Ординатура / Офтальмология / Английские материалы / Step by Step Minimally Invasive Glaucoma Surgery_Garg, Melamed, Bovet, Pajic, Carassa, Dada_2006
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142 Step by Step Minimally Invasive Glaucoma Surgery
of hypotonia that leads to proper complications (hyphema, choroidal detachment, cataract progression, etc.). Preoperatively the outflow facility index (C) did not exceed 0.04 mm3/min/mmHg while after the intervention this index (C) averaged 0.32 ± 0.02 mm3/min/mmHg, i.e. 7-9 times the increase. Moreover a tendency of the aqueous humor production (F) increase is revealed in a part of cases.
In the majority of cases (about 70% of eyes) an improvement of visual acuity is noted on an average by 0.1-0.2 obviously due to a decompression of optic disk fibers and a reduction of peripapillary edema that needs a further study. In the long-term follow-up the outflow facility index (C) decreased slightly, but remained within the norm (mean 0.20±0.04 mm3/min/mmHg) that provided a compensation of ophthalmotonus on a level of 17.0 ± 2.5 mm Hg (Fig. 9.7).
In the long-term follow-up in patients with initial and advanced stages of glaucoma the IOP was compensated in all cases. In the group of patients with the far-advanced stage of disease the YAG laser descemeto-goniopuncture (DGP)11,13 in the intervention area was required within periods from 4 to 6 months in 16 eyes (10% of cases). It
Fig. 9.7: IOP data after excimer laser treatment (ISELA) and NPDS
Laser Surgical Treatment of Glaucoma 143 
allowed to restore aqueous humor outflow pathways and to normalize the IOP (Fig. 9.8).
Within the follow-up of 1 year and more a development of cystic filtering bleb was observed in 2 eyes. A monotherapy with the 0.5 percent Betoptic solution instillation one or two times was administered in 12 patients with far-advanced glaucoma.
CONCLUSION
Thus, the creation of a domestic specialized excimer laser unit with 193 nm wavelength allowed to develop practically a new safe technology of glaucoma surgery that cannot be performed using traditional knife surgery.
Small dimensions (portability), presence of manipulator for a surgeon, price of the unit differentiate it advantageously from other foreign excimer laser and also allow to adapt it in conditions of an ordinary operating room.
A new technology of glaucoma surgery (ISELA) is developed that allows to restore natural aqueous humor outflow pathways without a destruction of the Schlemm’s canal, to return the greater part of aqueous humor to vessels
Fig. 9.8: The ultrasound biomicroscopy before and after the YAGlaser DGP (descemeto-goniopuncture) to create a microperforation in Descemet’s membrane behind Schwalbe’s line to improve filtration
144 Step by Step Minimally Invasive Glaucoma Surgery
of ciliary body. The procedure is especially efficient and safe in patients with initial and advanced stages of disease because allows to normalize ophthalmotonus and to maintain visual functions.
REFERENCES
1.Argento C, Sanseau AC, Basoza D, et al. Deep sclerectomy with a collagen implant using the excimer laser. J Cataract Refract Surg 2001;Apr.27(4):504-06.
2.Aron-Rosa DS, Boutnoy JL, Carré F, et al. Excimer laser surgery of the cornea: qualitative and quantitative aspects of photoablation according to the energy density. J Cataract Refract Surg 1986;12:27-33.
3.Beckman H, Fuller TA. Carbon dioxide laser scleral dissection and filtering procedure for glaucoma. Am J Ophthalmol 1979;88:73-77.
4.Berlin MS, Martinez M, Papaioannou T, et al. Goniophotoablation: excimer laser glaucoma filtering surgery. Lasers Light Ophthalmol 1988;2:17-24.
5.Brooks AM, Samuel M, Carroll N, et al. Excimer laser filtration surgery. Am J Ophthalmol 1995;119:40-47.
6.Ereskin NN, Takhchidi KP, Vartapetov SK, et al. Advantages of a new excimer laser for glaucoma surgery. 4th International Glaucoma Symposium-I.G.S. Barcelona, Spain,19-22 March 2003;P-28.
7.Fyodorov SN, Kozlov VI, Timoshkina NT, Sharova AB, Ereskin NN, Kozlova EE. Non-penetrating deep sclerectomy in open angle glaucoma. Ophthalmosurgery 1989;3- 4:52-55.
