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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 -
Clinical & Experimental Optometry Jul 2014Antimetropia, a sub-classification of anisometropia, is a rare refractive condition in which one eye is myopic and the fellow eye is hyperopic. This case report... (Review)
Review
Antimetropia, a sub-classification of anisometropia, is a rare refractive condition in which one eye is myopic and the fellow eye is hyperopic. This case report describes the ocular characteristics and atypical refractive progression in an adult male with a moderate degree of non-amblyopic antimetropia over a 20-year period. The potential mechanisms underlying unilateral axial elongation, anisometropia and myopia progression in adulthood are discussed.
Topics: Adult; Anisometropia; Axial Length, Eye; Disease Progression; Humans; Male; Middle Aged; Refraction, Ocular
PubMed: 24438511
DOI: 10.1111/cxo.12129 -
The British and Irish Orthoptic Journal 2020Clinically, aniseikonia (a perceived difference in shape and image size between the eyes) is often neglected in anisometropic amblyopia due to assumed measurement...
PURPOSE
Clinically, aniseikonia (a perceived difference in shape and image size between the eyes) is often neglected in anisometropic amblyopia due to assumed measurement difficulties. Therefore, we currently lack evidence on whether correction of aniseikonia is beneficial. This study aimed to determine whether subjective aniseikonia is measurable in anisometropia with or without amblyopia.
METHODS
Participants (15-52 years) with Anisometropic Amblyopia (n = 7), Anisometropia without amblyopia (n = 6) and Isometropic Controls (n = 6) were recruited. Subjective aniseikonia was measured using three clinical techniques: Robertson Technique (RT) (penlight and Maddox rod), Aniseikonia Inspector Version 3 (AI3), and the New Aniseikonia Test booklet (NAT), and a psychophysical adaptive method, the Contrast-balanced Aniseikonia Test (CAT), where dichoptic contrast adjustments compensate for any suppression.
RESULTS
Eighteen participants completed all tests, one Anisometropic Amblyopia participant could only complete the CAT and NAT due to fusion loss. The Anisometropic Amblyopia group exhibited the most aniseikonia (range -1.50-+10.50%) followed by Anisometropic Controls (range -3.30-+4.50%) and Isometropic Controls (range -1.50-+3.28%). There was a significant trend of more subjective aniseikonia with increasing amounts of anisometropia across all four tests (AI3 r = 0.630, p = 0.005; NAT r = 0.542, p = 0.017; RT r = 0.499, p = 0.035; CAT r = 0.440, p = 0.059. Bland Altman analysis demonstrated clinically significant levels of variability between the tests.
CONCLUSIONS
Subjective aniseikonia can be reliably measured in patients with anisometropia and suppression. Subjective aniseikonia measurement is recommended as four of the most commonly used clinical tests did not support the 1% per dioptre rule of thumb.
PubMed: 34278210
DOI: 10.22599/bioj.154 -
GMS Ophthalmology Cases 2020To report two cases of vitreous cysts with discussion of their pathophysiology and management. Clinical examination with fundus photography, ultrasound and optical...
To report two cases of vitreous cysts with discussion of their pathophysiology and management. Clinical examination with fundus photography, ultrasound and optical coherence tomography. Histopathology was performed in the first case. The first case illustrates a pigmented, free-floating cyst, which was removed during a 27-gauge vitrectomy. The histopathology shows a single layer of pigmented epithelium and confirms the previously reported presence of a PAS-positive basement membrane. The second case shows a sessile, non-pigmented cyst associated with significant anisometropia. Primary vitreous cysts are rare and can have a wide range in their clinical aspect. This likely reflects whether they originate either from the pigment epithelium or the primary hyaloidal system. The management of vitreous cysts is mostly conservative, but pars plana vitrectomy can be used safely if the symptoms are debilitating.
PubMed: 32676263
DOI: 10.3205/oc000145 -
Frontiers in Public Health 2022To investigate anisometropia's prevalence and associated factors in school-aged children.
OBJECTIVE
To investigate anisometropia's prevalence and associated factors in school-aged children.
METHODS
A cross-sectional school-based study was conducted in Shandong Province, China, including children aged 4 to 17 from 9 schools. Anisometropia was defined as the differences between the two eyes in spherical equivalent (SE) or cylinder degree of 1.00 diopter (D) or more [SE or cylindrical (CYL) difference ≥ 1.00 D] after cycloplegic autorefraction. The Generalized Linear Model (GLM) was used to analyze the effects of ocular parameters [the differences between eyes in axial length (AL), habitual visual acuity (HVA), and corneal astigmatism (CA)] and lifestyle parameters (time spent indoor near work and outdoor activities) on anisometropia.
