Ocular tumours present a therapeutic challenge because of the sensitive tissues involved and the necessity to destroy the tumour while minimising visual loss.
Radiotherapy (RT) is one of several modalites used apart from
surgery, laser,
cryotherapy, and
chemotherapy. Both external beam RT (EBRT) and
brachytherapy are used. Tumours of the bulbar conjunctiva,
squamous carcinoma and
malignant melanoma, can be treated with a radioactive plaque:
strontium-90,
ruthenium-106 (Ru-106), or
iodine-125 (I-125), after excision. If the tumour involves the fornix or tarsal conjunctiva,
proton therapy can treat the conjunctiva and spare most of the eye. Alternatively, an I-125 interstitial implant can be used with shielding of the cornea and lens. Conjunctival mucosal-associated lymphoid tissue
lymphoma can be treated with an anterior electron field with lens shielding and 25-30 Gray (Gy) in 2 Gy fractions. Discrete
retinoblastoma (RB), too large for
cryotherapy or thermolaser, or recurrent after these modalities, can be treated with plaque
therapy, I-125, or Ru-106. For large RB, multiple tumours, or vitreous seeds the whole eye can be treated with an I-125 applicator, sparing the bony orbit, or with EBRT, under anaesthetic, using X-rays or
proton therapy with vacuum
contact lenses to fix the eyes in the required position. Post-enucleated orbits at risk for recurrent RB can be treated with an I-125 implant with shielding to reduce the dose to the bony orbit. Uveal
malignant melanomas can be treated with plaque or
proton therapy with excellent local control. Preservation of vision will depend on the initial size and location of the tumour.