الفهرس 
Anatomy of the choroidOnly 14 pages are availabe for public view
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Abstract
The choroid is the brownish membrane composed of blood vessels, melanocytes, connective tissue. It extends from the optic disc to the ora serrata to form the posterior part of the uveal tract.
Tumours that invade the choroid include choroidal melanoma, haemangioma, osteoma, naevus and metastases. Choroidal melanoma is the most common tumour of the choroid.
Callender described five categories of choroidal melanoma based on cell type including spindle cells, fascicular type, epitheloid type, mixed cell type and necrotic type. Choroidal melanoma may be circumscribed or diffuse. About 30 – 50 % of patients with choroidal melanoma will die within 10 years from diagnosis; usually due to distant metastases.
Diagnosis of choroidal tumours especially choroidal melanoma can be done by many methods including history, examination by indirect ophthalmoscope through well-dilated pupil as it correctly diagnose melanoma in more than 95% of cases. Additionally diagnosis is confirmed by ultrasonography, flourescin angiography, position emission tomography / computed tomography (PET/CT), fundus autofluorescence (FAF) photography, CT, MRI, radio-active phosphorus uptake, biopsy and serological test.
Differential diagnosis of choroidal melanoma include choroidal naevus, age related macular degeneration, post scleritis, exudative retina detachment, choroidal detachment, choroidal rupture, choroidal haemangioma, metastatic disease of the choroid, melanocytoma of optic nerve head, benign reactive lymphoid hyperplasia of uvea, choroidal neovascularization, and macro-aneurysm.
Management of choroidal melanoma differ according to many factors. These factors include tumour size and location, age and general condition of the patient and the condition of the fellow eye. Scheme of management include observation, radiotherapy, phototherapy, local resection, enucleation or even excentration. Adjuvant therapy may be given.
Observation is indicated for small to medium sized tumours that appear dormant in the initial examination. It is also indicated for small to medium sized tumours in elderly patients and for tumours located in an only useful eye even if the tumour shows signs of slow growth. This type of management include clinical and sonographic follow-up.
Radiotherapy is the treatment of choice for medium sized melanomas. It includes brachytherapy, charged particle irradiation and stereotactic radiation. Phototherapy includes photo-coagulation, transpupillary thermotherapy and photodynamic therapy. Photo-coagulation is indicated for only small sized melanomas that are within 3 mm of the optic disc or fovea. Argon laser is employed in photo-coagulation. transpupillary therapy (TTT) depends on elevation of temperature above 37°C using an infra-red radiation. It is delivered by diode laser through a dilated pupil.
Photodynamic therapy employs a photosensitizing agent that is activated by light of an appropriate wave-length. It induces direct damage to tumour cells and occlusion of tumour vasculature.
Local resection is indicated for selected cases of peripheral choroidal melanoma. Enucleation is indicated for large choroidal melanoma especially if associated with irreversible loss of vision. It is also indicated for small or medium sized tumours documented to be growing and invading the optic nerve. Another situation for enucleation is a case in which radiotherapy induced complications or recurrence of the tumour. Exenteration is confined to a massive extra-scleral tumour extension or orbital recurrence following enucleation.
Adjuvant therapy includes immunotherapy, chemotherapy, anti-angiogenic therapy, resveratrol or cyclo-oxygenase-2 inhibition.