For several reasons, the prognosis should be guarded in cataract extraction following previous filtering operations for glaucoma. Such eyes may show varying degrees of visual loss from the glaucomatous process itself which preoperative tests for retinal function are not sufficiently sensitive to detect. Degenerative changes may have occurred in the ocular tissues that make the response of the eye to the trauma of surgery unpredictable. Fluid vitreous is commoner with added frequency of vitreous loss and attendant complications. The iris may show severe atrophy. The anterior chamber may be so shallow that operation is difficult. Sequelae of glaucoma surgery may greatly complicate cataract extraction and interfere with the final visual results. For example, extensive adhesions of the iris to the lens or cornea may have occurred. If the iris has been adherent to the cornea, there is predisposition to postoperative corneal edema and opacification, due to defects in the endothelium.
SCHEIE HG. A Method of Cataract Extraction Following Filtering Operations for GlaucomaPerpendicular Corneal Incision Anterior to the Cicatrix. AMA Arch Ophthalmol. 1956;55(6):818-829. doi:10.1001/archopht.1956.00930030822008