Refractive Change Research Articles

Smartwatch Measures of Outdoor Exposure and Myopia in Children

Time spent outdoors has been proven effective in preventing myopia, but little is known about the association of outdoor exposure patterns with myopia. To examine the association of outdoor exposure patterns with myopic shift in children. This 1-year prospective cohort study from December 2017 to December 2018 was a secondary analysis of a cluster-randomized trial (Shanghai Time Outside to Reduce Myopia [STORM]). STORM was a school-based intervention study, recruiting 16 schools from 8 districts in Shanghai, from October 2016 to December 2018. Children without myopia at baseline who consistently wore a smartwatch for a minimum of 6 hours daily, sustained for at least 90 days, and who had complete information were included. Data analysis was performed from December 2017 to December 2018. The outdoor exposure pattern was defined as the episode of time outdoors and instant sunlight intensity over a continuous period. Myopic shift was defined as the absolute change in refraction between the initial spherical equivalence and the follow-up spherical equivalence. This study included 2976 students (mean [SD] age, 7.2 [0.6] years; 1525 girls [51.2%]). The mean (SD) daily time outdoors was 90 (28) minutes, and the mean (SD) sunlight intensity was 2345 (486) lux. Of the 12 outdoor exposure patterns, the major outdoor exposure patterns were time outdoors with at least 15 minutes, accounting for 74.9% of minutes (33 677 584 of 45 016 800 minutes). Only patterns with at least 15 minutes accompanied with no less than 2000 lux were associated with less myopic shift in refraction (for ≥15 minutes and 2000 to 3999 lux, -0.007 diopter [D] [95% CI, -0.011 to -0.002 D]; for ≥15 minutes and ≥4000 lux, -0.006 D [95% CI, -0.010 to -0.002 D]). The isotemporal substitution of patterns with at least 15 minutes and 2000 lux for other outdoor exposure patterns was positively associated with less myopic shift. In this 1-year prospective cohort study of children with smartwatches, continuous outdoor exposure with at least 15 minutes accompanied with no less than 2000 lux sunlight intensity was associated with less myopic shift. These findings suggest that future outdoor interventions should focus not only on the overall time outdoors but also on the effective outdoor exposure patterns, as a means to effectively prevent myopia in children.

The influence of back optic zone diameter on relative corneal refractive power changes following orthokeratology fitting

The influence of back optic zone diameter on relative corneal refractive power changes following orthokeratology fitting

The efficacy and safety of combination therapy of repeated low-level red light and defocus-incorporated multiple segments spectacle lenses for myopia control in children: the study protocol for a 12-month, randomized, parallel-controlled, and single-center clinical trial

BackgroundMyopia is increasing in prevalence worldwide. Combination therapy showed a better effect on myopia control than monotherapy. Repeated low-level red light therapy (RLRL) therapy and defocus-incorporated multiple segment (DIMS) spectacle lenses have been reported to retard myopia progression significantly. However, whether these two therapies are better than one is still unknown. The present study aims to report the study protocol of a trial designed to evaluate the efficacy and safety of combination therapy of RLRL and DIMS versus DIMS alone for reducing the progression of myopia among Chinese school-aged children.MethodsThis study is a 12-month, randomized, parallel-controlled, single-center clinical trial. We will recruit children aged 8–12 years with spherical equivalence (SE) between − 0.50 D and − 6.00 D under cycloplegia in both eyes. We will recruit 66 participants with an allocation ratio of 1:1 from our hospital. Participants in the intervention group will be treated with an RLRL therapy device twice a day from Monday to Friday at home, 3 min per session, with a minimum interval of 4 h, under the supervision of their parents/guardians. They will wear DIMS spectacles for myopia correction during the day. Participants in the control group will not receive the RLRL therapy and will only wear DIMS spectacles to correct myopia. Participants from both groups will attend the hospital every 6 months.The primary outcome is the change in axial length at 12 months. Secondary outcomes include changes in refraction under cycloplegia, optical coherence tomography (OCT), multifocal electroretinogram (mfERG), color vision, and participants’ self-reporting of adverse events at 12 months.DiscussionThis study will report the efficacy and safety outcome of the combination therapy of RLRL and DIMS versus DIMS for school-aged children with myopia in detail.Trial registrationChiCTR2300075398. Registered 4 September 2023. https://www.chictr.org.cn/bin/project/edit?pid=200751.

