to a 4-mm pupil, and fitted with a 6th order Zernike expansion. Measurements, including axial length, were taken prior to commencing ortho-k treatment and then every six months over two years.ResultsAfter two years, the 5-MM group displayed a smaller horizontal treatment zone (TZ) diameter (by 1.14 ± 0.11 mm, P < 0.001) and less AE (by 0.22 ± 0.07 mm, P = 0.002) compared with the 6-MM group. A greater increase in total root mean square (RMS) of higher-order aberrations (HOAs), primary spherical aberration (SA) ({mathrm{C}}_{4}^{0}), and coma were also observed in the 5-MM group at all follow-up visits. The horizontal TZ diameter was significantly associated with changes in RMS HOAs, SA (RMS, primary and secondary SA), and RMS coma. After controlling for baseline parameters, RMS HOAs, RMS SA, RMS coma, and primary ({mathrm{C}}_{4}^{0}) and secondary ({mathrm{C}}_{6}^{0}) SA were significantly associated with AE.ConclusionsOrtho-k lenses with a smaller BOZD created a smaller horizontal TZ diameter and a significant increase in total HOAs, total SA, total coma, and primary SA and a decrease in secondary SA. Of these ocular aberrations, total HOAs, total SA, and primary SA were negatively correlated with AE over two years.Trial registration: ClinicalTrial.gov, NCT03191942. Registered 19 June 2017, https://clinicaltrials.gov/ct2/show/NCT03191942.

Color and composition under big data technology: the art of visual communication in film art

Abstract In modern film art design, there are different kinds of art requirements to be involved. These artistic requirements embody our profound national culture in modern film art, making the organic combination of art and culture, which in turn achieves the promotion of art and provides more excellent traits for the development of modern film visual communication. At the same time, modern film design draws on traditional art from five aspects: composition, perspective, image, color and allegory, and applies its advantages and strengths completely to the process of modern film art design. Among them, the most important is the modern color and composition design. To illustrate the art of visual communication in film art cannot be separated from color and composition. In this paper, we analyze the dynamic changes of higher-order aberrations of near-eye and ortho-eye groups over time, find the turning point of the dynamic changes of higher-order aberrations, and compare the differences between the dynamic changes of higher-order aberrations of the two groups by interaction analysis. By analyzing the application of modern color and composition design in film, it is concluded that the art effect of modern film is inseparable from the design elements, and the color and composition influence caused by the product of the combination of design elements for human senses.

Effect of pterygium on corneal astigmatism, irregularity and higher-order aberrations: a comparative study with normal fellow eyes

Pterygium is an abnormal growth of fibrous conjunctival tissue that invades the cornea, resulting in corneal distortion, astigmatism, and increased higher-order aberrations (HOAs). However, few studies have compared eyes with pterygium to normal fellow eyes when interpreting HOAs and there is no study that revealed the effect of the thickness or grading of the pterygium on the change of HOAs. Therefore, we evaluated the effects of nasal pterygium by comparing the normal fellow eye of 59 patients. The pterygium significantly increased with-the-rule corneal astigmatism and corneal irregularity. Trefoils, horizontal coma, and quatrefoils were significantly induced by the pterygium. The grading of the pterygium was not correlated with its characteristics except for the thickness. In multiple linear regression analysis, pterygium-induced corneal astigmatic/irregularity values and horizontal trefoil/quatrefoil were associated with the area of the pterygium. The length of the pterygium was an independent inducer of oblique trefoil/quatrefoil, while horizontal coma was independently associated with both its length and width. The thickness was not correlated with any optical parameters. Together, the results demonstrate that nasal pterygium significantly induces corneal astigmatism, irregularity and some HOAs. These pterygium-associated changes in optical parameters could be predicted by the length, width and area of the pterygium.

Higher order aberrations and retinal image quality during short-term accommodation in myopic and non-myopic children.

