Your Questions Answered
- How do I know which daily disposable to fit?
- How can I assess how much a soft toric lens has rotated off axis?
- How much should a soft lens move on blink?
- What is the best type of lens to fit a patient with dry eyes?
- What are the different sorts of filters that can be used on a slit lamp and when would you use them?
- How do CIBA VISION’s silicone hydrogels differ from other silicone hydrogel lenses?
- Can psuedopapillodema occur in high myopes?
How do I know which daily disposable to fit?
This is a question that students frequently ask and essentially there are three points that should be taken into account in order to determine the choice of lens.
- consider the individual prescription – the options could be narrowed down if the patient is astigmatic or presbyopic for example.
- consider is the material of the contact lenses, some lenses are developed using moisturising ingredients – if you have a patient who has dry eyes or works in a dry environment (air conditioning)
- it is important to establish the patient’s contact lens wear history, and discuss any concerns or issues that the patient may have expressed.
How can I assess how much a soft toric lens has rotated off axis?
You need to use the beam of the slit lamp to align it with the marking on the lens. The measurements on the slit lamp will allow you to measure the degree of rotation that has taken place.
How much should a soft lens move on blink?
Different types of lenses will move by different amounts and there isn’t really a definitive answer to this question. Ideally movement of approximately 0.5mm should occur, but this will vary depending on different factors. For example, lens design and manufacturing process will have a bearing on how much a soft lens moves. You also need to consider how much a patient blinks, how tight the lids are and how dry the patient’s eyes are. Rather than concentrating on the amount of movement, try to ensure that there is adequate lens centration with full limbal coverage.
What is the best type of lens to fit a patient with dry eyes?
A lens which resists dehydration, so either silicone hydrogel lenses because many have a low water content which makes the material more resistant to dehydration, or alternatively a daily disposable with added moisturisers.
What are the different sorts of filters that can be used on a slit lamp and when would you use them?
There are two different types of filters that can be used. The first is a red free filter; this would be used to look for corneal vascularisation. Secondly, there is the blue filter which helps you see any staining after instilling fluorescein.
How do CIBA VISION’s silicone hydrogels differ from other silicone hydrogel lenses?
AIR OPTIX lenses have a unique patented plasma surface treatment, which means that the surface is more wettable and deposit resistant. The surface treatment reduces the possibility of the lenses drying out and attracting lipid deposits which can lead to poor vision and discomfort.
Can psuedopapillodema occur in high myopes?
Yes - it is possible and more likely to occur in high myopia with a tilted disc and/or astigmatism, but it is usually more prevalent in hypermetropia because of the size of the optic nerve hear generally being smaller, so the nerve fibres tend to blur the disc margins giving the impression of blurred disc margins and swollen false appearance.
