A 32-year-old male patient with retinitis pigmentosa complained of intermittent diplopia for the past few years, with recent progression. His corrected vision was 0.8 in both eyes. Fundus examination revealed retinal pigmentory changes, narrowing vessels, and relatively pale discs bilaterally, and VF examination showed that only the central island remained bilaterally []. Prism-cover testing revealed 30 PD left hypertropia (LH) and 4 PD XT. Ocular-motility testing demonstrated slight overaction of the inferior oblique muscle and slight underaction of the superior oblique muscle in the left eye. On prism-adaptation testing, the patient reported no diplopia with a 16 PD prism. However, he did not like prism glasses and asked for surgical correction. We performed an inferior oblique myectomy in the left eye. One month after surgery, cover testing revealed 18 PD LH and 4 PD XT at the primary position. The patient experienced occasional diplopia only with right-up gazing, but there was no diplopia at the primary position or with near work. At the last follow-up visit 3 months later, prism-cover testing measurements were unchanged. The patient was satisfied with being free of diplopia in daily life.
A 22-year-old male patient visited our clinic complaining of diplopia after a traffic accident 1 year prior. There was no abnormal eye position noted before his accident. The trauma caused encephalomalacia and fracture of the frontal bone and orbital bone. His best-corrected visual acuity (BCVA) was 1.0 in both eyes. Fundus examination revealed bilateral bow-tie shaped optic atrophy. His VF examination showed complete bitemporal hemianopia []. Traumatic optic chiasmopathy was then diagnosed. Ocular motility testing revealed no ophthalmoplegia, and the prism-cover test demonstrated 16 prism-diopter (PD) exotropia (XT) and 7 PD right hypertropia (RH). To eliminate this diplopia, we performed lateral rectus muscle (LRM) recession of 6.5 mm and superior rectus muscle (SRM) recession of 3 mm in the right eye. Three months after strabismus surgery, the prism-cover test revealed 0.5 PD XT and 4 PD RH at the primary position. Eye-alignment examination with the Hess chart also showed improvement over the preoperative findings. However, the patient complained that his diplopia persisted and failed to fuse with any prism.