8.Iwach AG, Hoskins HD, Mora JS, et al. Update on the subconjunctival THC:YAG (holmium) laser sclerostomy Abexterno clinical trial: a 4-year report. Ophthalmic Surg Lasers 1996 Oct;27(10):823-31.
9.Jacobi PC, Dietlein TS, Krieglstein GK. Prospective study of ab externo erbium: YAG laser sclerostomy in humans. Am J Ophthalmol 1997, Apr; 123(4):478-86.
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10.Klink T, Lieb W, Grehn F. Erbium-YAG laser-assisted preparation of deep sclerectomy. Graefes Arch Clin Exp Ophthalmol 2000 Sep;238(9):792-96.
11.Kozlov V, Magaramov D, Ereskin N. Laser surgery for open-angle glaucoma in eyes with intraocular pressure elevation after non-penetrating deep sclerectomy. Ophthalmosurgery 1990;4:62-66.
12.Marshall J, Trokel S, Rothery S, et al. An ultrastructural study of corneal incisions induced by an excimer laser at 193 nm. Ophthalmol 1985;92:749-58.
13.Mermoud A, Karlen ME, Schnyder CC, et al. Nd:YAG goniopuncture after deep sclerectomy with collagen implant. Ophthalmic Surg Lasers 1999 Feb; 30(2):120-25.
14.Puliafito CA, Steinert RF, Deutsch TF, et al. Excimer laser ablation of the cornea and lens. Ophthalmol 1985;92(6): 741-48.
15.Takhchidi KP, Ereskin NN. Surgical treatment of glaucoma by excimer laser with 193 nm wavelength. Intraocular Implant and Refractive Society, India. 2005 May;1(5):1113.
16.Takhchidi KP, Ereskin NN, Doga AV, et al. A new microinvasive technology of glaucoma surgery by excimer laser. 5-th International Glaucoma Symposium-I.G.S. Cape Town, South Africa, 30 March-April 2,2005; P-A24.
17.Traverso CE, Murialdo U, Dilorenzo G, et al. Photoablative filtration surgery with the excimer laser for primary openangle glaucoma: a pilot study. Int Ophthalmol 1992;16:4- 5,363-5.
18.Schuman JS, Chang W, Wang N, et al. Excimer laser effects on outflow facility and pathway morphology. Inves. Ophthalmol Vis Sci 1999;40:1676-80.
148 Step by Step Minimally Invasive Glaucoma Surgery
OBJECTIVE AND INTRODUCTION
The arrival of glaucoma surgery into the framework of deep sclerectomy or cataract surgery using bimanual phacoemulsification, allows surgery to be performed on a closed anterior chamber. It was evident that these microinvasive techniques would use the same topical anesthesia technique.
Topical anesthesia is used in ambulatory surgery where the patient must be able to return home immediately without any risk to health or from postoperative risks.5
Another advantage of using this anesthesia in glaucoma surgery, is that it becomes possible to position the eye on the exact axis to enable dissection of the scleral flap. This is easier for the surgeon than when using retrobulbar or peribulbar anesthesia. which paralyze the external muscles, or - worse - place the eye in an unsuitable position.
In our experience, it appears that the length of hospitalization is about one hour:2 the amount of time needed to prepare and carry out the surgical operation. This is as long as the patient is kept calm and relaxed, which is simpler than it appears to be.
When caring for the patient, we must ensure his optimum comfort and that the stress inherent in any operation is kept to the minimum.6
Topical anesthesia is not necessarily enough. It depends on the type of the operation and also the type of patient. This anesthesia, in the course of years, has been improved or, rather, completed by various surgeons and anesthetists.
Glaucoma surgery is different from cataract surgery in that, at the beginning of the operation, an 12 mm incision is made in the conjunctiva with a perpendicular conjunctival cut. This dissection has to be made up to the tenon in order to find the sclera. It is sometimes necessary to use a cauter to coagulate the superficial vessels. For this
Topical Anesthetic and the Subconjunctival Bubble 149 
reason, topical anesthesia is sometimes not sufficient, making a subconjunctival bubble during glaucoma surgery that allows mobility to be maintained. This is very convenient, as it allows the operated eye to be kept in the best position for microdissection of successive layers.
