Transscleral Neodymium:YAG Thermal Cyclophotocoagulation in Refractory Glaucoma

Transscleral Neodymium:YAG Thermal Cyclophotocoagulation in Refractory Glaucoma A Preliminary Report RAPHAEL M. KLAPPER, MD, 1 THADDEUS WANDEL, MD, 2 ERIC DONNENFELD, MD, 1 HENRY D. PERRY, MD

Abstract: Thirty patients treated with transscleral neodymium:YAG laser cyclophotocoagulation (TSYLC) are reported. All patients had advanced glaucoma and had previously undergone one or more surgical procedures that failed, or were unsuitable for surgery. The average preoperative intraocular pressure (lOP) for the group was 43 ± 12 mmHg. The average follow-up time was 6 months. The average energy level used was 3.8 J (range, 3.5-4.5 J). The patients were divided into two groups. Group 1 consisted of 20 patients in whom laser lesions were applied 3 mm from the limbus. Group 2 consisted of ten patients in whom laser lesions were applied 2 mm from the limbus. Success was defined as an lOP between 22 and 5 mmHg, regardless of the number of treatments required. The overall success rate was 86%. However, group 2 required significantly more retreatment than did group 1. Complications were moderate and transient. [Key words: ciliary body, glaucoma, laser, neovascular glaucoma, YAG laser cyclophotocoagulation.] Ophthalmology 95:719722, 1988

Transscleral cyclophotocoagulation was initiated by Beckman et al 1 first with ruby laser in 1972 and then with neodymium glass laserin 1973. 2 In 1984, Beckman and Waeltermann3 reported on 241 eyes with intractOriginally received: November 10, 1986. Revision accepted: December 22, 1987. 1

2

Manhattan Eye, Ear & Throat Hospital, New York. Montefiore Medical Center/Albert Einstein College of Medicine, Bronx.

Supported in part by a grant from the National Society for the Prevention of Blindness. Presented at the American Academy of Ophthalmology Annual Meeting, New Orleans, November 1986. Reprint requests to Raphael M. Klapper, MD, 7 West 81 st St., New York, NY 10024.

able glaucoma treated with transscleral ruby laser. Their success rate ranged from 86% in patients with aphakic glaucoma to 59% in patients with neovascular glaucoma. In 1981, Fankhauser and associates4 - 8 completed their work on the design of a neodymium:YAG (Nd:YAG) laser system into which they incorporated a thermal mode to perform transscleral Nd:YAG laser cyclophotocoagulation (TSYLC). The availability of this apparatus has stimulated laboratory and clinical work in search of optimal parameters for this procedure. Wilensky et al9 investigated the effect of TSYLC in rabbits. They created burns in the ciliary body with laser pulses of0.5 to 2.0 J. With 1.5 J of energy and 30 lesions, they achieved sustained reduction in intraocular pressure (lOP). 719

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Table 1. Patient Characteristics Characteristics

Group 1

Group 2

Age (yrs) Average Range Preoperative lOP prior surgery

31-87

63

71 54-87

3

2

lOP = intraocular pressure.

Fankhauser et al 10 studied the effect of TSYLC in autopsy eyes with the aim of developing an initial strategy for TSYLC. They reported that pulse energies between 6.0 and 7.0 J, exposure duration of 20 ms, and maximal defocusing were optimal. Ultrastructural studies of the rabbit ciliary body after TSYLC with the thermal mode Nd:YAG laser were performed by England et al. 11 They reported that transscleral irradiation was effective in destroying the ciliary epithelium and the associated vessels. Recently, Cyrlin et al 12 and Schwartz and Moster 13 reported on the use of transscleral Nd:YAG cyclophotocoagulation. Cyrlin et al used power settings in the range of 6.4 to 9.5 J, whereas Schwartz et al used power settings ranging from 0.5 to 2.75 J. The purpose of this study is to determine the effect on success rate and complications of intermediate energy levels. In addition, we evaluate the effect of varying the distance from the limbus at which laser bursts were applied.

