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Acta Ophthalmologica Sep 2019Albinism degrades visual function due to developmental disorders of the eye and visual pathways, larger refractive errors, absent binocularity and poor fixation control.... (Comparative Study)
Comparative Study
PURPOSE
Albinism degrades visual function due to developmental disorders of the eye and visual pathways, larger refractive errors, absent binocularity and poor fixation control. Reading spectacles is commonly prescribed in our clinic and well tolerated. The purpose was to evaluate whether the accommodative response is typical or affected in comparison to a reference group.
METHODS
Twenty-two children with albinism (median: 13.5 years) and 12 controls (median: 13 years) underwent a full optometric examination and an objective accommodation measurement (WAM-5500 @ 6 Hz; Grand Seiko) in response to minus-lens-blur (-1, -2 and -3 D) and to a prolonged near viewing task (20 cm) for 5 min.
RESULTS
Children with albinism displayed less accommodation to minus lens-blur and during sustained near viewing (p < 0.001) compared to the reference group. Higher visual acuity correlates with a better accommodative response (r ≥ 0.5; p ≤ 0.04). The subjective and objective measures of accommodation did not correlate. The habitual reading distance was always closer than the point towards which the subjects with albinism seemed to accommodate according to the measurements at 20 cm.
CONCLUSION
Children with albinism benefits from reading spectacles due to a combination of close habitual reading distance and a poor accommodation. Objective recording of accommodation is not critical for a correct judgement of near visual function. Children already wearing reading spectacles were those with least accommodative response.
Topics: Accommodation, Ocular; Adolescent; Albinism; Child; Child, Preschool; Eyeglasses; Female; Humans; Infant; Infant, Newborn; Lens, Crystalline; Male; Reading; Refractive Errors; Vision, Binocular; Visual Acuity; Young Adult
PubMed: 30702212
DOI: 10.1111/aos.14040 -
Vision Research Jul 2021Many patients with concussion experience visual symptoms following injury that lead to a diagnosis of convergence insufficiency, accommodative insufficiency, or saccadic...
Many patients with concussion experience visual symptoms following injury that lead to a diagnosis of convergence insufficiency, accommodative insufficiency, or saccadic dysfunction. However, these diagnostic categories are based on aggregates of clinical tests developed from a non-concussed population and therefore may not accurately describe visual deficits in the concussed population. Thus, we sought to understand individual metrics of visual dysfunction in chronically symptomatic post-concussion patients. This retrospective cross-sectional study included patients examined at the multidisciplinary concussion clinic (MDCC) at Boston Children's Hospital over four years. Patients aged 5-21 years who had a complete assessment of eye alignment, vergence, accommodation, and visual tracking, and had visual acuity better than or equal to 20/30 in each eye were included. Patients with history of amblyopia, strabismus, or ocular pathology were excluded. Chart review yielded 116 patients who met inclusion criteria (median age 15 years, 64% female). The majority of patients (52%) experienced a single concussion and most were sports-related (50%). Clinical data show vergence, accommodation, or visual tracking deficits in 95% of patients. A receded near point of convergence (NPC, 70/116) and reduced accommodative amplitude (63/116) were the most common deficits. Both NPC and accommodative amplitude were significantly correlated with one another (r = -0.5) and with measures of visual tracking (r = -0.34). Patients with chronic post-concussion symptoms show deficits in individual metrics of vergence, accommodation and visual tracking. The high incidence of these deficits, specifically NPC and accommodative amplitude, highlights the need for a detailed sensorimotor evaluation to guide personalized treatment following concussion.
Topics: Accommodation, Ocular; Adolescent; Child; Convergence, Ocular; Cross-Sectional Studies; Female; Humans; Male; Retrospective Studies; Vision, Binocular
PubMed: 33838503
DOI: 10.1016/j.visres.2021.03.002 -
Ophthalmic & Physiological Optics : the... Jul 2023Individuals with different types of intermittent exotropia (IXT) may use neurally coupled accommodation and vergence responses differently from those without exotropia...
PURPOSE
Individuals with different types of intermittent exotropia (IXT) may use neurally coupled accommodation and vergence responses differently from those without exotropia to achieve eye alignment. This study examined the relationship between simultaneously recorded accommodation and vergence responses in children and young adults with a range of types of IXT while aligned and deviated.
