Semiconductor Diode Laser Transscleral Cyclophotocoagulation in Patients With Glaucoma Hugh L. Hennis, M.D., and William C. Stewart, M.D. We used the semiconductor diode laser to perform transscleral cyclophotocoagulation in 14 patients with glaucoma. Laser settings used for this procedure were 990 milliseconds, 100-fim spot size, and 1,200 mW of power. Applications were placed 1 mm posterior to the surgical corneoscleral limbus and 1 mm defocused toward the ciliary body. The mean preoperative intraocular pressure was 34.8 ± 13 mm Hg, and the mean intraocular pressure six months after a single treatment session was 24.3 ± 18 mm Hg (P > .001, paired t-test). The mean number of glaucoma medications decreased from 2.2 preoperatively to 1.4 postoperatively. Complications included conjunctival burns and uveitis in 14 patients, and pain in one patient. These results suggested that semiconductor diode transscleral cyclophoto coagulation may be useful as a treatment to reduce the intraocular pressure in patients with glaucoma.
1 RANSSCLERAL CYCLOPHOTOCOAGULATION Us ing laser energy may be effective in reducing the intraocular pressure in patients with glau coma in whom filtering operations have a poor prognosis or are not indicated. This procedure has been performed successfully in the past using ruby, argon-krypton, and Nd:YAG laser energy. We evaluated the transscleral cyclodestructive effects of a semiconductor diode laser to determine its safety and efficacy in decreasing the intraocular pressure in patients with glau coma.
Accepted for publication Oct. 23, 1991. From the Glaucoma Service, Department of Ophthal mology, Medical University of South Carolina, Charles ton, South Carolina. This study was supported in part by an unrestricted grant from Research to Prevent Blind ness, Inc., New York, New York. Reprint requests to William C. Stewart, M.D., Storm Eye Institute, 171 Ashley Ave., Charleston, SC 294252236.
Material and Methods Patients with glaucoma who underwent semiconductor diode transscleral cyclophoto coagulation and who were treated by us were included in this study. This procedure was recommended to preserve vision or relieve pain in patients who needed a reduction in intraocu lar pressure despite maximal tolerated medical therapy and argon laser trabeculoplasty. Filter ing operations were not recommended to pre serve vision because of poor prognosis. Initial ly, treatments were performed in patients who had no light perception or light perception visual acuity only. Later, however, patients with better visual acuity also were included in this study. Each patient signed an informed consent for this procedure after an explanation of the potential risks and benefits. We used the Microlase laser, which incorpo rates two infrared laser diodes with a wave length of 780 to 830 nm and is used as a slit-lamp attachment. It has a power capability of 0 to 1,200 mW, a pulse duration of 0 to 990 milliseconds, and a spot size of 100 to 500 |xm. Before each operation, each patient had an ocular and medical history taken and under went an examination that included the inspec tion of the ocular adnexa, Goldmann applanation tonometry, slit-lamp biomicroscopy, Snellen visual acuity, and ophthalmoscopy. Semiconductor diode transscleral cyclopho tocoagulation was performed in the after man ner. The patient was given a retrobulbar anes thetic consisting of 3.5 ml of bupivacaine 0.75%. A Barraquer speculum was used to sepa rate the eyelids. The patient then was placed at the biomicroscope, and laser applications were applied parallel to the visual axis without the use of a contact lens. The laser system was focused on the sclera 1 mm from the surgical corneoscleral limbus with Castroviejo calipers and then defocused posteriorly 1 mm, as mea sured by a millimeter rule at the base of the biomicroscope.
