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Acta Ophthalmologica May 2022The aim of the study was to evaluate strabismus, stereoacuity, accommodation and convergence in prematurely born young adults; screened for retinopathy of prematurity in...
PURPOSE
The aim of the study was to evaluate strabismus, stereoacuity, accommodation and convergence in prematurely born young adults; screened for retinopathy of prematurity in the neonatal period and compare with term-born individuals of the same age.
MATERIALS AND METHODS
The study participants included 59 prematurely born individuals with a birthweight of ≤1,500 grams and 44 term-born controls, all born during 1988-1990 in Stockholm County, Sweden. Ocular alignment was assessed with a cover test, stereoacuity with the TNO stereo test and the amplitude of accommodation and the near point of convergence with the Royal Air Force Rule.
RESULTS
Seven of 59 (12%) preterms had manifest strabismus, 4/59 (7%) had esotropia and 3/59 (5%) exotropia. One of 44 (2%) controls had esotropia; no other controls had manifest strabismus. Stereoacuity was within normal limits in 38/59 (64%) preterms and 43/44 (98%) controls, p < 0.01; the difference remained after excluding those with strabismus. A neurological complication at 2.5 years of age was the strongest risk factor for subnormal stereoacuity within the preterm group after excluding those with strabismus. The mean amplitude of accommodation was poorer in the preterms than the controls in better (p < 0.05) and worse eyes (p < 0.05). The preterms were more likely to have an amplitude of accommodation below the minimum, according to Hofstetter's equation. There were no differences between the groups regarding the near point of convergence.
CONCLUSION
Prematurely born young adults had a higher prevalence of strabismus, reduced stereoacuity and worse amplitude of accommodation than term-born controls.
Topics: Accommodation, Ocular; Esotropia; Humans; Infant, Newborn; Retinopathy of Prematurity; Strabismus; Visual Acuity; Young Adult
PubMed: 34313013
DOI: 10.1111/aos.14987 -
BMC Ophthalmology Jan 2022To longitudinally analyze and compare the accommodative micro-fluctuation (MFs) and accommodative function between myopic patients after implantable collamer lens (ICL)...
BACKGROUND
To longitudinally analyze and compare the accommodative micro-fluctuation (MFs) and accommodative function between myopic patients after implantable collamer lens (ICL) implantation and laser in situ keratomileusis (LASIK).
METHODS
Patients with good corrected visual acuity (20/20 or better) and underwent ICL (V4c) and LASIK for myopic-correction (ranging from - 3.50 to - 8.50 D) were recruited. Refraction, amplitude of accommodation (AMP), accommodative lag, higher-order aberration (HOA), and MFs were recorded before surgery and 1 and 3 months after surgery. The ACOMEREF automatic refractor was used to measure the high-frequency component (HFC) of the MFs, which suggested tension of the ciliary muscle.
RESULTS
The study comprised 120 eyes. At 3 months after surgery, the manifest refractive spherical equivalent of the ICL and LASIK groups were - 0.11 and - 0.09 D, respectively (p = 0.46). HFC values were significantly higher at 1 month (p = 0.03) and 3 months postoperatively (p = 0.03) in the ICL group compared to that in the LASIK group. The ocular HOA of the ICL group was 1.08 ± 0.43 μm, which was lower than the LASIK group 1.45 ± 0.54 μm (p = 0.01). No significant differences in AMP and accommodative lag between groups were noted at 3 months postoperatively. There was a positive correlation between HFC and vault of the ICL lens (r = 0.14, p = 0.005). There were no correlations between HFC and ocular HOA and postoperative MRSE in the two groups (all p>0.05).
CONCLUSIONS
The HFC increased significantly after an early period of ICL implantation compared to laser in situ keratomileusis for myopic correction, which indicated increased tension of the ciliary muscle, and had a positive correlation on the vault of the ICL lens; However, studies with longer follow-up time and more structural evaluation are needed.
Topics: Humans; Keratomileusis, Laser In Situ; Lens Implantation, Intraocular; Lenses, Intraocular; Myopia; Phakic Intraocular Lenses; Refraction, Ocular; Treatment Outcome; Visual Acuity
PubMed: 34983448
DOI: 10.1186/s12886-021-02217-6 -
Journal of Vision Feb 2023We describe a system-the Binocular Varichrome and Accommodation Measurement System-that can be used to measure and correct the eye's longitudinal and transverse...