HISTORICAL BACKGROUND
At the beginning of the twentieth century, we see the appearance of topical anesthetics, among them, cocaine.19 In 1910, Julius Hirschberg presented a cataract operation using a 2 percent solution of cocaine as a topical anesthetic.14 In 1988, Robert Smith presented a anesthesia technique for cataract surgery in EEC, using 1 percent drops of amethocaine and a superior conjunctival injection of a bubble of 2 percent lidocaine.18
More recently, in 1991, R Fischman reported using tetracaine as drops for a phacoemulsification cataract operation.17,10 C Williamson, in 1992, used lidocaine 4 percent in topical anesthesia, 4 drops before emulsification.25 In 1996, J P Gills improved the technique by introducing an introcamerular injection of lidocaine, diluted at 0.5 percent, which did away with the deep pains occurring with mobilization of the iris or the capsule.11,13
ANATOMICAL REVIEW OF CORNEAL INNERVATION
The cornea is the most innervated tissue. This innervation is supplied mainly by the ciliary branches of the ophthalmic division of the trifacial nerve. It enters the cornea radially at the level of the stroma moyenne, forming a dense plexus under the Bowmann membrane. The central epithelium receives terminal axones from this plexus. There is a small sympathetic innervation which is probably at the origin of the cellular proliferation.23
150 Step by Step Minimally Invasive Glaucoma Surgery
Contrary to earlier theories, corneal innervation is made at the central level by the plexus which goes through the Bowmann membrane and, on the periphery, by a more superficial conjunctival tract.
The innervation of the ciliary muscles and of the iris that generate during the deep pain occurring with mobilization of the globe. This comes from the plexus. This necessitates using a different anesthesia to get rid of the pains.
The innervation of the tarsal and bulbar conjunctives also come from the trifacial nerve but by way of a different route to the cornea.
PHARMACOLOGY
The ideal topical anesthetic must have neither local nor systemic, nor a corneal toxicity. It must not bring about an epithelial edema. Whilst working fast without causing pain when introduced, it must work for an adequate period of time. There are several types of topical anesthetics. The most frequently used are cocaine, proparacaine, tetracaine and lidocaine. All topical anesthetic drops sting when they are put in. Cocaine and proparacaine have been abandoned because of significant bulbar and epithelial toxicity.
Tetracaine is much less toxic but it doesn’t provide deep enough corneal anesthesia, and it becomes necessary to repeat the instillation of drops during the operation. This often causes an epithelial edema.17 This group of anesthetics includes an ester, increasing their solubility in water and diminishing cellular penetration. Tetracaine has been preferred in the United States for a long time, because it was the only preservative free solution.15
Lidocaine belongs to the amide group. It is lipid soluble which allows greater tissue penetration and has a longer
Topical Anesthetic and the Subconjunctival Bubble 151 
period of action. For corneal anesthesia, this anesthetic gives satisfactory anesthesia from 30 minutes to one hour, depending on the patient. At a concentration of 2 percent, it doesn’t present any toxicity problems and does not entail epithelial edema.21
Lidocaine given by intracamerula injection, at a dosage of not more than 0.5 percent, is not toxic for the human endothelium. This has been proved by multiple random prospective clinical studies.15 A study using rabbits has demonstrated that an injection of lidocaine can be toxic for the endothelium, but the dosage used and the conditions under which that study was done were far removed from those used in human microsurgery.16
DESCRIPTION OF TOPICAL
ANESTHESIA TECHNIQUES
Cataract
Before disinfection, a drop of oxybuprocaine (Novésine) is put in. Five minutes before the operation, five drops of lidocaine 2 percent without preservative (Astra) is put in. Topical anesthesia is completed by an intracamerular injection of 1cc lidocaine 0.5 percent without preservative, done after the paracenteses and during hydrodeliniationhydrodissection. This gets rid of the deep pain during mobilization of the iris or the capsule.11,13
Glaucoma
The initial stages of a glaucoma operation are similar to that of a cataract operation. Firstly, before disinfection, drops of oxybuprocaine are put in. Then, five minutes before the arrival of the patient in the operating theater, lidocaine 2 percent is put in. Then, instead of intracamerula