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

AIM: To investigate the long-term changes of corneal densitometry (CD) and its contributing elements after small incision lenticule extraction (SMILE). METHODS: 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. RESULTS: 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. CONCLUSION: 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.

Accurate prediction of myopic progression and high myopia by machine learning.

Background: Myopia is a leading cause of visual impairment in Asia and worldwide. However, accurately predicting the progression of myopia and the high risk of myopia remains a challenge. This study aims to develop a predictive model for the development of myopia. Methods: We first retrospectively gathered 612 530 medical records from five independent cohorts, encompassing 227 543 patients ranging from infants to young adults. Subsequently, we developed a multivariate linear regression algorithm model to predict the progression of myopia and the risk of high myopia. Result: The model to predict the progression of myopia achieved an R2 value of 0.964 vs a mean absolute error (MAE) of 0.119D [95% confidence interval (CI): 0.119, 1.146] in the internal validation set. It demonstrated strong generalizability, maintaining consistent performance across external validation sets: R2 = 0.950 vs MAE = 0.119D (95% CI: 0.119, 1.136) in validation study 1, R2 = 0.950 vs MAE = 0.121D (95% CI: 0.121, 1.144) in validation study 2, and R2 = 0.806 vs MAE = -0.066D (95% CI: -0.066, 0.569) in the Shanghai Children Myopia Study. In the Beijing Children Eye Study, the model achieved an R2 of 0.749 vs a MAE of 0.178D (95% CI: 0.178, 1.557). The model to predict the risk of high myopia achieved an area under the curve (AUC) of 0.99 in the internal validation set and consistently high area under the curve values of 0.99, 0.99, 0.96 and 0.99 in the respective external validation sets. Conclusion: Our study demonstrates accurate prediction of myopia progression and risk of high myopia providing valuable insights for tailoring strategies to personalize and optimize the clinical management of myopia in children.

Recent advances in the biosynthesis of fungal glucan structural diversity.

Glucans are the most abundant class of macromolecule polymers in fungi, which are commonly found in Ascomycota and Basidiomycota. Fungal glucans are not only essential for cell integrity and function but also crucial for the immense industrial interest in high value applications. They present a variety of structural characteristics at the nanoscale due to the high regulation of genes and the involvement of stochastic processes in synthesis. However, although recent findings have demonstrated the genes of glucans synthesis are relatively conserved across diverse fungi, the formation and organization of diverse glucan structures is still unclear in fungi. Here, we summarize the structural features of fungal glucans and the recent developments in the mechanisms of glucans biosynthesis. Furthermore, we propose the engineering strategies of targeted glucan synthesis and point out the remaining challenges in the synthetic process. Understanding the synthesis process of diverse glucans is necessary for tailoring high value glucan towards specific applications. This engineering strategy contributes to enable the sustainable and efficient production of glucan diversity.

Electroacupuncture for mild-to-moderate dry eye: study protocol for a multicentre, randomised, single-blind, sham-controlled trial.

INTRODUCTION: Dry eye (DE) is a multifactorial ocular surface disease causing considerable medical, social and financial implications. Currently, there is no recognised long-term, effective treatment to alleviate DE. Clinical evidence shows that electroacupuncture (EA) can improve DE symptoms, tear secretion and tear film stability, but it remains controversial whether it is just a placebo effect. We aim to provide solid clinical evidence for the EA treatment of DE. METHODS AND ANALYSIS: This is a multicentre, randomised, sham-controlled trial. A total of 168 patients with DE will be enrolled and randomly assigned to EA or sham EA groups to receive 4-week consecutive treatments and follow-up for 24 weeks. The primary outcome is the change in the non-invasive tear break-up time (NIBUT) from baseline to week 4. The secondary outcomes include tear meniscus height, the Schirmer I test, corneal and conjunctival sensation, the ocular surface disease index, corneal fluorescein staining, the numerical rating scale and the Chinese DE-related quality of life scale. ETHICS AND DISSEMINATION: The trial protocol and informed consent were approved by the Ethics Committee of Yueyang Hospital of Integrated Traditional Chinese and Western Medicine Affiliated to Shanghai University of Traditional Chinese Medicine (identifier: 2021-119), Shanghai Eye Disease Prevention and Treatment Center (identifier: 2022SQ003) and Eye and ENT Hospital of Fudan University (identifier: 2022014). TRIAL REGISTRATION NUMBER: NCT05552820.

