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Optometry and Vision Science : Official... Aug 2021The range of clear and single binocular vision differs between 3D displays and clinical prism vergences, but this difference is unexplained. This difference prevents...
SIGNIFICANCE
The range of clear and single binocular vision differs between 3D displays and clinical prism vergences, but this difference is unexplained. This difference prevents clinicians from predicting the range of clear and single binocular vision in 3D-viewing patients. In this study, we tested a hypothesis for this difference.
PURPOSE
The purpose of this study was to determine whether changing fixation target size in 3D viewing significantly affects the vergence ranges and, if so, then to determine whether the target size effect is driven by fusional vergence gain changes, threshold of blur changes, or both.
METHODS
Twenty-one visually normal adults aged 18 to 28 years viewed 3D images at 40 cm in an electronic stereoscopic. The fixation target, a Maltese cross, moved in depth at 2∆/s by way of changing crossed or uncrossed disparity until blur and diplopia ensued. We used four target sizes: (1) small (width × height, 0.21° × 0.63°), (2) medium (1.43° × 4.3°), (3) large (3.6° × 10.8°), and (4) 3D (size changing congruently with disparity). The effect of target size on responses was tested by mixed ANOVAs.
RESULT
Mean convergence blurs and breaks increased with target size by 40% (P < .001) and 71% (P < .001), respectively, and in divergence by 33% (P = .03) and 30% (P = .04), respectively. The increases in break magnitude with target size implicate fusional vergence gain change in the size effect. Increasing target size raised the threshold of blur from 1.06 to 1.82 D in convergence and from 0.97 to 1.48 D in divergence (P = .008).
CONCLUSIONS
Growing fixation target size in 3D viewing increases fusional vergence gain and blur thresholds, which together increase the limits of clear and single binocular vision. Therefore, the clarity of a 3D image depends not only on its disparity but also on the size of the viewed image.
Topics: Adult; Convergence, Ocular; Diplopia; Humans; Imaging, Three-Dimensional; Vision Disparity; Vision, Binocular
PubMed: 34460455
DOI: 10.1097/OPX.0000000000001745 -
Middle East African Journal of... 2019Natural honey in spite of its usefulness is known to contain certain microorganisms. In the present study, we describe a case of after using topical honey administered...
Natural honey in spite of its usefulness is known to contain certain microorganisms. In the present study, we describe a case of after using topical honey administered by a traditional medicine therapist. A 32-year-old male came with red eye and blurred vision. The pain and other symptoms became more severe after the 1st week, with appearance of radial perineuritis at the cornea. A repeated interview revealed that 1 week before appearance of ocular symptoms, the patient had instilled a drop of natural honey in his left eye. Confocal microscopic cornea imaging demonstrated cyst and trophozoite of in the corneal stroma.
Topics: Acanthamoeba; Acanthamoeba Keratitis; Adult; Honey; Humans; Male; Vision Disorders
PubMed: 32153338
DOI: 10.4103/meajo.MEAJO_56_18 -
BMC Ophthalmology Jun 2023To characterize the quality of vision after SMILE, FS-LASIK, and ICL implantation and evaluate the related factors.
BACKGROUND
To characterize the quality of vision after SMILE, FS-LASIK, and ICL implantation and evaluate the related factors.
METHODS
131 eyes of 131 myopic patients (90 female, 41 male) who underwent refractive surgeries including SMILE (35 patients), FS-LASIK (73 patients), and ICL implantation (23 patients) were analyzed. The Quality of Vision questionnaires were completed 3 months after surgery, and the results were characterized and analyzed with baseline characteristics, treatment parameters, and postoperative refractive outcomes using logistic regression analysis to find out predicted factors.
RESULTS
Mean age was 26.5 ± 4.6 years (range: 18 to 39 years) and mean preoperative spherical equivalent was - 4.95 ± 2.04 diopters (D) (range: -1.5 to -13.5). Safety and efficacy index was comparable between different techniques: the safety index was 1.21 ± 0.18, 1.22 ± 0.18, and 1.22 ± 0.16 and the efficacy index were 1.18 ± 0.20, 1.15 ± 0.17, 1.17 ± 0.15 for SMILE, FS-LASIK and ICL respectively. The mean overall QoV score was 13.40 ± 9.11, with mean frequency, severity, and bothersome score of 5.40 ± 3.29, 4.53 ± 3.04, and 3.48 ± 3.18 respectively, and there was no significant difference between different techniques. Overall, the symptom with the highest scores was glare, following fluctuation in vision and halos. Only the scores of halos were significantly different among different techniques (P < 0.000). Using ordinal regression analysis, mesopic pupil size was identified as a risk factor (OR = 1.63, P = 0.037), while postoperative UDVA was a protective factor (OR = 0.036, P = 0.037) for overall QoV scores. Using binary logistic regression analysis, we found that patients with larger mesopic pupil size had an increased risk to experience glare postoperatively; compared to ICL, patients who underwent SMILE or FS-LASIK tended to report fewer halos; patients with better postoperative UDVA were less likely to report blurred vision and focusing difficulty; with larger residual myopic sphere postoperatively, patients experienced focusing difficulties and difficulty judging distance or depth perception more frequently.
