The effects of monocular training on binocular functions in anisometropic amblyopia
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Intensive monocular perceptual learning can improve visual acuity, contrast sensitivity, and vernier acuity in the amblyopic eye in adults with amblyopia. It is however not clear how much monocular training can enhance binocular visual functions. In the current study, we aimed to evaluate effects of monocular training on a variety of binocular functions. Nineteen anisometropic amblyopes (18.5±1.26yrs, mean±s.e.) were trained in a grating contrast detection task near each individual's cutoff spatial frequency for 6-10days (630 trials/day). Visual acuity, stereoacuity, monocular and binocular contrast sensitivity functions (CSF), binocular phase combination and binocular rivalry were tested before and after training. Although monocular training can improve visual acuity and contrast sensitivity and eye dominance of the amblyopic eye, the magnitudes of improvements did not correlate with each other; the impact of monocular training on binocular phase combination was not significant. The results strongly suggest that structured monocular and binocular training is needed to fully recover deficient visual functions in anisometropic amblyopia.Keywords:
Monocular
Stereoscopic acuity
Vernier acuity
Binocular rivalry
Anisometropia
Stereoscopic acuity
Anisometropia
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To investigate the effects of anisometropia on binocular function and the relationship between stereopsis and fusion in anisometropia.Twenty-five patients with anisometropia were studied. The manifest refraction and best-corrected Snellen visual acuity of each patient was recorded. Patients, corrected with spectacles, were evaluated using Bagolini glasses, the 4-diopter (D) prism test, Worth four-dot test, and TNO stereotest.All patients indicated fusion by the Bagolini glasses. Although the 4-D prism test was positive in the anisometropic eye of all 25 patients, it was slower than the response of the other eye in 19 patients with reduced stereoacuity. On the distant Worth four-dot test, fusion response was positive in 15 patients. On theTNO test, stereoacuity levels were reduced or absent in 19 patients.The depth of amblyopia is more effective than the amount of anisometropia in causing a deterioration in binocularity. Even if fusion is weak, almost all patients with anisometropia have bifoveal fusion. Fusion becomes weak and stereoacuity decreases in proportion to the anisometropic amblyopia. Stereoacuity is related to the strength of fusion, and the TNO stereotest effectively detects those patients with significant anisometropic amblyopia.
Anisometropia
Stereoscopic acuity
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Objective To determine effects of induced anisometropia on stereopsis to assess the potentially detrimental effects of uncorrected anisometropia on stereoacuity in sailers.Methods Twenty-five healthy adult volunteers,who were 22-34 years old(mean:27 years old)and free of ocular diseases,participated in the study.The different lenses ranging from 1-3 D were planced in front of right eyes of subjects,which leaded to 4 different types of anisometropia(simple hypometropia,simple hypermetropia.Stereoacuity was measured by YAN Shao-ming Digital Stereoscopic Test Charts.Results The levels of stereoacuity decreased in all subjects as the degree of anisometropia increased.One diopter of spherical anisometropia had subjects'stereoaeuity reduced to 50″-54″ and that of cylindrical anisometropia had subjects'stereoacuity reduced to 50″-52″.Regardless of type,three diopters of anisometropia had all suhjeets'stereoacuity reduced significantly.Conclusions Low levels of anisometropia can have potentially significant adverse effect on highgrade binocular vision function in adults.Foveal suppression,which is directly related to the degree of anisometmpia,may be responsible for the reduction of stereopsis.
Key words:
Stereoaeuity; Anisometropia; Sailer
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Stereoscopic acuity
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Purpose:To examine the effect of experimental anisometropia on steroacuity in teenagers using Titmus Stereo Fly Test.Methods: Fifty-six teenage volunteers (ages ranging from 16-19 years) participated in the present study.Placing trial lenses over the dominant eye (from -3.50D to +1D), two different anisometropia types (including myopia and hyperopia), were induced.Steroacuity was measured using the Titmus Stereo Fly Test.Results: In all the anisometropia types, there was a decline in stereopsis as anisometropia increased (p<0.05).The greatest impairment in stereoacuity was due to compound myopic anisometropia, -1.00DS and -3.50DS, +1.00DS and +3.50DS, and +2.00Ds and -2.00DS giving 3552 arc seconds in Titmus circles. Conclusion:Anisometropia reduces stereopsis and compound myopic anisometropia gives the most noticeable change.The impairment had no gender correlation.
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Stereoscopic acuity
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To compare the stereoacuity in patients with anisometropia, isometropia, and emmetropia. A cross-sectional study was conducted on 1403 subjects (range: 5-45 years) divided into anisometropes (n = 403), isometropes (n = 500), and emmetropes (n = 500). There were 258 amblyopic eyes among anisometropes and 156 amblyopic eyes among isometropes. Stereoacuity was measured using the Titmus stereo test consisting of a combination of contour targets. There were 675 males and 728 females. A significant (P < 0.001) reduction in stereoacuity was found in anisometropes as compared to isometropes and emmetropes. The stereoacuity was even worse in amblyopes as compared to non-amblyopes. Most patients with anisometropia of <3.0 D had fair stereoacuity. However, as the degree of anisometropia increased to >3.0 D, stereoacuity deteriorated gradually. Marked reduction of stereoacuity was observed in severe degree of anisometropia (>6.0 D). Overall, an anisometropia of ≥2.12 D was associated with reduced stereoacuity. Among the anisometropes, it was found to be the poorest in myopia, followed by myopia with astigmatism, hypermetropia with astigmatism, and hypermetropia. The level of stereoacuity was worse in anisometropes as compared to isometropes and emmetropes. Amblyopes had a greater reduction in stereoacuity than non-amblyopes. Stereoacuity decreased as the degree of anisometropia increased. Among the anisometropes, myopes had worst stereoacuity than hypermetropes.
