作者：EShawn Goh, Boon Ang Lim , Leonard Yip 作者单位：1 新加坡陈笃生医院眼科；2 新加坡国立大学杨潞龄医学院眼科
【摘要】青光眼手术治疗方法已被分为睫状体破坏性（减少流入）或滤过性（增加流出）两大类。睫状体破坏性手术传统上用于视力预后差的青光眼以及难治性青光眼如外伤后、无晶状体眼、先天性青光眼和发育性青光眼。自从1992年Uram首次使用内窥镜下睫状体光凝术（endoscopic cyclophotocoagulation，ECP）以来，短期和长期的转归已经表明ECP的应用前景广阔。本文在PubMed查询、复习有关ECP的英文文献，并与新加坡一所眼科三级医院的有限结果进行比较。文献报告显示出ECP及联合白内障超声乳化术的ECP在治疗小儿及成人严重的、各种病因所致的青光眼方面的安全性和有效性。这在新加坡某眼科三级医院未发表的短期结果中也有报告，与那些已经发表的结果是一致的。已发表的报告和当前的经验证明，可直视目标组织的ECP，通过内窥镜直视将合适的红外波长激光能量应用于目标组织睫状上皮细胞，避免了“盲目”状态下经巩膜睫状体光凝术所引起的并发症。但是引进这项技术存在着显著的经费困难。ECP在控制眼压和减少抗青光眼药物的依赖性方面是安全有效的。广泛接受和使用这一技术仍有待于大规模的随机对照研究。
【关键词】青光眼，内窥镜下睫状体光凝术， 睫状体破坏性手术
Endoscopic cyclophotocoagulation: an overview and Asian perspective
EShawn Goh, Boon Ang Lim , Leonard Yip
1Department of Ophthalmology, Tan Tock Seng Hospital,
Singapore
2Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
Correspondence to: EShawn Goh. Department of Ophthalmomlogy, Tan Tock Seng Hospital, 11 Jln Tan Tock Seng Road, Singapore 308433. [email protected], [email protected]
AbstractSurgical treatment of glaucoma has been classified as cyclodestructive (reducing inflow) or filtering (increasing outflow). Cyclodestructive procedures have traditionally been reserved for eyes with poor visual prognoses and refractory glaucomas including posttrauma, aphakia, congenital and developmental glaucoma. Since Uram described the first use of endoscopic cyclophotocoagulation (ECP) in 1992, short and longterm outcomes for ECP have been promising. In the present article, we conduct a Pubmed search and review of published English literature on endoscopic cyclophotocoagulation and comparison with limited results in a single Singapore ophthalmic tertiary hospital. Safety and efficacy of ECP and combined phacoemulsificationECP procedures in treatment of pediatric and adult glaucomas of various etiologies and severities is reported. Local shortterm unpublished results from a single Singapore tertiary ophthalmic service is reported and concurs with previously published results.Published reports and current experience with ECP has demonstrated that ECP with direct visualization of the target tissues avoids the complications associated with blind transscleral cyclophotocoagulation by applying optimum energy to target tissue ciliary epithelium with endoscopic visualization and infrared laser wavelength application. Significant financial barriers exist to introducing this service. It is safe and effective in controlling IOP and reducing reliance on antiglaucoma medications. Widespread acceptance and use of this technique awaits largescale randomized controlled studies.
KEYWORDS: glaucoma; endoscopic cyclophotocoagulation; cyclodestructive procedures
INTRODUCTION
The heterogeneous group of conditions resulting in glaucomatous optic neuropathy have been treated with a combination of medical and surgical therapies. The advent of antiglaucoma medications has reduced the requirement for surgical procedures in glaucoma.
Surgical treatment of glaucoma has traditionally been classified as cyclodestructive (reducing inflow) or filtering (increasing outflow).
Filtering procedures have been the procedure of choice, and in an Asian context are increasingly performed with the use of adjunctive antimetabolites including mitomycinC and 5fluorouracil due to the increased propensity for scarring as well as early and late blebfailure in individuals of pigmented races [1]. Trabeculectomy performed alone or in combination with smallincision cataract surgery is the most commonly performed surgical procedure for glaucoma in Singapore. This is due to its efficacy and relative predictability [1]. However, trabeculectomy surgery is not without its own problems, as it requires frequent postoperative clinic visits and multiple interventions to ensure longterm bleb survivability. In addition, early/late bleb failure and blebrelated complications, ocular hypertension or hypotony, may further complicate the postsurgical course of trabeculectomy [2].
Cyclodestructive procedures have traditionally been reserved for eyes with poor visual prognoses and refractory glaucomas including posttrauma[3,4], aphakia[5], congenital/developmental glaucoma[5,6], and glaucoma associated with previous penetrating keratoplasties [7], as well as eyes with scarred conjunctiva not suitable for filtering procedures [3]. The reticence with the use of cyclodestructive procedures is related to the blind nature of transscleral procedures, and the high incidence of postprocedure inflammation, hypotony, cataract formation and treatment failure [8]. The earliest cyclodestruction methods were performed by surgical excision, diathermy, cryotherapy, light coagulation and eventually laser [4]. Laser cyclophotocoagulation may be performed with an Argon laser through a contact lens via the transpupillary route for aphakic eyes. More commonly, transscleral cyclodestruction is performed through a noncontact or contact probe.
Initial experience using the ruby laser was subsequently superceded by the Neodymium: YttriumAluminiumGarnet (Nd:YAG) laser which demonstrated improved scleral penetration [4]. Further developments in laser technology led to the employment of the compact and portable 810nm wavelength semiconductor diode laser which offers improved melanin absorption and hence selectivity, over the Nd:YAG.
