How do I…

Selecting the right lens

Independent optometrist, Lyndon Ferguson, advises on the importance of the tear film when selecting contact lenses

Lyndon Ferguson

There are very few situations in practice where I wouldn’t consider a patient for contact lenses nowadays. Most patients have an opportunity to benefit from contact lenses, and if it is not for full time wear, they may still find them convenient for certain tasks and activities.

When it comes to selecting the right lens for the patient, comfort is a key priority because it is one of the things that is most likely to discourage them from continuing. However, comfort tends to be less of a problem nowadays with the modern materials that are used to develop contact lenses. Therefore, in most cases, if the right lens is selected for the patient, comfort should not be a problem.

Common complaints

When it comes to addressing complaints in contact lens wear, patients can be broken down into two groups: the new fits who may return to discuss comfort, vision or handling; and the ‘normal’ wearers who might have been in lenses for 10 to 15 years and will occasionally present with a complaint.

For these patients, we must look at what they are complaining about and what has changed. More often than not, the contact lens, its materials and the changes to a patient’s tear film should be considered.

Tear film assessment

An assessment of the tear film is key to a patient’s future success as a contact lens wearer because having a really good tear film provides the ideal scenario.

There are a number of ways that practitioners can assess the tear film. For most practitioners in general practice, and the way I do it, is to look at the eye and its surface. I would add a staining agent such as fluorescein or lissamine green so that I can assess the tear film and look for any signs of pooling or staining on the surface of the eye.

"It’s very useful to ask the patient about the signs and symptoms of dry eye or tear film dysfunction that they may be experiencing. To do this, I use the OSDI questionnaire"

Dry eye dealings

As a practitioner in general High Street practice, I spend more time talking to people about dry eye than any other subject. It is the most common complaint that I come across.

Many people describe their symptoms of eye dryness as something they experience all day, every day. Ageing, combined with the work environment that many people find themselves in – looking at a screen in an air-conditioned office – can often lead to eye dryness symptoms.

It’s very useful to ask the patient about the signs and symptoms of dry eye or tear film dysfunction that they may be experiencing. To do this, I use the OSDI questionnaire, which was highlighted as a useful tool for diagnosing dry eye in the DEWSII report last year. 

I use this because it is quite thorough, but it only takes five minutes to fill in and it quantifies things and gives you a score at the end.

Selecting a lens

There are three things that I keep in mind when selecting a contact lens for a patient who has presented with eye dryness symptoms. Firstly, I would trial a modern silicone hydrogel lens because, while it will not necessarily work on everyone, in my opinion it provides me with the best chance of getting that person into a lens that performs well.

The lens that I select needs to have a low to mid water content –  put simply, having a lens with a high water content will not do a patient with dry eye any favours at all.

I also look for a lens that I know will maintain its hydration level consistently throughout the day – for me Acuvue Oasys 1-Day is the lens I usually go to due to all three considerations.