RlmQ: a newly discovered rRNA modification enzyme bridging RNA modification and virulence traits in Staphylococcus aureus.

rRNA modifications play crucial roles in fine-tuning the delicate balance between translation speed and accuracy, yet the underlying mechanisms remain elusive. Comparative analyses of the rRNA modifications in taxonomically distant bacteria could help define their general, as well as species-specific, roles. In this study, we identified a new methyltransferase, RlmQ, in Staphylococcus aureus responsible for the Gram-positive specific m7G2601, which is not modified in Escherichia coli (G2574). We also demonstrate the absence of methylation on C1989, equivalent to E. coli C1962, which is methylated at position 5 by the Gram-negative specific RlmI methyltransferase, a paralog of RlmQ. Both modifications (S. aureus m7G2601 and E. coli m5C1962) are situated within the same tRNA accommodation corridor, hinting at a potential shared function in translation. Inactivation of S. aureus rlmQ causes the loss of methylation at G2601 and significantly impacts growth, cytotoxicity, and biofilm formation. These findings unravel the intricate connections between rRNA modifications, translation, and virulence in pathogenic Gram-positive bacteria.

Phonological properties of logographic words modulate brain activation in bilinguals: a comparative study of Chinese characters and Japanese Kanji.

The brain networks for the first (L1) and second (L2) languages are dynamically formed in the bilingual brain. This study delves into the neural mechanisms associated with logographic-logographic bilingualism, where both languages employ visually complex and conceptually rich logographic scripts. Using functional Magnetic Resonance Imaging, we examined the brain activity of Chinese-Japanese bilinguals and Japanese-Chinese bilinguals as they engaged in rhyming tasks with Chinese characters and Japanese Kanji. Results showed that Japanese-Chinese bilinguals processed both languages using common brain areas, demonstrating an assimilation pattern, whereas Chinese-Japanese bilinguals recruited additional neural regions in the left lateral prefrontal cortex for processing Japanese Kanji, reflecting their accommodation to the higher phonological complexity of L2. In addition, Japanese speakers relied more on the phonological processing route, while Chinese speakers favored visual form analysis for both languages, indicating differing neural strategy preferences between the 2 bilingual groups. Moreover, multivariate pattern analysis demonstrated that, despite the considerable neural overlap, each bilingual group formed distinguishable neural representations for each language. These findings highlight the brain's capacity for neural adaptability and specificity when processing complex logographic languages, enriching our understanding of the neural underpinnings supporting bilingual language processing.

Behavioural plasticity compensates for adaptive loss of cricket song.

Behavioural flexibility might help animals cope with costs of genetic variants under selection, promoting genetic adaptation. However, it has proven challenging to experimentally link behavioural flexibility to the predicted compensation of population-level fitness. We tested this prediction using the field cricket Teleogryllus oceanicus. In Hawaiian populations, a mutation silences males and protects against eavesdropping parasitoids. To examine how the loss of this critical acoustic communication signal impacts offspring production and mate location, we developed a high-resolution, individual-based tracking system for low-light, naturalistic conditions. Offspring production did not differ significantly in replicate silent versus singing populations, and fitness compensation in silent conditions was associated with significantly increased locomotion in both sexes. Our results provide evidence that flexible behaviour can promote genetic adaptation via compensation in reproductive output and suggest that rapid evolution of animal communication systems may be less constrained than previously appreciated.

Surface mapping of gastric motor functions using MRI: a comparative study between humans and rats.

