Differences in refractive astigmatism, anterior corneal surface astigmatism and ocular residual astigmatism between dominant and non-dominant eyes in myopia / 中华实验眼科杂志

Objective:To investigate the differences in refractive astigmatism, the anterior corneal surface astigmatism and ocular residual astigmatism between dominant and non-dominant eyes in myopia.Methods:A corss-sectional study was conducted.Two hundred and seventy-six eyes from 138 patients with myopia who were to receive corneal refractive surgery in the Refractive Surgery Center of Tianjin Eye Hospital from January to March 2018 were included.Ocular dominance was assessed with the hole-in-the-card test.The manifest refraction and corneal topography were performed in order to measure the sphericity, spherical equivalent, the astigmatism of anterior corneal surface and total cornea.Vector analysis was used to calculate the value of the ocular residual astigmatism and the components of astigmatism, including J0 and J45 of both the refractive astigmatism and the astigmatism of anterior corneal surface.This study adhered to the Declaration of Helsinki.The study protocol was approved by the Ethics Committee of Tianjin Eye Hospital (No.201909).Results:It was found that 61.6%(85/138) of the subjects was right-eye dominant.There was no significant difference in sphericity and spherical equivalent, J0 and J45 of the refractive astigmatism and the astigmatism of anterior corneal surface between dominant and non-dominant eyes (all at P>0.05). The magnitude of the ocular residual astigmatism of the dominant eye was 0.607(0.451, 0.808)D, which was lower than 0.701(0.497, 0.901)D of the non-dominant eye, showing a statistically significant difference ( Z=-2.52, P=0.01). Conclusions:In the myopic population with no significant difference in the sphericity and spherical equivalent between the dominant and non-dominant eyes, the magnitude of the ocular residual astigmatism of the dominant eye is significantly lower than that of the non-dominant eye, which may play an important role in the ocular dominance formation.

Resultados del cálculo del poder del lente intraocular mediante la fórmula de Haigis / Results of the intraocular lens power calculation through Haigis´ formula

OBJETIVO: Determinar la efectividad de la fórmula de Haigis en el cálculo del poder dióptrico del lente intraocular. MÉTODOS: Se realizó un estudio descriptivo prospectivo, de pacientes operados de catarata mediante la técnica de Facoemulsificación en el Servicio de Microcirugía del Instituto Cubano de Oftalmología Ramón Pando Ferrer entre enero 2007 a enero 2008. Para el cálculo del poder del lente intraocular se empleó el IOL Máster y la fórmula de Haigis. La muestra de 101 pacientes, se seleccionó por el método aleatorio simple, de los cuales 28 fueron intervenidos en ambos ojos, para un total de 129 ojos. RESULTADOS: El equivalente esférico preoperatorio y posoperatorio no tuvieron diferencias, sí existieron entre esfera esperada y la obtenida. La mayor diferencia entre la esfera esperada y la obtenida fue encontrada en los pacientes hipermétropes. El astigmatismo refractivo fue bajo. La longitud axil posoperatoria no se modificó y la mejor agudeza visual sin corrección y con corrección mejoró en más de cuatro líneas en la cartilla de Snellen CONCLUSIÓN: Se demostró la efectividad de la fórmula de Haigis en el cálculo del poder del lente intraocular

OBJECTIVE: To determine the effectiveness of Haigis´formula in the intraocular lens power calculation. METHODS: A prospective and descriptive study was conducted in patients operated from cataract with phacoemulsification technique at the Microsurgery Service of Ramón Pando Ferrer Cuban Institute of Opththalmology from January 2007 to January 2008. The IOL Master and the Haigis´formula were used for the intraocular lens power calculation. The sample of 101 patients was selected by the simple random method, of whom 28 underwent surgery in both eyes, for a total number of 129 eyes. RESULTS: The Pre- and the post-operative spherical equivalents did not have any differences; but the expected sphere and the real sphere did show differences. The biggest difference between the expected sphere and the real one was found in the hypermetropic patients. The refractive astigmatism was low. The postoperative axil length did not change and the best visual acuity without/ with Correction improved by more than four lines in the Snellen´s chart. CONCLUSION: The effectiveness of Haigis´ formula was confirmed in the intraocular lens power calculation

Pseudophakic Residual Astigmatism

We investigated pseudophakic residual astigmatism in order to minimize postoperative refractive astigmatism. We examined 110 eyes of 87 patients who had undergone phacoemulsification with small incision and posterior chamber intraocular lens (IOL) implantation. Corneal astigmatism was measured using an autokeratometer (RK-5, canon), refractive astigmatism by manifest refraction, and residual astigmatism by vector analysis. Mean pseudophakic residual astigmatism was +0.47 X 176degrees, predominantly against-the-rule. Variations of pseudophakic residual astigmatism according to sex, age and IOL type were not statistically significant. When performing cataract surgery as refractive surgery, we may consider that pseudophakic residual astigmatism is approximately 0.50D against-the-rule.