CONCLUSIONS
SMILE, FS-LASIK, and ICL had comparable visual outcomes. Overall, glare, fluctuation in vision, and halos were the most frequently experienced visual symptoms 3 months postoperatively. Patients with ICL implanted tended to report halos more frequently compared with SMILE and FS-LASIK. Mesopic pupil size, postoperative UDVA, and postoperative residual myopic sphere were predicted factors for reported visual symptoms.
Topics: Adult; Female; Humans; Male; Young Adult; Corneal Stroma; Keratomileusis, Laser In Situ; Lasers, Excimer; Myopia; Refraction, Ocular; Treatment Outcome; Vision, Ocular; Visual Acuity; Lens Implantation, Intraocular
PubMed: 37365492
DOI: 10.1186/s12886-023-03045-6 -
Clinical Ophthalmology (Auckland, N.Z.) 2022Cycloplegic and mydriatic agents are essential in ophthalmological clinical practice since they provide the means for diagnosing and treating certain eye conditions. In... (Review)
Review
Cycloplegic and mydriatic agents are essential in ophthalmological clinical practice since they provide the means for diagnosing and treating certain eye conditions. In addition, cyclopentolate has proven to possess certain benefits compared to other available cycloplegics and mydriatics. Still, the incidence of some adverse drug reactions related to this drug, especially in susceptible patients, has created interest in reviewing the literature about the benefits and risks of using cyclopentolate. A literature search was conducted in Medline/PubMed and Google Scholar, focusing on identifying cyclopentolate's benefits and risks; the most important benefit was its usefulness for evaluating refractive errors, especially for hyperopic children, pseudomyopia, anterior uveitis, treatment of childhood myopia, idiopathic vision loss, and during examinations before refractive surgery, with particular advantages compared to other cycloplegics. While the risks were divided into local adverse drug reactions such as burning sensation, photophobia, hyperemia, punctate keratitis, synechiae, and blurred vision, which are relatively frequent but mild and temporary; and systemic adverse drug reactions such as language problems, visual or tactile hallucinations and ataxia, but unlike ocular, systemic adverse drug reactions are rare and occur mainly in patients with risk factors. In addition, six cases of abuse were found. The treatment with cyclopentolate is effective and safe in most cases; nevertheless, special care must be taken due to the potential severe ADRs that may occur, especially in susceptible patients like children, geriatrics, patients with neurological disorders or Down's syndrome, patients with a low blood level of pseudocholinesterase, users of substances with CNS effects, and patients with a history of drug addiction. The recommendations are avoiding the use of 2% cyclopentolate and instead employing solutions with lower concentrations, preferably with another mydriatic such as phenylephrine. Likewise, the occlusion of the nasolacrimal duct after instillation limits the drug's absorption, reducing the risk of systemic adverse events.
PubMed: 36411874
DOI: 10.2147/OPTH.S388982 -
Annals of Oncology : Official Journal... Jun 2016Many classes of anticancer therapy, including chemotherapeutic agents, hormonal and molecular targeted treatments, can produce ocular toxicity. Novel agents that target... (Review)
Review
Many classes of anticancer therapy, including chemotherapeutic agents, hormonal and molecular targeted treatments, can produce ocular toxicity. Novel agents that target different cellular pathways have been related to a wide spectrum of ophthalmologic toxicities that can range from mild to severe, and include conjunctivitis, blurred vision, keratitis and optic neuritis, among others. Special attention has been drawn to the inhibitors of the MEK signaling pathway, due to their sine qua non ocular toxicity, defined as MEK retinopathy and described as symmetrical bilateral disease that develops in a time-dependent and dose-dependent manner. In this review, we discuss ophthalmologic toxicities associated with molecular targeted therapies, with particular focus on MEK retinopathy, including its nomenclature, incidence, symptoms and management.
