Silicone Hydrogel Contact Lenses in Sweden

Anna Karin Dahl - O.D
Anna Karin Dahl is an Optometrist from Sweden. She did her optometry education in Stockholm, and until recently was employed at Contacta EyeWear in Gothenburg as the product manager for Contact lenses in the Contacta group. Her interest in Extended Wear started when she was employed at Contacta in Gothenburg in 1991. She has done several lectures about silicone hydrogels in Sweden, Norway and Finland, and this year also at the BCLA in England. She has recently accepted a position with Synoptik Sweden as the person responsible for contact lenses throughout Sweden.

Courtesy of www.contacta.nu

Contacta has a history of fitting contact lenses for Extended Wear since the beginning of seventies. Contacta's philosophy is to fit the best available product for each patient at all time. One of them is silicone hydrogels. Contacta have now been fitting silicone hydrogels since 1998.

The Swedish history of extended wear
Mr Klas Nilsson from Gothenburg in Sweden started to develop a lathe cut soft high water content lens in the beginning of the seventies. He was then the owner of Contacta. The lens was based on vinylpyrrolidone and methylmethacrylate and was launched in 1975. The name of the product was Scanlens 75 (S-75). The lens was 72% water content. Initially Klas Nilsson got a really good start with his lens for Extended Wear. After a while negative responses occurred, with intolerance and discomfort due to tight fits. The lens became successful when the lens was fitted very loose and with a small diameter, and was frequently replaced, normally every six months. Still some patients did get jellybumps and mechanical problems with this thick lens.

The allergic problems from the solutions (thimerosal) also became sometimes a problem. The knowledge that Klas fitted Extended Wear lenses became very popular and the number of patients increased very quickly. In Sweden it was a problem at that time to find optometrists to fit Extended Wear lenses. Klas Nilsson was the first person in Sweden to start a training program for fitting contact lenses. It was called the contact lens technical education. To fit contact lenses for extended wear wasn't so popular from the optometrist and ophthalmologist point of view then. Mr. Nilsson thought he knew what the patients really wanted and it was Extended Wear lenses.

The criticisms and fear of fitting Extended Wear lenses was maybe more based on a political thoughts then clinical experience and facts.

In that period it became like two camps in Sweden - the optometrists who fitted Extended Wear and those who didn't like it at all. In 1986 Klas Nilsson got the greatest award an optometrist can get in Sweden, The Gullstrand medal. In the end of the eighties and beginning of nineties the S-75 lens was the most common fitted lens in Sweden, though on a daily wear basis.

Mr. Nilsson later sold his production of S-75 to CIBA Vision.

During the nineties the Acuvue lens started to be more popular to fit on Extended Wear basis. Most of the mechanical and allergic problems disappeared when we got the thinner lens. Frequent replacement with the lens did have a positive effect on the patients' eyes, though most of the optometrists in Sweden fitted them on a daily wear basis.

Silicone hydrogels
In 1998 we were introduced to the new silicone hydrogels. We participated in a Swedish study with PureVision. 500 patients went through the one year long study, with 40 at Contacta in Gothenburg. We had at that time still a large number of extended wear patients with S-75.

It wasn't difficult for us to convert our patients from the now old S-75 in to silicone hydrogels. Everything was better with this type of lens except the freedom. It was the same as before. They didn't need to take the lens out. Contacta has today nearly 2500 patients with silicone hydrogels.

As with any type of new lens we have seen negative responses but we've learnt more and more about them.

The negative response we have seen is: SEALs (Superior Epithelial Arcuate Lesion), CLPUs (Contact Lens Peripheral Ulcers), CLPC (Contact Lens Papillary Conjunctivitis), and poor wettabillity on the surface of the lens.

The SEALs problem seems to decrease with the newer 8.4 basecurve design.

The CLPU problem seems to increase in the period when people easily get a cold, but it is one of the problems we do not know why they appear.

The CLPC problem is quite a rare problem. The local CLPC problems do we see more often. In some cases this may be caused by too flat a fit or the lens might has been inserted inside out.

The poor wettability we see sometimes occurs when the lipid layer of the tearfilm is too thick. The lipid layer seems to hold on to the surface and the patient complains of dry eyes. Smoking may be an issue in causing problems with the wettability on the surface.

We also see mucin balls with silicone hydrogels. Mucin balls appear on the surface of the cornea. We have found that the number of mucin balls decreases when the lens fit gets steeper.

When a patient hasn't worn contact lenses before, we start with daily wear for one or two weeks to be sure that the handling isn't a problem.

Our follow up schedule is as follows:

• Initial visit
  
• One night
  
• One week
  
• One month
  
• 6 months
  
• After the first 6 months we examine the patient 2 times a year.

We have now been fitting silicone hydrogels since 1998. What we have noticed during the period is that our patients are very satisfied with their concept of wearing the lens overnight. The convenience and the freedom are important factors for our contact lens patients.