©AMERICAN JOURNAL OF OPHTHALMOLOGY 113:81-85, JANUARY,
1992
81
82
January, 1992
AMERICAN JOURNAL OF OPHTHALMOLOGY
The laser variables used in this study were similar to those evaluated previously to create thermal lesions in the ciliary processes of ca daver eyes and included a 100-u.m spot size, a 990-millisecond pulse duration, and 1,200 mW of power.1,2 Forty to 45 applications were placed 360 degrees around the corneoscleral limbus, which was slightly greater than the number used previously in performing Nd:YAG transscleral cyclophotocoagulation. 3 Patients were reexamined at one and three hours after the operation with slit-lamp biomicroscopy and Goldmann applanation tonometry to observe for complications of the procedure. Patients were instructed to use prednisolone acetate 1% four times a day, as well as atropine 1% eyedrops twice a day in the operated-on eye and to continue their usual treatment for glaucoma. The next morning patients underwent an ocu lar examination which included slit-lamp biomicroscopy, Goldmann applanation tonometry, inspection of the ocular adnexa, and ophthalmoscopy. A similar examination was performed thereafter at one week as well as one, three, and six months postoperatively. The dosages of prednisolone acetate 1% and atro pine were tapered and discontinued as the postoperative ocular inflammation resolved. The number of glaucoma medications was re duced if the intraocular pressure decreased suf ficiently. Preoperative data evaluated in this study in cluded age, gender, race, eye to be operated on, glaucoma diagnosis, Snellen visual acuity, re sults of Goldmann applanation tonometry, number of glaucoma medications prescribed, and reason for the procedure. Postoperative data evaluated at six months included Snellen visual acuity, results of Gold mann applanation tonometry, number of glau coma medications prescribed, and whether the procedure was successful. Success was defined as relief of pain in patients with no light per ception or an intraocular pressure of 21 mm Hg or less without a change in Snellen visual acuity in patients with vision. Only data from a single laser treatment session were included in this report. Also noted were any complications in the operated-on eye during the six-month follow-up period. Statistical differences between the preopera tive and the postoperative intraocular pressures at each clinic visit were evaluated using a paired f-test. In patients whose eyes were reoperated on between three and six months after
the initial procedure the last intraocular pres sure measured before a second operation was used as a six-month measurement.
Results Fourteen patients (14 eyes) with an average age of 69.9 ± 13 years (range, 38 to 84 years) were included in this study. Eight patients were men and six were women; 12 were black and two were white. Seven of the treated eyes were right eyes and seven were left eyes. Nine patients had a preoperative diagnosis of chronic open-angle glaucoma, three had neovascular glaucoma, one had increased intraocu lar pressure associated with fungal endophthalmitis, and one had increased intraocular pressure after penetrating keratopathy. Diode laser cyclophotocoagulation was performed in ten patients to preserve vision and in four patients to relieve pain. The preoperative and six-month postopera tive intraocular pressures, visual acuities, and number of medications, as well as whether the laser treatment was a success or failure, were analyzed (Table). The mean preoperative intra ocular pressure decreased from 34.8 ± 13 mm Hg preoperatively to 24.3 ± 1 8 mm Hg six months postoperatively. The average number of glaucoma medications prescribed per patient decreased from 2.2 preoperatively to 1.4 at six months postoperatively. Six patients had a postoperative reduction in the number of medi cations and none required an increase. Laser treatment was considered successful according to the criteria in ten of the 14 patients. This included three of four patients in whom pain was relieved and seven of ten patients in whom intraocular pressure was controlled to less than 21 mm Hg with no decrease in visual acuity. The mean preoperative and postoperative in traocular pressures were determined at each clinic visit (Fig. 1). The postoperative change in intraocular pressure was statistically significant at each intraocular pressure measurement to P > .005. Complications included mild uveitis and conjunctival burns (Fig. 2) in each patient. Ocular pain developed in one patient and a transient intraocular pressure increase greater than 10 mm Hg on the day of the operation was ob served in one patient. No patient had visual acuity loss, hypotony, or phthisis bulbi. The treatments of four patients were consid-
Vol. 113, No. 1
Diode Laser Cyclophotocoagulation
83
TABLE EFFECT OF A SINGLE SEMICONDUCTOR DIODE TRANSSCLERAL CYCLOPHOTOCOAGULATION TREATMENT IN PATIENTS WITH GLAUCOMA POSTOPERATIVE DATA
PREOPERATIVE DATA INTRAOCULAR
INTRAOCULAR PATIENT
PRESSURE
VISUAL
NO. OF
PRESSURE
VISUAL
NO. OF
TREATMENT
NO.