RESULTS
Total 4,198 (93.4%) of the 4,494 children were included in the statistical analysis. The mean difference in inter-eye SE was 0.42 ± 0.61 D. The prevalence of anisometropia was 13.2% (95%CI: 12.1 to 14.2%) (SE anisometropia's prevalence:10.3%; CYL anisometropia's prevalence: 4.1%), increased with older age (OR = 1.10, = 0.002), the worse myopic eye (myopia vs. premyopia, OR = 1.87, = 0.002), the worse hyperopic eye (hyperopia vs. premyopia, OR = 1.77, = 0.013), larger difference in inter-eye AL (0.1-0.3 vs. ≤ 0.1, OR = 1.67, = 0.008; >0.3 vs. ≤ 0.1, OR = 28.61, < 0.001), HVA (>0.2 vs. ≤ 0.2, OR = 3.01, < 0.001), CA (OR = 6.24, < 0.001), the worse stereoacuity (>100 vs. ≤ 100, OR = 1.59, = 0.001), longer indoor near work time per day on weekends (4-8 vs. <4, OR = 1.41, = 0.038; ≥8 vs. <4, OR = 1.40, = 0.131), and shorter outdoor activity time per day on weekdays (≥1 vs. <1, OR = 0.75, = 0.046) in multivariable analysis. In the SE anisometropia group, the difference in inter-eye AL (>0.3 vs. ≤ 0.1, β: 0.556, 95%CI: 0.050 to 1.063), HVA (>0.2 vs. ≤ 0.2, β: 0.511, 95%CI: 0.312 to 0.710), and CA (β: 0.488, 95%CI: 0.289 to 0.688), stereoacuity (>100 vs. ≤ 100, β: 0.299, 95%CI: 0.110 to 0.488) had a positive impact on the difference in inter-eye SE.
CONCLUSIONS
Ocular parameters and lifestyle parameters are associated with the occurrence of anisometropia in children aged 4 to 17 years, including the difference in inter-eye AL, HVA, CA, stereoacuity, indoor near work time, and outdoor activity time. Preventing myopia and early treating anisometropic amblyopia may be effective ways to reduce the prevalence of anisometropia.
Topics: Humans; Child; Anisometropia; Prevalence; Cross-Sectional Studies; Amblyopia; Astigmatism; Myopia
PubMed: 36620276
DOI: 10.3389/fpubh.2022.1072574 -
Clinical & Experimental Optometry Jul 2014Anisometropia represents a unique example of ocular development, where the two eyes of an individual, with an identical genetic background and seemingly subject to... (Review)
Review
Anisometropia represents a unique example of ocular development, where the two eyes of an individual, with an identical genetic background and seemingly subject to identical environmental influences, can grow asymmetrically to produce significantly different refractive errors. This review provides an overview of the research examining myopic anisometropia, the ocular characteristics underlying the condition and the potential aetiological factors involved. Various mechanical factors are discussed, including corneal structure, intraocular pressure and forces generated during near work that may contribute to development of anisomyopia. Potential visually guided mechanisms of unequal ocular growth are also explored, including the influence of astigmatism, accommodation, higher-order aberrations and the choroidal response to altered visual experience. The association between binocular vision, ocular dominance and asymmetric refraction is also considered, along with a review of the genetic contribution to the aetiology of myopic anisometropia. Despite a significant amount of research into the biomechanical, structural and optical characteristics of anisometropic eyes, there is still no unifying theory, which adequately explains how two eyes within the same visual system grow to different endpoints.
Topics: Accommodation, Ocular; Animals; Anisometropia; Humans; Myopia; Refraction, Ocular
PubMed: 24939167
DOI: 10.1111/cxo.12171 -
Indian Journal of Ophthalmology Feb 2022To assess the level of stereopsis in school children with spectacle-corrected refractive errors using Titmus fly and Randot stereo tests, evaluate the factors associated...
PURPOSE
To assess the level of stereopsis in school children with spectacle-corrected refractive errors using Titmus fly and Randot stereo tests, evaluate the factors associated with the level of stereopsis, and determine the level of agreement between the two tests.
METHODS
A cross-sectional study was done on 5- to 18-year-old school-children wearing spectacles for at least 1-month duration. Visual acuity was assessed using Snellen's visual acuity chart, and their spectacle correction being used currently was measured using an auto lensmeter. The level of stereopsis was assessed using Randot and Titmus fly stereo tests. Data were entered using Microsoft Excel and analyzed using IBM-SPSS version 20, Chicago, IL. The associations between stereopsis and type of refractive error, visual acuity, age, and gender were analyzed. An agreement between Randot and Titmus fly test was done using Kappa statistics.
RESULTS
A total of 222 children (101 boys and 121 girls; mean age 13 years) were assessed. Astigmatism was the most prevalent refractive error (60.4%), followed by myopia (24.8%) and hypermetropia (1.4%). Thirty children (13.5%) had anisometropia. All hyperopes had normal stereopsis. Children with spherical myopia had better stereopsis, followed by astigmatism and anisometropia in the same order (P = 0.036). Children with anisometropia ≤1.5 D had better stereopsis than anisometropia more than 1.5 D. Stereopsis was also found to have no correlation with the age and visual acuity at the time of testing or the age at which the child first started wearing spectacles. Stereopsis values obtained from Randot and Titmus fly stereo tests showed moderate agreement with Kappa value 0.581.