The stomach's ability to store, mix, propel, and empty its content requires highly coordinated motor functions. However, current diagnostic tools cannot simultaneously assess these motor processes. This study aimed to use magnetic resonance imaging (MRI) to map multifaceted gastric motor functions, including accommodation, tonic and peristaltic contractions, and emptying, through a single noninvasive experiment for both humans and rats. Ten humans and 10 Sprague-Dawley rats consumed MRI-visible semisolid meals and underwent MRI scans. We used a surface model to analyze MRI data, capturing the deformation of the stomach wall on ingestion or during digestion. We inferred muscle activity, mapped motor processes, parcellated the stomach into functional regions, and revealed cross-species distinctions. In humans, both the fundus and antrum distended postmeal, followed by sustained tonic contractions to regulate intragastric pressure. Peristaltic contractions initiated from the distal fundus, including three concurrent wavefronts oscillating at 3.3 cycles/min and traveling at 1.7 to 2.9 mm/s. These motor functions facilitated linear gastric emptying with a 61-min half-time. In contrast, rats exhibited peristalsis from the midcorpus, showing two wavefronts oscillating at 5.0 cycles/min and traveling at 0.4 to 0.9 mm/s. For both species, motility features allowed functional parcellation of the stomach along a midcorpus division. This study maps region- and species-specific gastric motor functions. We demonstrate the value of MRI with surface modeling in understanding gastric physiology and its potential to become a new standard for clinical and preclinical investigations of gastric disorders at both individual and group levels.NEW & NOTEWORTHY A novel MRI technique can visualize how the stomach accommodates, mixes, and propels food for digestion in humans and animals alike. Digital models of gastric MRI reveal the functional maps, organization, and distinction of the stomach across individuals and species. This technique holds the unique potential to advance basic and clinical studies of functional gastric disorders.

A meta-analysis of letter-sound integration: Assimilation and accommodation in the superior temporal gyrus.

Despite being a relatively new cultural phenomenon, the ability to perform letter-sound integration is readily acquired even though it has not had time to evolve in the brain. Leading theories of how the brain accommodates literacy acquisition include the neural recycling hypothesis and the assimilation-accommodation hypothesis. The neural recycling hypothesis proposes that a new cultural skill is developed by "invading" preexisting neural structures to support a similar cognitive function, while the assimilation-accommodation hypothesis holds that a new cognitive skill relies on direct invocation of preexisting systems (assimilation) and adds brain areas based on task requirements (accommodation). Both theories agree that letter-sound integration may be achieved by reusing pre-existing functionally similar neural bases, but differ in their proposals of how this occurs. We examined the evidence for each hypothesis by systematically comparing the similarities and differences between letter-sound integration and two other types of preexisting and functionally similar audiovisual (AV) processes, namely object-sound and speech-sound integration, by performing an activation likelihood estimation (ALE) meta-analysis. All three types of AV integration recruited the left posterior superior temporal gyrus (STG), while speech-sound integration additionally activated the bilateral middle STG and letter-sound integration directly invoked the AV areas involved in speech-sound integration. These findings suggest that letter-sound integration may reuse the STG for speech-sound and object-sound integration through an assimilation-accommodation mechanism.

A pathogenesis-related protein, PRP1, negatively regulates root nodule symbiosis in Lotus japonicus.

The legume-rhizobium symbiosis represents a unique model within the realm of plant-microbe interactions. Unlike typical cases of pathogenic invasion, the infection of rhizobia and their residence within symbiotic cells do not elicit a noticeable immune response in plants. Nevertheless, there is still much to uncover regarding the mechanisms through which plant immunity influences rhizobial symbiosis. In this study, we identify an important player in this intricate interplay: Lotus japonicus PRP1, which serves as a positive regulator of plant immunity but also exhibits the capacity to decrease rhizobial colonization and nitrogen fixation within nodules. The PRP1 gene encodes an uncharacterized protein and is named Pathogenesis-Related Protein1, owing to its orthologue in Arabidopsis thaliana, a pathogenesis-related family protein (At1g78780). The PRP1 gene displays high expression levels in nodules compared to other tissues. We observed an increase in rhizobium infection in the L. japonicus prp1 mutants, whereas PRP1-overexpressing plants exhibited a reduction in rhizobium infection compared to control plants. Intriguingly, L. japonicus prp1 mutants produced nodules with a pinker colour compared to wild-type controls, accompanied by elevated levels of leghaemoglobin and an increased proportion of infected cells within the prp1 nodules. The transcription factor Nodule Inception (NIN) can directly bind to the PRP1 promoter, activating PRP1 gene expression. Furthermore, we found that PRP1 is a positive mediator of innate immunity in plants. In summary, our study provides clear evidence of the intricate relationship between plant immunity and symbiosis. PRP1, acting as a positive regulator of plant immunity, simultaneously exerts suppressive effects on rhizobial infection and colonization within nodules.

Associations Between Supported Accommodation and Health and Re-offending Outcomes: a Retrospective Data Linkage Study.

