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Clinical & Experimental Optometry Jan 2020Modern methods of measuring the refractive state of the eye include wavefront sensors which make it possible to monitor both static and dynamic changes of the ocular... (Review)
Review
Modern methods of measuring the refractive state of the eye include wavefront sensors which make it possible to monitor both static and dynamic changes of the ocular wavefront while the eye observes a target positioned at different distances away from the eye. In addition to monitoring the ocular aberrations, wavefront refraction methods allow measurement of the accommodative response while viewing with the eye's habitual chromatic and monochromatic aberrations present, with these aberrations removed, and with specific aberrations added or removed. A large number of experiments describing the effects of accommodation on aberrations and vice versa are reviewed, pointing out the implications for fundamental questions related to the mechanism of accommodation.
Topics: Accommodation, Ocular; Corneal Wavefront Aberration; Humans; Refraction, Ocular; Visual Acuity
PubMed: 31284325
DOI: 10.1111/cxo.12938 -
Journal of Physiological Anthropology Jan 2024Myopia, commonly known as near-sightedness, has emerged as a global epidemic, impacting almost one in three individuals across the world. The increasing prevalence of... (Review)
Review
BACKGROUND
Myopia, commonly known as near-sightedness, has emerged as a global epidemic, impacting almost one in three individuals across the world. The increasing prevalence of myopia during early childhood has heightened the risk of developing high myopia and related sight-threatening eye conditions in adulthood. This surge in myopia rates, occurring within a relatively stable genetic framework, underscores the profound influence of environmental and lifestyle factors on this condition. In this comprehensive narrative review, we shed light on both established and potential environmental and lifestyle contributors that affect the development and progression of myopia.
MAIN BODY
Epidemiological and interventional research has consistently revealed a compelling connection between increased outdoor time and a decreased risk of myopia in children. This protective effect may primarily be attributed to exposure to the characteristics of natural light (i.e., sunlight) and the release of retinal dopamine. Conversely, irrespective of outdoor time, excessive engagement in near work can further worsen the onset of myopia. While the exact mechanisms behind this exacerbation are not fully comprehended, it appears to involve shifts in relative peripheral refraction, the overstimulation of accommodation, or a complex interplay of these factors, leading to issues like retinal image defocus, blur, and chromatic aberration. Other potential factors like the spatial frequency of the visual environment, circadian rhythm, sleep, nutrition, smoking, socio-economic status, and education have debatable independent influences on myopia development.
CONCLUSION
The environment exerts a significant influence on the development and progression of myopia. Improving the modifiable key environmental predictors like time spent outdoors and engagement in near work can prevent or slow the progression of myopia. The intricate connections between lifestyle and environmental factors often obscure research findings, making it challenging to disentangle their individual effects. This complexity underscores the necessity for prospective studies that employ objective assessments, such as quantifying light exposure and near work, among others. These studies are crucial for gaining a more comprehensive understanding of how various environmental factors can be modified to prevent or slow the progression of myopia.
Topics: Child, Preschool; Child; Humans; Prospective Studies; Myopia; Refraction, Ocular; Accommodation, Ocular; Circadian Rhythm
PubMed: 38297353
DOI: 10.1186/s40101-024-00354-7 -
Brain Sciences Nov 2021Parinaud's syndrome involves dysfunction of the structures of the dorsal midbrain. We investigated the pathophysiology related to the signs and symptoms to better... (Review)
Review
Parinaud's syndrome involves dysfunction of the structures of the dorsal midbrain. We investigated the pathophysiology related to the signs and symptoms to better understand the symptoms of Parinaud's syndrome: diplopia, blurred vision, visual field defects, ptosis, squint, and ataxia, and Parinaud's main signs of upward gaze paralysis, upper eyelid retraction, convergence retraction nystagmus (CRN), and pseudo-Argyll Robertson pupils. In upward gaze palsy, three structures are disrupted: the rostral interstitial nucleus of the medial longitudinal fasciculus (riMLF), interstitial nucleus of Cajal (iNC), and the posterior commissure. In CRN, there is a continuous discharge of the medial rectus muscle because of the lack of inhibition of supranuclear fibers. In Collier's sign, the posterior commissure and the iNC are mainly involved. In the vicinity of the iNC, there are two essential groups of cells, the M-group cells and central caudal nuclear (CCN) group cells, which are important for vertical gaze, and eyelid control. Overstimulation of the M group of cells and increased firing rate of the CCN group causing eyelid retraction. External compression of the posterior commissure, and pretectal area causes pseudo-Argyll Robertson pupils. Pseudo-Argyll Robertson pupils constrict to accommodation and have a slight response to light (miosis) as opposed to Argyll Robertson pupils were there is no response to a light stimulus. In Parinaud's syndrome patients conserve a slight response to light because an additional pathway to a pupillary light response that involves attention to a conscious bright/dark stimulus. Diplopia is mainly due to involvement of the trochlear nerve (IVth cranial nerve. Blurry vision is related to accommodation problems, while the visual field defects are a consequence of chronic papilledema that causes optic neuropathy. Ptosis in Parinaud's syndrome is caused by damage to the oculomotor nerve, mainly the levator palpebrae portion. We did not find a reasonable explanation for squint. Finally, ataxia is caused by compression of the superior cerebellar peduncle.