(MM Hg)
ACUITY
MEDICATIONS
(MM Hg)
ACUITY
MEDICATIONS
SUCCESS
1 2 3 4* 5 6 7 8 9 10 11 12 13 14
58 42 22 40 24 44 23 31 25 48 28 20 54 24
N.L.P. N.L.P. H.M. H.M. H.M. N.L.P. C.F. C.F. C.F. 20/150 C.F. C.F. N.L.P. 20/80
0 2 2 2 4 0 3 2 3 3 3 3 2 2
44 15 9 20 14 37 12 24 18 25 7 16 72 26
N.L.P. N.L.P. H.M. H.M. H.M. N.LP. C.F. C.F. C.F. 20/150 C.F. C.F. N.LP. 20/80
0 2 2 1 3 0 1 2 3 3 0 0 0 2
Yes Yes Yes Yes Yes Yes Yes No Yes No Yes Yes No No
'Intraocular pressure was measured with a pneumotonometer and was not included in data analysis. N.L.P. indicates no light perception; H.M. indicates hand motion; C.F. indicates counting fingers.
ered failures according to study criteria because of inability to control intraocular pressure or persistent pain. Patient 8 had neovascular glau coma and had an increased intraocular pressure despite previous cyclocryotherapy. Her intra ocular pressure was initially controlled after diode laser transscleral cyclophotocoagulation for three months postoperatively, after which her intraocular pressure again increased to preoperative levels. Her intraocular pressure cur
rently is controlled after repeat cyclocryothera py. Patient 10 had an initial decrease in intraocular pressure from 42 mm Hg to 15 mm Hg for three months after diode cyclophotoco agulation. However, her pressure increased to 25 mm Hg, for which she underwent a repeat diode treatment, which currently controls her intraocular pressure. Patient 13 underwent cy clophotocoagulation to relieve pain. He discon tinued the use of both his glaucoma medica
5045" 40'
ls=
f,
c C
.15'
30-
^ \
25"
\
T
\
20
1510PREOP
I HOUR
1DAY
1WEEK
I HO.
J HOS.
6 MOS.
Time from surgery
Fig. 1 (Hennis and Stewart). Pre- and postoperative intraocular pressures (means and standard devia tions) in patients treated with semiconductor diode transscleral cyclophotocoagulation; IOP indicates in traocular pressure.
Fig. 2 (Hennis and Stewart). Clinical photograph showing conjunctival burns after semiconductor diode transscleral cyclophotocoagulation.
84
January, 1992
AMERICAN JOURNAL OF OPHTHALMOLOGY
tions postoperatively and had a postoperative intraocular pressure increase from 54 to 72 mm Hg six months over the preoperative levels with persistent ocular pain. Patient 14 had an initial decrease in intraocular pressure one week post operatively that increased to preoperative lev els three months later.
Discussion When indicated, laser transscleral cyclophotocoagulation has been shown to be a useful cyclodestructive procedure to reduce the intra ocular pressure in patients with glaucoma. Al though the ruby and the argon-krypton lasers 4,5 have been used previously, the Nd:YAG laser recently has been the instrument usually used for performing transscleral cyclophotocoagulation. The Nd:YAG laser has reduced intraocular pressure by 45% to 65% in patients with aphakic or neovascular glaucoma, or after penetrat ing keratoplasty. 3,68 In our study we used a portable semiconduc tor diode laser with a slit-lamp delivery system to perform noncontact transscleral cyclophotocoagulation in patients with glaucoma. Com pared to the Nd:YAG laser, the semiconductor diode laser has the potential advantage of bet ter melanin absorption and consequently less use of energy to perform cyclophotocoagulation. 9 In previous studies of cadaver eyes, ciliary process blanching and shrinkage with diode laser cyclophotocoagulation have been de scribed that were similar to lesions produced with the Nd:YAG laser. 121011 Diode laser trans scleral cyclophotocoagulation also reduced the intraocular pressure to an extent similar to that of the Nd:YAG laser for the first six postopera tive weeks in rabbits. 12 Our study showed that semiconductor diode transscleral cyclophotocoagulation causes a statistically significant decrease (P > .005) in the intraocular pressure in patients with glaucoma. Most of the intraocular pressure response was observed within the first post operative week. Diode laser transscleral cyclophotocoagulation was conveniently per formed as a slit-lamp attachment in an outpa tient setting. However, despite a statistical decrease in the mean intraocular pressure, the results were inconsistent among individuals. Some patients maintained an adequate ocular hypotensive ef