Following release from prison, housing and health issues form a complex and mutually reinforcing dynamic, increasing reincarceration risk. Supported accommodation aims to mitigate these post-release challenges. We describe the impact of attending Rainbow Lodge (RL), a post-release supported accommodation service for men in Sydney, Australia, on criminal justice and emergency health outcomes. Our retrospective cohort study using linked administrative data includes 415 individuals referred to RL between January 2015 and October 2020. Outcomes of interest were rates of criminal charges, emergency department (ED) presentations and ambulance attendance; and time to first reincarceration, criminal charge, ED presentation and ambulance attendance. The exposure of interest was attending RL; covariates included demographic characteristics, release year and prior criminal justice and emergency health contact. Those who attended RL (n = 170, 41%) more commonly identified as Aboriginal or Torres Strait Islander (52% vs 41%; p = 0.025). There was strong evidence that attending RL reduced the incidence criminal charges (adjusted rate ratio [ARR] = 0.56; 95% confidence interval [CI] 0.340.86; p = 0.009). Absolute rates indicate a weak protective effect of RL attendance on ED presentation and ambulance attendance; however, adjusted analyses indicated no evidence of an association between attending RL and rates of ED presentations (ARR = 0.88; 95% CI = 0.65-1.21), or ambulance attendance (ARR = 0.82; 95% CI = 0.57-1.18). There was no evidence of an association between attending RL and time to first reincarceration, charge, ED presentation or ambulance attendance. Greater detail about reasons for emergency health service contact and other self-report outcome measures may better inform how supported accommodation is meeting its intended aims.

Randomized, crossover trial: comparing the effects of standardized egg-white meal and Vital® on global gastric emptying parameters and intragastric meal distribution in healthy Asian participants.

BACKGROUND AND AIM: Measurements of gastric emptying and accommodation for alternative test-meal protocol during gastric emptying scintigraphy (GES), such as high-calorie nutrient drinks, are not fully established. We aimed to compare the effects of standardized egg-white meal (EWM) versus high-calorie nutrient drink (Vital®; Abbott Laboratories) on global GES parameters and intragastric meal distribution at immediate scan (IMD0h). METHODS: Of 84 screened participants, 60 asymptomatic healthy Asian population (38 females; 24.0 ± 1.5 years; 23.8 ± 2.6 kg/m2) were recruited in this 2 × 2 (AB/BA) crossover trial. Participants were randomized to a 4-h GES with 99mTc-radiolabeled EWM (~255.8 kcal), followed by a 200 mL Vital® (300 kcal), or vice versa, separated by a 2-week washout period. Global meal retention (GMR), power-exponential model emptying parameters (half-emptying [T1/2], lag phases [Tlag2%, Tlag5%, Tlag10%]), and IMD0h were determined and compared. RESULTS: GMRs for both test meals were within the international standard references for solid GES. Compared to EWM, Vital® exhibited significantly lower GMRs (faster emptying) from 0.5 to 3 h (all P < 0.001) but comparable at 4 h (P = 0.153). Similar observations were found for the model-based T1/2 and the different Tlag thresholds (all P < 0.001). Furthermore, IMD0h was found to be lower with Vital®, indicating lower gastric accommodation (faster antral filling) immediately post-ingestion (P < 0.001). Both test meals showed significant moderate-to-strong positive associations at the late-phase GE (GMR 2-4 h, T1/2) (all P < 0.05). CONCLUSIONS: Overall, Vital® is an acceptable alternative test meal to the EWM for GES; however, exercise caution when interpreting early-phase GE. The normative values for global GES parameters and IMD0h are also established.

Exploring the relationship between accommodation and intraocular pressure: a systematic literature review and meta-analysis.

