Correction of Abnormal Head Position in Pediatric Nystagmus Using Yoked Low-Value Prism Glasses: A Retrospective Study.

Purpose: Nystagmus involves abnormal head positions (AHPs) toward the null point for improving visual acuity. While surgical interventions are the standard therapy, the use of yoked prisms is a possibility not often used. Our team used low-value prisms in children to mitigate AHP. Methods: Yoked prisms were tailored to the direction of head turn. Thirty-one children were reviewed. Outcomes were binocular best-corrected visual acuity (BBCVA) and AHP measures with and without prisms. Results: Of the 31 patients aged 10.3 ± 3.6 years (16 male), 19 were diagnosed with idiopathic infantile nystagmus syndrome, 6 with oculocutaneous albinism, and 6 with other secondary nystagmus. Prism's average prescription was 3.9 ± 1.25 diopters. BBCVA for distance averaged 0.44 ± 0.22 logMAR, improving to 0.41 ± 0.23 logMAR (P = 0.001, small size effect). AHP reduced from 16.9° ± 9.9° to 4.6° ± 5.8° for distance vision (P < 0.0001) and 12.7° ± 12.9° to 3.8° ± 6.2° for near vision (P < 0.0001), both with large size effects. The angle of the prisms most frequently prescribed was 180° (26 cases), as well as 2 cases at 135°, 1 case at 30°, and 2 cases at 90°. Discussion: Our study found an improvement in AHP using low-value prisms in a pediatric population with nystagmus. Allowing the use of primary gaze position, prisms may be a therapeutic option to reduce the physical and social difficulties from AHP in these cases. Conclusions: This study provides the first quantitative assessment of the minimal prism values required to significantly reduce abnormal head posture in nystagmus, offering a valuable adjunctive treatment option for these patients.