Topics: Antineoplastic Agents; Humans; MAP Kinase Kinase Kinases; Molecular Targeted Therapy; Neoplasms; Protein Kinase Inhibitors; Retinal Diseases; Signal Transduction
PubMed: 26951625
DOI: 10.1093/annonc/mdw100 -
Biomedicines Mar 2021Phosphodiesterase type 5 (PDE5) inhibitors such as Viagra (sildenafil citrate) have demonstrated efficacy in the treatment of erectile dysfunction (ED) by inducing... (Review)
Review
Phosphodiesterase type 5 (PDE5) inhibitors such as Viagra (sildenafil citrate) have demonstrated efficacy in the treatment of erectile dysfunction (ED) by inducing cyclic guanosine monophosphate (cGMP) elevation followed by vasodilation and increased blood flow. It also exerts minor inhibitory action against PDE6, which is present exclusively in rod and cone photoreceptors. The effects of sildenafil on the visual system have been investigated in a wide variety of clinical and preclinical studies due to the fact that a high dose of sildenafil may cause mild and transient visual symptoms in some patients. A literature review was performed using PubMed, Cochrane Library and Clinical Trials databases from 1990 up to 2020, focusing on the pathophysiology of visual disorders induced by sildenafil. The aim of this review was not only to gather and summarize the information available on sildenafil clinical trials (CTs), but also to spot subpopulations with increased risk of developing undesirable visual side effects. This PDE inhibitor has been associated with transient and reversible ocular side effects, including changes in color vision and light perception, blurred vision, photophobia, conjunctival hyperemia and keratitis, and alterations in the electroretinogram (ERG). Sildenafil may induce a reversible increase in intraocular pressure (IOP) and a few case reports suggest it is involved in the development of nonarteritic ischemic optic neuropathy (NAION). Reversible idiopathic serous macular detachment, central serous retinopathy and ERG disturbances have been related to the significant impact of sildenafil on retinal perfusion. So far, sildenafil does not seem to cause permanent toxic effects on chorioretinal tissue and photoreceptors as long as the therapeutic dose is not exceeded and is taken under a physician's direction to treat a medical condition. However, the recreational use of sildenafil can lead to harmful side effects, including vision changes.
PubMed: 33809319
DOI: 10.3390/biomedicines9030291 -
Industrial Health 2016Various amines, such as triethylamine and N,N-dimethylethylamine, have been reported to cause glaucopsia in workers employed in epoxy, foundry, and polyurethane foam... (Review)
Review
Various amines, such as triethylamine and N,N-dimethylethylamine, have been reported to cause glaucopsia in workers employed in epoxy, foundry, and polyurethane foam industries. This symptom has been related to corneal edema and vesicular collection of fluid within the corneal subepithelial cells. Exposure to amine vapors for 30 min to several hours leads to blurring of vision, a blue-grey appearance of objects, and halos around lights, that are probably reversible. Concentration-effect relationships have been established. The visual disturbance is considered a nuisance, as it could cause onsite accidents, impair work efficiency, and create difficulties in driving back home. Occupational exposure limits have been established for some amines, but there is shortage of criteria. Volatility factors, such as vapor pressure, should be considered in industrial settings to prevent human ocular risks, while trying to reduce levels of hazardous amines in the atmosphere.
Topics: Air Pollutants, Occupational; Amines; Corneal Edema; Humans; Metallurgy; Occupational Exposure; Polyurethanes; Vision Disorders
PubMed: 26538000
DOI: 10.2486/indhealth.2015-0071 -
Documenta Ophthalmologica. Advances in... Feb 2021Visual evoked potentials (VEPs) can be used to measure visual resolution via a spatial frequency (SF) limit as an objective estimate of visual acuity. The aim of this... (Review)
Review
PURPOSE
Visual evoked potentials (VEPs) can be used to measure visual resolution via a spatial frequency (SF) limit as an objective estimate of visual acuity. The aim of this systematic review is to collate descriptions of the VEP SF limit in humans, healthy and disordered, and to assess how accurately and precisely VEP SF limits reflect visual acuity.
METHODS
The protocol methodology followed the PRISMA statement. Multiple databases were searched using "VEP" and "acuity" and associated terms, plus hand search: titles, abstracts or full text were reviewed for eligibility. Data extracted included VEP SF limits, stimulus protocols, VEP recording and analysis techniques and correspondence with behavioural acuity for normally sighted healthy adults, typically developing infants and children, healthy adults with artificially degraded vision and patients with ophthalmic or neurological conditions.
