The Consistency of Retinal Image Size Measurement Using Smartphone Application

@#Introduction: Unequal retinal image size (RIS) or aniseikonia is usually related with anisometropia. Higher differences of RIS may manifest symptoms such as dizziness, headache or disorientation. In worst case might cause suppression that leads to amblyopia. Current study aims to evaluate the consistency of aniseikonia measurement in Smart Optometry smartphone application among myopic, hyperopic, and astigmatic simulated anisometropia and real anisometropia groups. Methods: Fifteen real anisometropes (refractive error; -0.50 until -6.00 diopters; D) and fifteen emmetropes (refractive error: -0.25 until +0.50D) were recruited. Real anisometropes wore their habitual spectacle correction while each emmetropes were fitted using soft contact lenses of +4.00DS, -4.00DS and -4.00DC with base curve 8.6 and total diameter 14.2mm in random order to mimic myopic-, hyperopic- and astigmatic-anisometropia before testing. Participants with any ocular disease and binocular vision problem were excluded. The consistency of aniseikonia measurement was determined in two visits, separated by at least 24-hour interval. Three repetitive measurements were taken in each visit. Results: Independent t-test and paired t-test showed that real and simulated anisometropia gave insignificant aniseikonia percentage, p>0.05. ICC findings revealed moderate-to-good agreement for all simulated and real groups. Bland Altman analysis between two visits exhibited good agreement among all simulated group; myopic (mean difference 0.2047; 95%CI:-1.1386-1.549), hyperopic (mean difference 0.2200; 95%CI:-0.9286-1.3686) and astigmatic (mean difference 0.2533; 95%CI:-0.7114-1.2180). Real anisometropes demonstrated good agreement with bias value of 0.2247(95%CI:-0.9162-1.3656) using Bland Altman plot. Conclusion: Smart Optometry application provides consistent measurement of aniseikonia regardless any types of anisometropia.

Tratamento da aniseiconia induzida na correção óptica de anisometropia em escolares do ensino fundamental / Treatment of aniseikonia induced by optical correction of anisometropia in elementary school children

Resumo Objetivos: Comparar a aniseiconia e a estereopsia em escolares anisometropes do primeiro ano do ensino fundamental corrigidos com lentes oftálmicas de estoque com curvas-base selecionadas para minimizar a diferença de tamanho interocular das imagens retínicas e com lentes iseicônicas sugeridas pelo software Aniseikonia Inspector 3 e verificar a preferência dos escolares por uma destas formas de correção. Métodos: Dezenove escolares com anisometropia ≥ 1,5 D em meridianos correspondentes no uso de óculos com lentes oftálmicas de estoque e com lentes iseicônicas foram avaliados para aniseiconia (software Aniseikonia Inspector 3) e estereopsia (teste Stereo Fly test com símbolos LEA. A preferência por uma das formas de correção foi verificada após 40-50 dias de uso dos óculos. Resultados: As médias e os desvios-padrão das aniseiconias vertical e horizontal no uso de óculos com lentes oftálmicas de estoque e com lentes iseicônicas foram, respectivamente, -1,05% ± 2,20% e -1,37% ± 2,36% (p=0,82739) e -0,895% ± 2,23% e -1,16% ± 2,03% (p=0,77018). 31,6% dos escolares corrigidos com lentes iseicônicas e 21,1% dos escolares corrigidos com lentes oftálmicas de estoque identificaram os optotipos que sugerem estereopsia < 100 segundos de arco (p= 0,475). Em relação à preferência, 4/15 (26,7%) escolheram os óculos com lentes iseicônicas, 2/15 (13,3%) escolheram os óculos com lentes oftálmicas de estoque e para 9/15 (60%) a escolha foi indiferente. Conclusão: A aniseiconia induzida nos escolares anisometropes corrigidos com lentes iseicônicas sugeridas pelo software Aniseikonia Inspector 3 foi similar ao obtido na correção com lentes oftálmicas de estoque com curvas-base selecionadas para minimizar a diferença de tamanho interocular das imagens retínicas.

Abstract Objectives: To compare the aniseikonia and the stereopsis in school children anisometropes of the first-year of elementary school corrected with stock ophthalmic lenses with base curve selected to minimize the interocular size difference of retinal images and with size lenses suggested by the software Aniseikonia Inspector 3, and to check the preference of them for one of these forms of correction. Methods: Nineteen school children with anisometropia ≥ 1.5 D in corresponding meridians, in the use of glasses with stock ophthalmic lenses and with size lenses were evaluated for aniseikonia (software Aniseikonia Inspector 3) and stereopsis (Stereo Fly test with LEA symbols). The preference for one of the forms of correction was verified after 40-50 days of wearing glasses. Results: The mean and standard deviations of the vertical and horizontal aniseikonia in the use of glasses with stock ophthalmic lenses and with size lenses were, respectively, -1.05% ± 2.20% and-1.37% ± 2.36% (p = 0,82739) and -0.895% ± 2.23% and -1.16% ± 2.03% (p = 0,77018). 31.6% of the school children corrected with size lenses and 21.1% of the students corrected with stock ophthalmic lenses identified the optotypes that suggest stereopsis less than 100 seconds of arc (p = 0.475). Regarding the preference, 4/15 (26.7%) of the students chose the glasses with size lenses, 2/15 (13.3%) chose the glasses with stock ophthalmic lenses, and for 9/15 (60%) the choice was indifferent. Conclusion: The induced aniseikonia in school children with anisometropia corrected with size lenses suggested by the software Aniseikonia Inspector 3 was similar to that obtained in the correction with stock ophthalmic lenses with base curves selected to minimize the difference of interocular size of retinal images.