We describe a system-the Binocular Varichrome and Accommodation Measurement System-that can be used to measure and correct the eye's longitudinal and transverse chromatic aberration (LCA and TCA) and to perform vision tests with custom corrections. We used the system to investigate how LCA and TCA affect visual performance. Specifically, we studied the effects of LCA and TCA on visual acuity, contrast sensitivity, and chromostereopsis. LCA exhibited inter subject variability but followed expected trends compared with previous reports. TCA at the fovea was variable between individuals but with a tendency for the shift at shorter wavelengths to be more temporalward in the visual field in each eye. We found that TCA was generally greater when LCA was corrected. For visual acuity, we found that a measurable benefit was realized only with both LCA and TCA correction unless the TCA was low. For contrast sensitivity, we found that the best sensitivity to a 10-cycle/degree polychromatic grating was attained when LCA and TCA were corrected. Finally, we found that the primary cause of chromostereopsis is the TCA of the eyes.
Topics: Humans; Visual Fields; Visual Acuity; Accommodation, Ocular; Fovea Centralis; Contrast Sensitivity
PubMed: 36729421
DOI: 10.1167/jov.23.2.3 -
Saudi Journal of Ophthalmology :... 2023The aim of this study is to investigate the association between body mass index (BMI) and visual efficiency skills of university students.
PURPOSE
The aim of this study is to investigate the association between body mass index (BMI) and visual efficiency skills of university students.
METHODS
This study adopted an analytical and descriptive methodology whereby a comprehensive screening of 385 university students was conducted. Ultimately, 116 subjects were selected to ensure judicious distribution of subjects across the four categories of BMI. These 116 subjects were subjected to visual efficiency testing parameters, as referenced from "Clinical Management of Binocular Vision," by Scheiman and Wick.
RESULTS
BMI and visual efficiency anomalies were observed to be correlated with statistical significance to each other as indicated by a = 0.018 and = 15.22. It was also observed that the obese category exhibited the highest prevalence of accommodation and vergence anomalies, followed by the underweight category, as discerned from a detailed analysis of subjects classified according to the BMI categories. These findings imply a noteworthy and potentially deleterious impact of BMI on the visual system and underscore the importance of regular screening for visual efficiency skills in individuals across various BMI categories.
CONCLUSION
This study established a compelling association between BMI and visual efficiency skills anomalies. Consistent with prior research, the findings of this study suggest that individual with higher BMI is more prone to experiencing such anomalies.
PubMed: 38074302
DOI: 10.4103/sjopt.sjopt_95_23 -
Journal of Ophthalmic & Vision Research 2019To determine the distribution of the near point of convergence (NPC) and near point of accommodation (NPA) in a young student population in Iran. (Review)
Review
PURPOSE
To determine the distribution of the near point of convergence (NPC) and near point of accommodation (NPA) in a young student population in Iran.
METHODS
The subjects were selected using a cluster sampling method. All students underwent optometry tests, including visual acuity measurement, refraction, and cover test, as well as ophthalmic examinations. The NPC and NPA were measured using an accommodative target (near Snellen chart).
RESULTS
Of 1,595 students, the data of 1,357 were analyzed. The mean NPC and NPA in the total sample were 7.25 cm (95% confidence interval [CI], 7.02 to 7.48) and 9.99 cm (95% CI, 9.69 to 10.29), respectively. Older age was associated with an increase in the NPC, which increased from 6.98 cm in 18-20 years olds to 9.51 cm in those over 30 years. The NPA was significantly associated with age and refractive errors in the multiple linear regression model, increasing from 9.92 cm in 18-20 years olds to 11.44 cm in those over 30 years ( = 0.003). Hyperopic eyes had lower NPA than myopic and emmetropic eyes ( = 0.001). In younger age groups, the mean accommodation amplitude was lower than the mean Hofstetter value. Moreover, with age, especially after 30 years, the mean values surpassed those determined using the Hofstetter formula.
CONCLUSION
The NPC values in this study were lower than those previously reported for identical age groups. The Hofstetter formula is not always an accurate predictor of the accommodation amplitude in the Iranian adult population.
PubMed: 31660110
DOI: 10.18502/jovr.v14i3.4787 -
The British and Irish Orthoptic Journal 2022Virtual reality (VR) gameplay is popular with a range of games and educational resources available. However, it puts high demands on the visual system. Current evidence...
INTRODUCTION
Virtual reality (VR) gameplay is popular with a range of games and educational resources available. However, it puts high demands on the visual system. Current evidence shows conflicting impacts on visual parameters. Therefore, this study explores the changes to vision following VR gameplay.