Refractive outcomes after V4c Toric collamer lens implantation over 1y of follow-up.

To evaluate refractive outcomes and corneal astigmatism changes after Toric implantable collamer lens with a central port (V4c T-ICL) implantation over 1y of follow-up. A retrospective study was performed including 50 eyes of 50 patients that underwent V4c T-ICL implantation. Uncorrected (UDVA) and corrected (CDVA) distance visual acuities, refraction, refractive and corneal astigmatism changes and corneal coupling correction were evaluated preoperatively, 1 and 12mo postoperatively. Vector analysis was used for astigmatism changes. Coefficient of adjustment (CAdj) was calculated for corneal coupling analysis. The mean UDVA achieved was 0.03 logMAR at 1mo and remained unchanged throughout the whole follow-up (P=0.193). At the last visit, 84% of the eyes achieved a CDVA of 0.00 logMAR or better. Regarding spherical equivalent refraction (SEQ), 96% of eyes were ranges of ±1.00 D and 84% of them within ±0.50 D. Also, 94% of eyes had a remaining refractive cylinder within ±1.00 D and 78% of them within ±0.50 D. Both, SEQ and refractive cylinder, remain stable over the postoperative follow-up (P=1.000 and P=0.660, respectively). In terms of surgically induced astigmatism (SIA), no statistically significant differences were found over the follow-up (P=0.102) and under correction was found with a correction index lower than the unit at each visit. A keratometric astigmatism induced of 0.59±0.53 (vector mean: 0.26×73°) D was reached at the last visit. No significant changes in terms of corneal astigmatism orientation were reported over post-surgery visits (P=0.129 and P=0.097 at 1 and 12mo respectively). No clinical significance was found for CAdj on with-the-rule astigmatism. No postoperative complications resulting from the surgery were found. Refractive outcomes suggest that the V4c T-ICL implantation for correction of myopic astigmatism was satisfactory in terms of effectiveness, safety, and stability during 1y of follow-up. Corneal astigmatism induced by the incision around 0.5 D is achieved according to the remaining refractive cylinder found at one-year post-surgery. Corneal coupling analysis results in no unexpected spherical change.

Surgical approaches to correct corneal astigmatism at time of cataract surgery: a mini-review.

Among refractive errors, astigmatism is the most common optical aberration, where refraction changes in different meridians of the eye. It causes blurred vision at any distance and includes corneal, lenticular, and retinal astigmatism. Cataract surgery used to cause a progressive increase in the pre-exisiting corneal astigmatism because of creating a surgically induced astigmatism, for example, a large size surgery incision. The development of surgical techniques during last decades has made cataract surgery interchange to treat preoperative corneal astigmatism at time of surgery. Nowadays, three surgical approaches can be used. By placing a sutureless clear corneal incision on the steep meridian of the cornea, a preoperative corneal astigmatism less than 1.0 D can be corrected. Single or paired peripheral corneal relaxing incisions (PCRIs) provide 1.0-3.0 D corneal astigmatism correction. PCRIs are typically used for treating 1.0-1.5 D of regular corneal astigmatism, if more than 2.0 D, the risk of overcorrection and irregular astigmatism is increased. When toric intraocular lenses (IOLs) are unavailable in markets, PCRIs are still a reasonable option for patients with up to 3.0 D of pre-existing corneal astigmatism. Toric IOLs implantation can correct 1.0-4.5 D of corneal astigmatism. Several IOLs are approved to correct a high degree of corneal astigmatism with cylinder power up to 12.0 D. These approaches can be used alone or in combination.

Microkeratome versus manually dissected donor tissue for Descemet stripping endothelial keratoplasty: A randomized prospective study.