Forensic analysis of 109 cases of traumatic visual loss / 中国法医学杂志

Objective To analyze types, mechanism and forensic identification for traumatic visual loss. Methods 109 cases of the evaluation for impairment and disability on traumatic visual loss were retrospectively analyzed, including interocular differences, anisometropia, left or right eye and the distributions of visual acuity, etc. Results The male-to-female ratio was 5.8:1, mainly 30~59 years of age. The ratio of monocular versus binocular injuries was 17.17:1. The ratio of left versus right injured eye was 1.39:1 in intentional injury cases. 115 eyes were injured, 83 of which were in low vision or blindness. 95 patients(87.16%) had large interocular differences( ≥ 3 lines). There were 9 patients with anisometropia from 2.25D to 6.00D and 23 patients with anisometropia larger than 6.00D. Conclusion Interocular differences and anisometropia are common in practice, which are not included in the expertise standard yet. Functional vision should be considered when developing the expertise standard.

Aniseikonia secundaria a cirugías refractivas realizadas por lasik

Introducción: detectar la ocurrencia de Aniseikonia Meridional Horizontal en pacientes operados de cirugía refractiva por el sistema LASIK. Métodos: una muestra de 19 pacientes emetropizados por LASIK es comparada con una muestra de 20 pacientes naturalmente emétropes, con el objeto de estimar el efecto que los cambios de curvatura corneal tienen sobre el meridiano horizontal de la imagen retinal, teniendo en cuenta que las variaciones del poder óptico del ojo altera la posición del Punto Nodal, lo que a su vez altera el tamaño de la imagen retinal. Las ametropías preexistentes no fueron tomadas en cuenta. Para el estudio fue utilizado el Test Monocular de Merchán para detectar Aniseikonia (Merchán G. 2004): un elipsoide generado por computador incrementa su meridiano horizontal, contra orden dada, acercándose así a la figura de un círculo perfecto. El paciente activa el test y es instruido para detenerlo cuando considere que el elipsoide ha adquirido la forma de un círculo perfecto. En este momento el software compara los ejes horizontal y vertical de la figura resultante y muestra en porcentaje cualquier diferencia entre ellos; lo ideal es que el eje horizontal sea 100% igual al vertical, lo cual significa que la figura es realmente un círculo y así es percibido por el paciente, probando además que en el ojo examinado no existe ninguna Magnificación Meridional Horizontal. El ojo compañero es ahora sometido a la misma prueba y los resultados de los dos son comparados. Una diferencia entre ellos del 3% o superior (Borish, 1975) es considerada indicadora de Aniseikonia Meridional Horizontal. Resultados: los análisis estadísticos de proporciones, Z, tanto de una cola como de dos para el valor Z de diferencia entre proporciones, 36.8% de la primera muestra (emétropes por LASIK) y 5% de la segunda (naturalmente emétropes) es significativa, por lo cual se rechaza la hipótesis nula en favor de la alternativa. Conclusiones: la cirugía refractiva altera la curvatura corneal y consecuentemente la posición del Punto Nodal, lo cual puede causar una Aniseikonia Meridional Horizontal de grado bajo y asintomática aproximadamente en la tercera parte de los casos examinados.

Introduction: to detect the occurrence of Horizontal Meridional Aniseikonia in patients operated of refractive surgery with LASIK. Methods and materials: a sample of 19 patients made emmetropic by LASIK intervention is compared t a sample of 20 naturally emmetropic patients in order to asses the effect that changes in corneal curvature have over the horizontal meridian of the retinal image taking into account that variations of the optical power of the eye alters the position of the Nodal Point which in turn alters the size of the retinal image. Pre-existing ametropia was not specified or taken into account. Merchan Monocular Test for Aniseikonia was used for this study (Merchán G. 2004). A computer generated vertically elongated ellipsoid increases, upon command, the horizontal axis gradually approaching a perfect circle. The patient activates the test and is asked to stop the moment he or she considers that the ellipsoid has turned into a perfect circle. At this point the software compares the horizontal to the vertical axis of the resulting figure. Any difference between the axes is shown in percentage. Ideally, the horizontal axis should be 100% equal to the vertical axis which means that the figure is really a circle and is perceived as such by the patient, furthermore proving that no Horizontal Meridional Magnification is present in the eye under testing. The fellow eye is similarly tested and the results of the two eyes are compared. Differences above 3% (Borish, 1975) is considered indicative of the presence of Horizontal Meridional Aniseikonia. Results: statistical analyses for both one-tail and two-tails for the Z value for difference in proportions of the two groups show that 36.8% in the first group (emétropes by surgery) is statiscally significant from 5% in the second group (natural emmetropes), thus rejecting the null hypotheses. Conclusions:refractive surgery changes the corneal curvature and consequently the position of the Nodal Point all of which may cause a secondary asymptomatic low degree Horizontal Meridional Aniseikonia in approximately one third of the cases examined.

