retinal pigment epithelial rip during krypton red laser photocoagulation

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RETINAL PIGMENT EPITHELIAL RIP DURING KRYPTON RED LASER PHOTOCOAGULATION J. DONALD M. GASS, M.D. Miami, Florida In three patients (two women, 73 and 74 years old, and one man, 74 years old), a pigment epithelial rip occurred near the edge of a hypopigmented, partly organized choroidal neovascular membrane at the time of its treatment with krypton red photocoagulation. In all three cases, final visual acuity was 20/200. A tear or rip in the pigment epithelium may occur along the edge of a serous detachment of the pigment epithelium either spontaneously or days or weeks after photocoagulation treatment. 1 " 5 Three patients suffered such rips during krypton red photocoagulation of a partly organized choroidal neovascular mem- brane. 6 CASE REPORTS Case 1—A 73-year-old woman with a two-year history of loss of central vision in her right eye had a ten-day history of loss of reading vision in her left eye. Visual acuity was R.E.: 5/200 and L.E.: 20/200. The anterior ocular segments were normal. There was a large vascularized disciform scar in the right macula. In the left eye there was a large, irregularly shaped serous detachment of the pigment epithelium involving the temporal one half of the macula. This was contiguous with an area measuring 1 disk diameter of solid elevation of partly depigmented pigment epithelium at the inferior edge of the capil- lary free zone. There was a shallow retinal detach- ment in the central macular area. Some yellow exudate was present near the temporal border of the pigment epithelial detachment. Fluorescein angiog- Accepted for publication Sept. 13, 1984. From the Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Medical School, Miami, Florida. This study was supported in part by Research Grant EY02549 from the Public Health Service, Department of Health and Human Services, National Institutes of Health, National Eye Institute, Bethesda, Maryland. Reprint requests to J. Donald M. Gass, M.D., Bascom Palmer Eye Institute, P.O. Box 016880, Miami, FL 33101. raphy disclosed evidence of choroidal neovasculariza- tion within the area of pigment epithelial elevation along the inferior border of the capillary free zone (Fig. 1, top left). When the patient was examined five weeks later, her vision was unchanged. The area of serous detach- ment of the pigment epithelium temporally was less elevated and there was a small rent in the temporal edge of the detachment (Fig. 1, top right). Krypton laser treatment was applied to the neovascular com- plex. Because of difficulty in obtaining a visible burn, the intensity and duration of the 500-μιη size applica- tions were incrementally increased from 0.35 to 0.6 W and from 0.2 to 0.5 second. During the last few applications there was a sudden movement of the neovascular complex in a superior direction associat- ed with a prominent pigment epithelial tear just beyond the inferior border of the neovascular com- plex (Fig. 1, bottom left). The patient's vision improved during the five-day period after treatment. On the sixth day, however, she experienced a rapid worsening of vision. At that time her visual acuity was 20/200. There was addi- tional subretinal fluid in the macula. The large pigment epithelial rip adjacent to the area of treat- ment, as well as the smaller tear at the temporal edge of the area of serous detachment of the pigment epithelium were unchanged and were easily visual- ized angiographically (Fig. 1, bottom right). The development of a preoperative spontaneous pigment epithelial rip as well as the intraoperative rip suggested that the patient had some unusual predisposition to this complication. Case 2—A 73-year-old man with senile macular degeneration had lost central vision in his left eye several years previously. He had undergone argon laser treatment for a choroidal neovascular mem- brane located on the temporal border of the capillary free zone of his right eye one year previously, and had maintained a visual acuity of 20/25 for approxi- mately one year before metamorphopsia developed. Visual acuity in his right eye was 20/30. Examination disclosed a small patch of subretinal blood that partly covered the surface of a small organized area of elevation of the pigment epithelium along the inferi- 700 ©AMERICAN JOURNAL OF OPHTHALMOLOGY 98:700-706, 1984

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RETINAL P I G M E N T E P I T H E L I A L RIP DURING KRYPTON R E D LASER PHOTOCOAGULATION

J. D O N A L D M. GASS, M.D. Miami, Florida

In three patients (two women, 73 and 74 years old, and one man, 74 years old), a pigment epithelial rip occurred near the edge of a hypopigmented, partly organized choroidal neovascular membrane at the time of its treatment with krypton red photocoagulation. In all three cases, final visual acuity was 20/200.