Refractive outcomes and optical quality of PRESBYOND laser-blended vision for presbyopia correction.

AIM: To investigate the one-year refractive outcomes and optical quality following PRESBYOND laser-blended vision (LBV). METHODS: This retrospective study included 20 patients who underwent PRESBYOND treatment between Jan 2019 and Aug 2020. The patients were asked to attend a follow-up outpatient visit one year after surgery. Distance and near visual acuity as well as subjective refraction were examined. Optical quality was assessed using wavefront-supported custom ablation. A questionnaire evaluating optical quality and satisfaction was completed at the last visit. RESULTS: The average patient age was 48.1±7.4y (range, 41 to 58y). The mean preoperative spherical equivalent was -7.59±2.39 D. At the one-year follow-up, two eyes (both dominant eyes) lost one line of corrected distance visual acuity (CDVA), while the remaining eyes (38/40) maintained or gained lines of CDVA. The average binocular uncorrected distance visual acuity improved from 0.15±0.03 to 0.90±0.26 (decimal vision; P<0.001). The average binocular uncorrected near visual acuity increased from 0.34±0.28 to 0.97±0.07 (P<0.001). The spherical aberration was 0.04±0.06 µm in the nondominant eye and 0.09±0.09 µm in the dominant eye (P=0.02). All patients were satisfied with or accepted the outcomes of the surgery. The primary complaints were related to disturbances in night vision and relatively inferior near vision. CONCLUSION: Over the one-year observation period, PRESBYOND is a safe and effective option for presbyopia correction. The optical quality and near vision deserve further investigation.

Corneal histomorphology and electron microscopic observation of R124L mutated corneal dystrophy in a relapsed pedigree.

AIM: To investigate the histological characteristics and ultrastructure of recurrent Chinese R124L mutated corneal dystrophy after keratoplasty. METHODS: The subjects were enrolled from a Chinese family of corneal dystrophy with R124L heterozygous gene mutation and with a history of consanguineous marriage. Normal corneal samples were used as controls. RESULTS: In this family, 2 patients (3 eyes) underwent penetrating keratoplasty (PKP) and 2 patients (4 eyes) underwent lamellar keratoplasty (LKP). They had recurrence at 33.5±3.0 (range 30-36)mo after keratoplasty. Among them, 1 patient (1 eye) underwent PKP again and 1 patient (2 eyes) underwent LKP again. In the R124L mutated recurrent corneal dystrophy, the corneal turbidity was mainly distributed from the upper corneal cortex to the anterior stroma; the corneal epithelium surface was rougher and more uneven; and, the corneal erosions were larger. Hematoxylin-eosin staining showed that the thickness of the corneal epithelium was uneven; the arrangement of the epithelial cells was disordered; and, some corneal epithelial cells were swollen. The results of Congo red staining, Masson's trichrome staining and Periodic acid-Schiff staining were positive, while that of Alcian blue staining was negative. Under a transmission electron microscope, deposition of high electron density substances between epithelial and basal cells, and, apoptosis of basal cells were observed. Many high electron density depositions were observed in the sub-epithelial and anterior corneal matrix. CONCLUSION: In the Chinese family of recurrent corneal dystrophy with R124L gene mutation, the corneal epithelia of the recurrent cases are rougher, and the corneal depositions are extracellular amyloid fibrin.

One-step viscoelastic agent technique for ICL V4c implantation for myopia.

