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 40-year-old man complained of diplopia 4 days after trabeculectomy of the right eye 4 months before visiting our clinic. His corrected vision was 0.5 with − 5.50-diopter correction in the right eye and 1.0 with − 3.50-diopter correction in the left eye. Fundus examination revealed enlarged disc cupping in the right eye and a normal left eye. His VF examination showed an extremely constricted VF in the right eye, with only 7.5° × 5° remaining in the central island []. Prism-cover testing revealed 20 PD XT at the primary position. Ocular motility testing demonstrated no ophthalmoplegia. To eliminate the diplopia, we performed a right LRM recession of 7.0 mm. One month postoperatively, prism-cover testing revealed 3 PD right hypotropia. The patient described alleviation in diplopia, although it did occur sometimes. He also reported improved stereoacuity.