Despite the known associations between near work and myopia, and retinal image quality and eye growth, accommodation-induced changes in higher order aberrations (HOA's) and retinal image quality in children with different refractive errors are poorly understood. Ocular HOA's were measured using a Hartmann-Shack wavefront sensor (COAS-HD, Wavefront Sciences) in 18 myopic and 18 age- and sex-matched non-myopic children during short-term accommodation tasks (four demands of 0, 3, 6 and 9 D) presented using a Badal optometer. Eighth order Zernike polynomials were fitted across a 2.3 mm pupil diameter to determine refractive power vectors (M, J180 and J45 ) and the accommodation error, and a 4 mm pupil was used for HOA analyses. Retinal image quality was examined using the visual Strehl ratio based on the optical transfer function (VSOTF) for third to eighth radial orders only. Most refractive error group differences were observed for the 6 and 9 D demands. Myopic children underwent greater changes in with-the-rule astigmatism (J180 ), higher order and third order RMS values, primary vertical ( ) and horizontal coma ( ), and several other individual Zernike coefficients compared with non-myopic children (all refractive error group by demand interaction p-values of ≤0.02). Non-myopic children exhibited a greater negative shift in primary ( ) and positive shift in secondary spherical aberration ( ) (both refractive error group by demand interaction p-values of ≤0.002). The VSOTF degraded for the 6 and 9 D demands in both groups, but the myopic children underwent a greater mean (SE) reduction from 0 D of -0.274 (0.048) for the 9 D demand, compared with -0.131 (0.052) for the non-myopic children (p = 0.001). These results may have implications for the association between near work, accommodation and myopia development, particularly related to the use of short working distances during near tasks.

Evaluation of Higher Order Aberrations and Anterior Segment Parameters Changes After Implantable Collamer Lens Implantation for High Myopia.

To evaluate changes in higher order aberrations (HOAs) induced by implantable collamer lens (ICL) implantation in correction of high myopia and to compare the anterior segment parameters before and after surgery. Also, to correlate these parameters with HOAs, the best corrected visual acuity (BCVA) and intraocular pressure (IOP). This prospective interventional cohort case series study included 40 eyes with high myopia that underwent ICL V4c implantation. They were evaluated pre-operatively and post-operatively at 1st and 3rd month HOAs using Scheimpflug Sirius Camera. The anterior segment parameters were evaluated by optical biometry. Correlations between HOAs, BCVA and anterior segment parameters were evaluated. The mean pre-operative BCVA was 0.67 ± 0.17, while post-operative BCVA was 0.74 ± 0.16 (p-value < 0.001). The spherical equivalent was -13.66 ± 2.23 pre-operatively, while post-operatively it was -0.77 ± 0.65 (p-value < 0.001). The mean pre-operative root mean square (RMS) of HOAs was 0.62 ± 0.11 µm, while mean post-operative RMS in the 1st month was 0.82 ± 0.29 µm (p-value < 0.001). At 3rd month, it was 0.63 ± 0.17 µm (p-value = 0.685). The mean pre-operative anterior chamber depth (ACD) was 3.66 ± 0.26 mm. It decreased in the post-operative 1st month to 3.46 ± 0.30 mm, while in 3rd month 3.45 ± 0.24 mm (p-value < 0.001, < 0.001) respectively. The mean pre-operative anterior chamber angle (ACA) 45.98 ± 8.39 o while, the mean ACA was 31.65 ± 4.14, 31.03 ± 3.74 post-operatively (p-value < 0.001, < 0.001) respectively. There was significant increase in IOP (p-value < 0.001). ICL implantation is safe and effective in correction of high myopia, as HOAs increase at first month post-operatively then, return to the pre-operative level by 3rd month. However, anterior segment parameters show significant changes which may need longer follow up.

Changes in aberrations and biomechanics after femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK) in eyes with high astigmatism: a retrospective case control study

Background:To compare the 6-month changes in aberration and biomechanics after femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK) for high astigmatism.Methods:In this retrospective case control study, 47 eyes with high astigmatism (≥ 2.5 D, HA group) and 47 eyes with low astigmatism (≤ 1.0 D, LA group) underwent FS-LASIK. Preoperative and follow-up examinations included visual outcomes, higher order aberrations (HOAs) and biomechanics. Biomechanical parameters include a deformation amplitude ratio of 2 mm (DA ratio 2 mm), integrated inverse radius (IIR), stiffness parameter at first applanation (SP-A1), and ambrosio relational thickness through the horizontal meridian (ARTh).Results:Six months postoperatively, there was no significant difference in the efficacy and safety index (both P > 0.05) between the two groups, but the cylinder was higher in the HA group. The HOAs increased significantly after surgery in both groups (all P < 0.05). Six months postoperatively, the changes in spherical aberration and HOAs were larger in the HA group (both P < 0.005), but there was no significant difference between the changes in coma (P > 0.05). Significant decreases in SP-A1 and ARTh and significant increases in the IIR and DA ratio of 2 mm (all P < 0.05) were observed after surgery in both groups. The changes in the DA ratio 2 mm, IIR, SP-A1, and ARTh were not significantly different between the groups.Conclusion:FS-LASIK had relative comparable efficacy and safety in correcting high and low myopic astigmatism, with higher astigmatic under-correction in eyes with high astigmatism. High astigmatism in eyes after FS-LASIK could introduce larger corneal aberrations, but the impact on corneal stiffness was the same as that in eyes with low astigmatism.