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Stereoscopic acuity
Emmetropia
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ABSTRACT Purpose: To determine the effects of experimentally induced anisometropia on stereopsis in healthy adults to assess the potentially detrimental effects of uncorrected anisometropia on the development of stereoacuity during childhood. Methods: Twenty-one healthy adult volunteers ranging in age from 22-34 years (mean: 27 years) and free of ocular disease participated in the study. Four different types of anisometropia (unilateral myopia, unilateral hyperopia, or unilateral astigmatism [90° or 45°]) were induced in random order by placing trial lenses over the right eye in 1 diopter (D) increments ranging from 1-3 D. Stereoacuity was measured using the Titmus stereotest with patients placing the cross-polarizing stereoacuity glasses over their lenses or trial frames. Results: Stereoacuity levels were reduced in proportion to the degree of anisometropia in all patients. One diopter of spherical anisometropia reduced stereoacuity to an average 57-59 arc seconds; 1 D of cylindrical anisometropia reduced stereoacuity to an average 51-56 arc seconds. Three diopters of anisometropia, regardless of type, produced a marked reduction of stereoacuity in all patients. Conclusions: Low levels of anisometropia, both spherical and astigmatic, can have potentially significant adverse effects on high-grade binocular interaction in adults. Foveal suppression, which is directly related to the degree of anisometropia, may be responsible for the loss of stereopsis. The data suggest the effects of anisometropia on stereopsis should be considered in the empiric correction of anisometropic refractive errors in children. Journal of Pediatric Ophthalmology and Strabismus 2000;37:214-218.
Anisometropia
Stereoscopic acuity
Astigmatism
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Purpose: To compare the stereoacuity between patients with uncorrected and corrected non-amblyopic anisometropia, and to evaluate the correlation between the degrees of anisometropia and stereoacuity.Methods: We retrospectively reviewed the records of patients with non-amblyopic anisometropia who underwent the stereoacuity test. Patients were divided into uncorrected anisometropia (n = 33) and corrected by spectacles (n = 30) groups. The clinical characteristics and sensory status of patients were evaluated using the Worth 4-dot, Titmus, Lang II, and TNO tests, and compared between the groups. Correlation analysis was performed between the degree of anisometropia and the level of stereopsis.Results: The uncorrected and corrected anisometropia groups did not significantly differ in mean age (12.2 ± 3.7 and 11.8 ± 4.0 years) or degree of anisometropia (2.12 ± 1.21 and 1.81 ± 1.25 diopters). The rate of sensory fusion in the distant Worth 4-dot test was lower in the uncorrected anisometropia than the corrected anisometropia group. The level of stereopsis was also worse in the uncorrected anisometropia than the corrected anisometropia group in all stereoacuity tests. There was a strong positive correlation between the degree of anisometropia and the level of stereoacuity on the Titmus, Lang II, and TNO tests (r = 0.690, r = 0.614, and r = 0.655, respectively; all p < 0.001) in the uncorrected anisometropia group. However, the corrected anisometropia group showed a weak positive correlation between the degree of anisometropia and the level of stereoacuity only on the TNO test (r = 0.366; p = 0.047).Conclusions: Stereoacuity was better in the corrected anisometropia group than in the uncorrected group. It significantly worsened with increasing anisometropia in the uncorrected group, but only a weak correlation was observed in the corrected group. Therefore, prescribing glasses could be recommended to improve stereopsis in adolescents and young adults with anisometropia.
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To investigate the relationship between stereoacuity and factors associated with anisometropic amblyopia in children aged 4-8 years.44 participants had their stereoacuity thresholds measured using the Frisby Near Stereotest (FNS) and the TNO Randot Stereotest (TNO). Participants were divided into anisometropic amblyopes and controls (normal uniocular visual acuity (VA) with or without glasses). FNS and TNO stereoacuity thresholds were compared based on different factors, which included interocular acuity difference (IAD), VA levels, and the degree of anisometropia.All 44 participants achieved better stereoacuity with the FNS compared to the TNO (p = 0.045). The control group performed significantly better on the FNS (p = 0.012) and the TNO (p = 0.009) when compared with anisometropic amblyopes. The only statistically significant correlation was found between stereoacuity - as measured with FNS - and IAD (p = 0.009). However, the TNO showed a correlation in the presence of poor VA, larger IADs and a high degree of anisometropia.Stereoacuity thresholds are significantly affected by poor VA, large IAD and high degrees of spherical anisometropia when trying to distinguish the resolution of a target with the TNO yet the same factors do not appear to affect ability to distinguish the disparity of a target with the FNS. Controls also performed worse on the TNO.
Stereoscopic acuity
Anisometropia
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To assess the effect of experimental anisometropia and monovision on stereopsis using the Titmus, Randot, and TNO stereoacuity tests.Sixty adult volunteers were enrolled in the present study. Four different types of anisometropia-myopia, hyperopia, and astigmatism (both 90° and 45°)-were induced by placing trial lenses over the dominant eye (from 3 to 1 D). Stereoacuity was measured using the Titmus, Randot, and TNO tests.In all the anisometropia types, stereopsis deteriorated with increase in anisometropia in the three stereoacuity tests performed (P < 0.001). The largest decrease in stereopsis was attributed to 3 D myopic anisometropia-6.51 ± 2.10, 6.59 ± 2.35, and 7.36 ± 1.89 arc seconds in Titmus circles, Randot circles, and TNO, respectively. Minimal change in stereopsis was observed in 1 D astigmatism of 45°.Any type of anisometropia may reduce stereoacuity; this reduction is most noticeable with myopic anisometropia, especially in the TNO test, probably due to the lack of monocular cues.
Anisometropia
Stereoscopic acuity
Astigmatism
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