MY conclusion is that it is better not to risk spoiling an efficient fistula by making a cataract incision through the bleb. If another case of this kind should present itself, instead of making an upward corneal incision, I will make the incision downward and protect it by a sliding flap.
Reference: Gifford H. Removal of cataract from eyes that have been fistulized for glaucoma. Arch Ophthalmol. 1925;54:346-347.
A look at the past . . .. Arch Ophthalmol. 2001;119(7):1070–000. doi:10.1001/archopht.119.7.1070