CONCLUSION
Anisometropia and astigmatism are the most critical factors determining the level of stereopsis in refractive errors.
Topics: Adolescent; Anisometropia; Child; Cross-Sectional Studies; Depth Perception; Eyeglasses; Humans; Refractive Errors
PubMed: 35086245
DOI: 10.4103/ijo.IJO_997_21 -
Vision Research Jan 2011Amblyopia is usually associated with the presence of anisometropia, strabismus or both early in life. We set out to explore quantitative relationships between the degree...
Amblyopia is usually associated with the presence of anisometropia, strabismus or both early in life. We set out to explore quantitative relationships between the degree of anisometropia and the loss of visual function, and to examine how the presence of strabismus affects visual function in observers with anisometropia. We measured optotype acuity, Pelli-Robson contrast sensitivity and stereoacuity in 84 persons with anisometropia and compared their results with those of 27 persons with high bilateral refractive error (isoametropia) and 101 persons with both strabismus and anisometropia. All subjects participated in a large-scale study of amblyopia (McKee et al., 2003). We found no consistent visual abnormalities in the strong eye, and therefore report only on vision in the weaker, defined as the eye with lower acuity. LogMAR acuity falls off markedly with increasing anisometropia in non-strabismic anisometropes, while contrast sensitivity is much less affected. Acuity degrades rapidly with increases in both hyperopic and myopic anisometropia, but the risk of amblyopia is about twice as great in hyperopic than myopic anisometropes of comparable refractive imbalance. For a given degree of refractive imbalance, strabismic anisometropes perform considerably worse than anisometropes without strabismus--visual acuity for strabismics was on average 2.5 times worse than for non-strabismics with similar anisometropia. For observers with equal refractive error in the two eyes there is very little change in acuity or sensitivity with increasing (bilateral) refractive error except for one extreme individual (bilaterally refractive error of -15 D). Most pure anisometropes with interocular differences less than 4D retain some stereopsis, and the degree is correlated with the acuity of the weak eye. We conclude that even modest interocular differences in refractive error can influence visual function.
Topics: Amblyopia; Anisometropia; Contrast Sensitivity; Depth Perception; Humans; Refractive Errors; Strabismus; Visual Acuity
PubMed: 20932989
DOI: 10.1016/j.visres.2010.09.029 -
Cureus Sep 2022The aim of this article is to report two cases of Straatsma syndrome, a rare disease characterized by the traditional triad of unilateral myelinated retinal nerve...
The aim of this article is to report two cases of Straatsma syndrome, a rare disease characterized by the traditional triad of unilateral myelinated retinal nerve fibres, axial myopia, and amblyopia. The cases were a five-year-old and a three-year-old girl, both with unilateral myopia, visual acuity of 0.1 (decimal), and myelinated retinal nerve fibres in fundoscopy. Prescription of cycloplegic refraction findings and occlusion of the involved eye was attempted in both cases, but visual acuity did not improve. Poor-prognostic factors of Straatsma syndrome include a high degree of anisometropia and extensive myelination.
PubMed: 36340550
DOI: 10.7759/cureus.29779 -
Turkish Journal of Ophthalmology Feb 2018To evaluate the risk factors for strabismus in patients with anisometropia by comparing degree of anisometropia, depth of amblyopia, and binocular visual function in...
OBJECTIVES
To evaluate the risk factors for strabismus in patients with anisometropia by comparing degree of anisometropia, depth of amblyopia, and binocular visual function in anisometropic patients with and without strabismus.
MATERIALS AND METHODS
Sixty-five anisometropic patients older than 5 years with amblyopia in one eye who were followed in the Ankara University Faculty of Medicine, Department of Ophthalmology, Pediatric Ophthalmology and Strabismus Unit between May 2009 and April 2010 were included in this study. There were 27 cases of strabismus. The depth of amblyopia, degree of anisometropia, and binocular visual function were assessed in anisometropic cases with and without strabismus.
RESULTS
The 65 patients with anisometropia were divided into two groups: 27 patients with strabismus (group 1) and 38 patients without (group 2). Depth of amblyopia was greater in patients with strabismus compared to those without (p=0.006). In patients with strabismus, there was no correlation between angle of deviation and depth of amblyopia (p=0.453). In anisometropic amblyopia patients without strabismus, there was a positive correlation between depth of anisometropia and depth of amblyopia (p=0.35, Pearson's correlation coefficient=0.343). Comparison in terms of anisometropia showed that patients with strabismus had significantly larger spherical difference between the two eyes than in patients without strabismus (p=0.000, Mann-Whitney U test). There was no significant difference in terms of cylindrical values (p=0.146, Mann-Whitney U test). There was no statistically significant difference in the presence of fusion between anisometropic patients with and without strabismus.
CONCLUSION
The risk of developing strabismus increased as degree of anisometropia increased in anisometropic cases. In addition, depth of amblyopia was greater in anisometropic patients with strabismus.
PubMed: 29576894
DOI: 10.4274/tjo.44342