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Deutsches Arzteblatt International Oct 2016All over the world, refractive errors are among the most frequently occuring treatable distur - bances of visual function. Ametropias have a prevalence of nearly 70%... (Review)
Review
BACKGROUND
All over the world, refractive errors are among the most frequently occuring treatable distur - bances of visual function. Ametropias have a prevalence of nearly 70% among adults in Germany and are thus of great epidemiologic and socio-economic relevance.
METHODS
In the light of their own clinical experience, the authors review pertinent articles retrieved by a selective literature search employing the terms "ametropia, "anisometropia," "refraction," "visual acuity," and epidemiology."
RESULTS
In 2011, only 31% of persons over age 16 in Germany did not use any kind of visual aid; 63.4% wore eyeglasses and 5.3% wore contact lenses. Refractive errors were the most common reason for consulting an ophthalmologist, accounting for 21.1% of all outpatient visits. A pinhole aperture (stenopeic slit) is a suitable instrument for the basic diagnostic evaluation of impaired visual function due to optical factors. Spherical refractive errors (myopia and hyperopia), cylindrical refractive errors (astigmatism), unequal refractive errors in the two eyes (anisometropia), and the typical optical disturbance of old age (presbyopia) cause specific functional limitations and can be detected by a physician who does not need to be an ophthalmologist.
CONCLUSION
Simple functional tests can be used in everyday clinical practice to determine quickly, easily, and safely whether the patient is suffering from a benign and easily correctable type of visual impairment, or whether there are other, more serious underlying causes.
Topics: Astigmatism; Eyeglasses; Germany; Humans; Prevalence; Refractive Errors; Visual Acuity
PubMed: 27839543
DOI: 10.3238/arztebl.2016.0693 -
Vision Research Sep 2015Amblyopia is a neuro-developmental disorder of the visual cortex that arises from abnormal visual experience early in life. Amblyopia is clinically important because it... (Review)
Review
Amblyopia is a neuro-developmental disorder of the visual cortex that arises from abnormal visual experience early in life. Amblyopia is clinically important because it is a major cause of vision loss in infants and young children. Amblyopia is also of basic interest because it reflects the neural impairment that occurs when normal visual development is disrupted. Amblyopia provides an ideal model for understanding when and how brain plasticity may be harnessed for recovery of function. Over the past two decades there has been a rekindling of interest in developing more effective methods for treating amblyopia, and for extending the treatment beyond the critical period, as exemplified by new clinical trials and new basic research studies. The focus of this review is on stereopsis and its potential for recovery. Impaired stereoscopic depth perception is the most common deficit associated with amblyopia under ordinary (binocular) viewing conditions (Webber & Wood, 2005). Our review of the extant literature suggests that this impairment may have a substantial impact on visuomotor tasks, difficulties in playing sports in children and locomoting safely in older adults. Furthermore, impaired stereopsis may also limit career options for amblyopes. Finally, stereopsis is more impacted in strabismic than in anisometropic amblyopia. Our review of the various approaches to treating amblyopia (patching, perceptual learning, videogames) suggests that there are several promising new approaches to recovering stereopsis in both anisometropic and strabismic amblyopes. However, recovery of stereoacuity may require more active treatment in strabismic than in anisometropic amblyopia. Individuals with strabismic amblyopia have a very low probability of improvement with monocular training; however they fare better with dichoptic training than with monocular training, and even better with direct stereo training.
Topics: Adult; Age Factors; Amblyopia; Anisometropia; Child; Depth Perception; Humans; Strabismus; Vision, Binocular; Visual Acuity
PubMed: 25637854
DOI: 10.1016/j.visres.2015.01.002 -
Investigative Ophthalmology & Visual... Jan 2021To explore the association of choroidal vascularity and choriocapillaris blood perfusion with myopic severity in anisomyopes.
PURPOSE
To explore the association of choroidal vascularity and choriocapillaris blood perfusion with myopic severity in anisomyopes.
