SCANNING LASER OPHTHALMOSCOPE IMAGING OF FLUORESCEIN-LABELED BLOOD-CELLS

Purpose: To demonstrate the feasibility of a technique for the visuali zation by scanning laser ophthalmoscope (SLO) of fluorescein-labelled autologous leukocytes and platelets in retinal vessels. Method: Indivi dual blood samples from rats and rabbits were centrifuged to isolate p latelets and leukocytes, then passively labelled with fluorescein and reinjected into the same animal. An SLO was used to visualize and reco rd cell displacement in the retinal circulation. Labelled platelets we re analysed by flow cytometry. Results: By SLO, platelets appeared as a heterogeneous particle flow, and individual leukocytes appearing as brighter spots could easily be traced, Flow cytometry showed that afte r labelling platelets were well individualized and their size was slig htly increased. Conclusion: Circulating blood cells can be visualized in retinal vessels by a simple method consisting of passive labelling of autologous platelets and leukocytes by fluorescein. No platelet tox icity was detected. This method could be applied to the study of blood cell movement in human retinal vascular diseases.