An automated and spectral differentiating dark adaptometer--initial results of a clinical study

Abstract

Routine measurement of dark adaptation is a lengthy process and the presence of a qualified operator is required. Our dark adaptometer uses either a red or a green light-emitting diode to produce the threshold stimulus. Through an electronic circuit arrangement the dark adaptation curve is automatically measured. A computer stores the resulting data and renders the statistical analysis possible. To obtain the normal adaptation curve, 33 healthy volunteers were tested. We subsequently examined 32 patients in the clinical assay. The adaptation for the green test light results in an overlapping photopic/scotopic graph and is used as an analogy for the curve resulting from a white test light. The red LED produces the scotopic graph later on with a more elevated threshold. Of the patients examined, 14 with night blindness show the expected pathological results. Correlating to the type of disease, the other 18 patients without night blindness show normal dark adaptation. In 150 examinations the dark adaptometer proved to be easy to handle, yielding valid and reliable results. The automatic recording allows operator-independent measurements. The dark adaptation rate for red and green and the final cone and rod threshold can be evaluated. The computer control provides statistical analysis and the possibility to delegate the examination.