A tear or rip in the pigment epithelium may occur along the edge of a serous detachment of the pigment epithelium either spontaneously or days or weeks after photocoagulation treatment.1"5

Three patients suffered such rips during krypton red photocoagulation of a partly organized choroidal neovascular mem­brane.6

C A S E REPORTS

Case 1—A 73-year-old woman with a two-year history of loss of central vision in her right eye had a ten-day history of loss of reading vision in her left eye. Visual acuity was R.E.: 5/200 and L.E.: 20/200. The anterior ocular segments were normal. There was a large vascularized disciform scar in the right macula. In the left eye there was a large, irregularly shaped serous detachment of the pigment epithelium involving the temporal one half of the macula. This was contiguous with an area measuring 1 disk diameter of solid elevation of partly depigmented pigment epithelium at the inferior edge of the capil­lary free zone. There was a shallow retinal detach­ment in the central macular area. Some yellow exudate was present near the temporal border of the pigment epithelial detachment. Fluorescein angiog-

Accepted for publication Sept. 13, 1984. From the Department of Ophthalmology, Bascom

Palmer Eye Institute, University of Miami Medical School, Miami, Florida. This study was supported in part by Research Grant EY02549 from the Public Health Service, Department of Health and Human Services, National Institutes of Health, National Eye Institute, Bethesda, Maryland.

Reprint requests to J. Donald M. Gass, M.D., Bascom Palmer Eye Institute, P.O. Box 016880, Miami, FL 33101.

raphy disclosed evidence of choroidal neovasculariza-tion within the area of pigment epithelial elevation along the inferior border of the capillary free zone (Fig. 1, top left).

When the patient was examined five weeks later, her vision was unchanged. The area of serous detach­ment of the pigment epithelium temporally was less elevated and there was a small rent in the temporal edge of the detachment (Fig. 1, top right). Krypton laser treatment was applied to the neovascular com­plex. Because of difficulty in obtaining a visible burn, the intensity and duration of the 500-μιη size applica­tions were incrementally increased from 0.35 to 0.6 W and from 0.2 to 0.5 second. During the last few applications there was a sudden movement of the neovascular complex in a superior direction associat­ed with a prominent pigment epithelial tear just beyond the inferior border of the neovascular com­plex (Fig. 1, bottom left).

The patient's vision improved during the five-day period after treatment. On the sixth day, however, she experienced a rapid worsening of vision. At that time her visual acuity was 20/200. There was addi­tional subretinal fluid in the macula. The large pigment epithelial rip adjacent to the area of treat­ment, as well as the smaller tear at the temporal edge of the area of serous detachment of the pigment epithelium were unchanged and were easily visual­ized angiographically (Fig. 1, bottom right).

The development of a preoperative spontaneous pigment epithelial rip as well as the intraoperative rip suggested that the patient had some unusual predisposition to this complication.

Case 2—A 73-year-old man with senile macular degeneration had lost central vision in his left eye several years previously. He had undergone argon laser treatment for a choroidal neovascular mem­brane located on the temporal border of the capillary free zone of his right eye one year previously, and had maintained a visual acuity of 20/25 for approxi­mately one year before metamorphopsia developed. Visual acuity in his right eye was 20/30. Examination disclosed a small patch of subretinal blood that partly covered the surface of a small organized area of elevation of the pigment epithelium along the inferi-

700 ©AMERICAN JOURNAL OF OPHTHALMOLOGY 98:700-706, 1984

VOL. 98 , NO. 6 RETINAL P I G M E N T E P I T H E L I A L RIP 701

Fig. 1 (Gass). Case 1. Top left, Five weeks before photocoagulation. Note large serous detachment of the pigment epithelium and the smaller circular zone of organized pigment epithelial detachment (arrows). Top right, Immediately before photocoagulation. Note small rip (arrow) that occurred spontaneously at the edge of the detachment. Bottom left, Immediately after krypton treatment. Note large pigment epithelial rip (arrows) near inferior edge of treatment. Bottom right, Six days after treatment. Note hyperfluorescence at the site of the intraoperative rip (arrows) and the preoperative rip temporally.

or margin of the capillary free zone (Fig. 2 top left). There was a small area of serous retinal detachment in the central macular area. Angiography disclosed a poorly defined zone of staining in the area of the pigment epithelial elevation (Fig. 2 upper right). In an effort to create a visible krypton laser burn, the power was gradually increased to 0.6 W using 0.5-second 500-μιτι applications. Before a moderately intense bum was obtained, there was a sudden temporal movement of the neovascular complex and

a concomitant development of a vertical rip in the relatively normal-appearing pigment epithelium just beyond the apparent edge of the neovascular com­plex (Fig. 2, bottome left and right). When he re­turned three weeks later his visual acuity was 20/40. Blood was no longer evident and the pigment epithe­lial rip was clearly visible. Six months later the neovascular membrane extended into the center of the macula and his visual acuity was 20/200.

