Early Retinal Adhesion from Laser Photocoagulation JAMES C. FOLK, MD, SCOTI R. SNEED, MD, ROBERT FOLBERG, MD, PATRICK COONAN, MD, JOSE S. PULIDO, MD

Abstract: Histopathologic examination of eight cynomolgus monkey eyes and one human eye revealed that both argon and krypton laser photocoagulation cause adhesion between the neurosensory retina and the retinal pigment epi­thelium (RPE) within 24 hours of treatment. The neurosensory retina remained attached at the sites of laser burns despite surrounding retinal detachment in untreated areas. This early adhesion with the laser is useful for the treatment of eyes in which the retina has been recently reattached such as at the end of a vitrectomy for a retinal detachment with proliferative vitreoretinopathy (PVR) or after a pneumatic retinopexy. It is also useful for the treatment of retinal breaks without detachment. Ophthalmology 96: 1523-1525, 1989

Both argon laser photocoagulation and cryopexy are commonly used to create a chorioretinal adhesion around retinal breaks. Laser photocoagulation causes less break­down of the blood-ocular barrier and less release of chemoattractants for retinal pigment epithelial (RPE) cells than cryopexy.l,2 The laser may also cause less dispersion of RPE cells into the vitreous because indentation of the sclera is not required, and the treatment is applied after the retina is reattached.3 Argon laser endophotocoagula­tion is often used at the end of vi tree to my surgery in cases of detachments with proliferative vitreoretinopathy (PVR) to create a broad zone of adhesion anteriorly from the ora to posterior to the equator and around any posterior retinal breaks.4 With various manipulations such as min­imal scleral indentation and the use of coaxial light, this endophotocoagulation can be applied easily to any area of the retina. In addition, access to the sclera posteriorly

Originally received: October 5, 1988. Revision accepted: April 18, 1989.

From the Department of Ophthalmology, The University of Iowa Hospitals, Iowa City.

Presented as a poster at the Association for Research in Vision and Oph· thalmology Annual Meeting, Sarasota, May 1987, and the American Acad· emy of Ophthalmology, Annual Meeting Dallas, November 1987.

Supported in part by an unrestricted grant from Research to Prevent Blind· ness, Inc, New York, New York, and The Retina Research Fund, The University of Iowa, Iowa City, Iowa.

Reprint requests to James C. Folk, MD, C. S. O'Brien Library, Department of Ophthalmology, University Hospitals, Iowa City, IA 52242.

in areas previously buckled is not necessary as it is for transcleral cryopexy. We present evidence that an addi­tional advantage of either argon or krypton laser photo­coagulation is an adhesion between the RPE and neuro­sensory retina within 24 hours of application.

MATERIALS AND METHODS

One eye each of eight cynomolgus monkeys received argon blue-green and kypton red laser photocoagulation to various areas of the retina as part of an experiment on the transmission oflaser light through intraretinal blood. The monkeys were euthanatized and their eyes were enu­cleated for histopathologic study 24 hours after the laser treatment.

A 45-year-old diabetic patient underwent vitrectomy surgery with argon blue-green laser endophotocoaguiation for a macular traction retinal detachment. This patient had received minimal scatter laser treatment to the mid­peripheral retina before the vitrectomy. The argon laser endophotocoagulation was applied to areas of attached or very shallowly detached retina, and no intraocular gas was used. The retina appeared attached on the first post­operative day by indirect ophthalmoscopy. Later that day the patient died of a massive pulmonary embolus. Consent was obtained for an autopsy, and both eyes were enucle­ated for histopathologic study. The acute argon laser en­dophotocoagulation bums were easily identified under the dissecting microscope. These acute bums were dissected from the calotte and studied by light microscopy.

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OPHTHALMOLOGY • OCTOBER 1989 • VOLUME 96 • NUMBER 10

Fig 1. Top left. pathology of two argon blue-green laser burns placed in eye of a cynomolgus monkey 24 hours before death. The retina is artifactitiously detached except in the areas of laser application (hematoxylin-eosin; original magnification. X7). Top right. pathology of a krypton red laser burn placed in eye of a cynomolgus monkey 24 hours before death. The retina is artifactitiously detached except at the treatment site (hematoxylin-eosin; original magnification, X 16). Fig 2. Bottom. pathology of two argon blue-green laser endophotocoagulation burns placed in the eye of a diabetic patient 20 hours before death. The retina remained attached at the sites oflaser burns despite adjacent detachment. A physiologic adhesion occurred between the neurosensory retina and the retinal pigment epithelium as evidenced by the traction on the photoreceptor layers (hematoxylin-eosin; original magnification: bottom left. X7; bottom right. X 16).

RESULTS

The retinas of the cynomolgus monkeys detached artifactitiously upon fixation and sectioning. Even though the retinas were highly detached elsewhere, they remained firmly attached at the areas oflaser treatment applied only 24 hours previously (Fig 1). The areas of laser treatment remained attached regardless whether the burns were placed in normal retina or in retina with inner retinal hemorrhage, or whether the burns were caused by the argon green or the krypton red laser.

