Contact lens care

Series on the Roth Collection

The triumphant advance of soft contact lenses began 50 years ago, and in the meantime they have proven their worth as an alternative visual aid for millions of people, replacing glasses. After first attempts towards the end of the 19th century with the so-called "contact glasses" to compensate for corneal staphyloma, today known as keratoconus, there is now no refractive anomaly that cannot be treated with a contact lens. In addition, numerous corneal diseases or consequences of accidents can be treated with soft lenses as a bandage or as transparent dressing. By Dr. Hans-Walter Roth This small bottle labeled "HaftschalenPflegemittel" is a relic from the early years of contact optics. Its contents, a 10% peroxide solution, were indeed good for inactivating bacteria, fungi and viruses. The label says: Contact-"shell"- care product Clean and disinfect the lens with the cleaning agent before insertion. Put a drop in the shell, gently clean between thumb and forefinger. Rinse well in clear, preferably running water. Do not apply solution directly into the eye, it burns!

It was recognized quite early on that the tolerability of a contact lens depends essentially on careful cleaning and disinfection. Incorrect lens care led to inflammation of the anterior segments of the eye. Most feared was the corneal ulcer, which in extreme cases could lead to the loss of the eye. Especially in the time before the discovery of antibiotics, the course of the disease was usually fatal.

Therefore, not only a compatible contact lens material had to be searched for, but also a suitable care system had to be found. It became apparent that the disinfectants used in surgery at the time could sufficiently disinfect the lenses, which were initially still made of glass. However, with the introduction of PMMA as lens material, this was no longer advisable. Above all, the hydrocarbon compounds led to opacification of the material, and preparations containing iodine discolored the lens.

Thus, in the end, only hydrogen peroxide remained for lens care. It was dispensed by the pharmacist in dark vials to prevent the peroxide from decomposing due to light. A pipette with a rubber teat, as is still used today, made it possible to remove the peroxide from the bottle. One to two drops each were to be applied to the inner surface of the lens and rubbed in with the finger. Adhering substances from the environment or the tear fluid could be removed satisfactorily in this way. The only difficulties were with lipids, which often stuck stubbornly to the surface and could only be removed with soapy water. Some household dishwashing detergents were misused for lens cleaning. After this procedure, it was absolutely necessary to wash the lens and container with plenty of clean water, and some of the lenses, which were still expensive at the time, disappeared forever down the drain.

THUS, IN THE END, ONLY HYDROGEN PEROXIDE REMAINED FOR LENS CARE. SOME OF THE LENSES, WHICH WERE STILL EXPENSIVE AT THE TIME, DISAPPEARED FOREVER DOWN THE DRAIN.

carefully neutralized before inserting the lens. This was done either with a second solution containing catalase or elegantly with a platinum strip as a catalyst. Those who mixed up peroxide and catalase in the hectic morning insertion, or even forgot the latter, usually ended up in the ophthalmology emergency room.

An American contact lens manufacturer therefore relied on heat sterilization. Small stoves and heat-resistant lens containers were offered for this purpose. The advantage was that the risk of an allergic reaction from care products was avoided. The problem, however, was that before the lens could be inserted, it had to cool down and, above all, that dangerous microbes could be transferred by removing it with dirty fingers. When asked how to manage the heat, for example when camping without a power outlet, one was told to heat the lens in the camping stove. If the added breakfast egg was hard, the soft lense would be sterile.

This small bottle labeled "Haftschalen-Pflegemittel" is a relic from the early years of contact optics. Its contents, a 10% peroxide solution, were indeed good for inactivating bacteria, fungi and viruses. But if the solution accidentally got into the eye, it left tearful hours until the corneal epithelium, which had been burned, finally healed. n

If residues of the peroxide remained on the finger or the lens, the removal of the contact lens was already painfully pre-programmed. The solution, in the commercial concentration of 10%, accidentally applied to the eye, burned terribly and at the same time destroyed the corneal epithelium. Even after dilution, the peroxide still had to be

Dr. Hans-Walter Roth

Institut für Wissenschaftliche Kontaktoptik Ulm E-mail: institut.roth.ulm@t-online.de