CONTRAST SENSITIVITY AND SHIP PILOTING

Visual acuity measurement is the ophthalmological rest used for determ ining the majority of professional aptitude thresholds. In the case of ship pilotage however, the necessity to detect physical information o f size and variable contrast can only be partly assessed by this param eter. Aims of the study A test considered to be more ergonomic for the visual capacity evaluation of seamen, and for the early diagnosis of ocular abnormalities, was evaluated. Method At the rime of their statu tory aptitude visit, 159 professional seamen underwent a test for morp hoscopic sense al variable contrast and luminance, gradual. Results Tw enty-seven ametropias of -0.75 to +3.00 diopters, 2 hypertensive retin opathies and 2 optical neuropathies were detected. Despite their low v isual acuity, the myopic subjects were able to preserve normal visual efficiency in low contrast, without correction. Inversely, in spite of the correction, a deficiency was noted at medium and low contrasts, w ith a special increase at low luminance. The 7 patients operated on fo r radial keratotomy, although their visual acuity reached 10/10, prese nted a morphoscopic discrimination deficiency at low and medium contra sts. Conclusion The test used in this study is designed for morphoscop ic discrimination testing in which contrast and luminance ave variable . This determination of luminance contrast sensibility seems to be an informative, sensitive and reliable means of detecting uncorrected ame tropia and diverse organic pathologies at their inset.