fect, whereas in others the pressure became uncontrolled after the first postoperative month. All reasons for treatment failure were uncertain. With this commercially available in strument, the defocusing procedure using a millimeter rule probably was imprecise. Addi tionally, most laser applications made no ap parent external tissue alteration by which to judge accuracy. Also, the available wattage on the Microlase laser was well below the 4 to 6 J generally used for Nd:YAG transscleral cyclo photocoagulation. These factors may have con tributed to the intermittent failure of this proce dure. Complications included mild uveitis and conjunctival burns at the site of the laser applica tions in each patient. The uveitis resolved with in a week after treatment with topical administration of prednisolone acetate 1% four times a day. The conjunctival burns appeared as a blanched pit with a brown border and usually resolved within several days postopera tively. One patient suffered mild ocular pain from the diode laser cyclophotocoagulation for up to one week postoperatively. This study suggested the use of the semicon ductor diode laser to perform transscleral cy clophotocoagulation in a reasonably safe, com fortable, and effective manner. Treatment efficacy may be improved by development of a more precise focusing mechanism (for example, contact probe and an automatic defocus built into the laser) and slightly increased wattage capability. This study did not compare diode laser trans scleral cyclophotocoagulation to other cyclode structive techniques. Also, the potential benefit of repeat treatment with the diode laser was not explored. Further evaluation is needed to con firm the clinical usefulness of diode laser trans scleral cyclophotocoagulation and the factors that will determine its most efficient use. ACKNOWLEDGMENT
Keeler Instruments, Broomall, Pennsylva nia, provided the Microlase laser used in this study.
References 1. Hennis, H. L., Assia, E., Stewart, W. C, Legler, U. F. C, and Apple, D. J.: Transscleral cyclophotoco agulation using a semiconductor diode laser in ca daver eyes. Ophthalmic Surg. 21:274, 1991.
Vol. 113, No. 1
Diode Laser Cyclophotocoagulation
2. Assia, E. I., Hennis, H. L., Stewart, W. C , Legler, U. F. C , Carlson, A. N., and Apple, D. J.: Comparison of Nd:YAG and diode transscleral cyclo photocoagulation and cyclocryotherapy. Invest. Ophthalmol. Vis. Sci. 32:2774, 1991. 3. Stewart, W. C : Clinical Practice of Glaucoma. Thorofare, New Jersey, Slack, Inc., 1990, p. 399. 4. Beckman, H., and Waeltermann, J.: Transscleral ruby laser cyclocoagulation. Am. J. Ophthalmol. 98:788, 1984. 5. Peyman, G. A., Conway, M. D., Raichand, M., and Lin, J.: Histopathologic studies on transscleral argon-krypton photocoagulation with an exolaser probe. Ophthalmic Surg. 15:496, 1984. 6. Klapper, R. M., Wandel, T., Donnenfeld, E., and Perry, H. D.: Transscleral neodymium:YAG thermal cyclophotocoagulation in refractory glaucoma. A preliminary report. Ophthalmology 95:719, 1988. 7. Badeeb, O., Trope, G. E., and Mortimer, C : Short-term effects of neodymium:YAG transscleral cyclocoagulation in patients with uncontrolled glau coma. Br. J. Ophthalmol. 72:615, 1988.
85
8. Hampton, C , Shields, M. B., Miller, K. N., and Blasini, M.: Evaluation of a protocol for transscleral neodymium:YAG cyclophotocoagulation in one hun dred patients. Ophthalmology 97:910, 1990. 9. Sigelman, J.: Retinal Diseases. Pathogenesis, Laser Therapy, and Surgery. Boston, Little, Brown and Company, 1984, p. 77. 10. Fankhauser, F., van der Zypen, E., Kwasniewska, S., Rol, P., and England, C : Trans scleral cyclophotocoagulation using a neodymium YAG laser. Ophthalmic Surg. 17:94, 1986. 11. Hampton, C , and Shields, M. B.: Transscleral neodymium:YAG cyclophotocoagulation. A histologic study of human autopsy eyes. Arch. Ophthalmol. 106:1121, 1988. 12. Schuman, J. S., Jacobson, J. J., Puliafito, C. A., Noecker, R. J., and Reidy, W. T.: Experimental use of semiconductor diode laser in contact transscleral cyclophotocoagulation in rabbits. Arch. Ophthalmol. 108:1152, 1990.