METHODS
Responses of 29 participants with IXT (4-31 years) and 24 age-matched controls were recorded using simultaneous eye-tracking and eccentric photorefraction while they watched a movie in binocular or monocular viewing at varying viewing distances. Gradient response AC/A ratios and fusional vergence ranges were also assessed. Eight participants had divergence or pseudo-divergence excess type IXT, 5 had convergence insufficiency and 16 had basic IXT.
RESULTS
Control and IXT participants accommodated similarly both in monocular and binocular-aligned conditions to visual targets at 80 and 33 cm. When deviated in binocular viewing, most participants with IXT exhibited changes in accommodation <0.5D relative to alignment. Gradient response AC/A ratios were similar for control [0.56 MA/D (IQR: 0.51 MA/D)] and IXT participants [0.42 MA/D (0.54 MA/D); p = 0.60]. IXT participants showed larger vergence to accommodation ratios with changes from distance to near fixation [1.19 MA/D (1.45 MA/D)] than control participants [0.78 MA/D (0.60 MA/D); p = 0.02], especially among IXT participants with divergence or pseudo-divergence excess. Participants with IXT exhibited typical fusional divergence ranges beyond their dissociated position [8.86 Δ (7.10 Δ)] and typical fusional convergence ranges from alignment [18 Δ (15.75 Δ)].
CONCLUSIONS
This study suggests that control of IXT is typically neither driven by accommodative convergence alone nor associated with over-accommodation secondary to fusional convergence efforts. These simultaneous measurements confirmed that proximal vergence contributed significantly to IXT control, particularly for divergence or pseudo-divergence excess type IXT. For IXT participants in this study, achieving eye alignment did not conflict with having clear vision.
Topics: Child; Young Adult; Humans; Exotropia; Vision, Binocular; Convergence, Ocular; Accommodation, Ocular; Strabismus; Chronic Disease
PubMed: 36692334
DOI: 10.1111/opo.13093 -
Vestnik Oftalmologii 2022The article reviews the findings on the anatomy, morphological and biomechanical features of the accommodation apparatus. Modern methods of imaging and biometry confirm... (Review)
Review
The article reviews the findings on the anatomy, morphological and biomechanical features of the accommodation apparatus. Modern methods of imaging and biometry confirm the validity of the Helmholtz lenticular theory of accommodation, according to which its mechanism involves three main components: the ciliary body, the zonular fibres and the lens capsule, the lens itself. Based on this, there is certain interest in studying the degree of participation of each of these components in the development of age-related changes in accommodation (presbyopia).
Topics: Accommodation, Ocular; Aging; Ciliary Body; Humans; Lens Capsule, Crystalline; Lens, Crystalline; Presbyopia
PubMed: 36004600
DOI: 10.17116/oftalma2022138041117 -
Journal of the Optical Society of... Jun 2022Multifocal contact lenses are increasingly popular interventions for controlling myopia. This study presents the short-term effects of multifocal contact lenses on...
Multifocal contact lenses are increasingly popular interventions for controlling myopia. This study presents the short-term effects of multifocal contact lenses on foveal and peripheral vision. The MiSight contact lenses designed to inhibit myopia progression and the 1-Day Acuvue Moist contact lenses designed for presbyopia were investigated. The MiSight produced similar foveal results to spectacles despite the increased astigmatism and coma. The MiSight also reduced the low-contrast resolution acuity in the periphery, despite no clear change in relative peripheral refraction. When compared with spectacles, Acuvue Moist decreased accommodative response and reduced foveal high- and low-contrast resolution acuity, whereas peripheral thresholds were more similar to those of spectacles. The most likely treatment property for myopia control by the MiSight is the contrast reduction in the peripheral visual field and the changed accommodation.
Topics: Accommodation, Ocular; Contact Lenses; Eyeglasses; Humans; Myopia; Visual Acuity
PubMed: 36215526
DOI: 10.1364/JOSAA.450195 -
IEEE Transactions on Bio-medical... Jan 2022Presbyopia, an age-related ocular disorder, is characterized by the loss in the accommodative abilities of the human eye. Conventional methods of correcting presbyopia...
OBJECTIVE
Presbyopia, an age-related ocular disorder, is characterized by the loss in the accommodative abilities of the human eye. Conventional methods of correcting presbyopia divide the field of view, thereby resulting in significant vision impairment. We demonstrate the design, assembly and evaluation of autofocusing eyeglasses for restoration of accommodation without dividing the field of view.
