Cyclodestructive Procedures for Glaucoma
Marisse M. Solano
Shan C. Lin
Geoffrey P. Schwartz
Louis W. Schwartz
INTRODUCTION
Intraocular pressure is the major risk factor for glaucoma that ophthalmologists are able to control. Medically, either eye drops or pills are used to decrease aqueous production or increase aqueous outflow to effectively lower intraocular pressure. Most surgical and laser procedures, including trabeculectomy, tube shunts, goniotomy, iridectomies, laser trabeculoplasty, and laser iridotomy, decrease the intraocular pressure by increasing outflow. Cyclodestructive procedures are designed to destroy the ciliary processes, thereby decreasing aqueous production. Because of the unpredictability of these procedures in lowering intraocular pressure and the complications associated with their use, such cyclodestructive procedures are often considered a surgery of last resort. However, recent studies and practices have employed these procedures as a first-line surgery and even before medication treatment.
INDICATIONS
• Cyclodestruction of the ciliary body has traditionally been reserved for use in patients who have failed previous treatment with medicines or surgeries.
• Exceptions to this rule include patients who are not willing to undergo filtration surgery, those who cannot undergo surgery owing to medical conditions, and patients in underdeveloped countries. In underdeveloped countries, where medical care is expensive and not always available, diode contact transscleral cyclophotocoagulation (CPC), which is portable and relatively easy to use, may be effective and safe as the first line of treatment for glaucoma, although the energy delivered is typically lower than that used in nonseeing eyes.
• Nonpenetrating forms of CPC may have benefit in controlling pain in blind, painful eyes, and may allow the patient to avoid
removal of the eye as long as visualization or ultrasound reveals no intraocular tumor.
removal of the eye as long as visualization or ultrasound reveals no intraocular tumor.
Types of glaucoma that have been treated with varying degrees of success include end-stage open-angle glaucoma; neovascular glaucoma; glaucoma post penetrating keratoplasty; advanced angle closure, both primary and secondary; traumatic glaucoma; malignant glaucoma; silicone oil glaucoma; congenital glaucoma; pseudophakic and aphakic open-angle glaucoma; and secondary open-angle glaucoma.
Alternative treatments that are usually considered in this group of patients include filtering surgery with antimetabolite or tube shunts.
• Transscleral CPC, micropulse CPC, and endoscopic cyclophotocoagulation (ECP) have been used in cases of relatively good potential vision.1,2 In the case of ECP, this is often in the setting of combined cases with cataract surgery.2 Inflammation and cystoid macular edema (CME) are not infrequent complications and should be anticipated and prevented with appropriate steroid therapy.
CONTRAINDICATIONS
• There are relatively few strict contraindications to the various forms of CPC.
• A phakic patient with good vision has historically been the primary contraindication; however, recent studies have used transscleral CPC and ECP in such cases.1,2
• Marked uveitis is a relative contraindication because patients have increased inflammation and risk for CME following the treatment; care should be taken to try to quiet the eye as much as possible before the procedure. However, uveitic glaucoma is one of the secondary glaucomas that have been treated successfully with ECP and transscleral CPC.
• For all of the nonpenetrating forms of CPC, the procedure is usually performed in the office, and patient cooperation is required; inability to cooperate may be a contraindication in such cases.
• For ECP, very poor visual potential (no light perception or hand motions) is a contraindication because there are potential risks for endophthalmitis and choroidal hemorrhage with this intraocular surgery.
• Newer technologies such as micropulse transscleral cyclophotocoagulation (MP TCP) and ECP allow for the use of cyclodestructive procedures in eyes with better visual prognosis.
REFERENCES
1. Egbert PR, Fiadoyor S, Budenz DL, et al. Diode laser transscleral cyclophotocoagulation as a primary surgical treatment for primary open-angle glaucoma. Arch Ophthalmol. 2001;119(3):345-350.
2. Chen J, Cohn RA, Lin SC, et al. Endoscopic photocoagulation of the ciliary body for treatment of refractory glaucomas. Am J Ophthalmol. 1997;124(6): 787-796.
TECHNIQUES
Several techniques are used for cyclodestruction. They include noncontact transscleral CPC, contact transscleral CPC, MP TCP, cyclocryotherapy, transpupillary CPC, and ECP. All of the procedures may be repeated and the nonpenetrating forms may often require multiple treatments.
NONCONTACT TRANSSCLERAL CYCLOPHOTOCOAGULATION
• A neodymium (Nd):YAG laser is used to perform noncontact CPC. In the past, a semiconductor diode laser, Microlase (Keeler, Inc., Broomall, PA), was also utilized.1
• Retrobulbar anesthesia is given.
• A lid speculum is placed if a contact lens is not used.
• A contact lens developed by Bruce Shields may or may not be used. The contact lens has the advantages of having markers at 1-mm intervals to better judge the distance from the limbus, blocking some of the laser light from entering the pupil, and blanching an inflamed conjunctiva to decrease superficial charring of the conjunctiva2 (Fig. 27-1).
• Eight to 10 burns are placed 1 to 3 mm (optimal: 1.5 mm) from the limbus for 180 to 360 degrees, taking care to avoid the 3 and 9 o’clock meridians in order to avoid coagulating the long posterior ciliary arteries and causing anterior segment necrosis. Energy levels of 4 to 8 J are used. The laser beam is focused on the conjunctiva; however, the laser is defocused such that its effect is actually 3.6 mm beyond the conjunctival surface, with most of the energy being absorbed by the ciliary body (Fig. 27-2). In general, the greater the energy levels used, the greater is the inflammation.3,4,5
REFERENCES
1. Hennis HL, Stewart WC. Semi-conductor diode laser transscleral cyclophotocoagulation in patients with glaucoma. Am J Ophthalmol. 1992;113:81-85.
2. Simmons RB, Blasini M, Shields MD, et al. Comparison of transscleral neodymium:YAG cyclophotocoagulation with and without a contact lens in human autopsy eyes. Am J Ophthalmol. 1990;109:174-179.
3. Frankhauser F, Van der Zypen E, Kwasniewska S, et al. Transscleral cyclophotocoagulation using a neodymium YAG laser. Ophthalmic Surg Lasers. 1986;1:125-141.
4. Schwartz LW, Moster MR. Neodymium:YAG laser transscleral cyclodiathermy. Ophthalmic Laser Ther. 1986;1:135-141.
5. Crymes BM, Gross RL. Laser placement in noncontact Nd:YAG cyclophotocoagulation. Am J Ophthalmol. 1990;110:670-673.
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