METHODS
Refractive error, axial length (AL), and other biometric parameters were measured in 34 anisomyopic young adults. Macular choroidal thickness (ChT) and choroidal vascularity, including total choroidal area (TCA), luminal area (LA), stromal area (SA), and choroidal vascularity index (CVI), were determined from swept-source optical coherence tomography (SS-OCT) vertical and horizontal B-scans. The percentage of choriocapillaris flow voids (FV%) was obtained from en face SS-OCT-angiography.
RESULTS
The spherical equivalent refraction (SER) was -3.35 ± 1.25 diopters in the more myopic eyes and -1.25 ± 1.17 diopters in the less myopic eyes (P < 0.001). The interocular difference in SER was highly correlated with that in AL (P < 0.001). The macular ChT, TCA, LA, and SA were smaller in the more myopic eyes than in the less myopic eyes in both vertical and horizontal scans (all P < 0.001). Importantly, the CVIs in vertical and horizontal scans were smaller and the FV% was greater in the more myopic eyes (P < 0.05). In vertical scans, the interocular difference in CVIs was correlated with that in the SER, AL, and ChT (all P < 0.05). The interocular difference in FV% was correlated with that in SER, AL, and vertical and horizontal ChTs (all P < 0.05).
CONCLUSIONS
Choroidal vascularity and choriocapillaris blood perfusion were lower in the more myopic eyes of anisomyopic adults. These changes were correlated with the severity of myopia and choroidal thinning, indicating that choroidal blood flow is disturbed in human myopia.
Topics: Adult; Anisometropia; Biometry; Blood Physiological Phenomena; Choroid; Female; Fluorescein Angiography; Humans; Male; Myopia; Refraction, Ocular; Regional Blood Flow; Tomography, Optical Coherence; Young Adult
PubMed: 33393974
DOI: 10.1167/iovs.62.1.8 -
Acta Ophthalmologica Jun 2020This study examines aniseikonia, Aniseikonia tolerance range (ATR), anisometropia and patient-reported outcomes (PRO) in an anisometropic population compared with a... (Comparative Study)
Comparative Study Observational Study
PURPOSE
This study examines aniseikonia, Aniseikonia tolerance range (ATR), anisometropia and patient-reported outcomes (PRO) in an anisometropic population compared with a non-anisometropic population. The relationship between anisometropia and aniseikonia is determined, and the correlations between aniseikonia, anisometropia and ATR versus PRO are described.
METHODS
One hundred and twenty-three patients with IOL-induced anisometropia ≥1 dioptre (D) (the anisometropic group) and 17 patients who had IOL-induced anisometropia <1 D (the control group) were included. Best corrected visual acuity, aniseikonia, ATR and stereoacuity were examined, and two questionnaires were completed: convergence insufficiency symptom survey (CISS) and Visual Function Questionnaire (VFQ-39).
RESULTS
One hundred and thirteen patients had anisometropia >1 and <3 D, and 10 patients had anisometropia >3 D. There was no difference in PRO between the control group and the anisometropic group (Mann-Whitney, p-values VFQ: 0.96, CISS: 0.06). There was no correlation between anisometropia and PRO (Spearman's rank correlation test p-values: VFQ: 0.54, CISS: 0.57). Patients with low ATR were more sensitive towards anisometropia and had lower PRO than patients with high ATR (Mann-Whitney, p-values: VFQ: 0.0008, CISS: 0.11). A large tolerance of aniseikonia was observed.
CONCLUSION
No correlation between PRO and anisometropia or aniseikonia was found. Patients with low ATR are at risk of visual complaints if they are exposed to IOL-induced anisometropia. ATR might be a future screening tool in cataract patients.
