[The effect of selected drugs on the parameters of conjunctival photoplethysmography]

With a newly developed photoplethysmographical measuring device it is possible to record the conjunctival pulse of the human eye. The device consists of the self-constructed photoplethysmographical amplifier unit, the sucking electrode from silicone hard-rubber with photo-detector and luminescence diode, and a 3-channel recorder (3-NEK). Electrocardiogram and the conjunctival pulse are recorded simultaneously. Parameters that are derived from the curves allow to judge on the circulation in the tissue region investigated. Investigations were carried out in 70 test persons without clinical or other signs of pathological conditions regarding eye or vessels (classified into sex and age groups up to 40 years and over). 133 recordings with six consecutive curve waves were examined. Additionally, the influence of vasoactive drugs on the conjunctival pulse curves was investigated. The topical application of Oculoguttae Tolazolini 2% and Oculoguttae Epinephrini 2% showed no influence compared with the reference curves. Contrary to this, differences were proved after application of Nitrangin liquidum systemically in all parameters tested. The photoplethysmography of the conjunctiva bulbi is a noninvasive running-on method with good reproducibility without troubles for the patient, with an easy performance and only a small time demand. The results qualified the method to test the influence of systemically applied vasoactive drugs.