PubMed: 34827468
DOI: 10.3390/brainsci11111469 -
Vision (Basel, Switzerland) Mar 2022This review has identified evidence about pseudomyopia as the result of an increase in ocular refractive power due to an overstimulation of the eye's accommodative... (Review)
Review
This review has identified evidence about pseudomyopia as the result of an increase in ocular refractive power due to an overstimulation of the eye's accommodative mechanism. It cannot be confused with the term "secondary myopia", which includes transient myopic shifts caused by lenticular refractive index changes and myopia associated with systemic syndromes. The aim was to synthesize the literature on qualitative evidence about pseudomyopia in terms that clarify its pathophysiology, clinical presentation, assessment and diagnosis and treatment. A comprehensive literature search of PubMed and the Scopus database was carried out for articles published up to November 2021, without a data limit. This review was reported following the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines. Following inclusion and exclusion criteria, a total of 54 studies were included in the qualitative synthesis. The terms pseudomyopia and accommodation spasm have been found in most of the studies reviewed. The review has warned that although there is agreement on the assessment and diagnosis of the condition, there is no consensus on its management, and the literature describes a range of treatment.
PubMed: 35324602
DOI: 10.3390/vision6010017 -
Journal of Robotic Surgery Oct 2023Stereopsis may be an advantage of robotic surgery. Perceived robotic ergonomic advantages in visualisation include better exposure, three-dimensional vision, surgeon... (Review)
Review
Stereopsis may be an advantage of robotic surgery. Perceived robotic ergonomic advantages in visualisation include better exposure, three-dimensional vision, surgeon camera control, and line of sight screen location. Other ergonomic factors relating to visualisation include stereo-acuity, vergence-accommodation mismatch, visual-perception mismatch, visual-vestibular mismatch, visuospatial ability, visual fatigue, and visual feedback to compensate for lack of haptic feedback. Visual fatigue symptoms may be related to dry eye or accommodative/binocular vision stress. Digital eye strain can be measured by questionnaires and objective tests. Management options include treatment of dry eye, correction of refractive error, and management of accommodation and vergence anomalies. Experienced robotic surgeons can use visual cues like tissue deformation and surgical tool information as surrogates for haptic feedback.
Topics: Humans; Robotic Surgical Procedures; Asthenopia; Depth Perception; Accommodation, Ocular; Ergonomics
PubMed: 37204648
DOI: 10.1007/s11701-023-01618-7 -
JAMA Ophthalmology Nov 2020Because studies have suggested that atropine might slow the progression of myopia in children, randomized clinical trials are warranted to understand this potential... (Randomized Controlled Trial)
Randomized Controlled Trial
IMPORTANCE
Because studies have suggested that atropine might slow the progression of myopia in children, randomized clinical trials are warranted to understand this potential causal relationship.
OBJECTIVE
To evaluate the efficacy and safety of atropine, 0.01%, eyedrops on slowing myopia progression and axial elongation in Chinese children.
DESIGN, SETTING, AND PARTICIPANTS
This was a randomized, placebo-controlled, double-masked study. A total of 220 children aged 6 to 12 years with myopia of -1.00 D to -6.00 D in both eyes were enrolled between April 2018 and July 2018 at Beijing Tongren Hospital, Beijing, China. Cycloplegic refraction and axial length were measured at baseline, 6 months, and 12 months. Adverse events were also recorded.
INTERVENTIONS
Patients were randomly assigned in a 1:1 ratio to atropine, 0.01%, or placebo groups to be administered once nightly to both eyes for 1 year.
MAIN OUTCOMES AND MEASURES
Mean changes and percentage differences in myopia progression and axial elongation between atropine, 0.01%, or placebo groups.
RESULTS
Of 220 participants, 103 were girls (46.8%), and the mean (SD) age was 9.64 (1.68) years. The mean (SD) baseline refractive error and axial length were -2.58 (1.39) D and 24.59 (0.87) mm. Follow-up at 1 year included 76 children (69%) and 83 children (75%) allocated into the atropine, 0.01%, and placebo groups, respectively, when mean myopia progression was -0.49 (0.42) D and -0.76 (0.50) D in the atropine, 0.01%, and placebo groups (mean difference, 0.26 D; 95% CI, 0.12-0.41 D; P < .001), with a relative reduction of 34.2% in myopia progression. The mean (SD) axial elongation in the atropine, 0.01%, group was 0.32 (0.19) mm compared with 0.41 (0.19) mm in the placebo group (mean difference, 0.09 mm; 95% CI, 0.03-0.15 mm; P = .004), with relative reduction of 22.0% in axial elongation. Fifty-one percent and 13.2% of children progressed by at least 0.50 D and 1.00 D in the atropine, 0.01%, group, compared with 69.9% and 34.9% in the placebo group. No serious adverse events related to atropine were reported.
CONCLUSIONS AND RELEVANCE
While the clinical relevance of the results cannot be determined from this trial, these 1-year results, limited by approximately 70% follow-up, suggest that atropine, 0.01%, eyedrops can slow myopia progression and axial elongation in children and warrant future studies to determine longer-term results and potential effects on slowing sight-threatening pathologic changes later in life.
TRIAL REGISTRATION
http://www.chictr.org.cn Identifier: ChiCTR-IOR-17013898.
Topics: Accommodation, Ocular; Atropine; Axial Length, Eye; Child; China; Disease Progression; Double-Blind Method; Female; Follow-Up Studies; Humans; Incidence; Male; Mydriatics; Myopia, Degenerative; Ophthalmic Solutions; Refraction, Ocular; Retrospective Studies; Treatment Outcome; Visual Acuity
PubMed: 33001210
DOI: 10.1001/jamaophthalmol.2020.3820