Orbital infarction during drug abuse: tissues of the globe do not appear to recover function.

AIM: To describe the features of an orbital infarction syndrome arising after prolonged orbital pressure during drug-induced stupor in young people. PATIENTS AND METHODS: The clinical presentation and course for drug-induced orbital infarction is described, based on a retrospective review of clinical notes and imaging. RESULTS: Two cases of orbital infarction syndrome, due to prolonged orbital compression caused by sleeping with pressure on the orbit during drug-induced stupor, are described. Both patients presented with very poor vision and mydriasis, marked periorbital swelling with some pain, and complete external ophthalmoplegia. Whilst the orbital changes and eye movements recovered, the affected eyes had persistent wide mydriasis, and remained blind with marked optic atrophy. CONCLUSION: With a mechanism analogous to prolonged orbital pressure due to improper head positioning during neurosurgical procedures, drug-users appear to risk developing an orbital infarction syndrome if they rest with prolonged pressure on the orbit during a drug-induced stupor.

Kyrieleis plaques associated with Herpes Simplex Virus type 1 acute retinal necrosis.

We report the case of a 55-year-old immunocompetent male who presented with features typical of acute retinal necrosis (ARN). Polymerase chain reaction of the aqueous tap was positive for Herpes Simplex Virus (HSV) - 1. Following therapy with intravenous Acyclovir, followed by oral Acyclovir and steroids, there was marked improvement in the visual acuity and clinical picture. At one week after initiation of treatment, Kyrieleis plaques were observed in the retinal arteries. They became more prominent despite resolution of the vitritis, retinal necrosis and vasculitis and persisted till six weeks of follow-up, when fluorescein angiography was performed. The appearance of this segmental retinal periarteritis also known as Kyrieleis plaques has not been described in ARN due to HSV-1 earlier.

Macular infarction and traumatic optic neuropathy following blunt ocular trauma.

Macular infarction is a visually disabling condition caused by a variety of reasons. It has rarely been described in association with blunt ocular trauma. We describe the case of a young healthy male who sustained injury with a bull's leg and presented with severe visual loss owing to macular infarction and traumatic optic neuropathy. This report of an angiographically documented macular infarct secondary to ocular contusion highlights an additional feature in the spectrum of ocular findings following blunt trauma that might lead to a severe and permanent affliction of vision.

Lensectomy, vitrectomy, and transvitreal ciliary body photocoagulation as primary treatment for glaucoma in microspherophakia.

Microspherophakia is a rare, bilateral developmental anomaly of the crystalline lens. It can occur in isolation or as a component of a familial disorder. It has been associated with the Weill-Marchesani syndrome and Marfan syndrome. Angle clousure glaucoma can occur in microspherophakia and is the primary cause of visual loss. We describe the management of 2 sisters with bilateral microspherophakia and advanced angle closure glaucoma.

Different regions of bovine deep digital flexor tendon exhibit distinct elastic, but not viscous, mechanical properties under both compression and shear loading.

Tendons in different locations function in unique, and at times complex, in vivo loading environments. Specifically, some tendons are subjected to compression, shear and/or torsion in addition to tensile loading, which play an important role in regulating tendon properties. To date, there have been few studies evaluating tendon mechanics when loaded in compression and shear, which are particularly relevant for understanding tendon regions that experience such non-tensile loading during normal physiologic function. The objective of this study was to evaluate mechanical responses of different regions of bovine deep digital flexor tendons (DDFT) under compressive and shear loading, and correlate structural characteristics to functional mechanical properties. Distal and proximal regions of DDFT were evaluated in a custom-made loading system via three-step incremental stress-relaxation tests. A two-relaxation-time solid linear model was used to describe the viscoelastic response. Results showed large differences in the elastic behavior between regions: distal region stresses were 4-5 times larger than proximal region stresses during compression and 2-3 times larger during shear. Surprisingly, the viscous (i.e., relaxation) behavior was not different between regions for either compression or shear. Histological analysis showed that collagen and proteoglycan in the distal region distributed differently from the proximal region. Results demonstrate mechanical differences between two regions of DDFT under compression and shear loading, which are attributed to variations of composition and microstructural organization. These findings deepen our understanding of structure-function relationships of tendon, particularly for tissues adapted to supporting combinations of tension, compression, and shear in physiological loading environments.