Fitting & Verification
Rigid Lens Evaluation

Flourescein Patterns: Flourescein is a common dye or stain which can be used to help analyze the fit of rigid lenses. When it mixes with the tear film it will glow or flourescein in the presence of ultraviolet light or cobalt blue light. It allows the fitter to examine the shape and flow of the tear layer between the back surface of the lens and the front surface of the cornea. It is available in solution form or impregnated in paper strips. Dynamic flourescein patterns can be observed immediately after the patient has blinked.

Figure A indicates an ideal flourescein pattern. The even distribution of flourescein indicates good support of the lens by the cornea, and an even flow of tears under the lens. The flatter peripheral curve results in the added thickness of film around the lens periphery.

Figure B shows a lens which is fit too steep with central stagnation of dye. Intermediate touch is the result of a relative lack of flourescein just outside the region of pooling. The thin peripheral curve indicates a diminished lift of the lens edge.

Figure C indicates a flat lens, showing central touch and diminished dye. There is a greater amount of flourescein found under the peripheral rim of the lens.