Deep Sclerectomy

Abstract

Filtering surgery evolved from the classic trabeculectomy, in which penetration into the anterior chamber is a necessary step, toward nonpenetrating deep sclerectomy. The first procedure presents several serious complications such as durable hypotony, hyphema, flat anterior chamber, choroidal detachment, endophthalmitis and surgery-induced cataract. To avoid such drawbacks, a novel nonpenetrating technique was designed to improve predictability of the intraocular pressure-lowering action, while reducing the incidence of the immediate postoperative complications encountered with the penetrating method. This surgery works by building up new outflow pathways for the drainage of the aqueous humor while keeping intact the integrity of the anterior chamber. Deep sclerectomy acts at the bulk of main resistance to aqueous humor egress, located at the juxtacanalicular meshwork and the inner wall of Schlemm's canal. It consists of dissection of these two structures while keeping a thin filtering membrane though which aqueous humor is being drained. The membrane prevents overfiltration and ensures a reproducible postoperative intraocular pressure. This surgery is indicated for most of glaucoma except angle closure and neovascular cases. The procedure consists in opening the conjunctiva and Tenon's capsule and creating a 5 × 5 mm limbus-based superficial scleral flap. A deeper scleral flap measuring about 4 × 4 mm is dissected and the roof of Schlemm's canal is removed. A space maintainer is inserted and the flap and conjunctiva are closed. Results after 10 years are good with an IOP of 12.2 ± 4.7 mmHg and an overall success rate of 77.6%with few complications.

Visante Anterior Segment Optical Coherence Tomography Analysis of Morphologic Changes After Deep Sclerectomy With Intraoperative Mitomycin-C and No Implant Use

“…Furthermore, our results were good with a postoperative IOP level of 12.78 ± 3.48 mm Hg and an overall success rate of 89.4% comparable with previous studies that analyzed deep sclerectomy with scleral implants. [16][17][18] Implants are thought to improve the hypotensive effect of the surgery 19 by maintaining the decompression space (intrascleral lake) between the external flap and trabecular meshwork and acting as a space maintainer during the time of maximal healing, thus facilitating the scleral passage of aqueous humor to the capillaries and veins within the subconjunctival tissue and allowing the growth of new canals that will increase suprachoroidal filtration. 4,20 Some investigators have claimed that the use of an implant is virtually mandatory to maintain this decompression space open.…”

European Glaucoma Society Terminology and Guidelines for Glaucoma, 4th Edition - Chapter 3: Treatment principles and optionsSupported by the EGS Foundation

“…A collagen implant or a hyaluronic acid device is often used to keep this scleral lake open. In a number of cases, a filtration bleb forms; long-term IOP levels appear higher than with trabeculectomy 218-228 .…”

Surgical treatment of neovascular glaucoma with Ex-PRESS glaucoma shunt

“…Postoperative hypotonia did not develop in our patients. The main resistance to aqueous humor out ow is at the level of the trabecular meshwork in glaucoma, and the out ow can be signi cantly improved by surgically removing this resistance [17].…”