PURPOSE: To investigate the relationship between accommodation and intraocular pressure (IOP). METHODS: Systematic literature search and meta-analysis following PRISMA guidelines was conducted on studies analyzing the relationship between accommodation and intraocular pressure. After removal of duplicates, title and abstract screening, full-text analysis was performed to select relevant articles and meta-analysis was then conducted as well. RESULTS: Of the 1357 records identified, 17 met the selection criteria and were included. Overall, all studies showed that accommodation can influence IOP levels and meta-analysis indicated a significant IOP reduction of 1.10 mmHg (95%CI, -1.77; -0.42) following accommodative stimulus in healthy individuals, albeit with high heterogeneity among studies. Differences in IOP changes between emmetropic and progressing myopic individuals were not significant. Controversial results were obtained in patients with glaucoma with significantly lower IOP fluctuations being noted in eyes with previous trabeculectomy; however, the clinical heterogeneity of enrolled patients among studies made it not possible to combine results. Type of accommodative task, extraocular muscle contraction, head and body position all could potentially play a role in the measured IOP changes with, interestingly, near reading on a smartphone suggesting IOP increase. CONCLUSION: Accommodation has an impact on IOP measurements and, overall, determines IOP decrease in healthy individuals. While such variations might not hold clinical significance for individuals in good health, their impact in patients with glaucoma should be considered. Further studies focused on specific components of such relationship are required to elucidate their individual impact and to define their potential role as non-pharmacological strategies to reduce IOP levels in selected patient categories.

Impact of Refractive Status on Presbyopia Progression among Patients with Presbyopia.

PURPOSE: To explore the impact of refractive status on presbyopia progression among patients with presbyopia. METHODS: This retrospective observational study included patients with presbyopia who visited the Seventh Affiliated Hospital of Sun Yat-sen University and Shenzhen Polytechnic Medical College between May 2018 and August 2022. The amplitude of accommodation (AMP) and near addition power (ADD) at 6 months and 1 year were collected. RESULTS: A total of 103 patients with presbyopia were included in this study: 42 patients with myopia, 23 patients with emmetropia, and 38 patients with hyperopia. There were significant differences in ΔAMP(6-month) and ΔADD(6-month) among patients with different refractive statuses, and the values of emmetropic patients and hyperopic patients were higher than in myopic patients (all P < 0.001). The ΔAMP(1-year) and ΔADD(1-year) of hyperopic patients were significantly higher than in emmetropic patients and myopic patients (all P < 0.001). The ΔADD(1-year) of emmetropic patients was greater than in myopic patients (P = 0.045), but there were no significant differences in ΔAMP(1-year) between patients with emmetropia and myopia (P = 0.090). CONCLUSIONS: The progression of presbyopia in hyperopic patients was relatively more significant than for emmetropia, followed by myopia. The prescription of presbyopia glasses might need to be replaced more frequently in patients with hyperopia.

Comparison of visual quality after Q value-guided FS-LASIK and SMILE for correction of myopia with age-related accommodation deficiency.

PURPOSE: To investigate differences in objective and subjective visual quality 12 months following Q value-guided (Custom-Q) femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK) versus small incision lenticule extraction (SMILE) for correction of low-to-moderate myopia and compensate for age-related accommodation deficiency. METHODS: Clinical data of 45 patients were analyzed, of whom 23 were treated with FS-LASIK and 22 with SMILE. At the 12-month follow-up, the distance, intermediate, and near visual acuities; objective and subjective refractions; Q factor; corneal higher-order aberrations (HOAs); defocus curve; contrast sensitivity; stereopsis and a subjective visual quality questionnaire were evaluated. RESULTS: At 12 months postoperatively, the two groups had comparable binocular uncorrected distance and intermediate visual acuities (UDVA, UINA). A slightly better uncorrected near visual acuity (UNVA) was observed in the FS-LASIK group (P < 0.05), but patients reported equivalent near vision satisfaction and spectacle independence. Total HOAs and coma increased significantly in all treated eyes (P < 0.05). The Q value and spherical aberration (SA) became more positive, but the shifts were significant only in the SMILE group and the dominant eyes of the FS-LASIK group (P < 0.05). Binocular contrast sensitivity was better in the FS-LASIK group. No significant differences in visual disturbances were found between groups. CONCLUSION: For myopic patients with mild age-related accommodation deficiency, both FS-LASIK with Custom-Q protocol and SMILE could provide good efficacy, safety, predictability, and high patient satisfaction. The Custom-Q protocol could better preserve the original prolate shape of the cornea and achieve superior visual quality compared to SMILE. KEY MESSAGES: What is known Both femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK) and small-incision lenticule extraction (SMILE) have been widely applied in young myopic patients, with comparable efficacy and safety. Studies evaluating the clinical outcomes of FS-LASIK and SMILE in treating myopia with age-related accommodation insufficiency are lacking. What is new For myopic patients with mild age-related accommodation deficiency, both FS-LASIK with Custom-Q protocol and SMILE could provide good efficacy, safety, predictability, and high patient satisfaction. The Custom-Q protocol could better preserve the original prolate shape of the cornea and achieve superior visual quality compared to SMILE.

