Low dose radiation for subfoveal choroidal neovascularization in age-related macular degeneration. A pilot study: radiotherapy for age-related macular degeneration

Radiation therapy for neovascular age-related macular degeneration

In the enormity of the public health burden imposed by age-related macular degeneration (ARMD), much effort has been directed toward identifying effective and efficient treatments. Currently, anti-vascular endothelial growth factor (VEGF) injections have demonstrated considerably efficacy in treating neovascular ARMD, but patients require frequent treatment to fully benefit. Here, we review the rationale and evidence for radiation therapy of ARMD. The results of early photon external beam radiation therapy are included to provide a framework for the sequential discussion of evidence for the usage of stereotactic radiation therapy, proton therapy, and brachytherapy. The evidence suggests that these 3 modern modalities can provide a dose-dependent benefit in the treatment of ARMD. Most importantly, preliminary data suggest that all 3 can be used in conjunction with anti-VEGF therapeutics, thereby reducing the frequency of anti-VEGF injections required to maintain visual acuity.

Proton Beam Irradiation for Neovascular Age-Related Macular Degeneration

OBJECTIVE

To evaluate safety and visual outcomes after proton therapy for subfoveal neovascular age-related macular degeneration (AMD).

DESIGN

Randomized dose-ranging clinical trial.

PARTICIPANTS

One hundred sixty-six patients with angiographic evidence of classic choroidal neovascularization resulting from AMD and best-corrected visual acuity of 20/320 or better.

METHODS

Patients were assigned randomly (1:1) to receive 16-cobalt gray equivalent (CGE) or 24-CGE proton radiation in 2 equal fractions. Visual acuity was measured using standardized protocol refraction. Complete ophthalmological examinations, color fundus photography, and fluorescein angiography were performed before and 3, 6, 12, 18, and 24 months after treatment.

MAIN OUTCOME MEASURE

Proportion of eyes losing 3 or more lines of vision from baseline. Kaplan-Meier statistics were used to compare cumulative rates of vision loss between the 2 treatment groups.

RESULTS

At 12 months after treatment, 36 eyes (42%) and 27 eyes (35%) lost 3 or more lines of vision in the 16-CGE and 24-CGE groups, respectively. Rates increased to 62% in the 16-CGE group and 53% in the 24-CGE group by 24 months after treatment (P = 0.40). Radiation complications developed in 15.7% of patients receiving 16 CGE and 14.8% of patients receiving 24 CGE.

CONCLUSIONS

No significant differences in rates of visual loss were found between the 2 dose groups. Proton radiation may be useful as an adjuvant therapy or as an alternative for patients who decline or are not appropriate for approved therapies.

Radiotherapy for subfoveal choroidal neovascularization in age-related macular degeneration: a randomized clinical trial

PURPOSE

To report results of 18-month follow up of external beam radiation therapy with photons for subfoveal classic or occult choroidal neovascularization (CNV) in age-related macular degeneration (ARMD).

DESIGN

Randomized clinical trial.

METHODS

A total of 161 patients with subfoveal CNV in ARMD were recruited in a prospective double-masked study. The posterior pole of the afflicted eye was given 1 Gy (4 x 0.25 Gy) in the control group and 8 Gy (4 x 2 Gy) or 16 Gy (4 x 4 Gy) in the treatment groups. At the time of treatment, and 6, 12, and 18 months post treatment, best-corrected visual acuity (BCVA), reading ability, and CNV size were measured.

RESULTS

At the completion of the study 150 (93.2%), 139 (86.3%), and 137 (85.1%) patients were followed for 6, 12, and 18 months, respectively. The mean number of lines lost in the BCVA was -1.69, -2.2, and -3.23 in the 1 Gy group; -0.94, -1.25, and -1.73 in the 8 Gy group; -0.51, -0.67, and -1.93 in the 16 Gy group. The difference was significant after 12 months (P =.016 for 8 Gy vs. 1 Gy; P =.006 for 16 Gy vs. 1 Gy), and 18 months (P =.011 for 8 Gy vs. 1 Gy; P =.05 for 16 Gy vs. 1 Gy). The patients with classic CNV, or with an initial distance visual acuity >or=20/100, benefited more from treatment. A significant difference was not found between control group and treatment groups in the reading ability and in the CNV size. No radiation-associated side effects were reported thus far.

CONCLUSION

The number of lines lost in the BCVA was less in the 8 Gy and 16 Gy treatment groups than in the control group during the complete follow up examination. Radiation therapy with 8 Gy and 16 Gy, without showing any difference in efficacy, resulted in a near stabilization of the BCVA in patients with subfoveal classic or occult CNV in ARMD. Further studies are necessary to determine the significance of repeated radiotherapy series with a dose of 8 Gy to improve the effect on the CNV size and thereby to prolong stabilization of distance visual acuity.

Surgical removal of subfoveal choroidal neovascularization without removal of posterior hyaloid: a consecutive series in younger patients

PURPOSE

Subfoveal choroidal neovascularization (CNV) remains a common and important cause of visual loss. Previous studies have suggested that submacular surgery may improve or maintain visual acuity, particularly in younger patients. The majority of reported cases included removal of the posterior hyaloid during vitrectomy. The authors present a consecutive series of patients age 55 or younger with subfoveal CNV removal without posterior hyaloid removal.

