Glaucoma
Figure 1: Surgical Microscope Image of the Laser Fiber and Endoscopic Optics used in Excimer Laser Trabeculotomy
Goniopuncture
Nowadays goniopuncture describes an intervention with laser following deep sclerectomy. The laser is used to create a pore in the trabecular Descemet membrane, which enables an aqueous outflow from the anterior chamber to the intrascleral reservoir. Laser goniopuncture can be performed using a neodymium(Nd):yttrium–aluminum–garnet (YAG) laser. Puncturing the trabecular Descemet membrane leads to success rates similar to those of TE.52–54
Previously, Feltgen et al. used an erbium(Er):YAG laser. They reported that goniopuncture in combination with cataract surgery produced an IOP reduction comparable to that of combined TE and cataract surgery.55,56
In addition, the rate of post-operative complications is low.56
Excimer Laser Trabeculotomy ELT ab interno is a minimally invasive surgical technique to reduce IOP in patients with glaucoma or ocular hypertension by creating pores from the anterior chamber into Schlemm’s canal.57–72
There are almost no thermal side effects or damage to the outer wall of Schlemm’s canal.
The laser fiber tip overlaps the optics by approximately 3 mm. Table 1: Technical Data for the AIDA Excimer Laser Laser type
Wavelength Cooling
Pulse energy Pulse duration Repetition rate Laser spot size
Cannula diameter Cannula material Length of fiber
Goniotomy
Goniotomy is used to enhance the route for aqueous humor outflow into Schlemm’s canal. For this purpose, the tissue of the chamber angle is incised under direct visualization with an operating microscope and a surgical gonioscopy lens or with a fiber optic probe.45 surgical knife, a photoablative laser device can be used.46,47
Instead of a In 1997,
Medow and Sauer reported the first use of endoscopic goniotomy in human subjects.48
Goniotomy is known as the gold standard for the treatment of primary congenital (infantile) glaucoma. A successful goniotomy improves the aqueous outflow and IOP control can be maintained for extended periods of time.49
For the procedure, an incision just below the Schwalbe line is made to open Schlemm’s canal.
Early treatment is important, as the success rate of goniotomy is dependent on the patient’s age. From those patients who had glaucomatous anomalies at birth or older than two years and who underwent one or two goniotomies, about 26 % were controlled.50,51 However, in patients between one and 24 months of age the success rate is 90–94 %.50,51
34
1.2 mJ at fiber tip 60 ns 20 Hz
200 μm 500 μm
Stainless steel 2,000 mm
The punctual ablation of TM by an excimer laser was first described in 1996 by Vogel et al.68
They used a prototype laser and the application
XeCl excimer laser, laser class 4 308 nm Air
was monitored using a contact lens. The ELT technique differs from that of other minimally invasive glaucoma laser techniques like argon laser trabeculotomy (ALT) or selected laser trabeculotomy (SLT). The latter ones induce tissue alterations by heat or tissue remodeling, respectively. Therefore, the effects of ALT and SLT reduce over time. After ELT, the edges of the openings are found to be very smooth.68,71 This should minimize wound healing, and thus contribute to a long-lasting IOP reduction.
If filtering surgery is required following ELT, the outcome is not compromised by ELT. As there is no conjunctival touch during ELT, no conjunctival scarring that would influence the outcome of TE is expected. It is known that phacoemulsification in isolation results in reduced IOP.73–77
The IOP reduction of combined phaco and ELT (phaco-ELT) is greater than that of either cataract surgery or ELT alone.65,72
explanation is the deepening of the anterior chamber angle by extraction of the thickened cataractous lens.
ELT could easily be performed at the end of a clear cornea phacoemulsification or as a stand-alone procedure. It can reduce IOP for an extended period of time and is associated with a low rate of complications.65,72,78
The duration of cataract surgery is only prolonged
by 2–3 minutes for the ELT. The same corneal incision as for phacoemulsification is used.
In our procedure, at the end of the cataract surgery or at the beginning of a stand-alone procedure, a medical miosis is performed with acetylcholine chloride and the anterior chamber deepened with viscoelastics. An endoscopically guided photoablative laser (see Figure 1) operating at a wavelength of 308 nm (excimer laser, AIDA, TUI-Laser, Munich, Germany) is used to create ten microperforations into the TM spread over an area of 90°. Each microperforation is about 0.5 mm in diameter (diameter of the laser fiber). Further details of the device are given in Table 1. To transmit the complete energy of the laser to the TM,
US OPHTHALMIC REVIEW One likely
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