AIM: To investigate the safety and efficacy of using a one-step viscoelastic agent technique for posterior chamber phakic implantable collamer lens with a central hole (ICL V4c) implantation for myopia correction. METHODS: The one-step viscoelastic agent technique for ICL V4c implantation was used in 100 eyes of 52 patients. Refractive outcomes, intraocular pressure (IOP), corneal endothelial cell, and corneal densitometry values were evaluated at 1d, 1wk, 1 and 3mo postoperatively. RESULTS: All the surgeries were uneventful. No corrected distance visual acuity was lost after 3mo. IOP was 16.12±3.18 mm Hg before surgery, and 14.74±3.08 mm Hg at 1d and 14.50±2.56 mm Hg at 3mo after surgery (P<0.05). Corneal endothelial cell density was 2580±242 cell/mm2, the coefficient of variation in cell size was 42.11%±7.92%, and the percentage of hexagonal cells was 40.98%±9.46% before surgery. No significant difference was found when these outcomes were compared between the studied time points (P>0.05). The corneal densitometry values of the central 2 mm and 2 to 6 mm areas showed similar regularities. After surgery, the values significantly increased at 1d, then decreased to the preoperative values at 1wk, and then continued to decrease at 3mo (P<0.05). CONCLUSION: The one-step viscoelastic agent technique for ICL V4c implantation is found to be safe and effective for myopia correction and causes little disturbance to the cornea.

A Randomized Controlled Trial of the Effect of 0.01% Atropine Eye Drops Combined with Auricular Acupoint Stimulation on Myopia Progression.

BACKGROUND: Use of 0.01% atropine eye drops (0.01% A) is one of the most common treatments for myopia control for children in Asia. Auricular acupoint stimulation (AAS) was reported to enhance the effect of higher-concentration atropine (0.25%, 0.125%) on myopia control. This study was designed to compare the effect of 0.01% A combined with AAS and 0.01% A alone on myopia progression and choroidal thickness in children. METHODS: A total of 104 children were stratified by age and randomly assigned at 1 : 1 to receive 0.01% A or 0.01% A + AAS treatment for 6 months. Repeated measurements of cycloplegic spherical equivalent (SE) autorefraction, axial length (AL), and choroidal thickness were performed at baseline, 1 month, 3 months, and 6 months. RESULTS: The adjusted mean SE change over the 6 months was -0.38 ± 0.04 D in the 0.01% A group (n = 50) and -0.25 ± 0.04 D in the 0.01% A + AAS group (n = 50), demonstrating a significant between-group difference (P = 0.02). There was no statistically significant difference in the change of AL and choroidal thickness between the two groups (both P > 0.05). CONCLUSIONS: Adjunctive AAS compared with 0.01% A monotherapy slowed myopic progression in Chinese children by a statistically small amount, but had no effect on axial elongation and choroidal thickness during this 6-month observation. The trial is registered with ChiCTR1900021316.

Auricular acupressure for myopia prevention and control in children and its effect on choroid and retina: a randomized controlled trial protocol.

BACKGROUND: Nowadays, because of the increasing incidence, the prevention and control of myopia has become an urgent issue. In China, auricular acupressure has been commonly used in the clinical treatment of myopia in children, but the exact effectiveness remains unproven. The purpose of this trial is to observe the efficacy of auricular acupressure in myopia prevention and control, as well as its effect on the choroidal and retinal thickness. METHOD/DESIGN: A total of 480 subjects at 8-9 years old will be randomized in a 1:1 ratio to an intervention group versus a control group. The intervention group will receive auricular acupressure for 12 months, while the control group will be taken as a blank control. The primary and secondary outcomes will be measured at baseline, and again at 3, 6, 9, and 12 months after recruitment. The myopia incidence (spherical equivalent ≤ - 0.50 D) and the mean change of spherical equivalent will be taken as the primary variables; the secondary outcome measures include axial length, uncorrected visual acuity, and choroidal and retinal thickness. DISCUSSION: This trial aims to evaluate the effectiveness of auricular acupressure for myopia prevention and control with objective evidence and to preliminarily explore the plausible mechanism and provide reference for adopting this approach to retard the onset and control the progression of myopia. TRIAL REGISTRATION: Chinese Clinical Trial Registry ChiCTR2000038456 . Registered on September 23, 2020.

Measuring the Ocular Morphological Parameters of Guinea Pig Eye with Edge Detection and Curve Fitting.

