What is a Contact lens made of?
What is a Contact lens made of?
A water-swollen polymer gel — and the whole design problem is getting oxygen through it to the cornea.
The cornea has no blood supply and takes its oxygen directly from the air, so a contact lens is a barrier over a tissue that is already at the edge of its oxygen budget. That single constraint drives the whole material history: early PMMA lenses passed no oxygen at all, hydrogels passed some through their water, and silicone hydrogels — from around 1999 — raised transmissibility several times over. The risk that follows from getting it wrong is real: microbial keratitis, most seriously from Acanthamoeba, which is strongly associated with sleeping in lenses and with water exposure. Lenses should never be rinsed in tap water or worn swimming or showering.
Component by component
| Part | Material | Why that material |
|---|---|---|
| hydrogel lenses | poly(2-hydroxyethyl methacrylate) and related polymers, 38-70% water | Oxygen crosses a hydrogel dissolved in its water, so higher water content means more oxygen — and a more fragile, faster-drying lens. |
| silicone hydrogel lenses | siloxane monomers copolymerised with hydrophilic ones | Silicone passes oxygen far better than water does, breaking the old trade-off and making safe overnight wear possible. |
| surface treatment | plasma treatment or internal wetting agents | Silicone is hydrophobic, so an untreated silicone hydrogel lens attracts lipid deposits and feels dry within hours. |
| rigid lenses | fluorosilicone acrylate | A rigid lens holds its own optical shape over an irregular cornea, which is why keratoconus is corrected with them. |
| handling tint | a faint blue tint with no optical effect | It makes a nearly invisible lens findable in the case and in the sink, which is its entire purpose. |
Other medical and personal care objects
- Condom Dipped natural rubber latex, or synthetic polyisoprene or polyurethane for latex allergy — plus silicone lubricant.
- Surgical mask Three layers of polypropylene, of which only the electrostatically charged middle one does the filtering.
- Diaper (nappy) A superabsorbent polymer that holds many times its own weight in fluid, sandwiched between nonwoven plastic layers.
- Dental filling Either a mercury-silver amalgam or a light-cured resin packed with glass — and the resin shrinks as it sets.
- Tampon Compressed cotton, rayon or a blend, with a withdrawal cord and either a cardboard or plastic applicator.
- Eyeglass lens Almost never glass — usually CR-39, polycarbonate or a high-index plastic, under several thin coatings.
- Adhesive bandage (plaster) A plastic or fabric backing with pressure-sensitive adhesive, and a pad faced with a film that will not stick to the wound.
- Artificial hip A titanium or cobalt-chrome stem, a ceramic or metal ball, and a crosslinked polyethylene socket liner that is the wear surface.
- Syringe A polypropylene barrel and plunger with a rubber tip seal, and a stainless steel needle on a standard taper.
Common questions
- What is a Contact lens made of?
- A water-swollen polymer gel — and the whole design problem is getting oxygen through it to the cornea.
- What is the hydrogel lenses of a Contact lens made of?
- Poly(2-hydroxyethyl methacrylate) and related polymers, 38-70% water. Oxygen crosses a hydrogel dissolved in its water, so higher water content means more oxygen — and a more fragile, faster-drying lens.
- What is the silicone hydrogel lenses of a Contact lens made of?
- Siloxane monomers copolymerised with hydrophilic ones. Silicone passes oxygen far better than water does, breaking the old trade-off and making safe overnight wear possible.
Related pages
- Condom Dipped natural rubber latex, or synthetic polyisoprene or polyurethane for latex allergy — plus silicone lubricant.
- Surgical mask Three layers of polypropylene, of which only the electrostatically charged middle one does the filtering.
- Diaper (nappy) A superabsorbent polymer that holds many times its own weight in fluid, sandwiched between nonwoven plastic layers.
- Dental filling Either a mercury-silver amalgam or a light-cured resin packed with glass — and the resin shrinks as it sets.
- Tampon Compressed cotton, rayon or a blend, with a withdrawal cord and either a cardboard or plastic applicator.
- Eyeglass lens Almost never glass — usually CR-39, polycarbonate or a high-index plastic, under several thin coatings.
- Adhesive bandage (plaster) A plastic or fabric backing with pressure-sensitive adhesive, and a pad faced with a film that will not stick to the wound.
- Artificial hip A titanium or cobalt-chrome stem, a ceramic or metal ball, and a crosslinked polyethylene socket liner that is the wear surface.
- Pencil Stationery and paper
- Tennis ball Sport and games
- Banknote Around the house
- Golf ball Sport and games
- Paper Stationery and paper
- Glass Building materials
Sources
- Official vendor product documentation — At One Place