Clinical evaluation of radiotherapy for Graves' ophthalmopathy

[Radiotherapy of Graves' ophthalmopathy--state of the art and review of the literature]

Graves' ophthalmopathy (GO), the most frequent extrathyroidal manifestation of Graves' disease, is a disorder of autoimmune origin, the pathogenic mechanisms of which are still incompletely understood. Although GO is severe in only 3-5% of affected individuals, quality of life is severely impaired even in patients with mild GO. The role of radiotherapy in the management of GO is discussed controversially. However, recent randomized clinical trials have, with one exception, confirmed that orbital radiotherapy is an effective and safe therapeutic procedure for GO. This article describes the sequences, dosages and fractionation schemes as well as the risks and side effects of the radiotherapy.

Retrobulbar irradiation for thyroid-associated orbitopathy: double-blind comparison between 2.4 and 16 Gy

PURPOSE

Retrobulbar irradiation is used as a standard therapy for thyroid-associated orbitopathy. The evidence of its effectiveness is, however, scarce. Doses from 2.5 to 20 Gy have been recommended.

METHODS

Forty-three patients with active thyroid-associated orbitopathy were irradiated with 2.4 Gy and 43 with 16 Gy. Five measures of outcome were used: (1) appearance of the eye region, documented with photographs; (2) Hertel exophthalmometry; (3) range of vertical eye movements; (4) eye muscle thickness (sum of three MRI sections across the eight rectus eye muscles); and (5) complaints, indicated on a visual analog scale.

RESULTS

At 3 and 6 months after irradiation, no difference between 2.4 and 16 Gy was found in any of the five outcome measures (p between 0.099 and 0.993; Kruskal-Wallis test, Holm correction). Most outcome measures were slightly, but not significantly, improved in both the 2.4 and the 16 Gy groups. Patient complaints had improved significantly in both groups and the eye muscle thickness was significantly reduced in the 2.4 Gy group after 6 months.

CONCLUSION

The lack of a difference between 2.4 and 16 Gy is compatible with four different interpretations: (1) the irradiation could be ineffective; (2) the maximal effect could be already reached at 2.4 Gy; (3) the maximal effect could lie between 2.4 and 16 Gy; and (4) the effect could increase beyond a threshold of >or=16 Gy. From general experience with inflammatory disease, the last two possibilities are unlikely; only the first two interpretations carry some probability. Although the design of the study did not allow a distinction between these two possibilities, we conclude that retrobulbar irradiation for thyroid-associated orbitopathy should not exceed 2.4 Gy.

[Endocrine orbitopathy: comparison of the long-term result and classification after radiotherapy]

BACKGROUND

This study compares 4 classifications in patients with progressive refractory Graves orbitopathy (GO) and examines their prognostic value in long-term follow-up.

PATIENTS AND METHODS

From 1984 to 1994, 60 consecutive patients (49 female, 11 male) received 20 Gy (10 x 2 Gy) radiotherapy with 6 MV Linac photons. Ocular symptoms and functional impairment was evaluated according to 4 GO-classification systems: Werner-, modified ATA- and Stanford-Score and Ophthalmopathy-Index (OI) according to Grussendorf. In addition, all patients noted their subjective response on a linear scale (0 to 100%).

RESULTS

Improvement was achieved within 1 year after radiotherapy according to the Werner-Score in 28 (47%) patients in > or = 1 symptom category, according to the modified ATA-score in 48 (80%), the Stanford-score in 47 (78%) and the OI-Score in 55 (92%) patients (reduction of > 2 points). The Werner-Score correlated less to the other scores (coefficient r < 0.5) than the other scores among themselves (r approximately 0.9). The ATA-Score improved in the different symptom categories between 47% (stage VI) and 87% (stage V). The OI-Score was reduced by a mean of 6 points. The patients reached a mean subjective improvement of +70 +/- 25%. Acute or chronic side effects were not observed. In multivariate analysis the "male gender" (p = 0.08), a "symptom duration prior to radiotherapy > 1 year" (p = 0.14) and a "high symptom category" (p = 0.11) indicated a negative prognostic trend.

CONCLUSIONS

External radiotherapy is effective for severe, progressive GO after pretreatment. A minimum follow-up of at least 12 months and standardized classification and success criteria are required.