AIM: To identify the guinea pig eyeball with edge detection and curve fitting and devise a noncontact technology of measuring ocular morphological parameters of small experimental animal. METHODS: Thirty-nine eyeballs of guinea pig eyeballs were photographed to obtain the anterior and posterior surface; transverse and sagittal planes after the eyeballs were eviscerated. Next, the eyeball photos were input into digital image analysis software; the corresponding photo pixels-actual length ratio was acquired by a proportional scale. The contour lines of the eyeballs were identified by edge detection technology; conic curve fitting was applied to fit the contour line of the eyeball. The maximum and minimum diameters, the horizontal and vertical diameters, eccentricity, tilt angle, cross-sectional area, equatorial circumference, retrobulbar equatorial maximum length, corneal radius of curvature (CRC) in central region, and the whole cornea were calculated according to the geometric principles. The corneal data of in vitro study were compared with the in vivo results. RESULTS: The contour line of the selected guinea pig eye was identified correctly by edge detection. There were no significant differences between anterior and posterior surfaces of one eyeball in the maximum diameters, eccentricity, cross-sectional area, equatorial circumference, and tilt angle (P > 0.01). There were significant differences of eccentricity and CRC between central region and the whole cornea (P < 0.01). There were no significant differences between keratometer in vivo and cornea in vitro. CONCLUSION: It was feasible to measure an experimental animal eye in a noncontact way. Edge detection and curve fitting technology could accurately evaluate the ocular morphological parameters.

Objective optical quality and visual outcomes after the PresbyMAX monocular ablation profile.

AIM: To assess objective visual quality after presbyopia correction using the PresbyMAX monocular mode. METHODS: This prospective, nonrandomized study included 28 eyes from 18 patients (mean age 50.4±5.6y) who underwent presbyopia correction with the PresbyMAX monocular mode. Monocular and binocular visual acuities were evaluated preoperatively, 1d, 1wk, 1, 3mo, and 1y after surgery. Optical quality was analyzed by Hartmann-Shack wavefront aberration supported cornea ablation. Modulation transfer function (MTF) cutoff frequency, Strehl ratio, and objective scattering index (OSI) were analyzed using an optical quality analysis system. RESULTS: One year after surgery, 100% and 94.4% of patients achieved binocular uncorrected distance and near visual acuity of 20/25, respectively. At the last visit Spherical aberration and total higher aberration were higher than the corresponding preoperative levels (P<0.001); however, no significant difference was found in MTF, OSI, or Strehl ratio. Transient decreases in OSI and MTF mainly occurred in the nondominant eyes. There was no significant difference in optical quality between the dominant and nondominant eyes, except for spherical aberration and horizontal coma (P<0.05). CONCLUSION: The PresbyMAX monocular mode is safe and effective for presbyopia correction. It has little effect on optical quality, though short-term degraded optical quality occurred mainly in the bi-aspheric ablated eyes.

Safety and satisfaction of myopic small-incision lenticule extraction combined with monovision.

BACKGROUND: To investigate the safety and optical quality of small-incision lenticule extraction (SMILE) combined with monovision, and patient satisfaction with the procedure. METHODS: The present study assessed a non-random case series involving 60 eyes of 30 patients (mean age 45.53 ± 3.20 years [range 41 to 52 years]) treated bilaterally using the VisuMax 500 system (Carl Zeiss Meditec, Jena, Germany) between January and July 2016. The target refraction was plano for the distance eye, and between - 0.5 and - 1.75 diopters (D) for the near eye. Visual acuity, refraction errors, ocular aberrations, and satisfaction questionnaire scores were calculated 1 year after surgery. RESULTS: All surgeries were uneventful, with a mean safety index of 1.03 and 1.04 in dominant and nondominant eyes, respectively. Binocular uncorrected distance visual acuity of all patients was ≥20/32, while binocular uncorrected near visual acuity was ≥20/40 1 year postoperatively. Higher-order aberration (0.45 ± 0.14, 0.51 ± 0.15 µm), spherical (0.18 ± 0.15, 0.21 ± 0.14 µm) and coma aberration (0.31 ± 0.16, 0.27 ± 0.17 µm) were identical between dominant and nondominant eyes after surgery. The overall satisfaction rate was 86.7% (26/30), with large contributions from age (OR = 1.76 95% CI: 1.03-2.53; P = 0.036). Binocular uncorrected distance visual acuity was related to preoperative spherical diopter (r = - 0.500; P = 0.005). CONCLUSIONS: Monovision appears to be a safe and effective option for myopia patients with presbyopia who are considering the SMILE procedure. Patients with younger age were more satisfied with the procedure.