RESULTS
A total of 155 studies are included. Commonly used stimulus, recording and analysis techniques are summarised. Average healthy adult VEP SF limits vary from 15 to 40 cpd, depend on stimulus, recording and analysis techniques and are often, but not always, poorer than behavioural acuity measured either psychophysically with an identical stimulus or with a clinical acuity test. The difference between VEP SF limit and behavioural acuity is variable and strongly dependent on the VEP stimulus and choice of acuity test. VEP SF limits mature rapidly, from 1.5 to 9 cpd by the end of the first month of life to 12-20 cpd by 8-12 months, with slower improvement to 20-40 cpd by 3-5 years. VEP SF limits are much better than behavioural thresholds in the youngest, typically developing infants. This difference lessens with age and reaches equivalence between 1 and 2 years; from around 3-5 years, behavioural acuity is better than the VEP SF limit, as for adults. Healthy, artificially blurred adults had slightly better behavioural acuity than VEP SF limits across a wide range of acuities, while adults with heterogeneous ophthalmic or neurological pathologies causing reduced acuity showed a much wider and less consistent relationship. For refractive error, ocular media opacity or pathology primarily affecting the retina, VEP SF limits and behavioural acuity had a fairly consistent relationship across a wide range of acuity. This relationship was much less consistent or close for primarily macular, optic nerve or neurological conditions such as amblyopia. VEP SF limits were almost always normal in patients with non-organic visual acuity loss.
CONCLUSIONS
The VEP SF limit has great utility as an objective acuity estimator, especially in pre-verbal children or patients of any age with motor or learning impairments which prevent reliable measurement of behavioural acuity. Its diagnostic power depends heavily on adequate, age-stratified, reference data, age-stratified empirical calibration with behavioural acuity, and interpretation in the light of other electrophysiological and clinical findings. Future developments could encompass faster, more objective and robust techniques such as real-time, adaptive control.
REGISTRATION
International prospective register of systematic reviews PROSPERO ( https://www.crd.york.ac.uk/PROSPERO/ ), registration number CRD42018085666.
Topics: Adult; Amblyopia; Child; Child, Preschool; Electroretinography; Evoked Potentials, Visual; Humans; Infant; Vision, Ocular; Visual Acuity
PubMed: 32488810
DOI: 10.1007/s10633-020-09770-3 -
Australian Journal of General Practice Aug 2019Ocular dysfunction, including eye movement defects, has been documented in up to 69% of patients with concussion. However, standard sports-related concussion assessment...
BACKGROUND
Ocular dysfunction, including eye movement defects, has been documented in up to 69% of patients with concussion. However, standard sports-related concussion assessment protocols do not typically include any clinical examination of the ocular system.
OBJECTIVE
The aim of this article is to inform general practitioners (GPs) about ocular defects associated with concussion, identify test procedures and highlight the important role of GPs within the concussion paradigm.
DISCUSSION
Ocular dysfunction that commonly occurs with concussion includes abnormalities of accommodation, convergence, saccades and smooth pursuits. This may cause blurred vision, double vision, ocular pain and difficulty with close work. Symptoms can severely affect daily work, school or play activities. Patients complaining of extended ocular symptoms following concussion should be referred to an ophthalmologist for a complete ocular assessment.
Topics: Accommodation, Ocular; Brain Concussion; Humans; Oculomotor Muscles; Physical Examination; Saccades; Vision Disorders
PubMed: 31370123
DOI: 10.31128/AJGP-03-19-4876 -
Therapeutic Advances in Ophthalmology 2021Myopia is far beyond its inconvenience and represents a true, highly prevalent, sight-threatening ocular condition, especially in Asia. Without adequate interventions,... (Review)
Review
Myopia is far beyond its inconvenience and represents a true, highly prevalent, sight-threatening ocular condition, especially in Asia. Without adequate interventions, the current epidemic of myopia is projected to affect 50% of the world population by 2050, becoming the leading cause of irreversible blindness. Although blurred vision, the predominant symptom of myopia, can be improved by contact lenses, glasses or refractive surgery, corrected myopia, particularly high myopia, still carries the risk of secondary blinding complications such as glaucoma, myopic maculopathy and retinal detachment, prompting the need for prevention. Epidemiological studies have reported an association between outdoor time and myopia prevention in children. The protective effect of time spent outdoors could be due to the unique characteristics (intensity, spectral distribution, temporal pattern, etc.) of sunlight that are lacking in artificial lighting. Concomitantly, studies in animal models have highlighted the efficacy of light and its components in delaying or even stopping the development of myopia and endeavoured to elucidate possible mechanisms involved in this process. In this narrative review, we (1) summarize the current knowledge concerning light modulation of ocular growth and refractive error development based on studies in human and animal models, (2) summarize potential neurobiological mechanisms involved in the effects of light on ocular growth and emmetropization and (3) highlight a potential pathway for the translational development of noninvasive light-therapy strategies for myopia prevention in children.
PubMed: 34988370
DOI: 10.1177/25158414211059246