OPHTHALMIC MINIATURE
As I drove toward town I was thinking about that ancient and honorable bit of homely psychology, that myth of the ripeness of cataracts. The lens capsule can be removed as soon as it begins to get cloudy. But postoperative vision with corrective lenses is a poor resource at best, compared with normal sight. So the ripeness they speak of is the psychological ripeness of the patient, a time of diminishing vision which lasts long enough, and gets bad enough, so that the postoperative vision is, by comparison, a wonder and a delight. The patient is h a p p y because the basis of comparison has changed. John D. MacDonald, The Long Lavender Look N e w York, Ballantine Books, 1970, p p . 84-85
1 RANSSCLERAL CYCLOPHOTOCOAGULATION Us ing laser energy may be effective in reducing the intraocular pressure in patients with glau coma in whom filtering operations have a poor prognosis or are not indicated. This procedure has been performed successfully in the past using ruby, argon-krypton, and Nd:YAG laser energy. We evaluated the transscleral cyclodestructive effects of a semiconductor diode laser to determine its safety and efficacy in decreasing the intraocular pressure in patients with glau coma.
Accepted for publication Oct. 23, 1991. From the Glaucoma Service, Department of Ophthal mology, Medical University of South Carolina, Charles ton, South Carolina. This study was supported in part by an unrestricted grant from Research to Prevent Blind ness, Inc., New York, New York. Reprint requests to William C. Stewart, M.D., Storm Eye Institute, 171 Ashley Ave., Charleston, SC 294252236.
Material and Methods Patients with glaucoma who underwent semiconductor diode transscleral cyclophoto coagulation and who were treated by us were included in this study. This procedure was recommended to preserve vision or relieve pain in patients who needed a reduction in intraocu lar pressure despite maximal tolerated medical therapy and argon laser trabeculoplasty. Filter ing operations were not recommended to pre serve vision because of poor prognosis. Initial ly, treatments were performed in patients who had no light perception or light perception visual acuity only. Later, however, patients with better visual acuity also were included in this study. Each patient signed an informed consent for this procedure after an explanation of the potential risks and benefits. We used the Microlase laser, which incorpo rates two infrared laser diodes with a wave length of 780 to 830 nm and is used as a slit-lamp attachment. It has a power capability of 0 to 1,200 mW, a pulse duration of 0 to 990 milliseconds, and a spot size of 100 to 500 |xm. Before each operation, each patient had an ocular and medical history taken and under went an examination that included the inspec tion of the ocular adnexa, Goldmann applanation tonometry, slit-lamp biomicroscopy, Snellen visual acuity, and ophthalmoscopy. Semiconductor diode transscleral cyclopho tocoagulation was performed in the after man ner. The patient was given a retrobulbar anes thetic consisting of 3.5 ml of bupivacaine 0.75%. A Barraquer speculum was used to sepa rate the eyelids. The patient then was placed at the biomicroscope, and laser applications were applied parallel to the visual axis without the use of a contact lens. The laser system was focused on the sclera 1 mm from the surgical corneoscleral limbus with Castroviejo calipers and then defocused posteriorly 1 mm, as mea sured by a millimeter rule at the base of the biomicroscope.
©AMERICAN JOURNAL OF OPHTHALMOLOGY 113:81-85, JANUARY,
1992
81
82
January, 1992
AMERICAN JOURNAL OF OPHTHALMOLOGY
The laser variables used in this study were similar to those evaluated previously to create thermal lesions in the ciliary processes of ca daver eyes and included a 100-u.m spot size, a 990-millisecond pulse duration, and 1,200 mW of power.1,2 Forty to 45 applications were placed 360 degrees around the corneoscleral limbus, which was slightly greater than the number used previously in performing Nd:YAG transscleral cyclophotocoagulation. 3 Patients were reexamined at one and three hours after the operation with slit-lamp biomicroscopy and Goldmann applanation tonometry to observe for complications of the procedure. Patients were instructed to use prednisolone acetate 1% four times a day, as well as atropine 1% eyedrops twice a day in the operated-on eye and to continue their usual treatment for glaucoma. The next morning patients underwent an ocu lar examination which included slit-lamp biomicroscopy, Goldmann applanation tonometry, inspection of the ocular adnexa, and ophthalmoscopy. A similar examination was performed thereafter at one week as well as one, three, and six months postoperatively. The dosages of prednisolone acetate 1% and atro pine were tapered and discontinued as the postoperative ocular inflammation resolved. The number of glaucoma medications was re duced if the intraocular pressure decreased suf ficiently. Preoperative data evaluated in this study in cluded age, gender, race, eye to be operated on, glaucoma diagnosis, Snellen visual acuity, re sults of Goldmann applanation tonometry, number of glaucoma medications prescribed, and reason for the procedure. Postoperative data evaluated at six months included Snellen visual acuity, results of Gold mann applanation tonometry, number of glau coma medications prescribed, and whether the procedure was successful. Success was defined as relief of pain in patients with no light per ception or an intraocular pressure of 21 mm Hg or less without a change in Snellen visual acuity in patients with vision. Only data from a single laser treatment session were included in this report. Also noted were any complications in the operated-on eye during the six-month follow-up period. Statistical differences between the preopera tive and the postoperative intraocular pressures at each clinic visit were evaluated using a paired f-test. In patients whose eyes were reoperated on between three and six months after
the initial procedure the last intraocular pres sure measured before a second operation was used as a six-month measurement.
