New Glaucoma surgery improving Anterior Aqueous Drainage

Introduction Anti-glaucoma medicines, laser surgery and incisional surgery all seek to lower the intraocular pressure (IOP). Incisional surgery is indicated when medical treatment and/or laser surgery have failed, are likely to fail or are not available or practical. The most standard surgical procedure is trabeculectomy (or some variation thereof e.g. ExPRESS shunt): aqueous is shunted from the anterior chamber under Tenon’s capsule and conjunctiva anteriorly. Antimetabolites markedly improved the success rate of anterior filtration but brought potential long term problems of late leaking and endophthalmitis. When anterior filtering surgery fails or is likely to fail such as in some secondary glaucomas, tube and plate shunts drain aqueous humor to the equatorial region of the eye Core Concepts • Both the appearance of the optic nerve head (ONH) and the retinal nerve fibre layer (RNFL) as well as the visual function maybe influenced by age. • Age alone has been described to account for loss of appr. 25% of optic nerve fibres during a 70-year life span. • There is increasing evidence that ageing related loss of neuronal structures is not a linear process. • We increasingly rely on technology to diagnose and monitor glaucoma and it is essential that instruments differentiate between pathological changes and age related changes. • Most diagnostic devices do account for the effect, even though normative databases used are fairly limited. • Longitudinal studies and larger age-related normative databases are needed to use current technologies more optimally. under Tenon’s capsule and conjunctiva. These procedures are time-tested and generally succeed in experienced hands. Hypotony, anterior chamber bleeding, suprachoroidal hemorrhage, serous choroidal detachments, late bleb leaks, endophthalmitis, corneal decompensation and bleb scarring occasionally (but too often) bedevil our efforts to prevent vision loss. The last decade or so has seen some interesting efforts to provide an effective and safer alternative. Holmium laser sclerostomy, viscocanalostomy and deep sclerectomy achieved some success but have lost adherents because of ineffectiveness, complicated surgery or unanticipated problems. Several new approaches to improve aqueous drainage have have gained some enthusiasts. They can be classified either by the approach, ab interno vs. ab externo, by the tissue compartment into which the shunted aqueous flows or by the location of the actual surgical site. Some of the more popular of these as well as one that is still in its infancy are described, classified by the approach and the principles, and what is known about results. Recent approaches Three new ab interno procedures bypass trabecular meshwork by shunting fluid from the anterior chamber either directly into Schlemm’s canal or into the suprachoroidal space.