Scleral ultrastructure and biomechanical changes in rabbits after negative lens application.

AIM: To address the microstructure and biomechanical changes of the sclera of rabbits after negative lens application by spectacle frame apparatus. METHODS: Five New Zealand rabbits of seven weeks post-natal were treated with -8 D lens monocularly over the course of two weeks. Refractive errors and axial length (AXL) were measured at the 1st, 7th and 14th days of the induction period. Ultrastructure of sclera was determined with electron microscopy. Biomechanical properties were tested by an Instron 5565 universal testing machine. RESULTS: Lens-induced (LI) eyes elongated more rapidly compared with fellow eyes with AXL values of 15.56±0.14 and 15.21±0.14 mm (P<0.01). Fibril diameter was significantly smaller in the LI eyes compared with control ones in the inner, middle, and outer layers (inner layer, 63.533 vs 76.467 nm; middle layer, 92.647 vs 123.984 nm; outer layer, 86.999 vs 134.257 nm, P<0.01, respectively). In comparison with control eyes, macrophage-like cells that engulfed fibroblasts, dilated endoplasmic reticulum, and vacuoles in fibroblasts were observed in the inner and middle stroma in the LI eyes. Ultimate stress and Young's modulus were lower in the LI eyes compared with those in the control eyes. CONCLUSION: Negative lens application alters eye growth, and results in axial elongation with changes in scleral ultrastructural and mechanical properties.

Cap morphology after small-incision lenticule extraction and its effects on intraocular scattering.

AIM: To investigate cap morphology after small-incision lenticule extraction (SMILE) and its effects on intraocular scattering. METHODS: Sixty-five eyes of 33 patients undergoing SMILE were enrolled. In addition to regular evaluation, Fourier-domain optical coherence tomography was used to investigate cap thickness at 1d, 1wk, 1 and 3mo postoperatively. The optical quality including modulation transfer function cutoff frequency, Strehl ratio, Optical Quality Analysis System (OQAS) values, and objective scattering index (OSI), were evaluated using OQAS™. RESULTS: Cap thickness decreased from 1d to 1wk (P<0.001), but remained higher than intended thickness of 120 µm after 3mo (P<0.001). Cap thickness in central area was thinner than that of in the paracentral and peripheral areas (P<0.0001). Total number of microdistortions decreased from 1d to 3mo (P<0.0001). Pearson analysis revealed a weak correlation between OSI and standard deviation of cap thickness at 1d and 1mo, as well as between range of cap thickness and OSI at 1mo. No correlation was found between microdistortion and OSI, but a negative correlation existed between microdistortion and range at 1d and 1moafter surgery. CONCLUSION: The corneal cap tends to be more accurate and regular with time lapse. Better cap morphology tends to contribute less intraocular scattering in the eyes undergoing SMILE.

Refractive Regression and Changes in Central Corneal Thickness Three Years after Laser-Assisted Subepithelial Keratectomy for High Myopia in Eyes with Thin Corneas: A Retrospective Study.

This retrospective study aimed to explore refractive regression and central corneal thickness (CCT) following laser-assisted subepithelial keratectomy (LASEK) performed for the correction of high myopia in eyes with thin corneas. Forty patients (19 male, 21 female; mean age, 28.5 years) representing 76 treated eyes were included. The mean optical zone was 6.10 ± 0.32 mm, and the mean ablation depth was 121.53 ± 15.48 µm. CCT was significantly greater three years after surgery than at three months after surgery (425.66 ± 15.44 vs. 385.20 ± 12.81, respectively; p<0.001). The mean change in CCT from three months to three years was 40.46 ± 14.02 µm. The SE at three years was greater than that at three months (p<0.001). Although there was refractive regression, these data suggest that LASEK may have utility in the correction of high myopia in eyes with thin corneas.

