There are three groups of procedures which help to achieve successful contact lens wear. Determining optimum lens parameters (including mode of wear and material), appropriately assessing the fit of the lens and, at aftercare, assessing the effects of lens wear on the external structures of the eye.
This technique measures the curvature of the central cornea over 3 - 6 mm. It is used to assess the curvature, power, and toricity of the cornea, as well as the presence of any corneal distortion. The two types of keratometer are one-position and two-position. They differ in the way that the syst...
In two-position keratometers the doubling is fixed for a particular separation of the mires. The separation of the mires themselves has to be altered in order for the reading to be taken.
Everting the upper lid allows observation of the palpebral conjunctiva of the upper lid. It is useful to evert the lids and examine the palpebral conjunctiva using the slit-lamp prior to fitting a patient with contact lenses to establish a baseline. It is also indicated if the patient has a red e...
Prior to using the slit-lamp it is important to make sure that it is set up to provide ease of use and comfort for the patient and practitioner. Repeating this procedure for each patient will allow the maximum amount of clinical information to be gathered in a reasonable period of time.
Here is a way of calibrating the slit-lamp when the calibration plate is misplaced.
The parallelepiped illuminates a three-dimensional corneal area and is effective for detecting a range of lesions. An optic section illuminates a two dimensional area of tissue that is viewed obliquely and is used to localise the depth of lesions. It is used to examine the cornea and in particula...
For indirect illumination, the microscope is focused on an area adjacent to the illuminated tissue. It is useful for observing corneal neovascularisation and non-opaque corneal lesions such as microcysts. For retro-illumination, light is reflected off the anterior surface of the iris or the retin...
This is a difficult technique for the novice. Furthermore, it is of limited use during clinical evaluation because of the low magnification available on most slit-lamps and the small area of corneal endothelium that can be viewed at any one time. Assessment of the corneal endothelium when symptom...
Fluorescein is an orange dye that fluoresces green when illuminated with a cobalt filter. Areas of corneal or conjunctival epithelial damage will exhibit fluorescein dye uptake and will appear bright green. This positive fluorescein staining will help to identify the extent and distribution of ep...
Wratten 12 filters are yellow and absorb reflected blue light while transmitting green light. Fluorescein staining becomes more obvious.
The tear layer is comprised of the outer lipid layer, middle aqueous layer, and inner mucin layer. The tear film can be stained with fluorescein dye and then observed with the slit-lamp for tear break up and tear meniscus height.
Practitioners must be able to insert and remove contact lenses in order to fit new patients, and in the event that a contact lens patient presents with a problem. New patients, as well as those with poor manual dexterity will be unable to insert and remove contact lenses themselves.
Fit assessment determines whether or not a contact lens is fitting well and is suitable for the patient. Adequate fitting is necessary for optimal vision and comfort, and to minimise the risk of complications.