To compare the visual outcomes, postoperative complications, and graft asymmetry between precut and manually dissected donor tissues for Descemet stripping automated endothelial keratoplasty (DSAEK) and Descemet stripping endothelial keratoplasty (DSEK) procedures, respectively. Seventy eyes of 70 patients undergoing DSEK/DSAEK at a tertiary eyecare center in eastern India were included in this prospective randomized control study. The 70 eyes were divided equally into two groups. Group A (n = 35) and Group B (n = 35) underwent DSEK and DSAEK procedures, respectively. the operating surgeons prepared the manually dissected corneal grafts using lamellar dissectors. the eye bank technicians prepared the precut corneal grafts using a microkeratome. The patients were investigated postoperatively after 1 day, 1 week, 1 month, 3 months, and 6 months. The data were compared for visual outcomes [uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), spherical and cylindrical refraction, and spherical equivalent], incidence of postoperative complications, and pachymetry. The mean age was 56.5 (±17.8) years, and the male-to-female ratio was 1.3:1. The most common indications were pseudophakic bullous keratopathy (45.71%, 32/70), failed graft (32.86%, 23/70), and Fuchs' endothelial corneal dystrophy (10%, 7/70). The indications for surgery (P = 0.732) and donor (P = 0.258) and host pachymetry (P = 0.986) were comparable between both groups. There was no significant difference in change of UCVA, BCVA, and postoperative refraction (mean spherical refraction, P = 0.849; mean cylindrical refraction, P = 0.516; spherical equivalent, P = 0.518) between the two groups. Postoperative complications like graft detachment (P = 0.179), graft failure (P = 0.513), graft infiltrate (P = 0.428), and endophthalmitis (P = 0.493) were higher in the DSAEK group; however, the difference between the groups was insignificant. The graft asymmetry index was higher in DSAEK than in DSEK; the difference was significant till the 1-month follow-up (P = 0.005). The outcome was similar in both groups. Therefore, manual donor dissection can be an alternative for microkeratome-assisted dissection in low-resource centers and countries to achieve good results.

Refraction dynamics in schoolchildren with congenital partial atrophy of the optic nerve over a ten-year observation period

Introduction. Optic nerve atrophy is a degenerative condition and a prevalent cause of visual impairment, including in children. Data on refractogenesis in schoolchildren with partial atrophy of the optic nerve (PAON) are scarce, with existing literature focusing primarily on the correction of low vision associated with this disorder. Purpose: to assess the refraction dynamics in schoolchildren with congenital PAON over a ten-year observation period.Materials and methods. We conducted a retrospective analysis of refraction changes over a decade among three groups: 1) 47 schoolchildren with PAON, 2) 49 schoolchildren with ametropia without PAON, and 3) 49 schoolchildren without any ophthalmopathology.Results. All groups exhibited a trend towards myopization (р < 0.001). In groups with myopic and emmetropic refractions (without ophthalmopathology at the start), either the emergence or an increase in myopic refraction was noted. In hypermetropic children, a gradual decrease towards emmetropic refraction or a shift to myopic refraction was observed. For myopic schoolchildren using contact lenses and perifocal glasses from the ages of 11–13, myopia progression stabilized, particularly with perifocal optical correction (р < 0.01). Despite refractive changes during the school years, regular courses of functional treatment and accommodation training led to a slight improvement in visual acuity in PAON patients (by an average of 0.05 ± 0.01 (p = 0.001) in myopes and 0.06 ± 0.01 (р < 0.001) in hypermetropes) and a significant increase in visual acuity in children with normal fundus ametropia (by an average of 0.14 ± 0.02 (р < 0.001) in myopes and 0.18 ± 0.02 (р < 0.001) in hypermetropes).Conclusion. The ten-year observation demonstrates a myopization trend in all groups of schoolchildren, which holds particular relevance for those with PAON due to their inherently lower visual acuity. An optimal optical correction strategy, employing modern myopia control measures in tandem with regular functional treatment and accommodation training, is essential for a health-preserving educational approach in schoolchildren with PAON.