Topics: Adult; Anisometropia; Female; Humans; Male; Retrospective Studies; Vision, Binocular; Visual Acuity
PubMed: 31773911
DOI: 10.1111/aos.14310 -
Clinical & Experimental Optometry Nov 2019Aniseikonia is a difference in the perceived size or shape of images between eyes, and can arise from a variety of physiological, neurological, retinal, and optical... (Review)
Review
Aniseikonia is a difference in the perceived size or shape of images between eyes, and can arise from a variety of physiological, neurological, retinal, and optical causes. Aniseikonia is associated with anisometropia, as both anisometropia itself and the optical correction for anisometropia can cause aniseikonia. Image size differences above one to three per cent can be clinically symptomatic. Common symptoms include asthenopia, headache and diplopia in vertical gaze. Size differences of three and more impair binocular visual functions such as binocular summation and stereopsis. Above five per cent of aniseikonia, binocular inhibition or suppression tend to occur to prevent diplopia and confusion. Aniseikonia can be measured using a range of techniques and can be corrected or reduced by prescribing contact lenses or specially designed spectacle lenses. Subjective testing of aniseikonia is the only way to accurately measure the overall perceived amount of aniseikonia. However, currently it is not routinely assessed in most clinical settings. At least two-thirds of patients with amblyopia have anisometropia, thus we may expect aniseikonia to be common in patients with anisometropic amblyopia. However, aniseikonia may not be experienced by the patient under normal binocular viewing conditions if the image from the amblyopic eye is of poor quality or is too strongly suppressed for image size differences to be recognised. This lack of binocular simultaneous perception in amblyopia may also prevent the measurement of aniseikonia, as most common techniques require direct comparisons of images seen by each eye. Current guidelines for the treatment of amblyopia advocate full correction of anisometropia to equalise image clarity, but do not address aniseikonia. Significant image size differences between eyes may lead to suppression and abnormal binocular adaptations. It is possible that correcting anisometropia and aniseikonia simultaneously, particularly at the initial diagnosis of anisometropia, would reduce the need to develop suppression and improve treatment outcomes for anisometropic amblyopia.
Topics: Amblyopia; Aniseikonia; Anisometropia; Humans
PubMed: 30791133
DOI: 10.1111/cxo.12881 -
Vision Research May 2017We investigated the potential causal relationships between anisometropia, amblyopia and strabismus, specifically to determine whether either amblyopia or strabismus... (Review)
Review
We investigated the potential causal relationships between anisometropia, amblyopia and strabismus, specifically to determine whether either amblyopia or strabismus interfered with emmetropization. We analyzed data from non-human primates that were relevant to the co-existence of anisometropia, amblyopia and strabismus in children. We relied on interocular comparisons of spatial vision and refractive development in animals reared with 1) monocular form deprivation; 2) anisometropia optically imposed by either contact lenses or spectacle lenses; 3) organic amblyopia produced by laser ablation of the fovea; and 4) strabismus that was either optically imposed with prisms or produced by either surgical or pharmacological manipulation of the extraocular muscles. Hyperopic anisometropia imposed early in life produced amblyopia in a dose-dependent manner. However, when potential methodological confounds were taken into account, there was no support for the hypothesis that the presence of amblyopia interferes with emmetropization or promotes hyperopia or that the degree of image degradation determines the direction of eye growth. To the contrary, there was strong evidence that amblyopic eyes were able to detect the presence of a refractive error and alter ocular growth to eliminate the ametropia. On the other hand, early onset strabismus, both optically and surgically imposed, disrupted the emmetropization process producing anisometropia. In surgical strabismus, the deviating eyes were typically more hyperopic than their fellow fixating eyes. The results show that early hyperopic anisometropia is a significant risk factor for amblyopia. Early esotropia can trigger the onset of both anisometropia and amblyopia. However, amblyopia, in isolation, does not pose a significant risk for the development of hyperopia or anisometropia.
