Faculty Bibliography

Orbital myositis is a rare, commonly idiopathic, inflammatory condition that affects one or more extraocular muscles. We present a case of unilateral orbital myositis affecting the lateral rectus muscle presenting with gaze-evoked amaurosis, pain, and diplopia, with restrictive limitation of adduction. With improvement in adduction after initiating treatment, we noted narrowing of the palpebral fissure on attempted adduction, mimicking Duane retraction syndrome (DRS). Reported cases of "pseudo-DRS" are associated with multiple etiologies and are characterized by retraction on attempted abduction rather than adduction, as occurs in true DRS. In this case, pseudo-DRS occurred in the setting of idiopathic orbital inflammatory syndrome (orbital myositis) with a motility pattern more consistent with true DRS.

The majority of X-linked retinitis pigmentosa (XLRP) is due to mutations in the retinitis pigmentosa GTPase regulator (RPGR) gene. Determining the pathogenicity of novel variants is important for enrollment of patients into gene therapy trials. Sequencing and analysis of RPGR variants in ORF15 is challenging, as it is highly repetitive and rich in purines. Overlapping reading frames and polymorphic insertions / deletions add further complexity to the detection of mutations. Identifying systemic manifestations in affected males and carrier phenotype in related females expedites confirmation of pathogenic variants. The authors present a 16-year-old boy with a history of primary ciliary dyskinesia presenting with complaints of nyctalopia and visual field constriction. Multimodal imaging found peripheral thinning of the retina and a characteristic foveal hyperautofluorescent ring in the proband, and a carrier phenotype in the asymptomatic mother. A novel c.1059_1059+2delGGT, p.(?) variant in RPGR was identified as hemizygous in the affected boy and heterozygous in his mother. This case study expands the genotypic spectrum of RPGR variants associated with systemic manifestations. [Ophthalmic Surg Lasers Imaging Retina. 2018;49:548-552.].

Steroid-induced IOP elevation affects a significant number of patients. It results from a decrease in outflow facility of the aqueous humor. To understand the pathophysiology of this condition a number of model systems have been created. These include ex-vivo cell and organ cultures as well as in-vivo animal models in organisms ranging from rodents to primates. These model systems can be used to investigate specific aspects of steroid-induced IOP elevation. This brief review summarizes the strengths and limitations of the various model systems and provides examples of where these systems have been successfully used to advance our understanding of steroid-induced IOP elevation.