Progressive Enlargement of Laser Scars Following Grid Laser Photocoagulation for Diffuse Diabetic Macular Edema Howard Schatz, MD; Daniel Madeira, MD; H. Richard McDonald, MD; Robert N. Johnson, MD

\s=b\ Laser

photocoagulation in a grid pat-

tern is effective in many eyes in resolv-

ing diffuse stabilizing

diabetic macular edema and vision. We retrospectively studied 203 eyes of 203 patients, all of whom had diabetic macular edema treated with grid laser photocoagulation. During the follow-up period, 11 of these 203 eyes developed enlargement of the laser scars that progressed into the central fovea. Each of the 11 eyes experienced loss of vision, and in five, the visual loss was significant. Five of these eyes also developed a retinal pigment hyperplastic scar. After the laser treatment, but before the scars enlarged, the visual acuity of these eyes was unchanged from that before treatment. But after the atrophic scars enlarged into the central fovea, visual acuity in one eye decreased from 20/40 to 20/100, and the other 10 eyes had visual acuities of 20/200 or worse.

(Arch Ophthalmol. 1991;109:1549-1551)

'"The Early Treatment Diabetic Retinopathy Study has demonstrated the benefit of laser photocoagulation treatment for clinically significant focal diabetic macular edema.12 Treating eyes with diffuse diabetic macular ede¬ ma with a grid pattern of laser photocoagulation does cause résorption of edema and stabilization of visual acu¬ ity; a small percentage of eyes have

also

experienced

visual

ment.3-13

improve¬

We herein report the results involv¬ ing complications of laser scar enlarge¬ ment following grid laser treatment for diffuse retinal vascular leakage and macular edema in 11 of 203 eyes of 203 patients with diabetes. PATIENTS AND METHODS

We retrospectively reviewed the history, visual acuity, slit-lamp and contact-lens ex¬ amination results, fundus photographs, and fluorescein angiograms of 203 eyes of 203

Accepted for publication July 2,

1991. From the Retina Research Fund, St Mary's Hospital and Medical Center, San Francisco, Calif. Reprint requests to 1 Daniel Burnham Ct, Suite 210, San Francisco, CA 94109 (Dr Schatz).

patients consecutively laser photocoagulation

treated with grid for diffuse diabetic macular edema. Eleven (5.4%) of the 203 patients with diffuse diabetic macular ede¬

(RPE) atrophy caused by the laser lesions

had

enlarged. Five

years after laser treat¬

ment, the atrophie laser lesions had become so

coalescent that much of the macula

was

developed significant progressive en¬ largement of the laser scars following treat¬ ment with grid laser photocoagulation

atrophie. The visual acuity had decreased to 20/200 (Fig IG and H).

None of the 11 eyes had undergone previ¬ ous laser treatment of the macular region, undergone previous retinal surgery (other than panretinal photocoagulation in four eyes), glaucoma, myopia of greater than 2.5 diopters (Table 2), or any sign of agerelated macular degeneration. Six eyes were phakic, two were aphakic, and three

Eleven (5.4%) of 203 consecutive

ma

(Table 1).

were

pseudophakie. patient was

Each

treated with

light

to

light-medium argon green laser photocoag¬ Spots of 100 µ were placed ap¬ proximately 100 to 200 µ apart in a grid ulation.

pattern

over the area of diffuse retinal vascular leakage 200 µ from the perifo¬ veal capillary net in a manner described elsewhere.' To produce a light to lightmedium burn, 150 to 400 mW of power was used for 0.05 to 0.2 seconds. The longer duration (0.2 seconds) and the higher power (approaching 400 mW) were used when the media were not clear (due to cataract) or the retina was excessively edematous or thickened. The resultant photocoagulation lesions in each case, however, was light to light-medium. Three of the 11 eyes were retreated for persistent macular edema.

