RESUMO
PURPOSE: this research compared the dissociated phoria at near and distance fixation in free space using the Howell test, alternate Cover test, and Thorington test. METHODS: 220 healthy Mexican children (mean age 8.3±2.5 years) participated in this study. Phorias were quantified at both distances using each test, from the least to the most disruptive. The stereopsis degree and near point of convergence (break/recovery) were analyzed to understand their role in the visual system's sensorimotor balance. RESULTS: statistically significant differences were found among techniques, with a higher congruence for the EF. However, only the Howell and Thorington tests can be interchanged. The break value and near exophoria relate to each other and affect the stereopsis degree, whereas age is associated with the stereopsis degree and break value. CONCLUSIONS: the three techniques cannot be interchanged except for the Howell and Thorington test for the EF at far. The differences in the mode of dissociation could relate to the results.
RESUMO
Introducción: La heteroforia es la mala alineación de los ejes oculares, que es compensada durante la fijación binocular, al utilizar el mecanismo de fusión. Tiene una alta prevalencia en la población. Objetivo: Evidenciar la importancia de una corrección óptica personalizada en pacientes con heteroforias. Presentación de casos: Se presentan cuatro pacientes que acudieron a consulta de oftalmología, para refracción por presentar síntomas astenópicos. Después de una evaluación completa de cada uno, se constató en todos, la presencia de heteroforia. Se determinó la existencia de exoforia, en tres de ellos, fundamentalmente asociada a insuficiencia de convergencia y esoforia en uno, con exceso de convergencia. Se indicó en todos los casos la corrección óptica personalizada, teniendo en cuenta los resultados de exámenes y se logró la eliminación de las molestias en los pacientes. Conclusiones: Las heteroforias son una causa frecuente de síntomas astenópicos. Es necesario realizar un adecuado estudio, antes de indicar una corrección refractiva, teniendo en cuenta la identificación y cuantificación de la foria, evaluación de las vergencias fusionales, así como estudio del punto próximo de convergencia y la relación convergencia acomodación(AU)
Introduction: Heterophoria is the misalignment of the ocular axes, which is compensated during binocular fixation using the fusion mechanism. It has a high prevalence in the population. Objective: To demonstrate the importance of a personalized optical correction in patients with heterophorias. Cases report: Four cases who attended an ophthalmology consultation for refraction due to asthenopic symptoms are presented. After a complete evaluation of every one of the cases, the presence of heterophoria was found in all of them. The existence of exophoria, mainly associated with insufficient convergence, was determined in three of them; and convergence excess esophoria was identified in one case. Personalized optical correction was indicated in all cases, taking into account the results of the examinations; also, the discomfort in the patients was eliminated. Conclusions: Heterophorias are a frequent cause of asthenopic symptoms. It is necessary to carry out an adequate study before indicating a refractive correction, considering the identification and quantification of phoria, evaluation of fusional vergences, the study of the near point of convergence, and the accommodation-convergence relationship(AU)