AIM: To study refractive changes after horizontalrectus muscles surgery on children and determine time interval of the first mydriatic optometry after surgery.

METHODS: In a prospective interventional case series, 318 eyes of 178 patients aged of 3-8 years in the Second Affiliated Hospital of Nanchang University from January, 2009 to December, 2010 were evaluated in 4 groups:(Ⅰ)48 patients(83 eyes)who underwent external rectus muscle(s)recession;(Ⅱ)43 patients(79 eyes)who underwent internal rectus muscle(s)recession;(Ⅲ)45 patients(81 eyes)who underwent internal rectus muscle(s)recession combined external rectus muscle(s)resection;(Ⅳ)42 patients(75 eyes)who underwent external rectus muscle(s)recession combined internal rectus muscle(s)resection. Full ophthalmic examination and mydriatic optometry was carried out 1 month before surgery, as well 1 week and 1 month, 2, 4, 8 months after surgery.

RESULTS: In groupⅢ and Ⅳ, compared with pre-operation, there were statistically significant changes in spherical equivalent at 1 week(P<0.05), and no significant changes happened in all 4 groups at 1 month. Significant decrease was found in all groups at month 8(P<0.05). In all groups, there were statistically significant changes in cylinder equivalent at 1 week(P<0.05). At month 1 post-operation, same result was detected in group Ⅲ and Ⅳ. No significant changes in cylinder equivalent happened in all 4 groups at month 2(P>0.05). Astigmatic axis shift was little in all groups at any time point(P>0.05), and rule of eyes astigmatism were kept coincidence with pre-operation very well(P>0.05).

CONCLUSION: Refractive changes are assured in short-term after horizontalrectus muscle surgery, while generally speaking, refractive statues can recover to the level of pre-operation in a certain duration. No significant variation is found between different surgery methods. It does not seem necessary to perform cycloplegic refraction early than 2 months after surgery; however, considered about emmetropia proceeding in children, a precise refraction in all cases of strabismus should not be deferred later than 4 months.