The success of fistulizing operations for the relief of hypertension in glaucoma depends in large measure upon the creation of a filtering area in the subconjunctival spaces. While it can be argued that the filtration factor is not the entire answer to the problem, as maintained, for instance, in the neurohumoral theory, it is certainly one of the most potent reasons for the prevalence of these procedures in this country.
In order to secure permanent filtration from the anterior chamber to the immediate subconjunctival spaces, many substances working upon the principle of the seton operation have been employed, such as threads, gold drains, and horsehair, and quite recently Qadeer1 has employed acrylic plates made of the same material as that used for the Ridley implants. Most of these substances have been discarded after trial and failure because they were irritating to the eye and, as a result, frequently increased
LAVAL J. The Use of Absorbable Gelatin Film (Gelfilm) in Glaucoma Filtration Surgery. AMA Arch Ophthalmol. 1955;54(5):677-682. doi:10.1001/archopht.1955.00930020683009