Patients interested in contact lenses may have many questions, and the optical assistant (OA) is often the first point of contact.
In last month’s article, we looked at some advantages and disadvantages of contact lenses that patients may enquire about. This month, we look at some common questions that patients may ask regarding their suitability for contact lenses.
Although it is not possible to be certain whether a patient is suitable for contact lens wear without an assessment by an optometrist or contact lens optician (CLO), there are nonetheless some questions the OA can help with.
Most patients can be considered for contact lens wear, and it is important to explain that contact lenses do not completely replace spectacles, and that a back-up pair of spectacles is always needed.
Contact lens suitability is not based on prescription alone, but there are some prescriptions that are more straightforward than others when it comes to contact lens fitting. This does not mean, however, that less straightforward prescriptions are not suitable. The following are common questions you may encounter from patients when enquiring about contact lenses.
“I have been told I have astigmatism. Does this mean I can’t have contact lenses?”
There are different degrees of astigmatism. Generally, astigmatism up to +/-0.75D can usually be corrected with a soft spherical or aspherical contact lens. Astigmatism over 0.75D will usually need a toric lens, in which the astigmatism is included within the lens.
Toric lenses will incorporate two different powers, and an axis. It is important the axis direction is in the right position, because if the lens were to rotate away from the axis position, the prescription would change.
There are a few different way the lenses can be adapted to ensure the axis remains in the correct position, including adding prism (called prism ballast) base down. This makes the lens heavier at the bottom, and so gravity will orientate the lens into the desired position. Sometimes, a few fitting appointments are needed as the lens may rotate slightly.
As these lenses are more bespoke than a spherical prescription, they are not usually held in stock, and need to be ordered. They are also more expensive than spherical lenses.
Once the astigmatism is higher than 2.00D, it becomes more difficult to fit with soft lenses (although not impossible), but there are other lenses that can be fitted for higher levels of astigmatism.
Rigid gas permeable Lenses (RGPs) are smaller than soft lenses and they sit on the tear layer of the eye. They are not flexible like soft lenses and take longer to build up the wearing time – and they may not be as comfortable initially. They can, however, correct higher amounts of astigmatism.
“I have a prism correction in my prescription. Does this mean I can’t have contact lenses?”
Whilst having prism in a prescription does exclude most contact lenses, there are scleral contact lenses that can incorporate some prism. These are large, rigid lenses that vault the cornea. If you have a patient who needs prism, refer to the optometrist or CLO for advice. There are also some soft lens options that can incorporate smaller amounts of prism.
“My prescription is very low and I only wear my glasses occasionally. Would I be suitable for contact lenses?”
This is a more difficult question to answer as it depends on different factors. When does the patient wear their spectacles? What benefit do they find when wearing them? Occasional wear is possible in contact lenses, and the lens of choice would probably be a daily disposable lens, but it does depend on the benefit to the patient. A fitting appointment would be needed to determine suitability to lens wear.
“I currently wear progressive spectacle lenses. Would I be suitable for contact lenses?”
There are different types of multifocal contact lenses available, including soft and rigid lens designs, and so this is not a contraindication for contact lens wear. These lenses are more expensive than single vision lenses and can take a few fitting appointments to find the most suitable option.
It is also possible to fit the dominant eye with the distance correction and the non-dominant eye with the near correction (called monovision). This doesn’t work for all patients, and usually works better for lower reading additions.
“I don’t need spectacles for distance, only reading. Would I be suitable for contact lenses?”
If contact lenses were for reading only, they would need to be removed when the patient needed to look into the distance, which is not practical. The patient could be fitted with multifocal contact lenses, with no prescription in the distance, or possibly one contact lens fitted to the non-dominant eye for reading, but this would need to be discussed with the contact lens practitioner. As the patient has good distance vision without a correction, there might be a compromise to their distance vision with lenses.
These are just some common questions patients may ask regarding suitability of contact lenses. Always remember to let the patient know that a contact lens appointment is needed by a qualified professional, as there are other factors that can determine contact lens suitability, and that a full assessment will always be undertaken.
Sue Deal FBDO R is a practising dispensing optician, ABDO College examiner, senior tutor and supervisor for dispensing opticians. She is also a practice visitor and external moderator for ABDO. She was recently awarded the ABDO Medal of Excellence for her outstanding services to the profession.