|Year : 2016 | Volume
| Issue : 1 | Page : 1-2
Advances in glaucoma surgery: Paradigm shift in management
VST Centre for Glaucoma, L. V. Prasad Eye Institute, Hyderabad, Telangana, India
|Date of Web Publication||10-Feb-2016|
FRCS(Ed), FRCOphth(Lon), VST Centre for Glaucoma, L. V. Prasad Eye Institute, Road No. 2, Banjara Hills, Hyderabad - 500 034, Telangana
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Pathak-Ray V. Advances in glaucoma surgery: Paradigm shift in management. Oman J Ophthalmol 2016;9:1-2
Human nature is such that it is not at all keen to bring about change and seeks great amount of solace and comfort in maintaining status quo, more so glaucoma specialists than most. However, as has been well said before - change is the only constant in this world. Desire for change is the force that metamorphosed mutilating intracapsular cataract surgery into phaco and femtosecond laser-assisted cataract surgery; similarly, in corneal transplants, with capability of replacement in layers, forgoing the need for penetrating keratoplasty.
Glaucoma traditionally has been a disease where cautious step-wise approach to management is generally the norm. It is initially treated medically, proceeding to surgery only following failure of medical treatment, sometimes interspersed with laser trabeculoplasty, especially in open angle glaucoma. Management is not in that order in angle closure disease wherein it is laser (peripheral iridotomy) that is done first, and subsequent management is substantially dictated by the amount of synechial angle closure and damage to the optic disc, other than intraocular pressure (IOP).
Nonetheless, thus far, trabeculectomy, since its description in the late 1960's, has been the mainstay of surgical treatment in both open as well as closed angle glaucoma.  The guarded filtration technique, as described by Cairns, was an improvement on the full thickness filtration procedure, with unquestionable efficacy especially when adjuvant antifibrotics are used. However, it continued to be plagued by unique sight-threatening complications, including and not limited to hypotony and its sequelae and life-long risk of infection. Simultaneously, in the 1990s, there was a substantial improvement in medical management with the availability of several antiglaucoma medications. Perhaps both these factors, availability of newer drugs and risk of morbidity, were the prime determinants of its use mostly in medically resistant, usually advanced glaucoma. Drainage implants or tubes, also considered traditional surgery, with all its incumbent risks, hitherto reserved for refractory glaucomas, are increasingly making inroads into the management of primary glaucomas following publication of long-term results in the Tube versus Trab study. 
Perhaps spurred by a desire to find suitable alternatives with fewer sight-threatening complications, Kozlov et al. and Stegmann et al. described the nonpenetrating procedures in the 1990s' which produced minimal blebs. , Safer it is, but only with a moderate IOP lowering effect. It has a steep learning curve, and thus, favorable results have been reproducible only in small pockets around the world.
The Ex-Press Glaucoma Filtration Device (GFD, Alcon Laboratories, Fort Worth, TX, USA) implanted under a modified trabeculectomy-like scleral flap, restricts outflow by standardizing wound size and retarding flow by channeling, it through a cylindrical implant.  It too created a minimal bleb, with fewer complications when compared to trabeculectomy. However, it appears that its main contribution was to usher in a generational change in the design of glaucoma surgical devices, epitomized by the development of multiple ab-interno (inside-out) and ab-externo (outside-in) devices [Table 1] and procedures, developed by industry and refined in collaboration with ophthalmologists/glaucoma specialists.
|Table 1: Some of the micro invasive glaucoma surgery devices and procedures|
Click here to view
These newer devices and procedures are clubbed into a group called minimally or micro-invasive glaucoma surgery (MIGS) - unlike their predecessors, they are bleb-independent and hence have a better safety profile.  Furthermore, as conjunctiva is not disturbed, they do not compromise future filtration, if required. They can be easily combined with cataract surgery by anterior segment surgeons and usually take no more than 15 min. It is currently performed in open angle glaucoma patients with early to moderate disease. However, the flip side of some of these procedures is that only a modest reduction in IOP may be achieved, and long-term results are awaited. The expense, too, is a consideration, especially in developing countries. Furthermore, with the exception of endocyclophotocoagulation, these devices do not have relevance in synechial angle closure. Nonetheless, when seen from the perspective of the patient, it not only improves their quality of life with none or fewer antiglaucoma medications but also faster visual rehabilitation, postsurgery.
Hence, change we (glaucoma specialists) must! With the availability of MIGS devices and procedures, we need not wait for open angle disease to progress to offer surgical options, especially when it can be effortlessly combined with cataract extraction. Trabeculectomy had to step back once before, with the advent of the so-called "chemical trabeculectomy" when prostaglandin analogs were made available in the last decade of the last century. It is standing at a cusp, yet again, likely to be dethroned from its primacy in the overall surgical management of open angle glaucoma, as safer surgical alternatives are made possible earlier on in the disease process. A paradigm shift indeed!
| References|| |
Cairns JE. Trabeculectomy. Preliminary report of a new method. Am J Ophthalmol 1968;66:673-9.
Gedde SJ, Schiffman JC, Feuer WJ, Herndon LW, Brandt JD, Budenz DL; Tube versus Trabeculectomy Study Group. Treatment outcomes in the Tube Versus Trabeculectomy (TVT) study after five years of follow-up. Am J Ophthalmol 2012;153:789-803.e2.
Kozlov VI, Bagrov SN, Anisimova SY, Osipou AV, Mogileutseu W. Non-penetrating deep sclerectomy with collagen. Eye Microsurg 1990;3:44-6.
Stegmann R, Pienaar A, Miller D. Viscocanalostomy for open-angle glaucoma in black African patients. J Cataract Refract Surg 1999;25:316-22.
Dahan E, Carmichael TR. Implantation of a miniature glaucoma device under a scleral flap. J Glaucoma 2005;14:98-102.
Saheb H, Ahmed II. Micro-invasive glaucoma surgery: Current perspectives and future directions. Curr Opin Ophthalmol 2012;23:96-104.