Retinoblastoma is an exquisitely rathosensitive tumor, and irradiation is the most frequently indicated treatment.1"3 However, radiation with complications is often encountered. Various kinds of ocular damage remain after the tumor disappears.
Xenon arc photocoagulation is often an effective means of treatment for a small posterior retinoblastoma with few serious side effects. Argon laser photocoagulation seems to have the same possibilities of curing small tumors as xenon arc photocoagulation.1·3 In a patient whose other eye had been enucleated for retinoblastoma, we treated a small lesion in the fundus of the left eye, with argon laser photocoagulation under general anesthesia after failure with xenon arc photocoagulation and cryotherapy.
We are unable to find any report in the literature on the treatment of retinoblastoma with argon laser. We suggest that argon laser photocoagulation can be used for treatment of the same kinds of retinoblastoma as xenon arc photocoagulation.
The patient was first seen in the Department of Ophthalmology, Miyazaki Medical College Hospital on June 7. 1979, at the age of five months because of leukokoria in the right eye. No abnormality was reported in the family history. Most of the fundus of the right eye was occupied by a solid white tumor. On echography and CT scan, the tumor was seen occupying the posterior one-third of the globe. No lesions were detected in the left eye.
FIGURE 1: Light micrograph of the tumor in the right eye. Numerous Flexner-Wintersteiner rosettes are seen hematoxylin-easin, original magnification X570A
The right eye was enucleated. Pathologic examination showed a large endophytic retinoblastoma with numerous well -developed Fl exner- Wintersteiner rosettes and mitotie figures throughout the entire tumor ( Figure 1 1. There was no invasion of the optic nerve, sclera and anterior segment.
Six weeks later, a solid white tumor, approximately one disc diameter in size, was found in the inferolateral portion of the posterior pole of the left eye. The tumor was treated with a Nidek xenon arc photocoagulator set at a time duration of 0.5-1.0 sec, spot-size of 4.5-6.0 degrees and intensity V. The tumor appeared to be completely destroyed.
One month afterwards, the tumor was found to be growing in the same area as before. Xenon arc photocoagulation was performed again, but it failed to produce a sufficient bum due to lack of pigmentaion. In order to eradicate tumor cells and preserve vision, we performed cryotherapy on the tumor using an Amoilis CO^ unit. The repeated freeze-incomplete thaw-freeze technique was used. The duration of each freeze was 30 sec. The cryoprobe was placed under direct control with an indirect ophthalmoscope. The tumor and its adjacent retina could be completely frozen with the iccball reaching the head of the tumor several times. The tumor remained at the same size for some time following cryotherapy. However, these procedures did not completely destroy the tumor, and it gradually became bigger, reaching a size of 4x2 disc diameters with an elevation of 4 diopters (Figure 2).
FIGURE 2: Fundus photograph immediately before argon latter pholocoagulation. The tumor is 4 X. 2 disc diameters in size and 4 diopters in elevation.
FIGURE 3: Argon laser photocoagulatitin ivas performed under general anesthesia.
FIGURE 4; Fundus photograph immediately after argon laser photocoagulation. The tumor is charred and shrunken.
FIGURE 5: Fiindus photograph three months after argon laser photocoagulation. The iunior completely has disappeared and scar tissue is seen in the retina.
As a final resort, we treated the tumor with argon laser using a Coherent System i)00 photocoagulator. The photocoagulation was done under general anesthesia (Figure 3 ). First, feeding vessels from the retina to the tumor were coagulated and the adjacent retina was laaed to shut ofT circulation to the tumor. Then the tumor was thoroughly treated with strong doses of photocoagulation. These procedures were performed with settings of spot size 200-500 fun, exposure time of 0. 1-1, 5 sec and power of 500-1,00OmW The tumor was shot in about 300 spots. Photocoaguiation was performed at a long exposure time and large spot -size to burn deeply into the choroid. Expulsive photocoagulation forming vapor hubbies was avoided to prevent dissemination of the tumor cells and retinochoroidal hemorrhage. The tumor was charred, shrunken and became necrosed 'Figure 4i. There were no complications.
Three months after argon laser photocoagutation, the tumor disappeared, leaving behind white fibrogiial scar tissue. The optic disc and fovea showed a normal appearance (Figure 51. There has been no evidence of recurrence of the tumor during four years' follow-up. We could not examine the visual field because of the young age of the patient. Visual acuity was 20Í20.