Objetivo: detectar a ocorrência de Aniseiconia Meridional Horizontal em pacientes operados de cirurgia refrativa pelo sistema LASIK. Métodos: uma amostra de 19 pacientes emetropes por LASIK é comparada a outra amostra de 20 pacientes naturalmente amétropes, com o objetivo de estimar o efeito que as mudanças de curvatura da córnea tem sobre o meridiano horizontal da imagem da retina, tendo em conta que as variações do poder ótico do olho altera a posição do Ponto Nodal, que, por sua vez, altera o tamanho da imagem na retina. As ametropías preexistentes não foram levadas em consideração. Para o estudo foi utilizado o Teste Monocular de Merchán para detectar Aniseiconia (Merchán G. 2004) Um elipsoide gerado por computador incrementa seu meridiano horizontal, contra ordem dada, aproximando-se assim à figura de um círculo perfeito. O paciente ativa o teste e é instruído para detê-lo quando considere que o elipsóide adquiriu a forma de um círculo perfeito. Neste momento, o software compara os eixos horizontal e vertical da figura resultante e mostra em porcentagem qualquer diferença entre eles. O ideal é que o eixo horizontal seja 100% igual ao vertical, o que significa que a figura é realmente um círculo e assim é percebido pelo paciente, provando ademais, que no olho examinado não existe nenhuma Magnificação Meridional Horizontal. O olho companheiro é agora submetido à mesma prova e os resultados dos dois são comparados em seguida. Uma diferença entre eles de 3% ou superior (Borish, 1975) é considerada indicadora de Aniseiconia Meridional Horizontal. Resultados: as análises estatísticas de proporções, Z, tanto de uma fila como de duas para o valor Z de diferença entre proporções, 36,8% da primeira amostra (emétropes por LASIK) e 5% da segunda (naturalmente emértropes) é significativa pelo qual se rejeita a hipótese nula em favor da alternativa. Conclusão: a cirurgia refrativa altera a curvatura corneal e consequentemente, a posição do Ponto Nodal, pela qual pode causar uma Aniseiconia Meridional Horizontal de baixo grau e assintomática em aproximadamente a terceira parte dos casos examinados.

Effect of Correction Lens for Anisometropia on Aniseikonia and Binocular Function

PURPOSE: To study the effect of the corrective lens for anisometropia on aniseikonia and binocular function. METHODS: The study subjects were 30 patients without strabismus and amblyopia, who had anisometropia of more than 1.00D between the spherical equivalent of each correction lens. The amount of aniseikonia was measured by Awaya's New Aniseikonia Test. The degree of stereopsis and fusion were determined with Titmus Stereo Test and fusion card of major amblyoscope, respectively. RESULTS: The amount of aniseikonia increased significantly with increasing level of anisometropia (p=0.000). There was a statistically significant correlation between the amount of anisometropia and fusion (p=0.046). With increased aniseikonia, the stereopsis declined consequently, but the decline was not statistically significant. Aniseikonia was induced when there was more than 2.00D of anisometropia. With anisometropia increased by 1.00D, the odds ratio of induced aniseikonia was 7.197 (p=0.047). CONCLUSIONS: Anisometropia is an important factor for aniseikonia and can disturb binocular function.

Effect of Spherical Lens Induced Aniseikonia on Binocular Function

PURPOSE: To study the effect of spherical lens induced aniseikonia on stereopsis and fusion. METHODS: One hundred subjects, with normal binocular function without any ophthalmic disease or surgery history, were examined. The aniseikonia was induced with spherical lenses in 1 diopter (D) stepwise manner from -2 D to +2 D. The amount of aniseikonia was measured by Awaya's New Aniseikonia Test. Stereopsis and fusion were determined with Titmus Stereo Test and fusion card of major amblyoscope respectively. RESULTS: As the amount of aniseikonia was increased, the stereopsis and fusion were decreased. The change was statistically significant (ANOVA, p<0.001). Aniseikonia was more correlated to fusion than stereopsis. A significant decline in the stereopsis was detected when the size of aniseikonia changed from 1% to 2%. A significant decline in fusion was noticed when aniseikonia changed from 2% to 3% (Independent t-test, p<0.01). CONCLUSIONS: Our study suggests that binocular function can be disturbed by experimentally induced aniseikonia in normal subjects and that stereoacuities and fusional amplitude can be decreased as the degree of aniseikonia becomes larger.