REPORT OF A CASE A 48-year-old white woman (patient 6 in Table 1) with diabetes had undergone pan¬ retinal laser photocoagulation in her right eye for proliferative diabetic retinopathy. After 2 years, she had a visual acuity of 20/50 OD. Fluorescein angiography re¬ vealed the presence of diffuse retinal vascu¬ lar leakage in the macula, causing signifi¬ cant cystoid macular edema (Fig , B, and C). Argon-green grid laser photocoagulation was performed to produce light laser burns. Three months after laser treatment, her visual acuity was 20/40, and biomicros¬ copic examination showed significant reso¬ lution of the cystic macular edema (Fig ID, E, and F). Seventeen months after laser treatment, the visual acuity remained 20/40 and the macula was much less edematous. The laser lesions were seen to be small, fine, slightly pigmented, and well

separated.

Three years later, the visual acuity had decreased to 20/70. Examination deter¬ mined that the retinal pigment epithelial

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RESULTS

eyes developed progressive enlarge¬ ment of laser scars after grid laser photocoagulation treatment for diffuse

diabetic macular edema (Table 1). The laser burns produced were light to light-medium in all patients. After la¬ ser treatment, fluorescein angiography revealed intact and perfusing macular capillaries in each eye. During the follow-up period, five eyes developed significant visual loss of two or more lines (Table 1, cases 1, 6, 7, 10, and 11). Before grid laser photocoagulation, the visual acuity in the 11 eyes ranged from 20/40 to 10/200. After the laser scar enlarge¬ ment, visual acuity ranged from 20/100 to counting fingers. One eye went from 20/40 before treatment to 20/100 after the development of scar enlargement. The 10 other eyes had visual acuity of 20/200 or worse, and of these 10, six were 10/200 or worse. A retinal pig¬ ment hyperplastic scar formed in five of the 11 eyes. None of the patients

developed progressive retinopathy, re¬ current macular edema, or progressive macular ischemia. Subsequent angio¬ grams failed to reveal any other of visual loss.

causes

COMMENT

The most frequent cause of loss of visual acuity in patients with diabetes is macular edema due to either focal or diffuse retinal vascular leakage.14 Focal macular edema results from well-de¬ fined areas of leaking microaneurysms or dilated capillaries frequently associ¬ ated with lipoproteinaceous exudates. The edema can be successfully treated with laser photocoagulation.1'2 More problematic is macular edema that results from diffuse leakage of the retinal capillary bed in the macula.4 Cystoid macular edema is frequently present in these cases. Numerous

Table 1.—Eleven Eyes With Progressive Enlargement of Laser Scars After Grid Laser Patient No./

Visual

Acuity

Age, y/ Posttreatment

Follow-up, Mo

1/60/0/Mt

20/320

38

2/73/W/Mt

8/200 7/200

Race/Sex

Photocoagulation*

Pretreatment

RPE

atrophy,

Comments size, includes central fovea;

2 DD in

of RPE hyperplasia atrophy, 2 DD in size, includes central fovea atrophy, 1)4 DD in size, includes central fovea; few areas of pigment epithelial hyperplasia RPE atrophy, % DD in size, includes central fovea RPE atrophy, 1 DD in size, includes central fovea; area of hyperplasia adjacent to fovea RPE atrophy, Vi DD in size, includes central fovea RPE atrophy, 3 DD in size, includes central fovea 84 RPE atrophy, 2 DD in size, includes central fovea RPE atrophy, % DD in size, includes central fovea; few areas of RPE hyperplasia RPE atrophy, 2 DD in size, includes central fovea; some areas of pigment epithelial hyperplasia RPE atrophy, % DD in size, includes central fovea 132 retinal pigment epithelium; DD, disc diameter; and CF, counting fingers. some areas

3/69/W/F

20/200

4/67/W/F 5/61/W/M 6/48/W/F 7/84/W/M 8/84/W/F

RPE RPE

3/200

10/200 20/200 20/100 20/300

CF

CF 20/200

9/82/W/Ft 10/68/W/M 11/58/W/F *

All

20/40

treated with argon-green laser treatment a second time.

cases were

tUnderwent

_

20/100

photocoagulatton.