METHODS

Seventeen patients without age-related macular degeneration (ARMD), with subfoveal CNV from choroiditis, presumed ocular histoplasmosis syndrome, myopia, or idiopathic causes, underwent a small retinotomy technique to extract the membranes after vitrectomy without posterior hyaloid removal.

RESULTS

Median improvement in visual acuity was from 20/320 to 20/50. Eleven patients (65%) experienced an improvement of three or more lines of Snellen acuity (average 7.5), 4 (23%) were within two lines of preoperative acuity, and 2 (12%) had decreased acuity, with an average follow-up of 12 months (range 3-31). Choroidal neovascularization recurred in six patients (35%). Postoperative retinal detachment, epiretinal proliferation, or macular hole did not occur.

CONCLUSIONS

In this series of younger patients with subfoveal CNV not from ARMD, visual acuity was improved in the majority after submacular membrane removal. Omission of removal of the posterior hyaloid did not adversely affect outcome.

A 5-year follow-up study for distance visual acuity after low dose radiation on subfoveal choroidal neovascularization in age-related macular degeneration

In a prospective study with a 5-year follow-up, we assessed the effect of a single series of low-dose radiation on the distance visual acuity in eyes with angiographically confirmed subfoveal choroidal neovascularization (CNV) in age-related macular degeneration (ARMD). The posterior pole of 12 eyes was treated with 5 Gy (4 x 1.25 Gy), and 34 eyes treated with 8 Gy (4 x 2 Gy). The best corrected distance visual acuity was measured at the time of treatment, and annually thereafter for 5 years. The study obtained complete follow-up for 11 patients in the 5-Gy group (nine classic, two occult CNVs), and 29 patients in the 8-Gy group (12 classic, 17 occult CNVs). At baseline, the mean distance visual acuity of the treated eyes was 0.16 (20/125) in the 5-Gy group, and 0.2 (20/100) in the 8-Gy group. Five years later, an average loss of 3.2 lines was present in the 5-Gy group, and 4 lines in the 8-Gy group. After 5 years, an average loss of 2 lines was found in a control group consisting of 18 second eyes with low stage dry ARMD, with a mean distance visual acuity of 0.5 (20/40) at baseline. Statistical analyses with Wilcoxon and Mann-Whitney U-tests showed that a single series of low dose radiation with either 5 Gy or 8 Gy was not able to stabilize the distance visual acuity of eyes with subfoveal CNV in ARMD during a 5-year follow-up.

Treatment of age-related macular degeneration

Age-related macular degeneration (AMD), while rapidly becoming more prevalent due to an aging population, is still poorly understood and treatment modalities are limited. Fortunately, advances are being made in the treatment of AMD that may greatly alter the outcome of this debilitating disease. Treatments for both wet and dry AMD are reviewed.

A prospective, randomized, double-masked trial on radiation therapy for neovascular age-related macular degeneration (RAD Study). Radiation Therapy for Age-related Macular Degeneration

OBJECTIVE

To determine the efficacy of external beam radiation therapy on choroidal neovascularization (CNV) secondary to age-related macular degeneration (ARMD).

DESIGN

Multicenter, parallel, randomized, double-masked clinical trial performed at nine ophthalmic and radiotherapeutic centers.

PARTICIPANTS

Two hundred five patients were randomly assigned either to treatment with 8 fractions of 2 Gy external beam irradiation (n = 101) or to control with 8 fractions of 0 Gy (sham treatment, n = 104). Both patients and ophthalmologists were masked with regard to applied treatment. Patients with subfoveal classic or occult CNV, visual acuity of 20/320 or greater on the Early Treatment Diabetic Retinopathy Study chart, lesion size of 6 disc areas or less, history of visual symptoms of 6 months or less, and absence of foveal hemorrhage were recruited.

INTERVENTION

In the treatment group, external beam irradiation with 8 fractions of 2 Gy was performed, whereas in the control group, sham treatment with 8 fractions of 0 Gy was applied.

MAIN OUTCOME MEASURES

Primary outcome measure was the difference in visual acuity between baseline and after 1 year of follow-up.

RESULTS

One hundred eighty-three patients (89.3%) completed the 1-year follow-up. The mean reduction in visual acuity was 3.5 +/- 4.7 lines in 88 patients of the 8- x 2-Gy treatment group and 3.7 +/- 3.8 lines in 95 patients of the 8- x 0-Gy control group. This difference was not statistically significant (P = 0.53, Mann-Whitney U test). At 1 year, 51.1% of treated patients and 52.6% of control subjects lost three or more lines (P = 0.88). Visual acuity in the presence of classic CNV dropped by 3.7 +/- 4.4 lines in 33 patients of the treatment group versus 4.3 +/- 3.9 lines in 36 patients of the control group (P = 0.47). Visual acuity in 114 patients with occult CNV dropped by 3.4 +/- 4.9 in the treatment group (55 patients) versus 3.4 +/- 3.8 lines in the control group (59 patients) (P = 0.80).

CONCLUSIONS

In this randomized study, radiation therapy at a dose of 16 Gy applied in 8 fractions of 2 Gy provided no benefit as a treatment for subfoveal CNV secondary to ARMD at 1 year.