There are a number of options available for the treatment of retinoblastoma, depending on the size and extent of the tumor, whether the involvement is unilateral or bilateral, and on the patient's systemic status. In general, retinoblastoma is a highly rathosensitive tumor. Irradiation is an effective means of treatment in many eyes with retinoblastoma. '-3 Irradiation is most frequently indicated for treatment of the second eye after the eye with the more advanced tumor has been enucleated. It should be used for small retinoblastomas involving the fovea or optic disc, for which photocoagulation and/or cryotherapy would be dangerous,3
However, complications in irradiation are frequently encountered at dosage levels over 4,500 rads. In many cases various kinds of ocular damage are left after the tumor disappears. The ocular complication rate of irradiation is 00 high that only about 15% of eyes retain useful vision,4 The moat common complication of irradiation is vascular necrosis, while an important long-term complication of irradiation is the development of radiation- induced tumor.
Photocoagulation is indicated for the treatment of small retinoblastomas in Reese-Ellsworth group I. This procedure has fewer complications than irradiation and is especially valuable because it has no mutagenic effects. 3>a Because of its availability, xenon arc photocoagulation has been the type most commonly employed.
Zweng has reported that ruby laser, in contrast to xenon arc, does not have enough total energy to thoroughly destroy tumors. However, he has indicated that argon laser has the ability to completely photocoagulate posterior ocular tumors. e The argon laser has excellent energy density, beam divergence, penetration and absorption characteristics when applied to tumors in the ocular posterior segment. The effect of argon laser on vessels is estimated to be at least five times stronger than that of xenon arc.7 Argon laser by itself can be expected to cure small posterior retinoblastomas. We believe that argon laser is as effective as xenon arc when it is used under sufficient anesthesia. Another excellent advantage of argon laser photocoagulation is the possibility of obtaining accurate stereoscopic visualization of the fundus through contact lenses. We were able to perform exact coagulation with this accurate visualization. Such exactness is important in destroying the tumor completely. For these reasons we decided to apply argon laser for the treatment of the retinoblastoma in this case, as it had not responded to xenon arc photocoagulation and cryotherapy. The response to argon laser was satisfactory and no complications ensued.
The principle of argon laser is not only to destroy the tumor itself but also to isolate the tumor from its blood supply, because small retinoblastomas depend on retinal circulation alone for nutrition during a considerable period of their growth, and can be destroyed by photocoagulation if the retinal circulation is completely interrupted. Argon laser photocoagulation was done with settings of a long exposure time, high power and large spotsize to accomplish these purposes. Even if the tumor penetrates Bruch's membrane and gets a good vascular supply from the choroid, it is still destroyed since the thermal effect of argon laser extends to the choroid. The suggestion that this procedure may destroy Bruch's membrane, thereby permitting tumor extension into the choroid, has not been substantiated.5
As compared with cryotherapy, argon laser has stronger power to destroy tumors since in the case of a tumor larger than 3 disc diameters in size, multiple cryotherapy treatments may be required. Cryotherapy can be used as the primary treatment for small peripheral retinoblastomas located near the ora serrata, but this procedure requires surgical intervention when applied to posterior ocular tumors.3,5
In conclusion, argon laser photocoagulation can be performed safely and easily with the cooperation of an anesthesiologist. Thus far we have only one case of retinoblastoma treated with argon laser but this type of photocoagulation is expected to be an excellent means of treatment without serious complications for relatively small retinoblastomas. Further study will be needed to establish its usefulness.
1. Ellsworth RM: Current concepts in the treatment of retinoblastoma, in Peyman GA, et al (eds): Intraocular Tumors. New York, Appleton-Century-Croft, 1977, pp 335-355.
2. Hopping W, Schmitt G, Havers W: The treatment of retinoblastoma. Jpn J Op/ithalmol 1978; 22:420.
3. Shields JA, Augsburger JJ: Current approaches to the diagnosis and management of retinoblastoma. Surv Ophthalmo/ 1981; 2n:347.
4. Nicholson DH, Green WR: Tumors of the eye, lids, and orbit in children, in Harley ED led)·. Pediatrie Ophthalmology. Philadelphia, WB Saunders, 1975, pp 923-940.
5. Ellsworth RM: Diathermy, light coagulation, and cryotherapy in the management of intraocular tumors, in Reese AB (ed): Tumor of the eye. Hagerstown, Maryland, Harper & Row, 1976, pp 343-350.
6. Zweng HC, Little HI, Peabody RR: Intraocular tumor, in: Laser phalocoagu/afion and retinal angiography. St Louis, CV Mosby Co, 1969, pp 253-260.
7. Zweng HC, Little HI, Vassiliadis A: Light, laser and the retina, in: Argon Laser Photocaagulatkm. St Louis, CV Mosby Co, 1977, pp 1-24.