A Short History of Contact Lenses

Very early contact lenses, or those used prior to the 1950s, covered the entire front of the eye - not just the cornea as they do now. The cornea needs to take in oxygen and get rid of carbon dioxide and it must stay wet. The early contacts didn't permit oxygen and carbon dioxide to permeate, thus causing the cornea to swell, so the wearing time on these lenses was very limited.

So, “modern" contact lenses have been around since the 1950s, but they've come a long way since then in terms of the materials from which they're made, their comfort and "wearability," and the kinds of conditions that they can correct.

Contact lenses were originally made of hard, impermeable materials – even glass until the late 1940s, and a hard plastic until the 1970s. Then, in the 1970s, new materials became available, and lenses that were gas permeable and hydrophilic were developed.

Today, lenses are available in soft, rigid, and combination materials to suit a variety of needs. Despite the fact that, in general, today's contacts are much more comfortable than those of the past, not everyone who requires corrective lenses can wear them. Among those who have difficulty with contact lenses are people with chronically dry eyes because of a medical condition or medication and people who have allergies that make their eyes itch and swell. But, with the variety of materials and designs that are available today, most people are able to find something that fits their individual needs.

Let's review what has been available over the years, and what is currently available and recommended.

The Original Hard Contacts

The earliest contact lenses were developed in Germany in 1927. They were made of glass and covered the entire visible sclera. In 1937, an early type of plastic was developed for use in contact lenses, but the lenses still covered the whole visible sclera. These newer lenses were introduced in the United States in 1938. In 1940, a plastic called polymethylmethacrylate(PMMA) came into use for contacts, which were still made to cover the whole front of the eyeball.

It wasn't until 1955 that the first patent was granted for lenses made of PMMA that covered only the cornea. These smaller plastic lenses were routinely fitted during the 1950s. They were somewhat flexible, but they still earned the name "hard lenses." The plastic could be moulded  inexpensively, polished to a smooth optical surface, and modified with relative ease. A minor prescription change was an in-office procedure.

The lenses maintained a good optical transparency that did not fade with time. Moreover, they didn't crack too easily, they didn't sustain bacterial growth (which could cause infection), and they could be tinted

slightly to make them easier to find if dropped. These lenses also had a downside. The material had no ability to transmit oxygen or carbon dioxide, which made them unhealthy for the cornea.

In addition, solutions had to be used to help water or tears adhere to the surface. It took some determination to wear these lenses because they were so uncomfortable.

 

Soft Contacts for Daily Wear

In the early 1960s, a Czechoslovakian chemist named Dr. Otto Wichterle developed a new type of plastic that he originally thought could be utilized to make artificial blood vessels and organs.  Called hydroxyethylmethacrylate, or HEMA, this material changed the world of eye care forever. "Soft contacts" had arrived on the scene.

These soft contacts, now referred to as "daily-wear soft lenses", were introduced to the public in 1971. They marked the beginning of a whole new era in contact-lens technology. The material was 38 percent water and was called hydrophilic, or "water-loving," because it also absorbed water.

The lenses were more permeable to oxygen and carbon dioxide than hard lenses, and their comfort level was incredible compared to that

of the hard lenses. However, the vision through the soft lenses was not quite as sharp as that through the hard lenses, and these early lenses could not correct for astigmatism. The soft lenses also tended to yellow with age, could rip rather easily, and lasted for only a year or two.

But, for persons who were near-sighted, did not have astigmatism, and were reliable enough to disinfect the lenses every night and replace them every year or two, these lenses were wonderful. 

Today, soft contacts for daily wear are still available and can be chemically disinfected instead of needing to be sterilized with heat, so maintenance of the lenses is much easier.

Rigid Gas Permeable Contacts for Daily Wear

Introduced to the public in 1978, rigid gas permeable lenses were the Next advancement in technology for hard lenses. They looked and acted like hard lenses, but they could absorb small amounts of fluid and were able to transmit oxygen and carbon dioxide to and from the eye. This was due to the addition of silicone to the plastic material.

The silicone made the lenses more comfortable and adaptable than the original hard lenses because these new lenses were not as hard as the original lenses but they still held their shape on the eye, they were called "rigid" rather than "hard".

Many people who wore the old hard lenses but had some discomfort were now able to upgrade to the newer material with almost no change in their vision or care regimen. Today, there is a newer generation of gas

permeable lenses that can be comfortably worn all day by most people. They have increased oxygen transmission and fluid-attraction ability and these lenses are a good alternative for those patients who can't get good visual correction with soft lenses or who don't want the risk of infection that soft lenses pose.

 

Rigid Gas Permeable Contacts for Extended Wear

In the late 1980s, rigid gas permeable contact lenses we launched that could be worn overnight for up to seven days. These lenses were made of a material specifically designed for extended wear. They had the optical and handing advantages of hard lenses combined with a wearability closer to that of soft lenses.

The key difference was the addition of fluorine to the silicone material during the manufacturing process. This allowed the best combination of Gas transmission and moisture maintenance of any lenses yet developed.

The lenses offer many advantages in the areas of lens life and visual clarity. The material allows for a flexible wearing schedule similar to that of extended-wear soft lenses.

Disposable Soft Contacts

Also, in the late 1980s, the first disposable contact lenses were launched. These lenses were similar to extended-wear soft lenses, but they were made in an entirely new way. In fact, the new process enabled the lenses to be produced and sold so cheaply that they could be discarded after being worn on a daily-wear basis. 

Silicone Hydrogel Soft Lenses

In 2001, a new material was introduced. This material has incorporated the best of the traditional soft HEMA material with a blend of silicone to create a material that allows an enormous amount of oxygen through the lens. There is so much oxygen passing through the lens that even with the eyes closed that is, during sleep, the cornea receives enough oxygen to maintain its clarity and health.  There are five different lenses that fit into this category and all have their advantages over traditional soft lenses