A 16-year-old boy visited our clinic for diplopia after the removal of a brain tumor. The patient described difficulty reading: words such as “happy” would become “happpy.” There was no prior history of strabismus or amblyopia. Three years prior, he was diagnosed with a suprasellar germinoma for which he underwent craniotomy to excise the tumor, followed by radiotherapy. His BCVA was 0.2 in the right eye and 0.05 in the left eye. Fundus examination revealed bilateral diffuse optic atrophy, and VF examination showed bitemporal hemianopia and an inferonasal defect in the right eye []. Hirschberg testing revealed 15° of XT in the left eye, and the prism-cover test demonstrated approximately 30 PD XT. On the prism-adaptation test, he reported a narrowing image with a 35-PD base in prism while a widening image with a 25-PD base in the prism. He noted the most normal image with a 30-PD base in the prism. Ocular-motility testing revealed normal duction and version. To eliminate the diplopia, we performed LRM recession of 6.0 mm and medial rectus muscle (MRM) resection of 4.5 mm in the left eye. One month after surgery, prism-cover testing revealed residual 14 PD XT. Prism adaptation for challenging with a 14-PD base in led to image narrowing. He was free of diplopia at both near and distant fixation without any prism aid. The vision and eye position remained stable at 5-year follow-up.
A 29-year-old man presented with diplopia after a traumatic skull base and orbital bone fracture 4 years prior. He was an architect and the diplopia considerably hindered his work. Ocular examination revealed the BCVA to be 1.0 in both eyes. Fundus examination revealed bilateral optic atrophy, and VF examination showed bitemporal hemianopia []. The prism-cover testing revealed 18 PD XT and 6 PD RH at the primary position. Ocular-motility testing demonstrated normal eye movement bilaterally. The Bagolini striated glasses test demonstrated right-eye suppression. To eliminate the diplopia, we performed LRM recession of 9 mm and SRM recession of 2 mm in the right eye. One month after surgery, prism-cover testing revealed 10 PD XT and 5 PD RH. Three months later, synoptophore testing demonstrated an unstable subjective angle from 1 to 3 PD XT and from 3 to 6 PD RH. The patient still experienced diplopia and could not tolerate prism glasses.