Night-vision lenses

The adverse effects of pilocarpine are caused by the induction of miosis. The contraction of the ciliary muscle causes the lens to displace forward, which can lead to accommodation spasm, myopia, and brow ache. Pupillary constriction can also affect night vision. Pilocarpine should be avoided in patients with severe myopia, as it increases the risk of developing retinal detachment. Systemic effects may occur at higher concentrations and include, nausea, vomiting, diarrhea, and bradycardia. 

Argyrosis (deposition of silver in the eyes) appears to be the critical effect and is observed in workers exposed to silver compounds at concentrations in the range of 0.005-0.38mg/mh Disturbances with night vision and lens changes without visual impairment have been associated with argyrosis. ... 

Since NIR laser radiation is invisible, it is advisable - while wearing. safety glasses -to employ an infrared night vision instrument with a macro lens for the fine-adjustment of the sample. 

The germanium lens in night vision goggles focuses infrared radiation emitted from living things. 

Contact lenses come in a wide variety there are soft lenses and hard lenses there are some you can wear night and day for a month or more, and disposable ones that you need wear only for a day there are lenses that let your eyes breathe there are bifocal lenses and there are even lenses to correct astigmatism, a condition of the lens of the eye which makes everything seem blurred. All are products of years of research by chemical companies like Novartis, Ciba Vision, and Wesley Jessen. There are even coloured lenses that can make blue eyes bluer, and sport lenses that enable tennis players to keep their eye on the ball by enhancing the colour of a yellow tennis ball relative to its surroundings. 

The use of contact lenses, initially made from glass, to correct vision has been known since the 19th century. The first polymeric contact lens was a hard contact lens made in 1936 from polymethylmethacrylate (PMMA). " However, these lenses had to be taken out at night to prevent eye irritation and much research has been directed to making those that could be worn for much longer periods of time. This led to the development of the so-called soft lenses. 

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