Ophthalmic solutions filtration

Ophthalmic solutions filtration

Ophthalmic solutions (solutions for cleaning and storing contact lenses, solutions for flushing used in eye surgery, eye treatment products) must satisfy the strictest requirements and specifications for the product.

The main component of the most ophthalmic solutions is water (water for injection), as well as various ingredients (salts, such as sodium chloride, protective substances, various polymer substances).

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Process requirements
Purposes of filtration
Recommendations for filter cartridges

Process requirements

  • Filter cartridges must provide high flow rates.
  • Filters should not bind or adsorb the conservants from the product.
  • Sterilizing filters should ensure reliable removal of microorganisms.
  • The final membrane filters should have a low level of extractable substances, do not release pyrogens, successfully pass the integrity test.
  • Prefilters and sterilizing filters must withstand multiple cycles of sterilization (steam-in-line, autoclaving) or sanitary treatment with hot water.

The filtration scheme for ophthalmic solutions usually includes a pre-filtration stage through a depth filter to reduce the amount of contaminants and a sterilizing filtration step using a 0.2 μm membrane filter.

Without a prefilter, the membrane is clogged quickly, so the throughput of the filter system is reduced. The use of a depth filter as a prefilter allows to increase the resource of the system. The coordinated combination of the final filter and prefilter provides the required flow rate and all process requirements.

Purposes of filtration


  • Reduce particulate content and bioburden before sterilizing filtration.

Sterilizing filtration

  • Sterilizing filters of 0.2 microns should ensure reliable removal of microorganisms.

Recommendations for filter cartridges

Prefiltration: depth prefilters  EPV.S.

The filter cartridges of these series from microfiberglass with pore size 0.5 µm are capable of providing high flow rates, excellent mechanical and thermal resistance, high efficiency of microparticle retention, do not emit fibers into the filtrate, manufactured according to ISO 9001: 2000.

Final filtration: EPM.PS 045/020

Depending on the types of fluids, we recommend sterilizing membrane filter cartridges EPM.PS based on a high-performance asymmetric polyethersulfone membrane PES with pore size 0.2 and 0.45 µm. This filter material provides low binding conservants at high flow rates and life cycle (resource).

Sterilizing air filtration ("breathing" filters): EPM.F4.

We recommend membrane filter cartridges made of polytetrafluoroethylene EPM.F4 with 0.2 μm pore size.

Filter housings: DS-1-D(-/-)M – sanitary construction.

For the organization of the filtration process we propose the body equipment - the filter housing of the series DS sanitary construction made from high-quality steel AISI 316L or AISI 304.

Integrity test: TECHNOCHEK.

For the final choice of the scheme for the filtration process of ophthalmic solutions, please contact specialists of NPP “Technofilter”.