Case 3—A 74-year-old woman with idiopathic an-

702 A M E R I C A N J O U R N A L O F O P H T H A L M O L O G Y D E C E M B E R , 1984

Fig. 2 (Gass). Case 2. Top left and top right, Pretreatment. Note blood overlying organized pigment epithelial detachment (arrows) adjacent to previous white photocoagulation scar. Bottom left and bottom right, Posttreatment. Note vertical rip (arrows) most evident angiographically at temporal margin of the area of photocoagulation.

gioid streaks complained of having a paracentral scotoma in her left eye for three weeks. She had previously lost central vision in her right eye because of choroidal neovascularization and disciform detach­ment. Visual acuity in her left eye was 20/30. She had a lightly pigmented elevated subpigment epithelial fibrovascular complex extending from the optic disk almost to the nasal edge of the capillary free zone (Fig. 3, top left). Serous detachment of the retina extended from the edge of the complex into the center of the macula. Angiography confirmed the presence of the organized pigment epithelial detach­

ment. After I administered retrobulbar anesthesia, I used 34 applications (200 to 500 μπι, 0.2 to 0.5 second, and 0.5 to 0.6 W) to treat the temporal part of the neovascular complex. On two occasions there was a sudden nasal movement of this complex despite the presence of a slightly visible photocoagu­lation reaction at the level of the pigment epithelium. Only after the second movement did the vertical rip in the normal-appearing pigment epithelium appear near the center of the capillary free zone (Fig. 3, top right).

One week after treatment the patient's visual

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Fig. 3 (Gass). Case 3. Top left, Pretreatment. Arrows indicate site of elevated organized pigment epithelial detachment. Top right, Immediately after treatment. Arrows indicate vertical rip near temporal margin of treatment. Bottom left and bottom right, One week after treatment. Note blood partly obscuring the hyperfluorescent pigment epithelial rip (arrows).

acuity was 20/30 and there was a small amount of blood in the area of the pigment epithelial rip (Fig. 3, bottom left and right). Angiography showed evidence of the rip. Subsequently the neovascular membrane extended temporally into the center of the macula. Visual acuity eight months after treatment was 20/200.

DISCUSSION

In all three of these patients with ser­ous detachment of the macula associated

with senile macular disease, there was evidence of fibrous proliferation accom­panying the subpigment epithelial cho-roidal neovascular complex. In each case the fibrovascular complex was elevated and light gray in color. Angiographically, each one failed to show a well-defined vascular pattern and all stained slowly and irregularly. In all three patients, dur-

704 AMERICAN JOURNAL OF OPHTHALMOLOGY DECEMBER, 1984

ing the incremental increasing of the power and frequency of the krypton laser applications on the surface of the neo­vascular complex, a sudden unidirec­tional movement of the complex was observed and a tangential rip occurred nearby in the relatively normal pigment epithelium.

I suggest that sudden contraction of the fibrovascular tissue caused by the heat generated primarily beneath the neovas­cular complex was probably responsible for the shearing force causing a rip in the pigment epithelium. Figure 4 illustrates diagrammatically what apparently hap­pened. Contraction of that portion of the fibrovascular complex being treated caus­es it, together with the pigment epitheli­um adherent to its surface, to slide along the surface of Bruchs membrane toward the part of the complex that remains adherent to Bruch's membrane. This movement produces a shearing force in the pigment epithelium at the site where it adheres to Bruch's membrane near the edge of the neovascular complex. The occurrence of the rip in all three cases just beyond the edge of the complex suggests that there was a rim of shallow subclinical detachment of the pigment epithelium at its margin.