Radiation therapy for ocular choroidal neovascularization (phase I/II study): preliminary report

PURPOSE/OBJECTIVE

Choroidal neovascularization (CNV) is a major cause of severe loss of visual acuity in some ocular diseases such as age-related macular degeneration (ARMD) and angioid streaks. Laser photocoagulation has been used to treat patients with subfoveal neovascular lesions with well-demarcated boundaries. However, the treatment method is usually associated with a large decrease in visual acuity. Therefore, indications for this treatment are very limited. Recently, some investigators reported the effect of low dose irradiation on the subretinal neovascular membranes in CNV. We conducted a Phase I/II study to determine the toxicity and efficacy of external photon beam radiotherapy in patients with CNV.

METHODS AND MATERIALS

Between April, 1994 and July, 1995, 36 patients with choroidal neovascularization (34 with ARMD and 2 with angioid streaks) were treated with radiation therapy. Treatment planning was performed using a CT simulator that enables real-time treatment planning from multiple CT slices. The clinical target volume that included the macula and optic disc received a dose of 10 Gy/5 fractions/1 week (first 18 eyes) or 20 Gy/10 fractions/2 weeks (last 18 eyes). All eyes were irradiated with a single lateral 6 MV photon beam, angled 10 degrees posteriorly to exclude the ipsilateral lens and the contralateral eye from the radiation field. The ipsilateral lens was irradiated with less than 10% of the total reference dose. The field size averaged 3.0 x 2.5 cm. Records of the 17 eyes with CNV referred to our hospital in 1993, which satisfied the eligibility criteria for this study, were retrospectively analyzed for comparison.

RESULTS

There was no significant acute morbidity. All patients were followed regularly by both ophthalmologists and radiation oncologists. Cataract formation after 1 year of the treatment was observed in one patient who had received a dose of 20 Gy. One patient who had received 20 Gy complained of transient dry-eye sensation 2 months after treatment, but this had disappeared spontaneously by the fourth month. The subjective symptoms, visual acuity, and size of the neovascular membrane were evaluated at 6 and 12 months after treatment in each patient. In the group of patients irradiated with 10 Gy and with 20 Gy, respectively, subjective symptoms improved in five and seven eyes, did not change in seven and four eyes, and deteriorated in six and six eyes at 12 months. Although visual acuity was significantly decreased in the control group, the patients in both irradiated groups did not show such a decrease in visual acuity. The size of the neovascular membrane in the control group progressed significantly. However, the patients in the 20 Gy group showed significant regression of the membrane, although those in the 10 Gy group showed no significant change in size.

CONCLUSION

This Phase I/II study including a dose escalation study showed that radiation therapy seems to be useful for CNV. The dose of 20 Gy in 10 fractions was more useful in treating neovascular membranes than the dose of 10 Gy in five fractions. These results have encouraged us to start a multicenter randomized prospective study of the treatment of CNV with radiation therapy.

Echographic monitoring of response of extraocular muscles to irradiation in Graves' ophthalmopathy

PURPOSE

Confirmation of the efficacy of orbital irradiation in Graves' ophthalmopathy is needed due to the unpredictable natural history of the disease, the variation in individual clinical presentations, the contribution of other simultaneous treatments, and the lack of controlled studies using objective criteria to classify and assess response over time. Orbital echography before and at select intervals following orbital irradiation is proposed as an objective parameter of tissue response to orbital irradiation over time.

METHODS AND MATERIALS

From January, 1983 to September, 1993, 55 patients with progressive Graves' ophthalmopathy underwent 20 Gy retrobulbar irradiation. On retrospective review, standardized orbital echography was performed randomly prior to irradiation in 37 of the 55 patients to assess the acoustic characteristics of the extraocular muscles and to quantitate their individual and summed diameters. Twenty-one patients had at least one follow-up echographic evaluation at random intervals of 0 to 27.5 months following completion of irradiation. Twelve patients received steroids before or during irradiation, which were tapered in proximity to completion of radiation. Follow-up ranged from 2 to 65 months with the majority followed at least 6 months (18 patients).

