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How to use contact lens oxygen transmission rate tester?

How to use contact lens oxygen transmission rate tester?

Contact lenses, also called contact lenses, are lenses worn on the cornea of the eye to correct vision or protect the eyes. According to different materials, contact lenses can be divided into three types: hard, semi-rigid, and soft; , since the contact lens is directly worn on the cornea, the oxygen permeability of the contact lens is taken as an example, the oxygen permeability of the contact lens (unit: Dk/t) is usually as high as possible, and the oxygen permeability usually refers to the The amount of oxygen passing through. For the cornea, the structure usually has no blood vessels, and the main source of oxygen for corneal metabolism is intake from the air. Wearing contact lenses is equivalent to blocking the way for it to absorb oxygen, which is likely to cause corneal hypoxia, hypoxia, etc. Therefore, the higher the oxygen permeability of contact lenses, the better. Controlling the production process and strengthening the monitoring of the oxygen transmission rate of lenses is an important measure to ensure the stable oxygen barrier performance of contact lenses.

Keywords: contact lens oxygen transmission rate test method, contact lens oxygen transmission rate tester, contact lens oxygen permeability tester, contact lens oxygen permeability tester, contact lens oxygen transmission coefficient tester

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Reference mark: GB/T 11417.7-2012 "Ophthalmic Optical Contact Lenses Part 7: Test Methods for Physical and Chemical Properties"

Pubtester Zhongce Electromechanical will analyze the oxygen permeability performance of contact lenses in detail, and summarize the corresponding testing methods and testing equipment as follows:

1 Scope:

The standard states that this test method can be used to determine the oxygen transmission coefficient of finished sheets of hydrogel and non-hydrogel elastic materials. It can also be used to determine the oxygen permeability coefficient of hydrogel and non-hydrogel elastic material standard sheets.

2. Principle

Seal the sample on a test vessel with a desiccant and an open top, then place the entire test device in an environment with controllable temperature and humidity, and weigh it regularly to determine the water vapor entering the desiccant through the sample. in the amount.

3. Test requirements

There is no requirement for the radius of the rear optical area of the test sample, it can be a flat sample, and it can also vary from 7.00 mm to 9.00 mm. The posterior and anterior optical zone diameters should be larger than the chord diameter of the measured central zone for gas exchange (cathode diameter 2b). The surface of the test sample should be clean, and the polishing quality should be consistent with the normal use of human lens products. For hydrogel materials, before testing, samples should be kept at room temperature (20°C±2.0°C) in standard saline solution (refer to GB/T 11417.4-2012) for at least 24h, and at equivalent eye temperature (35°C) C±0.5°C) for at least 2 h.

4. Contact lens oxygen permeability testing equipment:

According to the standard test principle and required method, it is recommended to use Pubtester to produce OTR-O3 oxygen transmission rate tester independently.

4.1 Test principle:

Based on the coulometric oxygen analysis sensor and the test principle of coulometric analysis, the sample is installed between the sample gas and the carrier gas chamber in the test chamber, and the temperature of the test chamber is controlled. The oxygen in the sample gas chamber penetrates into the carrier gas chamber and is carried by the carrier gas to the trace Oxygen sensor; accurately measure the current generated by the trace oxygen sensor, calculate the oxygen transmission rate of the sample and other parameters

4.2 Test parameters:

1. Trace oxygen sensor, which can measure oxygen content down to ppb level;

2. pA-level micro-current measurement, higher measurement accuracy;

3. Precise flow control, combined with professional piping system and flushing technology, can effectively ensure the stability and cleanliness of the carrier gas;

4. Advanced sample installation anti-side leakage technology can effectively ensure the overall sealing of the test chamber;

5. Equipped with a fog-free humidifier, fully automatic and precise control of the humidity on the high-humidity side;

6. Semiconductor cooling and heating two-way temperature control technology, can heat up or cool down arbitrarily, precise temperature control, making the system more stable

7. The whole process of monitoring, automatic recording, adjustable sampling rate, and the whole test process can be reproduced

8. The three test chambers are completely independent and can test three same or different samples at the same time

The above are the testing instruments and method standards required for the oxygen permeability test of contact lenses, mainly based on GB standards. Welcome to come to consult.