We then moving on to examining the front of the eye using a biomicroscope called a Slit Lamp.
The first thing we look at with the slit lamp are the lids and lashes. It’s surprisingly common to have something as simple as ingrowing eyelashes that are irritating the eye. We have had a number of clients who’ve been treated for anything from allergies to conjunctivitis who simply require regular removal of an ingrowing eyelash. We can also see where there is a lack of eyelashes either due to age or chronic eye conditions such as dry eye. There may be a lot of debris and dry skin on or around the base of the lashes. This is anterior blepharitis and can be managed very effectively with an in-house procedure called Blephex then maintained at home with on going lid hygiene.
It is not uncommon to have mites at the base of the lashes called Demodex. There are 2 types of Demodex; Demodex follicullorum which live at the base of the eye lashes and Demodex Brevis which live on the surface of the skin. If there is an excessive population you get symptoms such as itchy eyelids and the lid margins can also look quite irritated. The Demodex can be effectively treated with a tea tree oil based solution in office and maintained at home with an appropriate lid cleanser.
If the tears look soapy we refer to that as saponification. It’s an indication that there’s an imbalance of the amount of bacteria in the eye. The bacteria breeds and produces this soap-like secretion which (like any soap) burns and irritates. The bacterial load can be reduced using a short course of antibiotic drops.
Using stains to assess dry eyes
Most people will recollect having yellow dye put in their eyes when having an eye exam. This is fluorescein. It’s a dye that colours the tears but also stains any damaged area of the cornea. It doesn’t affect your vision and simply rinses out on its own.
With the fluorescein, we can see how much damage has been done to the cornea by the degree and extent of corneal staining. In addition, we can get a really useful measure called the TBUT (tear break up time) which gives us an idea of the quality of your tears. Every time the tears “break up” there is an impetus to blink. When there is very little oil in the tears the tears break up quicker. If you over-ride your desire to blink e.g. when staring at a computer screen, the cornea will become damaged as the surface dries out.
There is another staining agent called Lissamine Green which is used less commonly than fluorescein but stains dead tissue so it’s very useful to determine where there is more severe damage and is especially useful when assessing the lid margin. Sometimes it is the edge of the lid is not working effectively because it has desiccated tissue along the lid margin. This can be removed somewhat like having a microdermabrasion with a beauty therapist.