Effectiveness of customized ortho-k lenses in controlling myopia in children

Background. The increasing prevalence of myopia in children highlights the need for effective treatments. Orthokeratology is a key approach to slow myopia progression, yet standard ortho-k lenses often fall short due to diverse corneal structures. Personalized ortho-lens designs are crucial for optimizing myopia control and maximizing the benefits of corneal refractive therapy.Aim: to evaluate the impact of custom ortho-k lens use on myopia control in children, specifically assessing changes in refraction and axial length during orthokeratology treatment.Materials and methods. In our study, 41 school-aged children underwent custom orthokeratology treatment with 81 ortho-k lenses. Utilizing a Medmont E300 for corneal topography and the OrthoTool for lens calculations, alongside Lenstar LS 900 for optical biometry, we assessed myopia progression and axial elongation. The subjects’ average age was 12.6 ± 2.4 years, with an average lens wear duration of 17.0 months (range 10.0 to 23.5 months). Initial mean myopia was –5.5 ± 2.0 D in both eyes.Results. During the study period, 87.8% of the participants (36 children) showed stabilization in refraction and axial length, indicating effective myopia control. However, 12.2% (5 children) experienced myopia progression at a rate of –0.5 diopters per year. Notably, all children undergoing orthokeratology treatment achieved high visual acuity (0.9–1.0). Complications were limited to 12.2% of the participants, who developed mild epitheliopathy (2 degrees) and/or Fleischner rings; no inflammatory complications were observed.Conclusions. Customized orthokeratology offers significant advantages over standard ortho-k lenses, tailoring treatment to individual corneal structures for more effective myopia control. The results advocate for further, long-term studies into customized orthokeratology and its role in managing myopia.

Refractive and topographic corneal changes associated with increased inflammatory mediators in tears after COVID-19

This is a rare case report of a sudden shift to myopic astigmatism and topography alterations in a patient who experienced mild coronavirus disease 2019 (COVID-19) symptoms. A complete ophthalmologic evaluation, slit-lamp examination, corneal topography, and tear sampling for biochemical analysis were performed. Elevated corneal K-values were found, indicating abnormal anterior corneal curvature, based on the asymmetric corneal steepening index (cone location and magnitude index) in a Galilei G6 study. Tear analysis demonstrated elevated levels of interleukin (IL)-1β, IL-6, IP-10, IL-8, interferon-β, and prometalloproteinase-9. Ophthalmologists should maintain a high level of suspicion when symptoms suggestive of corneal involvement arise in patients recently infected with severe acute respiratory syndrome coronavirus 2.

Combination effect of optical defocus and low dose atropine in myopia control: Study protocol for a randomized clinical trial.

Myopia, characterized by excessive axial elongation of the eyeball, increases risks of having sight-threatening diseases and impose a financial burden to healthcare system. Although myopic control interventions showed their effectiveness in slowing progression, the efficacy varies between individuals and does not completely halt progression. The study aims to investigate the efficacy of combining 0.01% atropine administered twice daily with optical defocus for myopia control in schoolchildren. This is a prospective, parallel-group, single-blinded, randomized, active-control trial (ClinicalTrials.gov identifier: NCT06358755). Myopic schoolchildren with no previous myopic control interventions aged between 7 to 12 years will be recruited. They will be randomly allocated into two groups (n = 56 per group) after baseline measurement. Both groups will receive 0.01% atropine twice per day for 18 months (one drop in the morning and the other drop at night before bedtime). Defocus incorporated multiple segments (DIMS) spectacle lenses will be prescribed in atropine plus optical defocus (ATD) treatment group while single vision spectacle lenses will be given in atropine only (AT) group. Cycloplegic refraction and axial lengths will be monitored every 6 months over 18-month study period. The primary outcomes are changes in cycloplegic refraction and axial lengths relative to the baseline over the study period. The result will examine the combination effect of low dose atropine and myopic defocus on myopia control in a randomized controlled study. The findings will also explore the potential benefits of applying 0.01% atropine twice per day on myopic control and its potential side effects.

Diagnosis of Dry Eye Syndrome During the Preparing Patients for Cataracts Phacoemulsification. Literature Review

The increasing patient demands for quality of life after surgery necessitate optimization of approaches in the field of surgical intervention, reduction of the frequency of refractive errors and correction of tactics of postoperative interventions. Literature data indicate that refractive errors are possible after surgical treatment for cataracts associated with the presence of dry eye syndrome in the preoperative period. Tear film is used as the first refractive medium, and the size of the refractive change at air­tear film interfaces is the most innovative of any interface in any other optical system. Thus, changes of tear film physiology affect overall vision with higher order aberrations and irregular astigmatism occurring. The presented literature review analyzes data from scientific studies aimed at studying risk factors for the development of dry eye syndrome and diseases associated with it when phacoemulsification of cataracts occurs. Considering the fact that, according to various studies, the incidence of dry eye syndrome after cataract surgery ranges from 9.8 to 96.6% in cataract surgery in collaboration with dry eye surgery, adequate approaches within the framework of preoperative preparation are an urgent development. The lack of clear recommendations for effective preoperative screening and respiratory preparation for surgery, unreliable biometric data, and lack of treatment strategy for postoperative dry eye syndrome are indicators of detectors to obtain the desired results. Adequate diagnosis and preparation of ocular surfaces before biometric measurements can reduce refractive errors after surgery.