METHODS
The study was conducted at the School of Health Sciences, University of Liverpool. All participants had binocular vision with good visual acuity and no manifest strabismus. Participants were assessed before and after playing 15 minutes of the VR game Beat Saber, which incorporated convergence and divergence movements. Clinical assessments including near point of convergence (NPC) and near point of accommodation (NPA) using the RAF rule; accommodative convergence to accommodation (AC/A) ratio; motor fusion using the prism fusion range (at 33cm), accommodation facility using +2.00/-2.00DS flipper lenses, and stereoacuity using the Frisby stereo test were assessed before and after playing.
RESULTS
Seventy-eight participants (19-25 years old) were included in the study, with 16 males and 41 females respectively. The breakpoint of convergence reduced by 0.5 cm (p = 0.001). The binocular accommodative facility improved by 2 cycles per minute (cpm); p = 0.004. The mean, near horizontal prism fusion range (PFR) base break and recovery points both worsened by of 5.0 dioptres (p = 0.003), whereas the mean near horizontal PFR base in recovery point improved by of 4.0 dioptres (p = 0.003).
DISCUSSION
The study validated previous findings as VR gameplay over-exercised and fatigued convergence muscles, but to a small degree. The VR experience improved the participants' ability to change focus quickly and improve accommodation, as well as the divergence function of the eye. However, as the participants were retested directly after the VR gameplay, the findings were limited to short term effects on vision.
PubMed: 35855495
DOI: 10.22599/bioj.257 -
Investigative Ophthalmology & Visual... Mar 2022Axial length increases during accommodation in adults and children; however, refractive error group differences are conflicting and have not been explored in pediatric...
PURPOSE
Axial length increases during accommodation in adults and children; however, refractive error group differences are conflicting and have not been explored in pediatric populations. This study aimed to evaluate differences in accommodation-induced axial elongation between myopic and nonmyopic children.
METHODS
A range of ocular biometric measurements were captured during brief accommodation tasks (0, 3, 6, and 9 D) using a Badal optometer mounted to a noncontact optical biometer (Zeiss IOLMaster 700). Reliable measurements were captured for 15 myopic and 15 age- and sex-matched nonmyopic children. The average central corneal thickness (CCT), anterior chamber depth (ACD), crystalline lens thickness (LT), anterior segment length (ASL), vitreous chamber depth (VCD), and axial length (AL) were determined for each accommodation stimulus. Raw measurements of AL and VCD were corrected for the estimated error associated with LT increases during accommodation.
RESULTS
All biometric parameters, except CCT, changed significantly during accommodation (all P < 0.001). Myopic children exhibited significantly greater accommodation-induced axial elongation than nonmyopic children (P = 0.002) at the 3, 6, and 9 D accommodation stimuli, with a mean difference of 7, 10, and 16 µm, respectively (all pairwise comparisons, P ≤ 0.03). The changes in all other biometric parameters were not different between the refractive error groups (P ≥ 0.23).
CONCLUSIONS
Accommodation-induced axial elongation was greater in myopic than nonmyopic children. This finding could support a potential mechanism linking near work, axial elongation, and myopia development in children or may reflect greater susceptibility to accommodation-induced axial elongation in children with established myopia.
Topics: Accommodation, Ocular; Adult; Anterior Eye Segment; Axial Length, Eye; Biometry; Child; Humans; Myopia; Refraction, Ocular; Refractive Errors
PubMed: 35275173
DOI: 10.1167/iovs.63.3.12 -
Investigative Ophthalmology & Visual... Nov 2023Uncorrected hyperopic children must overcome an apparent conflict between accommodation and vergence demands to focus and align their retinal images. This study tested...
PURPOSE
Uncorrected hyperopic children must overcome an apparent conflict between accommodation and vergence demands to focus and align their retinal images. This study tested hypotheses about simultaneous accommodation and vergence performance of young hyperopes to gain insight into ocular motor strategies used to maintain eye alignment.
METHODS
Simultaneous eccentric photorefraction and Purkinje image tracking were used to assess accommodative and vergence responses of 26 adult emmetropes (AE) and 94 children (0-13 years) viewing cartoons. Children were habitually uncorrected (CU) (spherical equivalent refractive error [SE] -0.5 to +4 D), corrected and aligned (CCA), or corrected with a history of refractive esotropia (CCS). Accommodative and vergence accuracy, dissociated heterophoria, and vergence/accommodation ratios in the absence of retinal disparity cues were measured for 33- and 80-cm viewing distances.