RPE indicates

Fig 1.—A, Red-free photograph of the right macula before grid laser photocoagulation treatment. The macula is edematous. Subtle cystic changes can be seen. B, Fluorescein angiogram of arteriovenous phase. The capillaries in the central macular area are dilated. Laser lesions (from previous panretinal photocoagulation) are present out¬ side the central macular area. C, Fluorescein angiogram of late phase. Note the severe cystoid macular edema resulting from a generalized, diffuse retinal vascular leakage of the macular capillaries. D. Right macula 3 months after grid laser photocoagulation treatment. Note the finely pigmented, small, discrete laser lesions fairly evenly and widely

in the central macular area. E, Fluorescein angiogram of later arteriovenous phase. Note the grid laser photocoagulation le¬ sions. F, Fluorescein angiogram of late phase. There ¡s a mild amount of retinal vascular leakage but the cystic edema has disappeared. G, 5 years after grid laser photocoagulation treatment. Note the area of atrophy in the central macula caused by coalescence of the grid laser lesions. H, Fluorescein angiogram of late arteriovenous phase. Note the area of atrophy in the central macula caused by spreading and coalescence of the laser atrophy.

dispersed

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Fig 2.—Schematic drawing of sequential change of grid laser spots progressing to cen¬ tral retinal pigment epithelial atrophy.

Table 2.—Refractive Errors of

Study Eyes* Patient No. 1 2

3 4 5

Refraction, diopters -2.25 s +0.75 s +0.50C X 75° +13.75 s -1.00

c

X 125°

—2.00 s + 1.25

c

X 125°

c

X 78°

c

X 95°

c

X 90°

c

X 95°

+1.25 -2.25

7

-2.75 s +3.00 +6.00 s -1.00

s

+12.75

10

+0.50

11

-1.00 +2.75 s -1.50

s

indicates

Phakic

Pseudophakie

s

-0.75

*

Pseudophakie

Phakic

6

9

Aphakic

Phakic

s

+ 1.00

8

Lens Status Phakic Phakic

s c

X 80°

c

X 10°

Pseudophakie Phakic

spherical,

and c, cylinder.

studies have shown that

photocoagulation

Aphakic

grid

laser

treatment is useful

for eyes with diffuse retinal vascular leakage and cystoid macular edema.3""13 These studies show a trend toward résorption of the cystoid macular ede¬ ma and an improvement in vision in 17% to 45% of eyes.511'1113 Most of these studies involve only short follow-up periods. Our 11 patients were followed up for at least 10 months (range, 10 to 132 months), with a mean of 52.8 months. Eleven (5.4%) of 203 eyes in this

study experienced progressively ex¬ panding laser scars that resulted in RPE atrophy following treatment with grid laser photocoagulation. Further¬ more, this atrophy expanded into the central fovea, causing significant visu¬ al loss (Fig 2); five patients lost two or more lines, and visual acuity of the other six decreased to very poor (Table

1).

Progressive atrophie enlargement of scars has been reported following specific (not grid) laser photocoagula-

laser

tion for other disorders. Yannuzzi and coworkers10 described progressive RPE atrophy, or "runoff," in patients

with pathologic myopia treated for subretinal neovascularization. Rice and coworkers"1 noted that progressive pigmentary changes develop at the edges of laser photocoagulation scars after treatment of subretinal neovas¬ cularization in the presumed ocular histoplasmosis syndrome. Morgan and Schatz17 reported that 70% (122 of 174) of laser scars in patients with agerelated macular degeneration treated subretinal neovascularization for showed an increase in the size of the original laser scar from 50 to 1016 µ 2 to 81 months after treatment. Visual acuity was reduced in three of the four cases in which the enlarging laser scar crossed the central fovea. In all three of these studies, the heavy, confluent, and specific (not grid) laser photocoag¬ ulation used for the treatment of subretinal neovascularization resulted in an enlarged area of RPE atrophy. In our series, laser spots of light to light-medium intensity were placed in a grid pattern throughout the macula up to the edge of the perifoveal capil¬ lary net. Expansion of the RPE atro¬ phy caused by the laser lesions oc¬ curred in 11 of 203 eyes. Five eyes also had a hyperplastic RPE response, which could contribute to loss of vision. Although it may be possible that these complications are avoided by using la¬ ser burns of very mild intensity, wider spacing between the laser burns, and no treatment to the perifoveal capil¬ lary net, treatment of all the patients met the Early Treatment Diabetic Retiopathy Study standards that recom¬ mend light to medium-light laser burns. Eight of the 11 eyes were treated only once. Three eyes were retreated for persistent diffuse macular edema. These three eyes, however, did not differ in preoperative or final visual acuity or length of follow-up from the eyes treated only once. Although the 203 patients were from a wide age range—mid-30s to mid80s—our 11 patients ranged in age from 48 to 84 years, with a mean age of 68.5 years; 10 were 58 years of age or older. Perhaps the tendency toward expanding atrophy of the laser lesions is related to the age of the patients and the effect of laser on older pigment epithelium. Eight eyes had visual acu¬ ity of 20/100 or worse before surgery. It is possible that in addition to intra¬ retinal fluid (retinal edema), these eyes also had some degree of subre¬ tinal fluid in the macula that contribut¬ ed to the atrophy of the RPE. It is important to consider the poten¬ tial for expanding RPE atrophy with significant visual loss following grid