The principles of transscleral cyclophotocoagulation remain identical, regardless of method of delivery. Laser delivery is blind, and requires transmission of laser energy through the sclera, ciliary body and ciliary vessels, before final absorption by the target tissues of ciliary epithelium[9]. Histopathological changes of different modalities of transscleral cyclophotocoagulation are identical, demonstrating moderate to severe disorganization of ciliary processes with fibrosis and atrophy of stroma, as well as nonpigmented and pigmented ciliary epithelium [10,11].
Transscleral cyclophotocoagulation has been demonstrated to be effective for treating severe end stage glaucoma in which other surgeries have failed or potential vision is limited. Within the limitations of varying definitions of success for this procedure, overall success rates vary between 34%81% of patients achieving target intraocular pressure (IOP) with or without concomitant use of antiglaucoma medications, over a mean followup period of 30 months [1215]. This procedure is also associated with a significant incidence of serious complications and postoperative discomfort [15]. In addition, due to the blind nature of treatment delivery, the use of transscleral cyclophotocoagulation is conventionally limited in eyes with disorganized anterior segments.
Uram [4] initially developed and described a novel method to directly photocoagulate the ciliary body under endoscopic guidance, termed endoscopic cyclophotocoagulation (ECP). He was the first to incorporate a diode laser emitting pulsed continuous wave energy at 810nm wavelength, coupled with a 175W xenon light source, heliumneon laser aiming beam and a video camera for imaging whilst recording.
These functions were housed in a 0.88mm (20gauge) probe which offered a 70° field of view (Endo Optiks, ittle Silver, NJ, USA). All elements of the probe are transmitted via fibreoptics. Initial descriptions of the endoprobe were performed in vitreous surgery [16], although the pplications to anterior segment cataract and glaucoma surgery followed.
ECP has been gaining increasing popularity, but concerns still linger about the inherently ablative nature of this therapy, as well as the requirement for intraocular access to perform this procedure.
PERFORMING ECP
Endoscopic cycloablation is performed through an 18gauge (1.2mm diameter probe with viewing angle of 110°) or 20gauge (0.88mm diameter probe with viewing angle of 70°) probe inserted intraocularly. Depth of focus varies from 1mm30mm for the 18 gauge probe, and 0.5mm15mm for the 20gauge probe [3,4]. Laser power (maximum of 1.2W) and duration are adjusted on the console. The actual duration of each treatment is determined by the period of pedal depression.
ECP may be performed in any patients including those of phakic, pseudophakic or aphakes. Due to the requirement for intraocular access in order to perform ECP, this procedure is frequently performed in conjunction with otherintraocular procedures, most commonly with phacoemulsification cataract surgery.
Anterior segment and glaucoma surgeons routinely perform endocycloablation through their choice of preferred clear cornea/scleral tunnel incision. If combined with cataract extraction, the preference is for extracapsular phacoemulsification and posterior chamber lens implantation.
Following placement of the intraocular lens (IOL) into an intracapsular position, the posterior chamber between the posterior surface of the iris and the anterior leaf of the anterior capsule is insufflated with ophthalmic viscoelastic device (OVD). The straight or curved tip endoprobe is oriented outside of the eye, and inserted through the incision and directed toward the posterior chamber. The ciliary processes are photocoagulated under direct visualisation with energy settings commencing between 40mW60mW and adjusted accordingly to achieve shrinkage and whitening of the ciliary processes whilst avoiding an audible “pop” (with bubble formation) indicating excess energy is administered. Energy delivered is minimized to avoid significant breakdown of the bloodaqueous barrier and excessive inflammation. Initial photocoagulation is directed at the raised processes without affecting the “valleys” of nondisplaced ciliary epithelium. A minimum of 270° to a maximum of 360° is treated. A single incision is adequate to perform 180° of photocoagulation with a straight probe, whilst a similar incision is adequate to perform treatment over 270° for a curved probe. At the conclusion of the procedure, remaining OVD is removed from the anterior chamber by irrigation with balanced salt solution, and the wound is closed in the usual manner.
A posterior approach may be indicated in certain clinical conditions including aphakia or severe posterior synechiae limiting ciliary sulcus access. This is performed via standard 3port pars plana vitrectomy with limited anterior vitrectomy. This would allow safe and adequate access to all ciliary processes. Treatment parameters and end points are identical to the anterior segment approach. Wound closure is in the usual manner for posterior segment surgery.
At the conclusion of surgery, an appropriate antiinflammatory and antibiotic regime is administered as per routine cataract surgery. Cycloplegics, nonsteroidal antiinflammatory drugs (NSAID) and routineglaucoma medications are administered. The exceptions include miotics and prostaglandin analogues which may theoretically exacerbate intraocular inflammation and its attendant sequelae. Oral acetazolamide is administered postprocedure in patients with advanced glaucomatous damage for prophylaxis against intraocular pressure spikes due to inflammation, or retained OVD. Glaucoma medications are expected to be continued for 24 weeks until the clinical effects of ECP suggest tapering of glaucoma medications are appropriate. Hollander and Lin [7] described an isolated case of delayedECP effect 3 months following treatment for penetrating keratoplastyassociated ocular hypertension. This suggests that delaying ECP retreatments in medically controlled glaucoma for patients with good visual potential may result in late treatment benefit, whilst offering the benefit of avoiding overtreatment. Topical antibiotics are administered for a minimum of 1 week, whilst steroids, NSAIDS and cycloplegics are tapered as inflammation subsides. Glaucoma medications are removed as clinically dictated.
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