Erratum to “Abstracts of the 29th BCLA Annual Clinical Conference, Brighton, 2005” [Contact Lens Anterior Eye 28 (3) 137–142]☆

Article Outline

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The publisher regrets that when the above Abstracts were printed, one abstract was omitted. The missing abstract is printed below.

Optimising Fluorescein Viewing with Slit-Lamp Biomicroscopy

James S. Wolffsohn^*, Rachael C. Peterson

Neurosciences Research Institute, Aston University, Birmingham, B4 7ET, UK

E-mail address: j.s.w.wolffsohn@aston.ac.uk

Purpose: To examine the spectral radiance output of slit-lamp cobalt blue illumination and the spectral transmission of yellow barrier enhancement filters to assess the optimisation of fluorescein image viewing and capture.

Method: The spectral radiance of seven different models of slit-lamp cobalt luminance was measured with a Spectrascan PR-650 photometer and the illumination outputs from three slit-lamps of the same model were measured. The spectral transmission of three barrier filters (two of which were integrated into the slit-lamp optics) were measured with a Cary 2300 Spectrophotometer.

Results: The spectral radiance of the cobalt blue illumination was typically between 404 and 504nm, with a peak at between 452 and 484nm. All the slit-lamps examined showed a similar light distribution (S.D. of difference 0.20–1.13%). Comparison between three slit-lamps of the same model showed a wide range of maximum light intensity (438–634cd/m²), but a similar spectral radiance distribution. The barrier filters had a cut-off at 510–520nm, achieving 90.0–98.5% transmission above 580nm. However, the external cardboard mounted filter excluded less light below 500nm (7.4%) compared to the two integrated filters (<0.1%).

Conclusion: For optimal fluorescence, the light source should have maximum power at the wavelengths absorbed by the fluorophore (∼485nm) and little power at the wavelengths emitted by the fluorophore (∼510–520nm). Of the slit-lamps examined, only between 8.9 and 29.3% of the illumination output was optimised for >80% fluorescein excitation and 1.9–10.6% of the illumination overlapped with that emitted by the fluorophore. A barrier filter enhances observation by obscuring the non-fluorescing reflected light. As the fluorescein excitation and emission spectra at the average pH of the eye overlap at 500nm, yellow barrier enhancement filters should ideally have a lower cut-off.