RESULTS
In binocular viewing, median accommodative lags for 33 cm were 1.0 D (AE), 1.33 D (CU), 1.25 D (CCA), and 1.0 D (CCS). Median exophorias at 80 and 33 cm were 1.2 and 4.5 pd (AE), 0.8 and 2.5 pd (CU), and 0 and 1.2 pd (CCA), respectively. Without disparity cues, most response vergence/accommodation ratios were between 1 and 2 meter angle/D (∼5-10 pd/D) (69% of AE, 44% of CU, 60% of CCA, and 50% of CCS).
CONCLUSIONS
Despite apparent conflict in motor coupling, uncorrected hyperopes were typically exophoric and achieved adultlike accuracy of both vergence and accommodation simultaneously, indicating ability to compensate for conflicting demands rather than bias to accurate vergence while tolerating inaccurate accommodation. Large lags and esophoria are therefore atypical. This analysis provides normative guidelines for clinicians and a deeper mechanistic understanding of how hyperopes avoid strabismus.
Topics: Adult; Child; Humans; Strabismus; Esotropia; Exotropia; Accommodation, Ocular; Cues; Hyperopia
PubMed: 37962529
DOI: 10.1167/iovs.64.14.17 -
Ophthalmic & Physiological Optics : the... Mar 2022This study aimed to investigate the effect of orthokeratology (OK) on accommodative function and aberrations, to explore the correlations between them and determine what...
PURPOSE
This study aimed to investigate the effect of orthokeratology (OK) on accommodative function and aberrations, to explore the correlations between them and determine what role they play in myopia control.
METHODS
In this prospective case-controlled study, 61 children were divided into an OK (n = 30) and a single-vision spectacles (SVS) (n = 31) group. Accommodation and ocular wavefront aberrations in the OK group were measured at baseline and after 1, 3, 6, 9 and 12 months of OK wear, and again at 1 month after stopping OK (13 month). The same procedure was performed in the SVS group at baseline and at 3, 6 and 12 months. Axial length (AL), accommodative lag area and aberrations including spherical aberration (SA), coma and total higher-order aberrations (HOAs) were analysed.
RESULTS
During OK wear, the accommodative lag area at each visit was lower than the baseline level (all p < 0.01); all aberrations at each visit were higher than pre-treatment (all p < 0.001). After 1 month of OK treatment, changes in accommodative lag area and SA did not show significant correlation (p = 0.16), but after OK cessation these changes were correlated (p = 0.01). In the OK group, multivariate regression analysis showed changes in accommodative lag area were associated with AL progression in the first 6 months but not in the 1-year analysis. For the SVS group, there were no significant changes in the accommodative lag area or any aberrations during the study period.
CONCLUSIONS
Increased HOAs and improved accommodative accuracy were observed during OK treatment, but began to regress after the cessation of OK. A significant positive correlation between improved accommodative accuracy and slowed axial elongation was only observed during the first 6 months of treatment.
Topics: Accommodation, Ocular; Axial Length, Eye; Child; Humans; Myopia; Orthokeratologic Procedures; Refraction, Ocular
PubMed: 34866209
DOI: 10.1111/opo.12930 -
Frontiers in Pharmacology 2022The purpose of the study is to evaluate the effects of 0.01% atropine eye drops on accommodative system parameters among teenagers with low myopia. Ninety-five myopic...
The purpose of the study is to evaluate the effects of 0.01% atropine eye drops on accommodative system parameters among teenagers with low myopia. Ninety-five myopic teenagers [39 boys (8.69 ± 2.473) and 56 girls (8.54 ± 2.054) aged 5-17 years] with no history of eye disease were enrolled. Biometric and accommodative system parameters were evaluated before and at 1 week, 1 month, 3 months, and 6 months of 0.01% atropine eye drop instillation. Participants without accommodative demand at 6 months demonstrated insignificant changes after the atropine instillation (all > 0.05). Nevertheless, there were significant differences in accommodative sensitivity, accommodative amplitude, accommodative responsiveness, and negative relative accommodation (NRA) at 3 months compared with baseline after atropine instillation (all < 0.05). Except spherical equivalent refraction, cornea thickness, intraocular pressure, and axial length were stable after the 0.01% atropine instillation (all > 0.05). Morphologically, current measurements suggested that 0.01% atropine had favorable reduction of accommodation for childhood low myopia over a half-year period.
PubMed: 35211016
DOI: 10.3389/fphar.2022.808440