Results Fourteen patients (14 eyes) with an average age of 69.9 ± 13 years (range, 38 to 84 years) were included in this study. Eight patients were men and six were women; 12 were black and two were white. Seven of the treated eyes were right eyes and seven were left eyes. Nine patients had a preoperative diagnosis of chronic open-angle glaucoma, three had neovascular glaucoma, one had increased intraocu lar pressure associated with fungal endophthalmitis, and one had increased intraocular pressure after penetrating keratopathy. Diode laser cyclophotocoagulation was performed in ten patients to preserve vision and in four patients to relieve pain. The preoperative and six-month postopera tive intraocular pressures, visual acuities, and number of medications, as well as whether the laser treatment was a success or failure, were analyzed (Table). The mean preoperative intra ocular pressure decreased from 34.8 ± 13 mm Hg preoperatively to 24.3 ± 1 8 mm Hg six months postoperatively. The average number of glaucoma medications prescribed per patient decreased from 2.2 preoperatively to 1.4 at six months postoperatively. Six patients had a postoperative reduction in the number of medi cations and none required an increase. Laser treatment was considered successful according to the criteria in ten of the 14 patients. This included three of four patients in whom pain was relieved and seven of ten patients in whom intraocular pressure was controlled to less than 21 mm Hg with no decrease in visual acuity. The mean preoperative and postoperative in traocular pressures were determined at each clinic visit (Fig. 1). The postoperative change in intraocular pressure was statistically significant at each intraocular pressure measurement to P > .005. Complications included mild uveitis and conjunctival burns (Fig. 2) in each patient. Ocular pain developed in one patient and a transient intraocular pressure increase greater than 10 mm Hg on the day of the operation was ob served in one patient. No patient had visual acuity loss, hypotony, or phthisis bulbi. The treatments of four patients were consid-
Vol. 113, No. 1
Diode Laser Cyclophotocoagulation
83
TABLE EFFECT OF A SINGLE SEMICONDUCTOR DIODE TRANSSCLERAL CYCLOPHOTOCOAGULATION TREATMENT IN PATIENTS WITH GLAUCOMA POSTOPERATIVE DATA
PREOPERATIVE DATA INTRAOCULAR
INTRAOCULAR PATIENT
PRESSURE
VISUAL
NO. OF
PRESSURE
VISUAL
NO. OF
TREATMENT
NO.
(MM Hg)
ACUITY
MEDICATIONS
(MM Hg)
ACUITY
MEDICATIONS
SUCCESS
1 2 3 4* 5 6 7 8 9 10 11 12 13 14
58 42 22 40 24 44 23 31 25 48 28 20 54 24
N.L.P. N.L.P. H.M. H.M. H.M. N.L.P. C.F. C.F. C.F. 20/150 C.F. C.F. N.L.P. 20/80
0 2 2 2 4 0 3 2 3 3 3 3 2 2
44 15 9 20 14 37 12 24 18 25 7 16 72 26
N.L.P. N.L.P. H.M. H.M. H.M. N.LP. C.F. C.F. C.F. 20/150 C.F. C.F. N.LP. 20/80
0 2 2 1 3 0 1 2 3 3 0 0 0 2
Yes Yes Yes Yes Yes Yes Yes No Yes No Yes Yes No No
'Intraocular pressure was measured with a pneumotonometer and was not included in data analysis. N.L.P. indicates no light perception; H.M. indicates hand motion; C.F. indicates counting fingers.
