Intraocular heavy particle radiation of experimental malignant melanoma in rabbits

Evaluation of eye melanoma treatments in rabbits: A systematic review

Melanomas are the most common cancer of the eye in canines, felines and humans. The treatment approaches vary, since no gold standard exists. Therefore, this systematic review aimed to compare the treatment modalities in ocular melanoma in rabbits. Medline/PubMed, Cochrane Library, Web of Science and Embase were searched for articles published until 21 April 2021 in English, Portuguese or Spanish, reporting animal studies evaluating photodynamic therapy (PDT), laser, radiotherapy or surgical excision. Twenty-seven articles were included for the qualitative synthesis, with publication dates from 1970 to 2018. Of the selected studies, 19 used PDT, six used radiotherapy and two used laser as treatment. No studies regarding surgical therapy that met the inclusion criteria were obtained. The tumour therapy results were evaluated in a heterogeneous manner for different periods and various methods, including microscopy, angiographic, histological examination, fundoscopy, ultrasound exam and electroretinogram. The treatment modalities analysed successfully treated the ocular melanoma, with tumour necrosis being commonly observed. Despite the therapeutic efficacy shown, side effects have been reported for all the therapies. The studies showed high heterogeneity, and therefore, in the future, new studies should be carried out to increase knowledge about ocular melanoma treatment. The analysed therapies can be used successfully in the treatment of ocular melanoma, with more conservative options such as PDT presenting great potential.

Malignant intraocular tumors

The role of the radiation therapist in the management of malignant intraocular tumors is changing. With more active identification of malignant intraocular tumors, and a better recognization of the manner in which one can deal with problems of radiation sensitivity, radiation techniques of all sorts will be more actively employed in the treatment of these tumors. Special techniques must be selected for appropriate circumstances of management in order to diminish to an absolute minimum the impact upon the lens, the impact upon visual acuity and the impact upon the cornea. Cobalt-60 plaques are being used more commonly in the treatment of melanomas of the choroid, and the role for radiation therapy in the management of retinoblastoma is changing markably to where it may be used as the primary treatment program rather than enucleation. In metastatic disease involving the uveal tract, radiation therapy has assumed the most important role for management. Chemotherapy should be considered as an active adjuvant in the management of not only those individuals with retinoblastoma but also in those identified circumstances where metastases to the uveal tract are being treated. The role for chemotherapy or immunotherapy in malignant melanoma is unclear.

Current approaches to the diagnosis and management of choroidal melanomas

Although malignant melanoma of the uveal tract is well known as the most common primary intraocular malignancy, many questions exist regarding the best approach to its diagnosis and treatment. In the past, diagnosis has been made by direct ophthalmoscopy alone and errors resulting in unnecessary enucleation have been frequent. However, recent studies have shown that the adequate use of new techniques such as indirect ophthalmoscopy, fluorescein angiography, ultrasonography, and the 32P test can reduce the incidence of error substantially. A 12-step procedure for diagnosis utilizing these aids is outlined. Traditionally, enucleation has been accepted as the treatment of choice. However, with earlier and more accurate diagnosis, alternative treatments are being applied in selected cases. Although photocoagulation, irradiation, cryotherapy, diathermy and local resection of choroidal melanomas have been used with some success, these methods require further trial and followup before their value can be established. Techniques and indications for use of these procedures are discussed, and the complications and potential effectiveness of each is evaluated.