Effect of keratometric astigmatism on visual outcomes following small incision lenticule extraction.

To investigate the influence of keratometric astigmatism on visual outcomes following small incision lenticule extraction (SMILE). Eighty eyes undergoing SMILE for myopia correction were classified into two groups based on preoperative keratometric astigmatism: low keratometric astigmatism (LA) and high keratometric astigmatism (HA) groups. Refractive outcomes, vector components, and changes in higher order aberrations (HOAs) were evaluated preoperatively and 6 months postoperatively. At the postoperative 6-month visit, no significant difference was observed in the decentered distance between the HA and LA groups (HA: 0.17 ± 0.08 mm, LA: 0.16 ± 0.08 mm, P = 0.189). No significant differences in the correction index (P = 0.481), absolute angle of error (P = 0.104), or index of success (P = 0.147) were observed between the two groups. There was no significant difference in the induction of corneal aberrations between the two groups. Furthermore, there were no significant associations between the decentered distance and the vector components of astigmatic correction or induction of higher-order aberration in the HA group (P ≥ 0.294, P ≥ 0.112) or the LA group (P ≥ 0.323, P ≥ 0.080). SMILE for high keratometric astigmatism could achieve comparable treatment centration and visual quality to that of low keratometric astigmatism.

Serially Checked Spherical Aberration Can Evaluate the Anti-Myopia Effect of Orthokeratology Lens in Children.

We aimed to investigate the changes in higher-order aberrations (HOAs) after wearing orthokeratology (OK) lenses in myopic patients. The study included 15 eyes from ten myopic patients, whose refractive error was myopia less than −4.5 diopters (D) and astigmatism less than 1.5 D. Uncorrected visual acuity (UCVA) and best-corrected visual acuity (BCVA) were measured, and Zywave® aberrometry was performed at baseline and 1, 3, and 6 months following OK lens wear. The mean age was 11.5 years (range: 9–15 years). There was a significant improvement in UCVA (p ≤ 0.001) and a decrease in the spherical equivalent measured with auto-refraction at 6 months (p ≤ 0.001). Total HOAs significantly increased after OK lens wear (p ≤ 0.001), with spherical aberration increasing approximately 3.9-fold (p = 0.05). Spherical aberration demonstrated statistically significant positive correlations with the change in spherical equivalent at 3 and 6 months (p = 0.007 and 0.003, respectively). After wearing properly prescribed OK lens, all subjects had significantly improved UCVA and decreased myopic spherical equivalent, with increased total HOAs and positive spherical aberration at 1 month, and the changes were maintained at 6 months. Serially checked spherical aberration could evaluate the anti-myopia effect of the orthokeratology lens in children.

Evaluation of morphological features: femtosecond-LASIK flap vs. SMILE cap, and the effects on corneal higher-order aberrations.

