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High-frequency deep sclerotomy another option for surgical treatment of glaucoma
The procedure may allow earlier surgical treatment of glaucoma patients and reduce the number of drops they use.
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The challenge in the glaucoma surgery arena is the continued search for the ultimate glaucoma surgery technique that provides long-term IOP reduction, leading to the elimination of topical glaucoma eye drops, preservation of the ocular surface, along with low to no intraoperative and postoperative complications. Although trabeculectomy, initially described in the 1960s, continues to be the standard for effective IOP lowering, it is not readily welcome by ophthalmic surgeons due to its associated potential postoperative complications such as hypotony and choroidal detachment. A search for alternative techniques has led surgeons through the path of non-penetrating deep sclerectomy with or without a collagen implant, viscocanalostomy, penetrating sclerectomy, perforating deep sclerectomy, tube shunts and, more recently, minimally invasive glaucoma surgery procedures.
While the menu of glaucoma surgical procedures continues to expand, there is no single procedure to date that provides the ideal glaucoma surgery for our patients. The enemy of a successful filtration procedure is the fibroblastic proliferation that ultimately leads to the demise of the filtering channel and obliteration of the bleb. In the absence of this ideal surgical procedure, surgeons have to pick from the available surgical procedures to best match the needs of the individual glaucoma patient.
In this column, Dr. Vukosavljević and colleagues describe a new glaucoma surgical procedure: high-frequency deep sclerotomy. Although a promising technique, it is not FDA approved and requires larger patient series and longer follow-up to fully understand the overall safety and efficacy of this glaucoma procedure.
Thomas “TJ” John, MD
OSN Surgical Maneuvers Editor
Although trabeculectomy is still the gold standard in the surgical treatment of glaucoma, it could be followed by a number of complications, and postoperative results are not always predictable. Therefore, its place in the surgical glaucoma treatment algorithm is at the end of the treatment scale. For these reasons, we are still looking for glaucoma surgical procedures that will be efficient but safe and predictable.
In recent years, glaucoma surgery has been evolving to a so-called minimally invasive approach. Those minimally invasive glaucoma surgeries (MIGS) tend to bring us good results in IOP reduction, with limited manipulation of conjunctival and scleral tissues. MIGS procedures seem to be better than trabeculectomy in terms of safety and surgical duration, but at the same time, they are not as effective as trabeculectomy in lowering IOP. Safety and short surgical time make these procedures more suitable for combined cataract and glaucoma surgery, which could help them find a prime place in the glaucoma treatment paradigm.
Images: Vukosavljević M
Technique
One of these new methods for lowering IOP is high-frequency deep sclerotomy (HFDS) (Figures 1 and 2). In this procedure, a diathermic high-frequency dissection probe is used. A bipolar current of 500 kHz is used through this 19-gauge probe with a tip of 0.3 mm × 1 mm. Six pockets are made in the nasal sclera ab interno through the trabecular meshwork, Schlemm’s canal and into the sclera. These pockets are 1 mm deep, 0.3 mm high and 0.6 mm wide. A modulated current generates a temperature of approximately 130°C at the tip of the probe. The setup provides high-frequency power dissipation in close vicinity to the tip. As a result, collateral or local heating of the tissue is limited.
Two clear corneal incisions, 1.2 mm wide, are made in the temporal and nasal upper quadrant, similar to cataract surgery, 120° apart from each other. High-density cohesive ophthalmic viscoelastic device (OVD) is injected to fill the anterior chamber. The high-frequency diathermic probe is inserted through the temporal corneal incision. Visual inspection of the target zone (opposite iridocorneal angle) is achieved using a four-mirror gonioscopic lens (Figure 1). The high-frequency tip is then penetrated up to 1 mm nasally into the sclera through the trabecular meshwork and Schlemm’s canal, forming a deep sclerotomy.
After the deep sclerotomy, OVD is evacuated from the anterior chamber with bimanual irrigation and aspiration. Postoperatively, tobramycin/dexamethasone eye drops are administered in the treated eye four times daily for 1 month, along with pilocarpine eye drops three times daily.
Studies and follow-up
In our first study, complete success was defined as IOP of 21 mm Hg and lower without IOP-lowering medications, and it was achieved in 52.17% of the treated patients. Qualified success was defined as IOP of 21 mm Hg and lower with additional IOP-lowering medications, and it was achieved in 26.09% of patients. The total number of medications used in the beginning of the study was 2.78, and after 12 months it was 0.61.
During the follow-up period, we have encountered a few complications. In seven eyes (30.43%), we found a transient IOP rise above preoperative values during the first 4 weeks, and we believe that it was secondary to inflammatory reaction.
In 21.7% of the patients during the first year of follow-up, IOP was above 21 mm Hg even with all tolerated glaucoma medications, and these patients were subsequently scheduled for filtration surgery. There was some peripheral anterior synechiae (PAS) at the site of the scleral opening in patients who needed trabeculectomy. In others who had a postoperative IOP increase that responded well to topical medications, PAS was not observed. Only minor complications have been seen during and after surgery. There were no cases with postoperative hypotony or shallow or flat anterior chamber. There was one case of hyphema that resolved by day 7 postoperatively.
Conclusion
We believe that HFDS could find its place in the glaucoma surgical treatment armamentarium as a quick and simple method that could also be done as a combined procedure with cataract surgery. In cases with a suboptimal result, other glaucoma surgical procedures can be performed after HFDS.
Even though trabeculectomy gives the best results for IOP lowering and complication rate, this method should be the last line of surgical defense in the overall glaucoma management spectrum.
In our opinion, HFDS, possibly combined with cataract surgery, could enable earlier surgical treatment of glaucoma patients and thus reduce the number of eye drops they are using, giving them a better chance of not developing ocular surface disease secondary to prolonged use of eye drops.
- References:
- Ferrari E, et al. J Cataract Refract Surg. 2005;doi:10.1016/j.jcrs.2004.10.050.
- Lüke C, et al. Acta Ophthalmol Scand. 2007;doi:10.1111/j.1600-0420.2006.00785.x.
- Pajic B, et al. Graefes Arch Clin Exp Ophthalmol. 2006;doi: 10. 1007/s00417-010-1561-0.
- Pajic B, et al. J Glaucoma. 2011;doi:10.1097/IJG.0b013e3181dddf31.
- Ruben S, et al. Eye (Lond). 1993;doi:10.1038/eye.1993.87.
- Sawchyn AK, et al. Curr Opin Ophthalmol. 2016;doi:10.1097/ICU.0000000000000236.
- For more information:
- Miroslav Vukosavljević, MD, a professor at medical faculty of Military Medical Academy, University of Defence, Crnotravska 17, Belgrade, can be reached at email: mvukosavljevic@milmedic.rs.
- Edited by Thomas “TJ” John, MD, a clinical associate professor at Loyola University at Chicago and in private practice in Oak Brook, Tinley Park and Oak Lawn, Ill. He can be reached at email: tjcornea@gmail.com.
Disclosures: Vukosavljević and John report no relevant financial disclosures.