Method and apparatus for measuring oxygen transmission through contact lenses
US5817924A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 21, 1998 |
| Grant date | Oct 6, 1998 |
| Priority date | — |
| Expiry date | Jan 21, 2018 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N15/0806
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An apparatus for measuring the gas transmission rate through contact lens material, and a method of measuring, using a test cell having an upper and lower gas chamber and separating the upper and lower chamber with a layered group of films, including a contact lens film material clamped between an upper and lower guard film, and flowing oxygen through the upper chamber and an inert gas through the lower chamber, the lower chamber being connected to a coulometric sensor to measure oxygen content in the inert gas at defined intervals, to obtain a first series of oxygen transmission rates. A second series of oxygen transmission rates are made with the same apparatus, but with the contact lens material removed from the apparatus, and the transmission rate through the contact lens material is calculated by subtracting the reciprocal of the second measured transmission rate from the reciprocal of the first measured transmission rate, then taking the reciprocal of the difference.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.