Topics: Amblyopia; Animals; Anisometropia; Disease Models, Animal; Macaca; Strabismus; Visual Acuity
PubMed: 28404522
DOI: 10.1016/j.visres.2017.03.004 -
F1000Research 2021This research was developed to study the epidemiology of anisometropia. It aims to estimate the prevalence of anisometropia in Portuguese children and adolescents at... (Observational Study)
Observational Study
This research was developed to study the epidemiology of anisometropia. It aims to estimate the prevalence of anisometropia in Portuguese children and adolescents at various educational stages, studying its association with sociodemographic variables. Observational cross sectional study envolving 749 children and adolescents (from 3 to 16 years old) from the central region of Portugal. The refraction was performed with a paediatric, open field auto refractometer (PlusOptix), without cycloplegia and under binocular conditions, to determine the rate of anisometropia and its association with gender, study cycle and area of residence. The prevalence of anisometropia in the studied sample was 6.1%, varying from 2.9% in pre-school education to 9.4% in the 3rd study cycle. Myopic anisometropia was the most prevalent and hyperopic and astigmatic anisometropia showed identical proportions of occurrence. No statistical differences were found between genders or between areas of residence regarding the rate of anisometropia. Regarding spherical equivalent anisometropia, there was a pattern of variation that increased with the cycle of studies (p = 0.012), with myopic anisometropia being the main contributor to this variation. This study found an increase in anisometropia with the educational stage. The high rate of anisometropia found in adolescents (9.4%) as well as the progressive increase in this rate throughout school progress (from 2.9% to 9.4%) suggests the need to extend the detection strategies of this condition beyond childhood.
Topics: Adolescent; Anisometropia; Child; Child, Preschool; Cross-Sectional Studies; Female; Humans; Male; Myopia; Prevalence; Refraction, Ocular
PubMed: 35035896
DOI: 10.12688/f1000research.73657.4 -
Progress in Retinal and Eye Research Sep 2013This review aims to disentangle cause and effect in the relationship between anisometropia and amblyopia. Specifically, we examine the literature for evidence to support... (Review)
Review
This review aims to disentangle cause and effect in the relationship between anisometropia and amblyopia. Specifically, we examine the literature for evidence to support different possible developmental sequences that could ultimately lead to the presentation of both conditions. The prevalence of anisometropia is around 20% for an inter-ocular difference of 0.5D or greater in spherical equivalent refraction, falling to 2-3%, for an inter-ocular difference of 3D or above. Anisometropia prevalence is relatively high in the weeks following birth, in the teenage years coinciding with the onset of myopia and, most notably, in older adults starting after the onset of presbyopia. It has about one-third the prevalence of bilateral refractive errors of the same magnitude. Importantly, the prevalence of anisometropia is higher in highly ametropic groups, suggesting that emmetropization failures underlying ametropia and anisometropia may be similar. Amblyopia is present in 1-3% of humans and around one-half to two-thirds of amblyopes have anisometropia either alone or in combination with strabismus. The frequent co-existence of amblyopia and anisometropia at a child's first clinical examination promotes the belief that the anisometropia has caused the amblyopia, as has been demonstrated in animal models of the condition. In reviewing the human and monkey literature however it is clear that there are additional paths beyond this classic hypothesis to the co-occurrence of anisometropia and amblyopia. For example, after the emergence of amblyopia secondary to either deprivation or strabismus, anisometropia often follows. In cases of anisometropia with no apparent deprivation or strabismus, questions remain about the failure of the emmetropization mechanism that routinely eliminates infantile anisometropia. Also, the chronology of amblyopia development is poorly documented in cases of 'pure' anisometropic amblyopia. Although indirect, the therapeutic impact of refractive correction on anisometropic amblyopia provides strong support for the hypothesis that the anisometropia caused the amblyopia. Direct evidence for the aetiology of anisometropic amblyopia will require longitudinal tracking of at-risk infants, which poses numerous methodological and ethical challenges. However, if we are to prevent this condition, we must understand the factors that cause it to develop.
Topics: Adolescent; Adult; Age Factors; Amblyopia; Anisometropia; Child; Child, Preschool; Humans; Infant; Prevalence; Refractive Errors; Risk Factors
PubMed: 23773832
DOI: 10.1016/j.preteyeres.2013.05.001