Analyses of eye movement parameters in children with anisometropic amblyopia.

OBJECTIVE: To investigate the characteristics of eye movement in children with anisometropic amblyopia, and to compare those characteristics with eye movement in a control group. METHODS: 31 children in the anisometropic amblyopia group (31 amblyopic eyes in group A, 31 contralateral eyes in group B) and 24 children in the control group (48 eyes in group C). Group A was subdivided into groups Aa (severe amblyopia) and Ab (mild-moderate amblyopia). The overall age range was 6-12 years (mean, 7.83 ± 1.79 years). All children underwent ophthalmic examinations; eye movement parameters including saccade latency and amplitude were evaluated using an Eyelink1000 eye tracker. Data Viewer and MATLAB software were used for data analysis. RESULTS: Mean and maximum saccade latencies, as well as mean and maximum saccade amplitudes, were significantly greater in group A than in groups B and C before and after treatment (P < 0.05). Mean and maximum saccade latencies were significantly different among groups Aa, Ab, and C (P < 0.05). Pupil trajectories in two detection modes suggested that binocular fixation was better than monocular fixation. CONCLUSIONS: Eye movement parameters significantly differed between contralateral normal eyes and control eyes. Clinical evaluation of children with anisometropic amblyopia should not focus only on static visual acuity, but also on the assessment of eye movement.

Case report: Topical pilocarpine ameliorated the accommodation loss and pupillary dilation after micropulse transscleral laser treatment.

BACKGROUND: The present study elucidates a common significant postoperative complication of micropulse transscleral laser treatment (mTLT) and explores its potential management strategies for younger patients with good central vision. CASE PRESENTATION: Three younger Chinese glaucoma patients with good central vision maintained high intraocular pressures (IOPs) (36, 25, and 30 mmHg) on maximally tolerated topical anti-glaucoma medications. All patients were treated with mTLT because of a higher risk of complications with filtering surgery. After the procedure, their best-corrected visual acuities were not significantly changed, IOPs were significantly decreased, and the number of topical anti-glaucoma medicines was gradually decreased. However, all patients complained about reduced near visual acuity (NVA) for 1-5 months. Slit-lamp examination revealed pupillary dilation, and binocular accommodative function examination indicated accommodation loss. After treatment with 2% topical pilocarpine, all patients reported an improvement in NVA. Among them, we could observe pupillary constriction, recovery of accommodation function, and improved NVA, even discontinuation of pilocarpine in Patient 2. CONCLUSION: In younger patients with good central vision, topical pilocarpine might ameliorate accommodation loss and pupillary dilation after mTLT.

(Over)crowded house: exploring asylum seekers' experiences of the COVID-19 pandemic while living at accommodation centers in Sweden.

BACKGROUND: The COVID-19 pandemic has made visible the scale of health disparities in society, highlighting how the distribution of infection and deaths differs between population subgroups within countries. Asylum seekers represent a potentially vulnerable group; early in the pandemic, concerns were raised about their housing situation, usually involving overcrowded, camp-like accommodations, and the effects of COVID-19 in relation to this. Hence, this study aimed to explore asylum seekers' experiences of the COVID-19 pandemic while living at accommodation centers. METHODS: In this qualitative study, 14 semi-structured interviews were conducted with asylum seekers at two accommodation centers in Sweden. Participants represented a diverse group of asylum seekers in regard to age, educational background, and gender. Data were analyzed using qualitative content analysis. RESULTS: Experiences related to COVID-19 were highly dependent on the living situation at the accommodation centers and the experience of feeling unsafe in shared spaces. This was enhanced by the experiences of a challenging mix of COVID-19 messages where different understandings of COVID-19 and related measures existed, together with a feeling of loss of control and safety in shared rooms. Additionally, participants felt more isolated from the outside society and missed prior social activities. Adding to this experience of isolation was an increasing mistrust regarding the authorities' pandemic response. CONCLUSION: This study highlights the importance of understanding the specific challenges and vulnerabilities of asylum seekers at accommodation centers during the pandemic, shaped by their housing situation and legal status. The findings underscore the need for context-specific support, holistic disease prevention approaches, and tailored health communication strategies using diverse formats. Additionally, the findings emphasize the crucial need to identify and mobilize existing community resources in planning and implementing pandemic control measures. Furthermore, the study emphasizes governmental responsibility in providing secure housing, and to address long-term vulnerabilities beyond pandemics.