MATERIALS AND METHODS All patients had advanced glaucoma of different etiologies in which maximal medical treatment and surgical procedures had failed, and all were candidates for either cyclocryotherapy or TSYLC. Table 1 lists characteristics of patients in this study. The investigational nature of the procedure was discussed with the patient, and informed consent was obtained. Anesthesia was achieved with a retrobulbar injection of 2% lidocaine with hyaluronidase. A lid speculum was placed between the eyelids. Guide marks were made with a surgical marking pencil and calipers at the designated distance from the limbus. A Microruptor 2 Nd:YAG laser (LASAG, Thun, Switzerland) was used in the thermal mode. With the telescope removed, the laser was set for a 20-msec pulse and defocused 9 relative units. The He-Ne aiming beam of the Nd:YAG laser was focused on the conjunctival surface, and 32 evenly spaced bursts were applied circumferentially at the limbus for 360°. The energy levels for the 30 patients ranged from 3.5 to 4.5 J (average, 3.8 J). The patients were examined 1 hour after the procedure at a slit lamp. If no complications had occurred, they were discharged on topical cycloplegics and steroid-antibiotic eye drops. Miotics were discontinued, but all other glaucoma medications were maintained. Tylenol with codeine (acetaminophen) was provided in case of discomfort. The 720

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patients were examined 24 hours later, and then at 1 week, 1 month, 3- and 6-month intervals, and thereafter as necessary. The statistical analysis for this study consisted of the Fisher exact test and chi-square analysis. Successful control ofiOP was defined as an lOP ranging from 22 to 5 mmHg, regardless of the number of TSYLC procedures required.

RESULTS POST LASER COURSE

Immediately after the procedure, the perilimbal conjunctival surface was hyperemic with the areas of laser impact visible as discrete white lesions (Fig 1). Only 1 of 30 patients reported considerable discomfort. A mild iritis occurred in all patients and subsided after 1 week on local steroids. One patient who had a history of Still's disease experienced an exacerbation of uveitis and vitreitis that resolved after 2 months. In three patients with rubeosis iridis, a small hyphema occurred, which reabsorbed from 1 to 4 weeks. A dellen, which subsided after 1 week, developed in one patient, and a sterile hypopyon, which subsided after 1 week, developed in two patients. During the follow-up period (average, 6 months), there was no case of phthisis bulbi. INTRAOCULAR PRESSURE CONTROL

In successful patients, both groups showed the same curve ofiOP decrease with time (Fig 2). For this reason, we merged the data and found that 24 hours postlaser, the lOP decreased by an average of 49%. At the end of our follow-up period, the lOP had decreased by an average of68%. It is noteworthy that on initial treatment, the success rate of both groups differed. However, after retreatment, there was no statistical difference between the two groups. In group 1, the overall success rate was 90%. To achieve this success rate, two patients underwent retreatment. Two additional patients in this group refused further laser procedures. One of these patients underwent cyclocryotherapy, which was unsuccessful. In group 2, the overall success rate was 80% (not statistically different from group 1). However, to achieve this success rate, five patients underwent retreatment. Of these five patients, one required two additional TSYLC treatments. The other three patients required only one retreatment to lower the lOP. In one patient, retreatment did not normalize the lOP, but the eye with no light perception became comfortable. EFFECT ON VISUAL ACUITY

Twenty-three of 30 patients in this series had visual acuity of counting fingers or less. Of the seven patients who had a visual acuity of 20/400 or better, no patient lost more than one line of visual acuity at the end ofthe follow-up period. Four patients had improved visual acuity by more than one line as the corneal microcystic

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TSYLC IN GLAUCOMA

Pre-Op

1 day

1 mo

1 week

3 mo

6 mo

TIME

Fig 1. Top left, appearance ofTSYLC lesions immediately postlaser in patient with neovascular glaucoma. Fig 2. Top right, intraocular pressure after TSYLC. Fig 3. Bottom, goniophotograph showing ciliary processes 24 hours post-TSYLC.

edema cleared with the drop in lOP. All patients who had counting fingers, hand motion, or light perception vision retained these levels of vision at the end of the follow-up period except for one patient in whom vision decreased from counting fingers to hand motion. No patient lost light perception during our study.

bulbi and visual loss. 14 Transscleral cyclophotocoagulation is a ciliodestructive procedure in which optimally, laser energy, while applied to the sclera, is focused on the ciliary processes (Fig 3). It permits dosimetry by varying a number of parameters (Table 2). Of the variable parameters, two are of major importance: the amount of energy used and the distance from the limbus.

