New stroboscopic light source and technique for intraoperative retinal fluorescein angiography during penetrating keratoplasty

Purpose: We report the development of a new stroboscopic light source system and technique for performing intraoperative fluorescein angiography during penetrating keratoplasty for aphakic or pseudophakic bullous keratopathy. Method: A controllable pulse xenon light source system (Strobex lamp; Chadwick-Helmuth Inc, El Monte, CA) with a fiberoptic endoilluminator probe is used to perform high quality intraoperative fluorescein angiography during penetrating keratoplasty in pigmented rabbits and human subjects. Following corneal trephination and extraction of the intraocular lens (crystalline lens in rabbits), a temporary Cobo keratoprosthesis is secured while a 20 gauge endoilluminator is inserted into the vitreous cavity through a limbal incision. The endoilluminator is advanced to a retinal illumination area of ∼3 DD and 10% fluorescein is injected intravenously. A microscope camera coupled to a 50:50 beamsplitter photographs the passage of fluorescein dye while the surgeon maintains an unaltered view through the operating microscope. Results: Angiograms through a keratoprosthesis show excellent contrast and resolution, comparable to standard fluorescein angiography. Fine peripapillary vessels are seen reproducibly and with great detail in the rabbits. All the phases of retinal angiography can be seen, including arteriolar constriction and capillary nonperfusion in one of four human subjects examined. Conclusions: High quality intraoperative fluorescein angiography can be performed in patients undergoing penetrating keratoplasty for aphakic/pseudophakic bullous keratopathy. With this technology, pre-existing retinal disorders such as cystoid macular edema might be identified in the perioperative setting allowing for important management decisions to be made intraoperatively.