The effect of multifocal contact lenses on the dynamic accommodation step response.

PURPOSE: To measure the dynamic accommodation response (AR) to step stimuli with and without multifocal contact lenses (MFCLs), in emmetropes and myopes. METHODS: Twenty-two adult subjects viewed alternating distance (0.25D) and near (3D) Maltese crosses placed in free space, through two contact lens types: single vision (SVCL) or centre-distance multifocal (MFCL; +2.50D add). The AR level was measured along with near to far (N-F) and far to near (F-N) step response characteristics: percentage of correct responses, magnitude, latency, peak velocity and duration of step response. RESULTS: There was no difference between N-F and F-N responses, or between refractive groups in any aspect of the accommodation step response dynamics. The percentage of correct responses was unaffected by contact lens type. Through MFCLs, subjects demonstrated smaller magnitude, longer latency, shorter duration and slower peak velocity steps than through SVCLs. When viewing the near target, the AR through MFCLs was significantly lower than through SVCLs. When viewing the distance target with the MFCL, the focal points from rays travelling through the distance and near zones were approximately 0.004D behind and 2.50D in front of the retina, respectively. When viewing the near target, the respective values were approximately 1.89D behind and 0.61D in front of the retina. CONCLUSION: The defocus error required for accommodation control appears not to be solely derived from the distance zone of the MFCL. This results in reduced performance in response to abruptly changing vergence stimuli; however, these errors were small and unlikely to impact everyday visual tasks. There was a decrease in ocular accommodation during near tasks, which has previously been correlated with a reduced myopic treatment response through these lenses. With MFCLs, the estimated dioptric myopic defocus was the largest when viewing a distant stimulus, supporting the hypothesis that the outdoors provides a beneficial visual environment to reduce myopia progression.

Digital device viewing behaviour in children.

INTRODUCTION: Habitual viewing behaviour is widely believed to be an important contributing factor to the onset and progression of myopia and may be task dependent. The purpose of this study was to quantify the habitual viewing distance of children performing five different tasks on a smartphone digital device. METHODS: The real-time viewing distance in 38 children with their habitual correction was measured using software (MyopiaApp) on a handheld (Google Pixel 3) device. Five tasks were performed in a randomised sequence: playing a game, watching video in a light (680 lux) and dark (5.5 lux) environment and reading small (8 pt) and large (16 pt) text. ANCOVA statistical analysis was used to evaluate the effect of task, group (myope vs. non-myope) and arm length on the median relative viewing distance. RESULTS: Arm length was not correlated with viewing distance in any of the tasks, and there was no significant difference in viewing distance between any of the tasks. Specifically, a two-way mixed ANCOVA indicated that task, refractive group (myopic vs. non-myopic), age and arm length, as well as all two-way interactions were not significantly associated with viewing distance. Overall, 60% of the total variance in viewing distance was accounted for by individual differences. CONCLUSIONS: The average handheld viewing distance was similar across a variety of everyday tasks in a representative sample of myopic and emmetropic children. Neither arm length, age nor refractive group were associated with viewing distance in any of the tasks. Importantly, myopic children of a given size did not hold the smartphone digital device at a different distance for any task than their equally sized non-myopic peers. However, both groups exhibited high inter-individual variability in mean viewing distance, indicating some subjects performed all tasks at further distances while other subjects used at nearer distances.

Longitudinal changes in objective accommodative response, pupil size and spherical aberration: A case study.

