Clinical evaluation of graded Anderson's procedure in idiopathic infantile nystagmus

Aim: To study the efficacy of graded, bilateral, single, horizontal yoked rectus muscle recession for correction of anomalous head posture (AHP) in idiopathic infantile nystagmus (IIN). We hypothesize that the above procedure would sufficiently correct AHP in IIN. Methods: Case records of patients who presented with IIN and AHP due to eccentric null position were included in a retrospective study following IRB approval. Best-corrected visual acuity (binocular Snellen's acuity for distance, in both null position and primary position), anterior segment evaluation using slit lamp biomicroscopy, fundus examination, ocular motility examination and stereopsis (using TNO for adults and older children, Titmus fly test for younger children) were recorded. In all cases recession of the yoke muscles was performed with a gradation of recession, depending on the initial head turn as elaborated in Table 1. AHP was recorded before surgery and 1 and 3 months after surgery. Visual acuity and stereopsis before and after surgery were recorded. Results: Mean AHP improved from 22.5 ± 6.12 degrees of head turn preoperatively to 7.58 ± 3.62 degrees at 1-month postoperative visit (p < .001). The mean binocular visual acuity improved from 0.47 ± 0.15 preoperatively to 0.25 ± 0.17 after surgery (p < .001). Conclusion: Graded yoke muscle recession based on the initial head turn was found to be successful in correcting moderate AHP in patients with IIN. This procedure leaves behind two recti muscles for further surgical intervention in cases with residual AHP.