The aim of this study is to evaluate morphological features of corneal flap/cap and the correlations with corneal higher-order aberrations (HOAs) changes after femtosecond laser in situ keratomileusis (FS-LASIK) and small incision lenticule extraction (SMILE). This was a retrospective study. Pre- and postoperative (1 and 3months) corneal HOAs were assessed with Pentacam HR. The corneal flap/cap thickness at 32 points (± 1.5mm, ± 2mm, ± 2.5mm, and ± 3mm from the corneal vertex on meridian 0°/45°/90°/135°) were measured using anterior segment optical coherence tomography at 3months postoperatively. Morphological features of corneal flap/cap including predictability (P), uniformity (U), and symmetry (S) were calculated and used for correlation analysis with corneal HOAs changes. Eighty-six eyes (44 patients) and ninety-six eyes (50 patients) were involved in FS-LASIK and SMILE groups, respectively. Significant thicker corneal flap/cap than the predicted was observed at each measuring point and meridian in both groups (difference > 2.225μm, the within-subject standard deviation over 6-mm optical zone). There was no statistically significant difference in predictability of corneal flap/cap thickness, while U6mm (P < .0001), U0 (P < .001), U45 (P = .002), U90 (P < .0001), U135 (P = .004), S6mm (P < .0001), S0 (P < .001), and S90 (P < .0001) over 6mm zone were less in SMILE than in FS-LASIK. The changes of corneal tHOAs, Z (3, - 1), Z (3, 1), and SA were significantly correlated with morphological features of corneal flap/cap. Both FS-LASIK and SMILE had good predictability in flap or cap thickness, while the uniformity and symmetry of SMILE cap were better than FS-LASIK flap. The quality of flap/cap was closely associated with the changes of corneal HOAs.

Comparison of safety and efficacy of silicone hydrogel contact Lens-assisted CXL and accelerated CXL in keratoconus patients with thin corneas.

To evaluate the efficacy and safety of silicone hydrogel contact lens-assisted corneal cross-linking (CL-CXL) and compare 12-month visual and topographic outcomes with accelerated CXL using hypo-osmolar riboflavin (A-CXL) in keratoconus patients with thin corneas (below 400 μm with epithelium). This retrospective study included 27 eyes of 27 keratoconus patients who underwent CL-CXL (n = 14) or A-CXL (n = 13). Uncorrected and corrected distance visual acuity (UDVA and CDVA) and data obtained from corneal topography were analyzed at baseline and again at 6- and 12-month follow-ups. Corneal demarcation line depth (DLD) was measured at one month, and changes in the corneal endothelial cell density (ECD) at 12 months were also assessed. Mean UDVA improved significantly in both groups at 12 months (all p < 0.05). Maximum keratometry (K-max) decreased by 1.04 ± 1.90 D in the CL-CXL group and by 0.87 ± 1.89 D in the A-CXL group at 12 months, which was not statistically significant (all p>0.05). Total corneal higher-order aberrations (HOAs) analysis showed a significant improvement in only the CL-CXL group at 12 months (p = 0.041). Average DLD was 227.18 ± 65.60 μm in the CL-CXL group and 245.30 ± 66.84 μm in the A-CXL group (p = 0.275). No significant change in ECD was found in either group (all p>0.05). Mean changes in UDVA, CDVA, K-max, K-mean, HOAs, and ECD were not statistically significant between the groups (all p>0.05). Silicone hydrogel CL-assisted CXL seems as effective as A-CXL in halting keratoconus progression in thin corneas with no side effects during the one-year follow-up period.

Corneal morphological changes after small incision lenticule extraction for myopic anisometropia.

PurposeThis research aims to study the corneal morphological changes in adult patients with myopic anisometropia after small incision lenticule extraction (SMILE) and the safety, efficacy, and predictability of clinical outcomes.MethodsThis was a prospective cohort study. Patients with myopic anisometropia [refractive difference >2.0 diopters (D)] were included in this study who underwent SMILE at our hospital from September 2019 to March 2021. For the two eyes of each patient, the one with higher myopia was defined as group A, and the fellow eye was group B. The follow-up time points were set as 1 week, 1 month, 3 months, and 6 months after the surgery. The data collected were uncorrected and best-corrected distance visual acuity (UDVA and CDVA), spherical equivalent (SE), efficacy and safety indexes, posterior corneal elevation (PCE), anterior and posterior corneal radius of curvature in the 3 mm area at the center of the thinnest point of the cornea (ARC and PRC), and higher-order aberrations (HOAs).ResultsThe study included 36 patients (72 eyes), and the mean age was 25.2 ± 6.4 years. The preoperative SEs were −6.45 ± 1.25 D in group A and −3.76 ± 1.29 D in group B. Six months after surgery, the SEs in groups A and B were −0.09 ± 0.50 D and 0.07 ± 0.47 (P = 0.059), respectively. The efficacy indexes were 1.06 ± 0.16 in group A and 1.07 ± 0.14 in group B (P = 0.750). The safety indexes were 1.08 ± 0.14 in group A and 1.12 ± 0.15 in group B (P = 0.173). The PCE was significantly reduced at 6 months after surgery in pagebreak both groups (P < 0.05). The ARC was significantly higher than before the surgery (P < 0.05) in the two groups. The two groups showed significant increases in total HOAs, coma 90°, and spherical aberrations (P < 0.05).ConclusionSMILE is predictable, effective, and safe in correcting myopic anisometropia. The postoperative changes in HOAs are characteristic.