Analysis of Refractive Error Changes in Elementary School Children under 13 Years of Age before and after COVID-19 Pandemic: A Hospital-Based Study

Purpose: To analyze changes in refractive error among elementary school children under the age of 13 who visited an outpatient clinic for eye examinations before and after the onset of the COVID-19 pandemic.Methods: A retrospective analysis of medical records was conducted to calculate the spherical equivalent refractive error of the right eye for 3,854 children aged 6 to 12 who attended our ophthalmology department from 2016 to 2023. We analyzed the average refractive error and myopia prevalence by year and subsequently performed a subgroup analysis by dividing the children into two age groups: 6-9 years old and 10-12 years old. To provide insight into long-term trends, data from 4,351 subjects aged 6-12 years from the 4th, 5th (2008-2012), and 7th (2016) Korea National Health and Nutrition Examination Surveys were also analyzed for reference.Results: The mean refractive error for subjects visiting our clinic throughout the study period was -1.51 ± 2.12 D. A trend of increasing myopic values in refractive error was observed from 2017 to 2021, with a more substantial change noted in 2020 compared to other years, though not reaching statistical significance. In the subgroup analysis, the change in refractive error for the 6-9-year-old group was more pronounced in 2020 but did not reach statistical significance, and no specific trend was identified in the 10-12-year-old group. Myopia prevalence exhibited a consistent increase since 2019 in the 6-9 age group, with a higher proportion of moderate myopia in 2020 compared to previous years. Conversely, no distinct trend was observed in the 10-12-year-old group.Conclusions: Although statistical significance was not reached, it appears that the increase in indoor activities due to COVID-19 had an impact on the changes in refractive values for elementary school children, especially in the lower grades of elementary school in 2020.

Determination of the time of refractive stability after uneventful phacoemulsification in Indian eyes.

Knowledge about refractive stabilization and the accuracy of postoperative refractive error measurements are crucial for improved patient outcomes after phacoemulsification. Existing guidelines typically recommend waiting 4-6 wk before prescribing corrective lenses. Our research focused on identifying factors that influence refractive errors in the early stages of post-cataract surgery, thus contributing to the existing literature on this topic. To investigate the time required for refraction stability after uneventful phacoemulsification surgery. We compared the variation and statistical significance of the difference in spherical, cylindrical components, and the spherical equivalent between the 1- and 6-wk follow-up period in a group of 257 eyes that underwent uneventful phacoemulsification with foldable intraocular lens implantation, all performed by a single experienced surgeon. The Wilcoxon-Signed Rank Test was utilized to assess the magnitude of the change and determine its statistical significance. The refractive stability was defined as the point at which the change in spherical equivalent was within ± 0.5 dioptres for two consecutive visits. The average age of the patients was 64.9 ± 8.9 yr. The differences observed in both the visits in spherical power (0.1 ± 0.2), cylinder power (0.3 ± 0.4), and spherical equivalent (0.2 ± 0.2) were minimal and not statistically significant. The majority of eyes (93.4%) achieved refractive stability within 6 wk after the surgery. The cylindrical power differed between age groups at the 6th wk post-operative and the difference was statistically significant (P value 0.013). There were no significant differences in refractive stability when considering sex and axial length. Phacoemulsification with foldable intraocular lens implantation results in no significant changes in refraction for the majority of cases during the 6-wk follow-up period. Therefore, a spectacle prescription can be given at the completion of 1 wk.

The optimal atropine concentration for myopia control in Chinese children: a systematic review and network Meta-analysis.