PURPOSE: Previous transverse and a handful of longitudinal studies have shown that the slope of the static accommodation response/stimulus curve declines as complete presbyopia is approached. Changes in pupillary miosis and ocular spherical aberration (SA) are also evident. This study further investigated longitudinal changes in the relationships between the monocular static accommodative response, pupil diameter and SA of a single adult. METHODS: A wavefront analysing system, the Complete Ophthalmic Analysis System, was used in conjunction with a Badal optometer to allow continuous recording of the aberration structure of the dominant eye in a low myope for a range of accommodative demands (-0.83 to 7.63 D) over a period of 17 years until the age of 50. Monocular accommodative response was calculated as the equivalent refraction minimising wavefront error. The associated longitudinal changes in pupil size and SA with accommodation were also recorded. RESULTS: A decrease in accommodation response with age was found at almost all target vergences, with the changes being greatest for higher vergences. In addition, although absolute pupil diameter decreased with age, the rate of change in pupil diameter with accommodative stimulus remained approximately constant with age. Pupil constriction occurred for near stimuli even in full presbyopia. SA changed linearly with the accommodation response at all ages. CONCLUSIONS: The objective amplitude of accommodation declined linearly with age as complete presbyopia was approached, while the slope of the response/stimulus curve also fell. It was hypothesised that the retinal image blur associated with the larger lags of accommodation at higher accommodative stimuli was reduced by pupil constriction and the resulting lower levels of SA.

Intracapsular accommodation mechanism in terms of lens curvature gradient.

The intracapsular accommodation mechanism (IAM) may be understood as an increase in the lens equivalent refractive index as the eye accommodates. Our goal was to evaluate the existence of an IAM by analysing observed changes in the inner curvature gradient of the lens. To this end, we fitted a gradient index and curvature lens model to published experimental data on external and nucleus geometry changes during accommodation. For each case analysed, we computed the refractive power and equivalent index for each accommodative state using a ray transfer matrix. All data sets showed an increase in the effective refractive index, indicating a positive IAM, which was stronger for older lenses. These results suggest a strong dependence of the lens equivalent refractive index on the inner curvature gradient.

Sources of reduced visual acuity and spectacle treatment options for individuals with Down syndrome: Review of current literature.

Individuals with Down syndrome are known to have a greater prevalence of ocular conditions such as strabismus, nystagmus, elevated refractive error, poor accommodative function, elevated higher-order optical aberrations and corneal abnormalities. Related to these conditions, individuals with Down syndrome commonly have reduced best-corrected visual acuity at both far and near viewing distances across their lifespan. This review summarises the various optical sources of visual acuity reduction in this population and describes clinical trials that have evaluated alternative spectacle prescribing strategies to minimise these optical deficits. Although refractive corrections may still have limitations in their ability to normalise visual acuity for individuals with Down syndrome, the current literature provides evidence for eye care practitioners to consider in their prescribing practices for this population to maximise visual acuity. These considerations include accounting for the presence of elevated higher-order aberrations when determining refractive corrections and considering bifocal lens prescriptions, even for young children with Down syndrome.

Vergence and accommodation deficits in paediatric and adolescent patients during sub-acute and chronic phases of concussion recovery.

INTRODUCTION: Visual function deficits have been reported in adolescents following concussion. We compared vergence and accommodation deficits in paediatric and adolescent patients at a tertiary medical centre in the sub-acute (15 days to 12 weeks) and chronic (12 weeks to 1 year) phases of concussion recovery. METHODS: The study included patients aged 7 to <18 years seen between 2014 and 2021, who had a binocular vision (BV) examination conducted within 15 days and 1 year of their concussion injury. Included patients had to have 0.10 logMAR monocular best-corrected vision or better in both eyes and be wearing a habitual refractive correction. BV examinations at near included measurements of near point of convergence, convergence and divergence amplitudes, vergence facility, monocular accommodative amplitude and monocular accommodative facility. Vergence and accommodation deficits were diagnosed using established clinical criteria. Group differences were assessed using nonparametric statistics and ANCOVA modelling. RESULTS: A total of 259 patients were included with 111 in the sub-acute phase and 148 in the chronic phase of concussion recovery. There was no significant difference in the rates of vergence deficits between the two phases of concussion recovery (sub-acute = 48.6%; chronic = 49.3%). There was also no significant difference in the rates of accommodation deficits between the two phases of concussion recovery (sub-acute = 82.0%; chronic = 77.0%). CONCLUSION: Patients in both the sub-acute and chronic phases of concussion recovery exhibited a high frequency of vergence and accommodation deficits, with no significant differences between groups. Results indicate that patients exhibiting vision deficits in the sub-acute phase may not resolve without intervention, though a prospective, longitudinal study is required to test the hypothesis.