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For many optical applications, for example in automotive manufacture, but also in camera phones, displays or lifestyle products, thermoplastics have overtaken traditional glass as the standard material. In addition to a significant weight reduction, their main advantages are great design flexibility, low production costs and the fact that no post-machining is usually necessary. However, their lower thermal and chemical resistance compared with glass, as well as their lower stability against high-energy radiation such as UV, has to be considered at the design stage. Thermoplastic optics are reaching their limits, particularly through the use of increasingly high-performance light-emitting diodes (LEDs). However, the class of materials of the highly transparent liquid silicone rubbers (LSRs) can meet the stringent requirements enabling new areas of application to be opened up for polymer optics.

Purpose Amniotic membrane transplantation is currently being used as an alternative approach to treat severe corneal surface disorders refractory to medical therapy. The authors report complications of corneal surface disorders after successful amniotic membrane transplantation.Methods Case series.Results Twenty-eight patients with corneal surface disorders due to severe chemical burns, corneal ulceration, or persistent epithelium defects were treated with amniotic membrane transplantation. Four of these patients showed a spontaneous perforation and three patients developed a descemetocele within 6 weeks after the amniotic membrane transplantation.Conclusions In this case series, descemetocele and corneal perforation occurred in 25% of the patients after amniotic membrane transplantation. This might be due to the severity of the underlying disease or to the impact of amniotic membrane on corneal fibroblasts and collagenases. The risk of corneal thinning and perforation should be considered in the decision of treatment with amnion and follow-up regimen.

Purpose:Tonometry in corneal oedema is a current problem. In clinical routine intraocular pressure (IOP) may be measured erroneously too low in edematous thickened cornea using Goldmann applanation tonometry.

Purpose:To compare flow velocities of the retrobulbar vessels in chronic vascular neuropathy in normal tension glaucoma (NTG) to those of acute circulatory disorder of anterior ischemic neuropathy (AION).

Purpose:Altered blood flow regulation might contribute to the pathogenesis of glaucoma. The purpose of the study is to investigate retrobulbar flow velocities during hypercapnia in patients with normal tension glaucoma (NTG) without systemic vasospasm and healthy controls.