These structures were removed with a slice of sclera beneath a superficial scleral flap: hence the term deep sclerectomy. In , Vaudaux et al. At that time, Watson et al. At the time, however, they were the benchmark, driving the search for an alternative. Ideal surgery would create consistently an immediate, controlled IOP reduction with stable visual acuity and a minimal surgical learning curve. A realistic goal would be an operation that did not give rise to problems associated with early hypotony, late leaks, cataract formation or endophthalmitis, one that necessitated infrequent follow-up and was not bleb-dependent for success.
DS and viscocanalostomy VC represent attempts to achieve this goal. In particular, VC aims to be bleb-free. Both operations may provoke less post-operative inflammation than trabeculectomy surgery, 8 with smaller amounts of post-operative steroids required. These advantages translate into less intensive follow-up than following trabeculectomy.
Another challenge is the relative complexity of these procedures compared with trabeculectomy. A high level of skills is required to dissect a longer scleral flap of uniform thickness and to create a trabeculo-Descemet window TDW without entering the anterior chamber.
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To many ophthalmologists, this acronym suggests one type of operation, perhaps with a few ndividual nuances. As surgical techniques have evolved, there are now several variations of the original DS. The many variations of NPGS make it difficult to compare meaningfully results of trabeculectomy surgery and between surgeons. The multiple variations in surgical technique lead to confusion, even among glaucomatologists.
For example, Fyodorov is often credited as one of the fathers of NPGS, yet the operation he described, DS, 11 involves a basal iridectomy. The natural evolution of NPGS has rendered the term inaccurate and obsolete.
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We have identified several significant permutations in surgical techniques that may lead to a difference in outcome and have analyzed them separately. There are two broad categories: the deep sclerectomies and the viscocanalostomies.
As explained by Mendrinos et al. The main advantages are reduced hypotony in the immediate post-operative period, lower risk of endophthalmitis, and less inflammation from not entering the anterior chamber and not performing a peripheral iridectomy. These groups are all examined separately. Both DS and VC have been combined with cataract extraction, with further separation in this article for analytical purposes.
More recently, VC has been combined with canaloplasty, which again is discussed separately. Nd:YAG laser goniopuncture GP rates and post-operative use of antimetabolites are included where published. As several tonometric definitions of success have been used, for homogeneity, we have used the following: Table 1. Khairy et al.
Bissig et al. The use of an implant may improve the long-term success of DS. Kozobolis et al. In the context of DS, the use of concomitant MMC may lead to similar post-operative complications to trabeculectomy. Anand et al. The disruption of the canalicular wall may allow aqueous to percolate through from the anterior chamber, in the manner of a trabeculotomy. Nine percent required GP. Carassa et al. The inter-group difference was not statistically significant.
One patient required GP. While Carassa et al. Wishart and Dagres 28 used five to seven sutures for the scleral flap.
Laser-Assisted Techniques for Penetrating and Nonpenetrating Glaucoma Surgery
Wishart and Dagres found no blebs. From these reports, it can be deduced that the more sutures are applied to the scleral flap, the less there is a chance of a subconjunctival drainage bleb. This is important, both to establish the mechanism through which VC may work and to disseminate results accurately according to technique. If VC results in a bleb, is it functioning similarly to DS?
Are VC results comparable with DS outcomes? In trabeculectomy, establishing subconjunctival flow of aqueous is essential to bleb survival. Speculatively, by creating two routes for the aqueous to drain, i. Loose suturing of the scleral flap may be detrimental to the success rates of VC surgery.
Tanito et al. This might explain the lower rates of post-operative GP in this group.
Penetrating and non-penetrating surgery | Institut de l'oeil des Laurentides (IOL)
If the same-site keratotomy wound used for phacoemulsification does remain patent post-operatively, thereby acting as an ab interno goniotrabeculotomy, then separate-site PhacoVC might be expected to have poorer success rates than same-site PhacoVC. Indeed, Park et al. The average number of glaucoma meds pre-operatively and post-operatively was 4. All patients who underwent laser experienced a positive pressure control effect. The average IOP 2 measurements pre-laser was Visual acuity was unaffected following surgery in all patients. Complications included choroidal effusions, hyphema, and iris incarceration; all resolved without sequelae or intervention.
One patient was lost to follow-up after 15 months, one patient expired after 25 months follow-up, and one patient failed IOP control after 18 months. Conclusions: Non-penetrating glaucoma surgery that utilizes the CGDD appears to be a safe and effective procedure in patients at high risk for surgical complication with traditional filtration surgery.
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