METHODS
The adaptive optics eyeglasses comprise of two variable-focus liquid lenses, a time-of-flight range sensor and low-power, dual microprocessor control electronics, housed within an ergonomic frame. Subject-specific accommodation deficiency models were utilized to demonstrate high-fidelity accommodative correction. The abilities of this system to reduce accommodation deficiency, its power consumption, response time, optical performance and MTF were evaluated.
RESULTS
Average corrected accommodation deficiencies for 5 subjects ranged from -0.021 D to 0.016 D. Each accommodation correction calculation was performed in ∼67 ms which consumed 4.86 mJ of energy. The optical resolution of the system was 10.5 cycles/degree, and featured a restorative accommodative range of 4.3 D. This system was capable of running for up to 19 hours between charge cycles and weighed ∼132 g.
CONCLUSION
The design, assembly and performance of an autofocusing eyeglasses system to restore accommodation in presbyopes has been demonstrated.
SIGNIFICANCE
The new autofocusing eyeglasses system presented in this article has the potential to restore pre-presbyopic levels of accommodation in subjects diagnosed with presbyopia.
Topics: Accommodation, Ocular; Eyeglasses; Humans; Optics and Photonics; Presbyopia; Visual Acuity
PubMed: 34232861
DOI: 10.1109/TBME.2021.3094964 -
Journal of Binocular Vision and Ocular... 2022Blur is the subjective awareness that the edges of a high contrast image are indistinct. The concept of blur is fundamental to the understanding of vision,... (Review)
Review
Blur is the subjective awareness that the edges of a high contrast image are indistinct. The concept of blur is fundamental to the understanding of vision, accommodation, refractive error, concomitant strabismus, and asthenopia. It is easy for clinicians to believe that blur always needs to be avoided or resolved, or that everyone responds to blur similarly. This narrative review outlines the literature on blur and the accommodation to resolve it, and relates it to current clinical practice. Laboratory studies have traditionally been highly controlled, using expert observers, but more recent research using naïve participants suggests that variability and tolerance of blur are common and more widespread than often thought, especially in children and clinical groups. Objective and subjective responses can differ widely, and it cannot be assumed that because we expect accommodation to have occurred, that it always has. A deeper understanding of the role of blur and objective accommodation in vision, refractive error and strabismus may help us understand the variability that exists in clinical practice. We may use blur to help investigation and treatment but also be relaxed about what is normal. Many patients are led to believe that they should always achieve constant clear vision, when this is unrealistic. Although pathological blur must be identified and treated, normal everyday blur may become medicalized into "a problem" by well-meaning professionals.
Topics: Accommodation, Ocular; Asthenopia; Child; Convergence, Ocular; Humans; Refractive Errors; Strabismus
PubMed: 35157555
DOI: No ID Found -
Strabismus Mar 2023Accommodation anomalies are frequently caused or exacerbated by psychological problems such as anxiety. Patients share many features with those with other anxiety based...
INTRODUCTION
Accommodation anomalies are frequently caused or exacerbated by psychological problems such as anxiety. Patients share many features with those with other anxiety based somatic symptoms such as stomach-ache, palpitations and headaches. They can be difficult to treat, and the ophthalmic literature rarely goes beyond diagnosis and ocular treatment. This study reports characteristics and outcomes of a short case series of patients with accommodation spasms and weaknesses assessed objectively, and outlines a psychological approach to treatment.
METHODS
23 patients (13 severe accommodative weakness or "paralysis," 10 accommodative spasm) aged between 8-30 years, were referred to our laboratory after diagnosis by their referring clinician and exclusion of pathology or drug-related causes. Their accommodation and convergence were assessed objectively with a laboratory photorefractive method, as well as by conventional orthoptic testing and dynamic retinoscopy. All interactions with the patients used an evidence-based psychological approach, to give them insight into how stress and anxiety can cause or exacerbate eye symptoms and help them to break a vicious cycle of anxiety and risk of deterioration.
RESULTS
83% were female and 57% had previously diagnosed anxiety or dyslexia (with many more acknowledging being "worriers"). Inconsistency of responses was the rule and all showed normal responses at some time during their visit. Responses were poorly related to the visual stimuli presented and objective responses often differed from subjective. Dissociation between convergence and accommodation was more common, compared to our large, previously reported, control groups. No participant had true paralysis of accommodation. Responses often improved dramatically within one session after discussion and explanation of the strong relationship between anxiety and accommodative anomalies. None have returned for further advice or treatment.