I wondered why I had not observed this complication during argon and xenon treatment of similar partly organized cho­roidal neovascular complexes. The long wavelengths of the red laser are absorbed primarily in the melanin in the choroidal melanocytes and retinal pigment epithe­lium and generate greater amounts of heat within the depth of the choroid than is possible with argon, blue-green, or white light. This characteristic of krypton red laser is partly responsible for the greater incidences of choroidal hemor­rhage and occlusion of large choroidal vessels that accompany its use.7,8 During krypton treatment of a light-colored fi­brovascular membrane covered by

Fig. 4 (Gass). Diagram of pathogenesis of pigment epithelial rip occurring during krypton (K) laser. Top two drawings show frontal and cross-sectional view of pretreatment choroidal neovascular complex (bd) with subclinical marginal serous detachment of the pigment epithelium (ab). Bottom two illustrations show contracted neovascular complex (cd) after laser treatment and tear in pigment epithelium (ab).

atrophie pigment epithelium, the thera­pist may generate considerable heat with­in the choroid beneath the neovascular complex while producing no visible reti­nal burn near its surface. If, in an effort to produce a visible burn, the therapist in-

VOL. 98, NO. 6 RETINAL PIGMENT EPITHELIAL RIP 705

creases the power, duration, and fre­quency of the applications too abruptly, the result may be a sudden contraction of the membrane and a pigment epithelial rip. Similar rips probably could occur with excessive treatment with other types of photocoagulation.

Rips or tears in the retinal pigment epithelium may occur either spontane­ously or several days or weeks after

photocoagulation in patients with large serous detachments of the pigment epi­thelium.1"5 Most spontaneous and post-treatment rips occur because of the presence of an undetected organized neovascular complex lying beneath and at one edge of the serous detachment of the pigment epithelium. The rip occurs at the junction of the attached and detached retinal pigment epithelium remote from

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706 AMERICAN JOURNAL OF OPHTHALMOLOGY DECEMBER, 1984

the area of the organized neovascular complex, probably in response to in­creased subretinal pigment epithelium hydrostatic pressure generated within the complex (Fig. 5).

The subretinal pigment epithelium fi-brovascular complex is important in the pathogenesis of intraoperative, postoper­ative, and spontaneous retinal pigment epithelial rips. Although its presence and location can be detected biomicro-scopically, it is most accurately identified by stereoscopic angiograms as an area of elevation of the pigment epithelium that fails to stain rapidly and evenly.4,9 To avoid a retinal pigment epithelial rip dur­ing krypton laser treatment of these or­ganized complexes, particularly when they are covered by hypopigmented pig­ment epithelium, the clinician should use caution in increasing the power, dura­tion, and frequency of laser applications and not insist on the production of a moderately intense gray photocoagula-tion reaction.

R E F E R E N C E S

1. Hoskins, A., Bird, A. C , and Sehmi, K.: Tears of detached retinal pigment epithelium. Br. J. Oph­thalmol. 65:417, 1981.

2. Green, S. N., and Yarian, D.: Acute tear of the pigment epithelium. Retina 3:16, 1983.

3. Cantrill, H. L., Ramsay, R. C , and Knobloch, W. H.: Rips in the pigment epithelium. Arch. Oph­thalmol. 101:1074, 1983.

4. Gass, J. D. M.: Pathogenesis of tears of the retinal pigment epithelium. Br. J. Ophthalmol. 68:513, 1984.

5. Swanson, D. E., Kalina, R. E., and Guzak, S. V.: Tears of the retinal pigment epithelium. Oc­currence in retinal detachment and a chorioretinal scar. Retina 4:115, 1984.

6. Gass, J. D. M.: Present indications and future promises of the krypton laser. In March, W. E. (ed.): Ophthalmic Laser. Current Clinical Uses. Thorofare, Charles F. Slack, 1984, pp. 133 and 134.

7. Marshall, J., and Bird, A. : A comparative histo-pathologic study of argon and krypton laser irradia­tions of the human retina. Br. J. Ophthalmol. 63:657, 1979.

8. Peyman, G. A., Li, M., Shin, Y., Yoneya, S., Goldberg, M. F., and Raichand, M.: Fundus photo-coagulation with the argon and krypton lasers. A comparative study. Ophthalmic Surg. 12:481, 1981.

9. Gass, J. D. M.: Serous retinal pigment epitheli­al detachment with a notch. A sign of occult choroidal neovascularization. Retina. In press.