Changes in asphericity of anterior and posterior corneal surfaces for mild-moderate and high myopia after topography-guided FS-LASIK.

To compare changes in asphericity of anterior and posterior corneal surfaces for different myopia patients after corneal topography-guided femtosecond-assisted laser in situ keratomileuses (FS-LASIK), and to analyze correlations between asphericity of corneal surfaces and preoperative spherical equivalence (SEQ). In this prospective study, 59 patients who underwent corneal topography-guided FS-LASIK surgery were enrolled and divided into the mild-moderate myopia group (67 eyes) and the high myopia group (44 eyes). Postoperative follow-ups were performed at 1, 3, and 6months. Postoperative changes in aspherical coefficient (Q values), corneal higher-order aberrations (HOAs), and spherical aberrations (Z40) were compared between the two groups. Relevance between Q value changes and SEQ, HOAs, and Z40 as well as between SEQ and changes of HOAs and Z40 was analyzed. There was a significant increase in Q values of the anterior (each diameter) and posterior (6-8mm) corneal surface in both groups than before surgery (P < 0.001). Q values of corneal anterior (each diameter) and posterior (7-9mm) surface in the high group were considerably larger than the mild-moderate group (P < 0.05). Corneal anterior surface HOAs and Z40 values in the high group largely exceeded those of the mild-moderate group (P < 0.001). The preoperative SEQ was linearly correlated with postoperative anterior Q change (ΔQ), HOAs change (ΔHOAs), and spherical aberration change (ΔZ40). The changes of corneal asphericity in patients with high myopia were greater than mild-moderate myopia, with more corneal HOAs and Z40 introduced when corneal topography-guided FS-LASIK was conducted.

Corneal higher-order aberration changes after accelerated cross-linking for keratoconus

AimTo evaluate changes in corneal higher-order aberrations (HOAs) following epithelium-off accelerated corneal cross-linking (A-CXL) and to explore the impact on visual acuity.MethodsIn this retrospective case series, 32 eyes of 24 patients with keratoconus (KC) underwent A-CXL. Treatment was delivered at 10 mW/cm2 for 9 min with a total dose of 5.4 J/cm2. The following anterior corneal HOAs: total corneal HOAs, trefoil, secondary trefoil, coma, secondary coma, secondary astigmatism and spherical aberrations were analysed using the Scheimpflug-Placido Sirius (CSO, Italy) corneal topographer at baseline and 12 months following treatment. Multivariate analysis was used to evaluate the independent effect of HOA subtypes on changes in uncorrected distance visual acuity (UDVA) and corrected distance visual acuity (CDVA).ResultsAt one year post CXL, UDVA and CDVA were significantly improved, -0.13 ± 0.19 LogMAR (P = 0.0005) and -0.08 ± .0.11 LogMAR (P = 0.0003), respectively. The mean preoperative trefoil, secondary trefoil, secondary coma and secondary astigmatism were 0.95 ± 0.46; µm, 0.20 ± 0.11; µm, 0.29 ± 0.19; µm and 0.42 ± 0.17 µm, respectively. At one year, the mean values decreased significantly to 0.77 ± 0.47 µm, 0.15 ± 0.11 µm, 0.25 ± 0.18 µm and 0.34 ± 0.18 µm, respectively (P < 0.05, for all). No independent relationship between any HOA changes and change in UDVA was observed. A reduction in secondary coma aberration was associated with a change in CDVA (95% CI 0.01–1.34, P = 0.048; β = 0.67).ConclusionA 9-min protocol of Accelerated corneal cross-linking is an effective treatment in improving corneal HOAs at 12 months follow up, in eyes with progressive keratoconus at one year follow-up. A change in secondary coma had a statistically significant and independent effect on CDVA.