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Deep sclerectomy, preparation of the inner wall of Schlemm's canal and intraoperative fluorescein-testF. J. Rentsch
Introduction: The aim of the present study is to make the outflow of the aqueous humor visible following deep sclerectomy and micropreparation of the inner wall of Schlemm`s canal.
Methods: Before starting the micropreparation, the sites of outflow of the aqueous humor through the trabecular meshwork and through the cornea are checked by a drop of Fluorescein Dinatrium SE® (fluorescein-test 1). Following microsurgical thinning of the inner wall of Schlemm's canal a second drop of fluorescein is given on top of the trabecular meshwork (fluorescein-test 2).
Results: The fluorescein-test demonstrates where aqueous humor penetrates through the tissue. Outflow of aqueous humor through Descemet's membrane was never observed as long as there were no microperforations. Following micropreparation the permeability of the inner wall of Schlemm's canal is increased. Microperforations give rise to destinct and very active leacage-points. Partial removal of the inner wall leads to a slower, diffuse or spotlike penetration of the aqueous humor (video). The rate of penetration is increased if the pressure in the anterior chamber is rised. In cases of very advanced pathology of the trabecular meshwork the penetration of aqueous humor can be completely blocked even if micropreparation of the trabecular meshwork had been performed. In such cases microperforation should be performed. Following the intraoperative use of Fluorescein-Dinatrium SE® no problems of healing or postoperative irritation were seen.
Discussion: Micropreparation of the inner wall of Schlemm's canal is effective in decreasing the resistance and increasing the outflow of the aqueous humor without opening of the anterior chamber. This can be demonstrated by a simple fluorescein drop test which is capable to provide the surgeon with a general idea of the sites and intensity of the outflow of aqueous humor. Broad exposure of Descemet`s membrane is not effective and unnecessary.
According to our observations, the intraoperative use of several drops of Fluorescein Dinatirum SE® is not dangerous. Hyperergic reactions should be excluded preoperatively.
Director Eyeclinic, St.-Vincentius-Hospitals, Steinhäuserstraße 18, D-76135 Karlsruhe