Abstract
AIMS Design and use of a 'coloured mediameter' to diagnose and assess the prognosis of vitreous haemorrhage. METHODS The technique of transillumination has gone into oblivion due to its subjective nature. We have designed a mediameter, in which a light-sensitive sensor is placed on the cornea and adjoining sclera during the process of transillumination. We can thus record the trans-corneal and trans-scleral light transmittance objectively. These recordings are made with white, red and green lights of appropriate wavelengths produced by interposing pure filters on the light source. RESULTS In normal eyes, the transmittance recorded with these three lights is more or less in the same range. In cases of vitreous haemorrhage, the white and red lights pass through the vitreous relatively unhindered, while the green wavelength is absorbed by the blood, resulting in a very poor transmittance of green light. This difference of light transmittance readings with different lights can be used to diagnose vitreous haemorrhage even in the presence of a cataract or an opaque cornea. Repeated recordings at regular intervals can give an accurate assessment whether the vitreous haemorrhage is resolving or not. CONCLUSION This instrument is very simple, inexpensive, portable and easy to use to diagnose and assess vitreous haemorrhage.