Comparação entre o uso de incisões relaxantes limbares e lentes intraoculares tóricas no tratamento do astigmatismo corneano pré-existente na facoemulsificação

Abstract

OBJECTIVE: To compare limbal relaxing incisions (LRI) and toric intraocular lenses (IOL) i n terms of non-vectori a l methods and both Alpins and Thibos vectorial analises in the treatment of preexisting corneal astigmatism during phacoemulsification. METHODS: This longitudinal , randomized, prospective study assessed 62 eyes of 31 consecutive cataract patients with preoperative corneal astigmatism between 0.75 and 2.50 diopters in both eyes. Patients were randomly assorted among two phacoemulsification groups: one assigned to receive AcrySof ToricTM IOL in both eyes and another assigned to have AcrySof NaturalTM IOL associated with LRI, also in both eyes. All patients were evaluated postoperatively at 1 , 3 and 6 months, when refractive astigmatism analys is was performed using non-vectorial and vectorial methods. Outcomes variability within each group and between groups was assessed. The ratio between Thibos postand preoperative astigmatic power vectors (APVratio) and its linear regression to Alpins indices were also assessed. RESULTS: There was no statistical difference in safety index between LRI and toric IOL groups. Predictability and efficacy index seldom exhibited differences, favorable to one or another group. Within each group, toric IOL group showeds lightly greater outcomes stability . Mean magnitudes of target induced astigmatism vectors were similiar between groups, but mean magnitudes of surgically induced astigmatism, difference vectors and indices derived from such vectors were advantageous in the toric IOL group. A greater number of eyes achieved the intended correction in the toric IOL group. Overcorrection cases occured more often in the toric IOL group. Significant negative correlation between the ratio of post- and preoperative Thibos APVratio and Alpins percentage of success (%Success ) was found (Spearmans =-0.93); linear regression we found is given by the following equation: %Success=(-APVratio +1.00)x100. CONCLUSIONS: Our data suggest that both LRI and toric IOL are predictable, safe and efficient options in the treatment of preexisting astigmatism. However, toric IOLs exhibited as lightly greater stability in outcomes over time. Vectorial analisys also suggests lesser differences between planned and achieved reductions were observed more often in toric IOL group. Linear regression we found between APVratio and %Success permits a validated mathematical inference concerning the overall success of astigmatic surgery.