RESULTS

Of the 21 patients with serial studies, 18 showed an interval decrease in individual and summed muscle size over time and return of symmetry. Interval improvement was documented as early as the 1 month follow-up study, with continued improvement seen during the 3-9-month studies, with stability typically achieved within 12 months. One patient had further changes between the 21 and 27.5 month follow-up studies. Exacerbation of disease was, however, echographically demonstrated in three patients at 6.5, 8.5, and 13 months. Follow-up studies in two of these patients again revealed improvement, one following tapered steroids. The third patient required orbital decompression.

CONCLUSION

Objective parameters of response are needed to document both the immediate and long-term outcome of orbital irradiation on the course of Graves' ophthalmopathy and confirm its efficacy. Serial echography is proposed as a new technique for providing parameters to judge response.

Graves' ophthalmopathy

Graves' ophthalmopathy is an organ-specific autoimmune process strongly linked to Graves' hyperthyroidism. Although the hyperthyroidism can be successfully treated, it is often the ophthalmopathy that produces the greatest long-term disability for patients suffering from this disease. Eyelid retraction, proptosis, periorbital edema, chemosis, and disturbances of ocular motility have both cosmetic and functional consequences. In some cases, the disease may progress to visual loss by exposure keratopathy or compressive optic neuropathy. This article discusses the manifestations of Graves' ophthalmopathy that require urgent attention and the relationship of the activity of Graves' ophthalmopathy to thyroid function status.

Therapy of Graves' ophthalmopathy with intravenous high-dose steroid followed by orbital irradiation

We investigated the effects of intravenous high-dose steroid therapy followed by orbital irradiation for Graves' ophthalmopathy in eight patients. All patients presented with diplopia or fixed globes. Extraocular muscle dysfunction showed excellent improvement after the combined therapy; diplopia disappeared completely in five of them, and one patient with fixed globes showed normal eye movement. Two other patients also exhibited great improvement, although their diplopia persisted. Their ophthalmopathy index was decreased from (mean +/- SD) 4.25 +/- 0.82 to 0.75 +/- 1.48. Extraocular muscle enlargement, assessed by magnetic resonance imaging study after the radiotherapy, was also reduced after the combined therapy, although two patients did not show remarkable enlarged extraocular muscles. There was no change in extraocular muscle thickness 6-9 months after the therapy, and the ophthalmopathy index did not show change in a long follow-up (maximum 37 months after the therapy). These results suggest that high-dose methylprednisolone followed by orbital radiotherapy is a good therapeutic design for Graves' ophthalmopathy and justify a prospective randomized trial.

Results of transantral orbital decompression in 428 patients with severe Graves' ophthalmopathy

We reviewed records from 428 consecutive patients with severe Graves' ophthalmopathy to determine early and late results after transantral orbital decompression. Optic neuropathy was present in 217 (50.7%) patients. Post-operatively, 402 (89%) of 453 eyes with preoperative visual acuity worse than 20/20 improved or remained the same. Visual field scotomas improved or resolved in 245 (91%) of 269 eyes tested pre- and postoperatively. Preoperative papilledema resolved or improved in 99 (94%) of 105 eyes, and preoperative exposure keratitis improved or resolved in 178 (92%) of 195 eyes. Average proptosis reduction was 4.7 mm. Postoperatively, new diplopia developed in 74 (64%) of 116 patients who had no diplopia before orbital decompression, although 300 patients ultimately had strabismus surgery. At late follow-up (N = 293 patients), 226 (77%) had single vision and 44 (15%) had correction with prism. Complications included sinusitis (18 patients), lower eyelid entropion (38 patients), numb lip (23 patients), cerebrospinal fluid leaks (15 patients), and one frontal lobe hematoma (one patient). The average duration of follow-up was 8.7 years. Transantral orbital decompression effectively reduces proptosis and usually corrects optic neuropathy. In other circumstances, the benefits achieved and the side effects incurred must be carefully balanced for each patient before transantral orbital decompression is considered.

Orbital fat removal. Decompression for Graves orbitopathy

BACKGROUND

Orbital decompression has been used to describe surgical procedures that remove some portion of the orbital walls to reduce pressure on the orbital contents. Substantial morbidity associated with these procedures includes infraorbital anesthesia, worsened extraocular motility, globe displacement, and blindness. The authors believe that orbital contents also may be decompressed by removing orbital fat.