ered failures according to study criteria because of inability to control intraocular pressure or persistent pain. Patient 8 had neovascular glau coma and had an increased intraocular pressure despite previous cyclocryotherapy. Her intra ocular pressure was initially controlled after diode laser transscleral cyclophotocoagulation for three months postoperatively, after which her intraocular pressure again increased to preoperative levels. Her intraocular pressure cur
rently is controlled after repeat cyclocryothera py. Patient 10 had an initial decrease in intraocular pressure from 42 mm Hg to 15 mm Hg for three months after diode cyclophotoco agulation. However, her pressure increased to 25 mm Hg, for which she underwent a repeat diode treatment, which currently controls her intraocular pressure. Patient 13 underwent cy clophotocoagulation to relieve pain. He discon tinued the use of both his glaucoma medica
5045" 40'
ls=
f,
c C
.15'
30-
^ \
25"
\
T
\
20
1510PREOP
I HOUR
1DAY
1WEEK
I HO.
J HOS.
6 MOS.
Time from surgery
Fig. 1 (Hennis and Stewart). Pre- and postoperative intraocular pressures (means and standard devia tions) in patients treated with semiconductor diode transscleral cyclophotocoagulation; IOP indicates in traocular pressure.
Fig. 2 (Hennis and Stewart). Clinical photograph showing conjunctival burns after semiconductor diode transscleral cyclophotocoagulation.
84
January, 1992
AMERICAN JOURNAL OF OPHTHALMOLOGY
tions postoperatively and had a postoperative intraocular pressure increase from 54 to 72 mm Hg six months over the preoperative levels with persistent ocular pain. Patient 14 had an initial decrease in intraocular pressure one week post operatively that increased to preoperative lev els three months later.
Discussion When indicated, laser transscleral cyclophotocoagulation has been shown to be a useful cyclodestructive procedure to reduce the intra ocular pressure in patients with glaucoma. Al though the ruby and the argon-krypton lasers 4,5 have been used previously, the Nd:YAG laser recently has been the instrument usually used for performing transscleral cyclophotocoagulation. The Nd:YAG laser has reduced intraocular pressure by 45% to 65% in patients with aphakic or neovascular glaucoma, or after penetrat ing keratoplasty. 3,68 In our study we used a portable semiconduc tor diode laser with a slit-lamp delivery system to perform noncontact transscleral cyclophotocoagulation in patients with glaucoma. Com pared to the Nd:YAG laser, the semiconductor diode laser has the potential advantage of bet ter melanin absorption and consequently less use of energy to perform cyclophotocoagulation. 9 In previous studies of cadaver eyes, ciliary process blanching and shrinkage with diode laser cyclophotocoagulation have been de scribed that were similar to lesions produced with the Nd:YAG laser. 121011 Diode laser trans scleral cyclophotocoagulation also reduced the intraocular pressure to an extent similar to that of the Nd:YAG laser for the first six postopera tive weeks in rabbits. 12 Our study showed that semiconductor diode transscleral cyclophotocoagulation causes a statistically significant decrease (P > .005) in the intraocular pressure in patients with glaucoma. Most of the intraocular pressure response was observed within the first post operative week. Diode laser transscleral cyclophotocoagulation was conveniently per formed as a slit-lamp attachment in an outpa tient setting. However, despite a statistical decrease in the mean intraocular pressure, the results were inconsistent among individuals. Some patients maintained an adequate ocular hypotensive ef
fect, whereas in others the pressure became uncontrolled after the first postoperative month. All reasons for treatment failure were uncertain. With this commercially available in strument, the defocusing procedure using a millimeter rule probably was imprecise. Addi tionally, most laser applications made no ap parent external tissue alteration by which to judge accuracy. Also, the available wattage on the Microlase laser was well below the 4 to 6 J generally used for Nd:YAG transscleral cyclo photocoagulation. These factors may have con tributed to the intermittent failure of this proce dure. Complications included mild uveitis and conjunctival burns at the site of the laser applica tions in each patient. The uveitis resolved with in a week after treatment with topical administration of prednisolone acetate 1% four times a day. The conjunctival burns appeared as a blanched pit with a brown border and usually resolved within several days postopera tively. One patient suffered mild ocular pain from the diode laser cyclophotocoagulation for up to one week postoperatively. This study suggested the use of the semicon ductor diode laser to perform transscleral cy clophotocoagulation in a reasonably safe, com fortable, and effective manner. Treatment efficacy may be improved by development of a more precise focusing mechanism (for example, contact probe and an automatic defocus built into the laser) and slightly increased wattage capability. This study did not compare diode laser trans scleral cyclophotocoagulation to other cyclode structive techniques. Also, the potential benefit of repeat treatment with the diode laser was not explored. Further evaluation is needed to con firm the clinical usefulness of diode laser trans scleral cyclophotocoagulation and the factors that will determine its most efficient use. ACKNOWLEDGMENT
Keeler Instruments, Broomall, Pennsylva nia, provided the Microlase laser used in this study.