CONCLUSIONS
Our approach explicitly addresses psychological factors in causing, or worsening, accommodation (and co-existing convergence) anomalies. Many of these patients do not realize that a certain amount of blur is normal in everyday life. Ocular symptoms are often a sign of anxiety, not the primary problem. By recognizing this, patients can be helped to address the triggering issues and symptoms often subside or resolve spontaneously. Well-meaning professionals, offering only ocular treatments, can deflect attention away from the real cause and can unwittingly be making things worse.
Topics: Humans; Female; Child; Adolescent; Young Adult; Adult; Male; Accommodation, Ocular; Retinoscopy; Orthoptics; Convergence, Ocular
PubMed: 36710250
DOI: 10.1080/09273972.2023.2171070 -
Scientific Reports Sep 2023This study investigated the accuracy and stability of accommodative and vergence functions in children with and without hyperopia while engaged in two sustained near...
This study investigated the accuracy and stability of accommodative and vergence functions in children with and without hyperopia while engaged in two sustained near tasks. The sustained accommodative and vergence characteristics of participants without refractive correction (n = 92, aged 5-10 years) with and without hyperopia (defined as cycloplegic retinoscopy ≥ + 1.00D and less than + 5.00D) were measured using eccentric infrared photorefraction (PowerRef 3; PlusOptix, Germany). Binocular measures of accommodation and eye position were recorded while participants engaged in 2 tasks at 25 cm for 15 min each: (1) reading small print on an Amazon Kindle and (2) watching an animated movie on liquid crystal display screen. Comprehensive visual assessment, including measurement of presenting visual acuity, amplitude of accommodation, and stereoacuity was conducted. The magnitude of accommodative and vergence responses was not related to refractive error (P > 0.05). However, there were inter-task differences in the accuracy and stability of the accommodative responses across refractive groups (P < 0.05). The relationship between accommodation and vergence was not significant in both tasks (P > 0.05). However, increased accommodative and vergence instabilities were associated with total accommodative response (P < 0.05). Despite having greater accommodative demand, uncorrected hyperopes accommodate comparably to emmetropic controls. However, uncorrected hyperopes have increased instabilities in their accommodative and vergence responses, which may adversely impact their visual experience.
Topics: Child; Humans; Hyperopia; Accommodation, Ocular; Refractive Errors; Refraction, Ocular; Visual Acuity
PubMed: 37658084
DOI: 10.1038/s41598-023-41244-9 -
Journal of Visualized Experiments : JoVE Mar 2023Through the purposeful stimulation and recording of eye movements, the fundamental characteristics of the underlying neural mechanisms of eye movements can be observed....
Through the purposeful stimulation and recording of eye movements, the fundamental characteristics of the underlying neural mechanisms of eye movements can be observed. VisualEyes2020 (VE2020) was developed based on the lack of customizable software-based visual stimulation available for researchers that does not rely on motors or actuators within a traditional haploscope. This new instrument and methodology have been developed for a novel haploscope configuration utilizing both eye tracking and autorefractor systems. Analysis software that enables the synchronized analysis of eye movement and accommodative responses provides vision researchers and clinicians with a reproducible environment and shareable tool. The Vision and Neural Engineering Laboratory's (VNEL) Eye Movement Analysis Program (VEMAP) was established to process recordings produced by VE2020's eye trackers, while the Accommodative Movement Analysis Program (AMAP) was created to process the recording outputs from the corresponding autorefractor system. The VNEL studies three primary stimuli: accommodation (blur-driven changes in the convexity of the intraocular lens), vergence (inward, convergent rotation and outward, divergent rotation of the eyes), and saccades (conjugate eye movements). The VEMAP and AMAP utilize similar data flow processes, manual operator interactions, and interventions where necessary; however, these analysis platforms advance the establishment of an objective software suite that minimizes operator reliance. The utility of a graphical interface and its corresponding algorithms allow for a broad range of visual experiments to be conducted with minimal required prior coding experience from its operator(s).
Topics: Eye Movements; Saccades; Accommodation, Ocular; Movement
PubMed: 36939267
DOI: 10.3791/64808