METHODS

Eighty-one patients with nonactive Graves orbitopathy were selected for orbital fat decompression based on the presence of proptosis and associated signs and symptoms to avoid bone removal. Soft-tissue analysis by computed tomography (CT) scan showed distended pockets of fat extending into the intraconal space, which were removed through medial-upper and lateral-lower anterior orbitotomies. Decompression with bone removal was reserved for those few patients with compressive optic neuropathy unresponsive to medical treatment and those patients with residual deforming exophthalmos after fat removal.

RESULTS

One hundred fifty-eight fat decompressions were performed on 81 patients over 9 years. The authors measured an average reduction in proptosis of 1.8 mm (range, 0-6.0 mm). The greatest average reduction in proptosis (3.3 mm) was produced in patients with preoperative Hertel measurements of greater than 25.0 mm. Morbidity was limited to temporary motility impairment of the inferior oblique in two patients.

CONCLUSION

The concept of orbital decompression can include removal of orbital fat to reduce proptosis, eliminate symptoms, and improve appearance with far less morbidity than when bone decompression is used as the primary decompressive procedure.

Treatment of acute Graves orbitopathy

The therapeutic options for the treatment of acute Graves orbitopathy include high-dose oral corticosteroids, surgical decompression, and radiotherapy. The former two treatments are associated with significant morbidity. Although there have been a number of reports of the efficacy of radiotherapy, its role in the management of this disease is still questioned. The authors reviewed 84 cases of acute Graves orbitopathy treated with either high-dose systemic corticosteroids or radiotherapy (2000 rad to each involved orbit). Radiotherapy resulted in significant improvement in subjective and objective signs of orbital congestion and was more effective than high-dose corticosteroids in relieving compressive optic neuropathy. Of the patients with compressive optic neuropathy, only 1 of 29 treated with radiotherapy required surgical decompression, whereas, 6 of 16 treated with corticosteroids required surgery. This study suggests that radiotherapy has greater efficacy and fewer complications than high-dose systemic corticosteroids in the treatment of acute Graves orbitopathy.

Prognostic factors in the radiotherapy of Graves' ophthalmopathy

Between April 1968 and February 1988, 311 patients with symptomatic and progressive Graves' ophthalmopathy were treated with megavoltage orbital radiotherapy. The patients were divided into three groups: I (156 patients) treated with 20 Gy/2 weeks; II (69 patients) treated with 30 Gy/3 weeks, and III (a most recent set of 86 patients) received 20 Gy/2 weeks. The degree of eye involvement was evaluated numerically before and after therapy for each of five parameters: soft tissue signs, proptosis, eye muscle impairment, corneal involvement, and sight loss. Pre-treatment and current thyroid diagnosis and status were also noted. To evaluate the effects of radiotherapy alone, follow-up was terminated at the time any eye surgery was done; for those not treated surgically the minimum follow-up was 12 months. Because there were significant demographic differences between the patient groups, the results of each group were analyzed separately. A stepwise linear regression analysis was performed to determine if there were any significant variables affecting outcome. Based on these data formulae were derived which enable outcome to be predicted in any patient. Before therapy more than 90% of patients in all groups had soft tissue and eye muscle involvement, whereas 65-75% had proptosis and about half 50% had some degree of sight loss. Radiotherapy arrested progression of ophthalmic parameters in all but 1-6% of the patients. Objective and symptomatic improvement was noted for all parameters assessed, but there was marked individual variability. The best responses were noted for soft tissue, corneal involvement, and sight loss; however over half the patients had some improvement in eye muscle function and proptosis. Factors which resulted in less favorable outcome included male gender, advanced age, need for concurrent therapy for hyperthyroidism, and no history of hyperthyroidism. No complications have been observed. No significant differences in outcome were observed between the two dosage schedules. Following radiotherapy 29% of patients subsequently underwent some form of eye surgery, mostly eye muscle surgery to correct diplopia. After radiotherapy corticosteroid therapy was stopped without relapse in 76%. Orbital radiotherapy can result in improvement in signs and symptoms of Graves' ophthalmopathy in the majority of patients. For the remainder of patients the disease manifestations can be stabilized to allow functional surgical correction.