Ординатура / Офтальмология / Английские материалы / Step by Step Minimally Invasive Glaucoma Surgery_Garg, Melamed, Bovet, Pajic, Carassa, Dada_2006
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132 Step by Step Minimally Invasive Glaucoma Surgery
deep sclerectomy for the surgical treatment of primary open angle glaucoma.
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2.Benedikt O, Hiti H. Die Ziliarkörperfreilegung. Eine neue Operationsmethode zur Behandlung des irreversiblen Winkelblockglaukoms und des Aphakieglaukoms. Klin Monatsbl Augenheilkd 1976;169:711-16.
3.Burian HM. A case of Marfan’s syndrome with bilateral glaucoma. With a description of new type of operation for developmental glaucoma (trabeculotomy ab externo). Am J Ophthalmol 1960;50:1187-92.
4.Cairns JE. Trabeculectomy. Preliminary report of a new method. Am J Ophthalmol 1968;66:673-79.
5.Demailly P, Lavat P, Kretz G, et al. Non-penetrating deep sclerectomy with or without collagen device in primary open-angle glaucoma: middle-term retrospective study. Int Opthalmol 1997;20:131-40.
6.Edmunds B, Thompson JR, Salmon JF, et al. The National Survey of Trabeculectomy. III. Early and late complications. Eye 2002;16:297-303.
7.El Sayyad F, Helal M, El-Kholify H, et al. Nonpenetrating deep sclerectomy versus trabeculectomy in bilateral primary open-angle glaucoma. Ophthalmology 2000;107: 1671-74.
8.Fjodorov SN, Loffe DI, Ronkina TI. Deep sclerotomy: technique and mechanism of new glaucomatous procedure. Glaucoma 1984;6:281-83.
9.Fronimopoulos J, Lambrou N, Pelekis N, et al. Elliot’s trepanation with scleral cover (procedure for protecting the fistula in Elliot’s trepanation with a lamellar scleral cover). Klin Monatsbl Augenheilkd 1970; 156:1-8.
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11.Johnson DH, Johnson M. How does nonpenetrating glaucoma surgery work? Aqueous outflow resistance and glaucoma surgery. J Glaucoma 2001;10:55-67.
12.Konstans AGP, Jay JL, Marshall GE, et al. Prevalence, diagnostic feature, and response to trabeculectomy in exfoliation glaucoma. Ophthalmology 1993;100:619-27.
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136 Step by Step Minimally Invasive Glaucoma Surgery
INTRODUCTION
There is an increasing interest in the use of the excimer laser in ophthalmology, particularly in refractive surgery. The argon fluoride excimer laser (193 nm) ablates tissue with a high precision and without any mechanical or thermal damage to surrounding structures. Within the fiveyear follow-up the intrastromal excimer laser ablation (ISELA) was smooth and regular and there was no evidence of inflammation or thermal damage. Our study demonstrates a beneficial effect of the excimer laser (193 nm) during the non-penetrating glaucoma surgery.
BACKGROUND AND OBJECTIVE
The initial application of excimer lasers has been oriented to the cornea and to refractive surgery.2,14 Today, different types of lasers have been used in the treatment of glaucoma (the Holmium laser, Erbium:YAG laser, Carbondioxide laser and Excimer lasers).3,8-10
All authors use well-known «traditional» methods of glaucoma treatment, but apply for this purpose the excimer laser with 193 nm wavelength: external trabeculoectomy, sclerostomy, trans-scleral sinusotomy, filtering sclerostomy, deep sclerectomy, NPDS, etc.1,4,5,17
The argon fluoride excimer laser ablates the tissue with a high precision (1 micron per pulse) and without mechanical or thermal damage to surrounding structures and also has a cytostatic effect (Figs 9.1 and 9.2).6,12,18
The current technology does not allow the 193 nm wavelength to transmit through the fiber optics, which limits the endo-ocular use of this laser.