To figure out whether various atropine dosages may slow the progression of myopia in Chinese kids and teenagers and to determine the optimal atropine concentration for effectively slowing the progression of myopia. A systematic search was conducted across the Cochrane Library, PubMed, Web of Science, EMBASE, CNKI, CBM, VIP, and Wanfang database, encompassing literature on slowing progression of myopia with varying atropine concentrations from database inception to January 17, 2024. Data extraction and quality assessment were performed, and a network Meta-analysis was executed using Stata version 14.0 Software. Results were visually represented through graphs. Fourteen papers comprising 2475 cases were included; five different concentrations of atropine solution were used. The network Meta-analysis, along with the surface under the cumulative ranking curve (SUCRA), showed that 1% atropine (100%)>0.05% atropine (74.9%) >0.025% atropine (51.6%)>0.02% atropine (47.9%)>0.01% atropine (25.6%)>control in refraction change and 1% atropine (98.7%)>0.05% atropine (70.4%)>0.02% atropine (61.4%)>0.025% atropine (42%)>0.01% atropine (27.4%)>control in axial length (AL) change. In Chinese children and teenagers, the five various concentrations of atropine can reduce the progression of myopia. Although the network Meta-analysis showed that 1% atropine is the best one for controlling refraction and AL change, there is a high incidence of adverse effects with the use of 1% atropine. Therefore, we suggest that 0.05% atropine is optimal for Chinese children to slow myopia progression.

Micro-optical elements from optical-quality ZIF-62 hybrid glasses by hot imprinting

Hybrid glasses derived from meltable metal-organic frameworks (MOFs) promise to combine the intriguing properties of MOFs with the universal processing ability of glasses. However, the shaping of hybrid glasses in their liquid state – in analogy to conventional glass processing – has been elusive thus far. Here, we present optical-quality glasses derived from the zeolitic imidazole framework ZIF-62 in the form of cm-scale objects. These allow for in-depth studies of optical transparency and refraction across the ultraviolet to near-infrared spectral range. Fundamental viscosity data are reported using a ball penetration technique, and subsequently employed to demonstrate the fabrication of micro-optical devices by thermal imprinting. Using 3D-printed fused silica templates, we show that concave as well as convex lens structures can be obtained at high precision by remelting the glass without trading-off on material quality. This enables multifunctional micro-optical devices combining the gas uptake and permeation ability of MOFs with the optical functionality of glass. As an example, we demonstrate the reversible change of optical refraction upon the incorporation of volatile guest molecules.

Ex Vivo Histological Analysis of Corneas with Manually Implanted Intracorneal Stromal Ring Segments.

Backgrond: Intracorneal ring segments (ICRSs) are utilized to correct refractive changes impacting visual acuity, commonly implanted via femtosecond laser but can also inserted manually. Corneal deposits alongside the ICRS channels are seen commonly. Methods: This study explores the histological characteristics of corneal deposits following manual ICRS implantation, comparing them to previously published articles describing femtosecond laser-assisted cases. Results: This is a retrospective analysis of three cases involving manual ICRS implantation, accumulation of whitish deposits and later explanation of the corneas due to penetrating keratoplasty (PKP). Patient demographics, ocular history, and surgical details were collected. Histological analysis employed Hematoxylin and Eosin (H&E) and Masson's trichrome staining. Whitish deposits along ICRS tracts were observed in all cases, with minimal fibroblastic transformation of keratocytes adjacent to the segments. Comparing these cases of manual to femtosecond laser-assisted ICRS implantation, in most cases, similar deposits were identified, indicating the deposits' association with the stromal tissue reaction to the ring segment and not to the surgical technique. Conclusions: This study contributes insights into the histopathology of manually implanted ICRS, emphasizing the shared nature of deposits in both insertion methods. The findings highlight the link between deposits and the stromal tissue reaction to the ring segment, irrespective of the insertion technique.

The archerfish uses motor adaptation in shooting to correct for changing physical conditions

The archerfish is unique in its ability to hunt by shooting a jet of water from its mouth that hits insects situated above the water’s surface. To aim accurately, the fish needs to overcome physical factors including changes in light refraction at the air-water interface. Nevertheless, archerfish can still hit the target with a high success rate under changing conditions. One possible explanation for this extraordinary ability is that it is learned by trial and error through a motor adaptation process. We tested this possibility by characterizing the ability of the archerfish to adapt to perturbations in the environment to make appropriate adjustments to its shots. We introduced a perturbing airflow above the water tank of the archerfish trained to shoot at a target. For each trial shot, we measured the error, i.e., the distance between the center of the target and the center of the water jet produced by the fish. Immediately after the airflow perturbation, there was an increase in shot error. Then, over the course of several trials, the error was reduced and eventually plateaued. After the removal of the perturbation, there was an aftereffect, where the error was in the opposite direction but washed out after several trials. These results indicate that archerfish can adapt to the airflow perturbation. Testing the fish with two opposite airflow directions indicated that adaptation took place within an egocentric frame of reference. These results thus suggest that the archerfish is capable of motor adaptation, as indicated by data showing that the fish produced motor commands that anticipated the perturbation.