DISCUSSION

ENERGY LEVELS

Glaucoma patients who are not controlled by medical therapy or by filtering procedures present a difficult challenge to the ophthalmologist. Currently, the most common modality of treatment for these refractive glaucomas is cyclocryotherapy. Two major complications limit the usefulness of cyclocryotherapy-phthisis

The choice of energy level appears to influence the incidence of phthisis bulbi. The early work of Beckman and Waeltermann 3 with ruby transscleral cyclophotocoagulation demonstrated that when high energy levels were used (7 .5 J), the incidence of phthisis bulbi was 14%. Lower energy levels produced an incidence of only 3%. 3 Recently, Schwartz and Moster, 13 using a commer721

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Table 2. Variables Power Distance from limbus Number of lesions Defocus Duration Tangential or Perpendicular

cially available thermal mode ofthe Nd:YAG laser applying energy levels from 0.50 to 2.75 J, reported no phthisis. In selecting the energy level parameter for our study, we opted for a value of3.8 J (the actual range, 3.5-4.5 J). Our results indicate that TSYLC performed at this energy level is effective in lowering lOP. During an average follow-up period of 6 months, phthisis bulbi did not develop in any of the patients. Although literature reports indicate a higher success rate for uncomplicated aphakic glaucoma and a lower success rate for neovascular glaucoma, 3 we were unable in our small series to correlate glaucoma etiology to success rate. DISTANCE FROM THE LIMBUS

In order to best evaluate the optimallimbal distance, we divided our patients into two groups. The designated limbal distance for group 1 was 3 mm and for group 2, 2 mm from the limbus. We hypothesized that proximity closer than 2 mm to the limbus could result in a more severe anterior segment reaction. In our series, the overall success rates in group 1 and group 2 were not statistically different. However, the need for retreatment was statistically less in group 1 as defined by the Fisher exact test for groups with small populations.

CONCLUSION In a preliminary study of 30 patients with refractory glaucoma, TSYLC has proven to have an important therapeutic effect.

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An energy level of 3.5 to 4.5 J combined with a limbal distance of 3 mm is effective in lowering lOP without causing serious complications.

REFERENCES 1. Beckman H, Kinoshita A, Rota AN, Sugar HS. Transscleral ruby laser irradiation of the ciliary body in the treatment of intractable glaucoma. Trans Am Acad Ophthal Otolaryng 1972; 76:423-36. 2. Beckman H, Sugar HS. Neodymium laser cyclocoagulation. Arch Ophthalmol 1973; 90:27-8. 3. Beckman H, Waelterman J. Transscleral ruby laser cyclocoagulation. Am J Ophthalmol1984; 98:788-95. 4. Fankhauser F, Kwasniewska S, van der Zypen E. Some new anterior segment applications of the SIRIUS-MICRORUPTOR 2 System. Anales dellnstituto Barraquer 1985; 18:101-7. 5. Fankhauser F, U:iertscher H, van der Zypen E. Clinical studies on high and low power laser radiation upon some structures of the anterior and posterior segments of the eye. lnt Ophthalmol 1982; 5:15-32. 6. Fankhauser F, Rol P. Microsurgery with the neodymium:YAG laser: an overview. lnt Ophthalmol Clin 1985; 25(3):55-84. 7. Fankhauser F, van der Zypen E, Kwasniewska S, U:iertscher H. The effects of thermal mode Nd:YAG laser radiation on vessels and ocular tissues: experimental and clinical findings. Ophthalmology 1985; 92:419-26. 8. Fankhauser F, Kwasniewska S. Neodymium:YAG laser photodisruptive and thermal-mode microsurgery. In: Stark WJ, Terry AC, Maumenee AE, eds. Anterior Segment Surgery: IOLs, Lasers, and Refractive Keratoplasty. Baltimore: Williams & Wilkins, 1987; 370-8. 9. Wilensky JT, Welch D, Mirolovich M. Transscleral cyclocoagulation using a neodymium:YAG laser. Ophthalmic Surg 1985; 16:95-8. 10. Fankhauser F, van der Zypen E, Kwasniewska S, et al. Transscleral cyclophotocoagulation using a neodymium YAG laser. Ophthalmic Surg 1986; 17:94-100. 11. England C, van der Zypen E, Fankhauser F, Kwasniewska S. Ultrastructure of the rabbit ciliary body following transscleral cyclophotocoagulation with the free-running Nd:YAG laser: preliminary findings. Lasers Ophthalmol1986; 1:61-72. 12. Cyrlin MN, Beckman H, Czedik C. Neodymium:YAG laser transscleral cyclocoagulation treatment for severe glaucoma. Presented at The Association for Research in Vision and Ophthalmology annual meeting, Sarasota, Florida, May 8, 1985. 13. Schwartz LW, Moster MR. Neodymium:YAG laser transscleral cyclodiathermy. Ophthalmic Laser Ther 1986; 1:135-41. 14. Caprioli J, Strang SL, Spaeth GL, Poryzees EH. Cyclocryotherapy in the treatment of advanced glaucoma. Ophthalmology 1985; 92:947-54.