References 1. Hennis, H. L., Assia, E., Stewart, W. C, Legler, U. F. C, and Apple, D. J.: Transscleral cyclophotoco agulation using a semiconductor diode laser in ca daver eyes. Ophthalmic Surg. 21:274, 1991.
Vol. 113, No. 1
Diode Laser Cyclophotocoagulation
2. Assia, E. I., Hennis, H. L., Stewart, W. C , Legler, U. F. C , Carlson, A. N., and Apple, D. J.: Comparison of Nd:YAG and diode transscleral cyclo photocoagulation and cyclocryotherapy. Invest. Ophthalmol. Vis. Sci. 32:2774, 1991. 3. Stewart, W. C : Clinical Practice of Glaucoma. Thorofare, New Jersey, Slack, Inc., 1990, p. 399. 4. Beckman, H., and Waeltermann, J.: Transscleral ruby laser cyclocoagulation. Am. J. Ophthalmol. 98:788, 1984. 5. Peyman, G. A., Conway, M. D., Raichand, M., and Lin, J.: Histopathologic studies on transscleral argon-krypton photocoagulation with an exolaser probe. Ophthalmic Surg. 15:496, 1984. 6. Klapper, R. M., Wandel, T., Donnenfeld, E., and Perry, H. D.: Transscleral neodymium:YAG thermal cyclophotocoagulation in refractory glaucoma. A preliminary report. Ophthalmology 95:719, 1988. 7. Badeeb, O., Trope, G. E., and Mortimer, C : Short-term effects of neodymium:YAG transscleral cyclocoagulation in patients with uncontrolled glau coma. Br. J. Ophthalmol. 72:615, 1988.
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8. Hampton, C , Shields, M. B., Miller, K. N., and Blasini, M.: Evaluation of a protocol for transscleral neodymium:YAG cyclophotocoagulation in one hun dred patients. Ophthalmology 97:910, 1990. 9. Sigelman, J.: Retinal Diseases. Pathogenesis, Laser Therapy, and Surgery. Boston, Little, Brown and Company, 1984, p. 77. 10. Fankhauser, F., van der Zypen, E., Kwasniewska, S., Rol, P., and England, C : Trans scleral cyclophotocoagulation using a neodymium YAG laser. Ophthalmic Surg. 17:94, 1986. 11. Hampton, C , and Shields, M. B.: Transscleral neodymium:YAG cyclophotocoagulation. A histologic study of human autopsy eyes. Arch. Ophthalmol. 106:1121, 1988. 12. Schuman, J. S., Jacobson, J. J., Puliafito, C. A., Noecker, R. J., and Reidy, W. T.: Experimental use of semiconductor diode laser in contact transscleral cyclophotocoagulation in rabbits. Arch. Ophthalmol. 108:1152, 1990.
OPHTHALMIC MINIATURE
As I drove toward town I was thinking about that ancient and honorable bit of homely psychology, that myth of the ripeness of cataracts. The lens capsule can be removed as soon as it begins to get cloudy. But postoperative vision with corrective lenses is a poor resource at best, compared with normal sight. So the ripeness they speak of is the psychological ripeness of the patient, a time of diminishing vision which lasts long enough, and gets bad enough, so that the postoperative vision is, by comparison, a wonder and a delight. The patient is h a p p y because the basis of comparison has changed. John D. MacDonald, The Long Lavender Look N e w York, Ballantine Books, 1970, p p . 84-85
