Design considerations for a fluorophotometer for ocular research

Abstract

Fluorometric studies have been made with modified slit-lamp microscopes. These instruments offered considerable versatility in modifying experimental parameters, but were seldom optimized in terms of detector and illuminator apertures, filter band-pass characteristics, detection system, light-source stabilization, or optical resolution. Improper control of these parameters can result in artifacts which override useful information. A new fluorophotometer for ocular research has been designed that utilizes an optical system, which eliminates the need for a contact lens. An effort was made to optimize both the axial resolution and the minimum detectable signal. The characteristics of standard barrier filters and excitation filters were examined and compared with photomultiplier sensitivity curves. It was necessary to use double filters in order to reduce artifacts due to excitation light that was not rejected by the barrier filter. In order to optimize the signal-to-noise ratio, a photon counting detection system was used. A dark current equivalent to 3 X 10(-10) g/ml allows a useful detection range of 1 X 10(-10) g/ml.

Lens autofluorescence in healthy individuals

“…Cycloplegia reduced accommodative artifacts during the lens scan. The best longitudinal resolution can be obtained by both reducing the slit width and increasing the angle between the exciting and emitted beam which determines the depth of the 'focal diamond' (Munnerlyn et al 1985). Our fluorometer is designed to reduce the depth of focus; although an exact analysis of axial resolution has yet to be made.…”

The effect of isosorbide-mononitrate eye drops on the human intraocular pressure and aqueous humor dynamics

“…Fluorotron Master anterior chamber protocol was used to quantify the changes in aqueous humor dynamics [2,3,5,9,13]. The depth of the anterior chamber was measured by ultrasound-A-scan.…”

Autofluorescence methods in ophthalmology

“…The overlap of their transmission bands should be minimal. Munnerlyn et al 40 recommend increasing the separation between the excitation and barrier filters to about 30 nm at the 50% transmission points and possibly doubling both filters for maximum reduction in the overlap.…”