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In the diabetic patient the retina was also detached post mortem in many areas but remained attached at the sites of argon laser endophotocoagulation which was applied only 20 hours previously (Fig 2).

DISCUSSION

Kain5 believed that retinal adhesion was reduced rather than enhanced during the first few days after photoco­agulation because argon burns did not resist the spread of fluid from an experimental expanding subretinal bleb.

FOLK et al • EARLY RETINAL ADHESION FROM LASER

It was difficult to be sure from his photographs, however, whether the fluid, which was dyed with fluorescein, had indeed spread between the RPE and photoreceptors in the areas of the argon burns. The fluorescein may have simply leaked into the areas of retinal edema caused by the laser burns. Another alternative is that the fluid did not detach but rather split the neurosensory retina in the treated areas. Clinically cases are occasionally seen where the retina detaches soon after laser photocoagulation either from exudation in diabetic eyes which have had extensive scatter laser treatments or from the reopening of a break in eyes with retinal detachments. The elevated inner layer is usually very thin and sometimes tissue fragments can still be seen beneath this inner layer lying on the RPE. This may indicate that the retina has actually split at the junction of the outer retinal burn and the normal inner retina rather than detached from the RPE.

From our histopathologic findings in monkey and hu­man eyes, we can only state conclusively that the adhesion at the sites of argon and krypton laser photocoagulation administered 20 to 24 hours previously was greater than the postmortem adhesion of the retina to the RPE in the nontreated areas. This postmortem adhesion in untreated retina has been found to be very low.6 The histopathologic appearance of the laser burns, however, seems to indicate that the adhesion there was significant and strong. The outer retina was tightly adherent to the RPE even between areas of otherwise highly elevated retinal detachment. In the diabetic eye, retinal traction to the site of RPE adhe­sion was also shown (Fig 2).

The experimental work of Yo on and Marmor? collab­orated our findings oflaser adhesion 24 hours after treat­ment. They found in rabbits that the adhesion between the retina and RPE was greater than that of normal at­tached retina 24 hours after argon laser photocoagulation. This adhesion was greater whether the photocoagulation was placed in attached retina or in retina that had just settled after experimental detachment. The maximal adhesion of the laser scars placed in retina that had just reattached was reached at 2 weeks after treatment and was three times the normal adhesion. In contrast, the areas of retina which reattached but had no photocoagulation showed only 10% of normal adhesion at 24 hours and only 75% of normal adhesion after 4 weeks. The prolonged reduced adhesion of reattached but untreated retina would probably be even greater in eyes with chronic detachments

or recurrent detachments with PVR. Y oon and Marmor believed that the reduced adhesion could be due to a combination of photoreceptor degeneration, damage to the RPE transport mechanisms, and a necessary delay to resynthesize matrix components and reestablish outer segment sheathing by the RPE microvilli. Another expla­nation for the reduced adhesion is found in the report of Johnson et al8 who showed histopathologically that there was a persistent thin layer of subretinal fluid in the macula (which was not treated with laser) 2 days after apparent reattachment of the retina with intraocular gas.

Our findings in monkeys and humans and Y oon and Marmor's work in rabbits indicate that there is adhesion between the neurosensory retina and RPE 24 hours after laser treatment. The adhesion in rabbits increased rapidly and was always much greater than that in recently reat­tached but untreated retina. Therefore, it appears that this early and rapidly increasing adhesion with laser pho­tocoagulation would be useful for the treatment of eyes in which the retina has been recently reattached such as at the end of a vitrectomy for a detachment with PVR or after a pneumatic retinopexy. It would also be useful for the treatment of retinal breaks without detachment.

REFERENCES

1. Jaccoma EH, Conway BP, Campochiaro PA. Cryotherapy causes extensive breakdown of the blood-retinal barrier: a comparison with argon laser photocoagulation. Arch Ophthalmol1985; 103:1728-30.

2. Campochiaro PA, Bryan JA III, Conway BP, Jaccoma EH. Intravitreal chemotactic and mitogenic activity: implication of blood-retinal barrier breakdown. Arch OphthalmoI1986; 104:1685-7.

3. Campochiaro PA, Kaden IH, Vidaurri-Leal J, Glaser BM. Cryotherapy enhances intravitreal dispersion of viable retinal pigment epithelial cells. Arch Ophthalmol1985; 103:434-6.

4. Parke OW II, Aaberg TM. Intraocular argon laser photocoagulation in the management of severe proliferative vitreoretinopathy. Am J Ophthalmol1984; 97:434-43.

5. Kain HL. Chorioretinal adhesion after argon laser photocoagulation. Arch Ophthalmol1984; 102:612-5.

6.. Kain HL. A new model for examining chorioretinal adhesion experi­mentally. Arch OphthalmoI1984; 102:608-11.

7. Yoon YH, Marmor MF. Rapid enhancement of retinal adhesion by laser photocoagulation. Ophthalmology 1988; 95:1385-8.

8. Johnson RN, Irvine AR, Wood IS. Endolaser, cryopexy, and retinal reattachment in the air-filled eye: a clinicopathologic correlation. Arch Ophthalmol1987; 105:231-4.

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