The archerfish uses motor adaptation in shooting to correct for changing physical conditions.

The archerfish is unique in its ability to hunt by shooting a jet of water from its mouth that hits insects situated above the water's surface. To aim accurately, the fish needs to overcome physical factors including changes in light refraction at the air-water interface. Nevertheless, archerfish can still hit the target with a high success rate under changing conditions. One possible explanation for this extraordinary ability is that it is learned by trial and error through a motor adaptation process. We tested this possibility by characterizing the ability of the archerfish to adapt to perturbations in the environment to make appropriate adjustments to its shots. We introduced a perturbing airflow above the water tank of the archerfish trained to shoot at a target. For each trial shot, we measured the error, i.e., the distance between the center of the target and the center of the water jet produced by the fish. Immediately after the airflow perturbation, there was an increase in shot error. Then, over the course of several trials, the error was reduced and eventually plateaued. After the removal of the perturbation, there was an aftereffect, where the error was in the opposite direction but washed out after several trials. These results indicate that archerfish can adapt to the airflow perturbation. Testing the fish with two opposite airflow directions indicated that adaptation took place within an egocentric frame of reference. These results thus suggest that the archerfish is capable of motor adaptation, as indicated by data showing that the fish produced motor commands that anticipated the perturbation.

Relation between change of effective lens position and toric IOL rotation after toric IOL implantation

PurposeTo evaluate the relationship between change of effective lens position (ELP) and toric intraocular lens (IOL) rotation in patients with increasing postoperative refractive astigmatism after successful toric IOL implantation. MethodsThe subjects include 61 people (61 eyes) with increasing residual astigmatism >0.5 D 3 months after successful toric IOL implantation. Clinical measurements included preoperative, 1-week, and 1-, 2-, and 3-month postoperative visual acuity; refraction; keratometer; anterior and posterior corneal astigmatism; ELP by Scheimpflug camera imaging; and IOL axis by slit-lamp biomicroscopic photograph with pupil dilation. ResultsResidual astigmatism in postoperative month 3 (0.81 ± 0.50 D) is higher than that at postoperative week 1 (0.41 ± 0.38 D; p < 0.05). ELP decreased by 264.44 ± 163.25 μm, and the IOL rotated by 2.91 ± 1.44 degrees from week 1 to month 3 (p < 0.05). The ELP change had a positive correlation with IOL rotation (R2 = 0.383; p = 0.006), and the postoperative refractive astigmatic change had a positive correlation with ELP change (R2 = 0.272; p = 0.027) and IOL rotation (R2 = 0.272; p = 0.0001) from week 1 to month 3. ConclusionELP change can influence toric IOL rotation and increase residual astigmatism after toric IOL implantation.

Femtosecond laser inscribed fiber Bragg grating and Mach-Zehnder interferometer cascade sensing structure for temperature and relative humidity simultaneous measurement

A femtosecond (fs) laser inscribed cascade structure of a fiber Bragg grating (FBG) and a gap-coupled cladding waveguide Mach-Zehnder interferometer (CWMZI) is proposed and demonstrated, which can be used to simultaneously measure temperature and relative humidity. The structure can also be used as a breathing sensor. Transmission dip wavelength of the FBG is used for the temperature monitoring based on its temperature response. Meanwhile, gap-coupled CWMZI is used for relative humidity monitoring because the gap part of the CWMZI is very close to the cladding surface, it is very sensitive to refractive changes caused by ambient humidity variations. Experiments show a temperature sensitivity of 0.01104 nm/°C in a temperature range of 20 °C to 125 °C, and a high relative humidity sensitivity response of −0.0793 nm/%RH in a relative humidity range of 50 % to 80 %. Breathing signal monitoring is also successfully demonstrated using the FBG-CWMZI cascading structure.