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laser photocoagulation when weighing the risks and benefits of such laser treatment in patients with diabetes who also have diffuse macular edema. It is also possible that with a longer follow-up period, more eyes will devel¬ op an increase of laser scar size and loss of visual acuity. This study was supported by the Retina Re¬ search Fund of St Mary's Hospital and Medical Center, San Francisco, Calif, and through a grant from the Wayne and Gladys Valley Foundation, San Ramon, Calif.

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1985;103:1796-1806.

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5. McDonald RH, Schatz H. Grid photocoagulation for diffuse macular edema. Retina. 1985;5:65\x=req-\ 72. 6. Olk J. Modified grid argon (blue-green) laser photocoagulation for diffuse diabetic macular ede-

Ophthalmology. 1986;93:938-950. Pugesgaard T, Laursen AB. Modified grid pattern treatment of diabetic perifoveal edema by orange dye laser photocoagulation. Acta Ophthalma.

7.

mol. 1988;66:286-292. 8. McNaught EI, Foulds WS, Allan D. Grid photocoagulation improves reading ability in diffuse diabetic macular oedema. Eye. 1988;2:288-296. 9. Striph GG, Hart WM, Olk RJ. Modified grid laser photocoagulation for diabetic macular edema.

Ophthalmology. 1988;95:1673-1679.

10. Brancato R, Menchini U, Scialdone A, Bandello F. Focal versus scattered argon-green in diffuse diabetic macular edema. In: Gitter K, Schatz H, Yannuzzi LA, McDonald HR, eds. Laser Photocoagulation of Retinal Disease. San Francisco, Calif: Pacific Medical Press; 1988;69-73. 11. Whitelocke RAF, Kearns M, Blach RK, Hamilton AM. The diabetic maculopathies. Trans Ophthalmol Soc U K. 1979;99:314-320. 12. Kayazawa F, Tolentino GDJ, Miyake K. Grid-pattern laser photocoagulation for diffuse macular edema (the Japanese experience). In: Gitter K, Schatz H, Yannuzzi LA, McDonald HR, eds. Laser Photocoagulation of Retinal Disease. San Francisco, Calif: Pacific Medical Press; 1988;65-68. 13. Blankenship GW. Diabetic macular edema and argon laser photocoagulation: a prospective randomized study. Ophthalmology. 1979;86:69-78. 14. Bresnick GH. Diabetic macular edema. Oph-

thalmology. 1986;93:989-997.

15. Yannuzzi LA, Shakin JL, Milch FA. Complications of laser photocoagulation of subretinal neovascularization secondary to pathologic myopia. In: Gitter K, Schatz H, Yannuzzi LA, McDonald HR, eds. Laser Photocoagulation of Retinal Disease. San Francisco, Calif: Pacific Medical Press; 1988:219-226. 16. Rice TA, Murphy RP, Fine SL, Patz A. Stability ofsize of argon laser photocoagulation scars in ocular histoplasmosis. In: Fine SL, Owens SL, eds. Management of Retinal Vascular and Macular Disorders. Baltimore, Md: Williams & Wilkins; 1983:187-190. 17. Morgan CM, Schatz H. Atrophic creep of the retinal pigment epithelium after focal macular pho-

tocoagulation. Ophthalmology. 1989;96:96-103.