We present design and first demonstration of optics for a telescopic contact lens with independent optical paths for switching between normal and magnified vision. The magnified optical path incorporates a telescopic arrangement of positive and negative annular concentric reflectors to achieve 2.8 x magnification on the eye, while light passing through a central clear aperture provides unmagnif...

RGP materials In choosing appropriate materials, it is important to remember that keratoconic patients (as well as in other primary corneal ectasias) demand high levels of comfort because they wear their lenses for long periods of time. With steep high minus lenses, which are often required, materials with high dimensional stability are recommended in order to minimise lens distortion. Mid to h...

In the last in our three-part series on myopia, Catherine Viner considers the assessment and correction of myopia in practice. Module C15569, one general point for optometrists and DOs Part 3: Assessment and correction T he predominant symptom in uncorrected (or undercorrected) myopia is blurred distance vision.1-3 It is suggested that because this symptom is so readily apparent, myopes account...

Anterior segment fluorophotometry (topical) and central endothelial cell photography were performed on 40 long-term (2-23 years) contact lens wearers (four groups of ten each: hard, soft, gas permeable, and gas permeable plus prior lens usage) and 40 non-contact lens wearers of similar ages. Morphologically, the endothelial cells of contact lens wearers showed greater variability in size and sh...

BACKGROUND Corneal infections due to contact lens contamination are risks associated with contact lens wear. Care systems which reduce these risks are desirable. METHODS This study evaluated a contact lens cleaning device using normal saline initially and then four contact lens solutions. RESULTS Using saline, six out of 10 tests resulted in complete removal of challenge organisms or showed...

Two methods can be employed to carry out this examination after insertion of the lens in an anaesthetized eye: (1) Examination by Reflected Light.-A very narrow slit-lamp beam is projected on to the area of angle to be examined, with the eye looking slightly away from the direction of the beam. The beam is focused on the angle and the various structures in it, and the examination is carried out...

We describe the design, fabrication, and testing of a 1.6 mm thick scleral contact lens providing both 1× and 2.8× magnified vision paths, intended for use as a switchable eye-borne telescopic low-vision aid. The F/9.7 telescopic vision path uses an 8.2 mm diameter annular entrance pupil and 4 internal reflections in a polymethyl methacrylate precision optic. This gas-impermeable insert is cont...

BACKGROUND The aim of this study was to assess the combined use of a high-reflective index vitrectomy (HHV) meniscus contact lens and a noncontact wide-angle viewing system in vitreous surgery. METHODS Twenty-three gauge vitrectomy was performed with combined use of a HHV meniscus contact lens and a noncontact wide-angle viewing system. When delicate manipulation of the retina such as interna...

● Tear film assessment should be undertaken with minimal invasion of the structure – non-invasive techniques should be used whenever possible ● Assessment must be made both prior to and during contact lens wear. Tear film quality should be assessed both with the lens in situ and without the lens ● Use of the Tearscope in clinical practice allows a more detailed examination of the tears to be un...

The early 1990s saw a large increase in the number of contact lens wearers in the UK. It is estimated that this figure doubled between 1990 and 1996 to reach approximately three million wearers. The increased uptake of contact lenses during this period is thought to have been due to a number of factors, including the availability of frequent replacement soft lenses, the introduction of daily di...