Implantable collamer lens for residual refractive error after corneal refractive surgery.

AIM: To assess the safety, efficacy, predictability and stability of implantable collamer lens (ICL) for residual refractive error after corneal refractive surgery. METHODS: This study evaluated 19 eyes of 12 patients who underwent ICL implantation after corneal refractive surgeries. They were followed up for 1y to 5y of uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest refractive error, flat and steep K value, axial length, intraocular pressure, corneal endothelial cell density, adverse events after ICL surgery. RESULTS: The mean follow-up period was 39.05±19.22 mo (range, 1-5y). Spherical equivalent refractive error changed from -7.45±3.02 D preoperatively to -0.85±1.10 D 1wk to 1mo after ICL implantation, with the safety and efficacy indices being 1.12 and 1.15, respectively. A total of 52.63% of eyes were within ±0.5 D of the predicted spherical equivalents, 73.68% were within ±1.0 D. A trend of mild regression towards myopia with axial elongation after 5y was observed. One eye with mild anterior capsule opacity and retinal detachment 1y after surgery were observed. CONCLUSION: ICL implantation is safe and effective for the correction of residual refractive error after corneal refractive surgeries, especially in moderate to high residual myopia.

Evaluating the association between pathological myopia and SNPs in RASGRF1. ACTC1 and GJD2 genes at chromosome 15q14 and 15q25 in a Chinese population.

BACKGROUND: This study investigated the association of the 27 SNPs located in RASGRF1. GJD2, and ACTC1 genes with pathological myopia in a Chinese Han population. METHODS: Myopia patients were stratified according to whether they did (n = 274) or did not (n = 131) have myopic macular degeneration (MMD). The SNPbrowser software was used to identify specific SNPs for analysis and minimal allele frequency of >20%, and a pairwise r(2) < 0.85 were genotyped using MALDI-TOF mass spectrometry. RESULTS: Before controlling for false discovery rate, the frequency of the rs1867315 C/C genotype compared with healthy controls was lower in the myopia group (p = 0.006) and in myopia patients without macular degeneration (p = 0.019). The frequency of the rs670957A/A genotype was also lower in patients without MMD compared with controls (p = 0.045). For rs2070664, the frequency of the A allele was higher in the patients with MMD compared to those without MMD (p = 0.032). After controlling for a false discovery rate of 5%, there was no significant difference in genotype and allele frequencies between these groups. CONCLUSION: In this study, there was no association of the analyzed SNPs located in RASGRF1. GJD2, and ACTC1 with pathological myopia, suggesting that SNPs included in our study have no or a limited role in causing pathologic myopia in this Chinese Han population.

The effects of monochromatic illumination on early eye development in rhesus monkeys.

PURPOSE: Influence of longitudinal chromatic aberration (LCA) on emmetropization during early eye development has not been studied in primates. We investigated the effects of quasi-monochromatic lighting on refractive development and eye growth in rhesus monkeys. METHODS: Infant rhesus monkeys were raised under one of three lighting conditions for 51 weeks: quasi-monochromatic blue light (peak 455 nm), red light (peak 610 nm), and white light (color temperature 5000 K). All animals underwent biometric measurements using cycloplegic streak retinoscope, keratometry, and A-scan ultrasonography for refraction, corneal power, and axial components, respectively, at designated time points. RESULTS: At the 51st week, the mean difference in refraction of the white light and blue light groups, compared with that of the red light group, reached 1.71 diopters (D) and 1.43 D, respectively (both P < 0.001). Two monkeys in the red light group developed myopia at the 16th week, whereas the other seven remained hyperopic throughout the experiment. No significant difference in mean refraction was observed between the blue light group and white light group. CONCLUSIONS: Illumination from long-wavelength light during early life could be a risk factor for the development of myopia in a small proportion of rhesus monkeys that are sensitive to L-cone stimulation.