Silica Sand is found in nature generally in a ‘contaminated’ condition, most commonly by iron causing a brown colour.  Silica sand in common parlance is recognisable by its creamy white appearance and as such is the major ingredient of all types of glass in common use.  Most silica sand will require processing to refine the silica to between 99.97% and 99.99% purity.  Whilst it can be fused to make glass in its pure condition various additives are used to enable fusion at reduced temperatures and to give stability and durability.

The optical properties of glass most useful for eyeware are found in glass which is transparent to visible light.  The surface of such glass is smooth, which when coupled with its clearness make it an attractive material for eyeware products.  Optical glass reflects, refracts and transmits light in ways which have been extensively explored and understood.  Perhaps most usefully, glass does not scatter light passing through it, although it does absorb some of its strength.  It is in widespread use for lenses, windows, translucent partitions

Glasses worn for vision correction and protection from the sun are in widespread use in developed countries and may possibly be the single most common factor in enabling poor-sighted people to continue in work.  The use of plastics which have a greater index of refraction than most types of glass allows shaping and lightweight in uses to correct vision abnormalities such as myopia.  More recent innovations correct for retinal, lens and corneal aberrations of the human optical system.

At FTMINS we remain concerned to try to help those people who are trying to introduce the teaching of optometry, production of eyeware of all kinds and provision at affordable costs to those people in parts of the world who most need it.  We would encourage you to visit the links to the International Centre for Eyecare Education and also Vision Aid Overseas and help if you wish.

http://www.icee.org/make_a_donation/index.asp