We designed a special excimer laser unit with 193 nm wavelength for glaucoma surgery in 1999. It is possible to use this device in the standard operating room under the
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Fig. 9.1: Light photomicrograph and scanning electron microscopy of the stroma of rabbit cornea after excimer laser
Fig. 9.2: Light photomicrograph and scanning electron microscopy of rabbit cornea after surgical incision
operating microscope. Portable in dimensions it has a special mobile manipulator to deliver the laser energy to the operating field. The laser beam works in “eraser mode” without the necessity of a special mask. The focal distance between the manipulator and the ocular tissues is about several millimeters, the beam area in the focal point is 0.5 × 1 mm (Fig. 9.3).
This study was conducted to find out the effectiveness and longevity of non-penetrating glaucoma surgery (NPDS)7 with the use of excimer laser with 193 nm wavelength.7,15,16
PATIENTS AND METHODS
In a non randomized prospective study there were 160 eyes of 154 patients aged from 18 to 88 years, between March
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Fig. 9.3: A special mobile manipulator for a surgeon, that delivers the laser energy to the operating field of the eye
2000 and May 2005. The majority of patients had advanced and far-advanced stages of open-angle and narrow-angle glaucoma. Laser iridotomy was performed in 44 patients with narrow-angle glaucoma to enlarge the profile of the anterior chamber angle. Intraocular pressure (IOP) was
Laser Surgical Treatment of Glaucoma 139 
recorded preoperatively and postoperatively at 1, 7, 14 days, at 1, 3, 6 and thereafter every 6 months.
SURGICAL TECHNIQUE
We describe a new technique of non-penetrating glaucoma surgery that uses the excimer laser to reduce the risk of perforation the trabeculo-descemet’s membrane. With this technique the ablation is precise and homogeneous.
The procedure can be performed with topical anesthesia. Excimer laser surgery consists of:
•fornix-based conjunctival flap 2.0-2.5 mm in the upper quadrant;
•minimal episcleral cautery;
•dissection of a superficial corneal groove;
•dissection of a 2.5 × 2.5 mm rectangular in half thickness lamellar scleral flap;
•excimer laser ablation;
•closure of scleral flap and conjunctival closure with a running 8.0 silk suture.
The deep layers of sclera were evaporated layer by layer
with laser energy of a 150 mJ/cm2 density until vessels of ciliary body appeared (Fig. 9.4).
Then the Schlemm’s canal was covered with a protector, and the deep layers of corneal stroma were removed by laser up to the Descemet’s membrane until the moment of the aqueous humor drop appearance (energy density -
50mJ/cm2) (Fig. 9.5).
Postoperative treatment consisted of antibiotics and
dexamethasone drops instilled four times a day during 2 weeks.
RESULTS AND DISCUSSION
As a result of intrastromal excimer laser ablation (ISELA) the ophthalmotonus normalization was achieved in all
140 Step by Step Minimally Invasive Glaucoma Surgery
Fig. 9.4: The deep layers of sclera were evaporated by excimer laser until vessels of ciliary body appeared
Fig. 9.5: The deep layers of corneal stroma were removed by excimer laser up to the Descemet’s membrane until the moment of the aqueous humor drop appearance
Laser Surgical Treatment of Glaucoma 141 
cases independently of disease stages. The IOP averaged 10±2 mm Hg in the early postoperative follow-up. There were observed no cases of hemorrhagic or other complications, and the postoperative period was notable for a favorable course. All patients did not note any painful sensations both intraand post-operatively, in this connection this procedure may be transferred to the outpatient category. The B-scanning and ultrasound biomicroscopy were performed thoroughly in patients with hypotonia in order to reveal a choroidal detachment. As the rule, only edema and thickening of choroid by 50-100 μm took place in the first postoperative days that indirectly was evidence of aqueous humor resorption by vessels of ciliary body. The surgical technique supposes a creation of bypass between the Descemet’s membrane and vessels of ciliary body which absorbability is 50 times more than in ordinary capillaries (Fig. 9.6).
In our opinion the normalization of intraocular pressure after the intrastromal excimer laser ablation is achieved owing to an improvement of uveal scleral outflow of aqueous humor, an elimination of Schlemm’s canal collapse and a recovery of its functionally maintained sites. As a result there are no sharp IOP fluctuations in the direction
Fig. 9.6: Basic outflow pathways of aqueous humor in ultrasound biomicroscopy: 1- into the intrascleral space and vessels of ciliary body; 2 - into the flat filtering bleb