|Year : 1989 | Volume
| Issue : 4 | Page : 162-163
Ocular tumours-some newer and controversial aspects
Prof. of Ophthalmology, BHU, Varanasi, India
H V Nema
Prof. of Ophthalmology, BHU, Varanasi
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Nema H V. Ocular tumours-some newer and controversial aspects. Indian J Ophthalmol 1989;37:162-3
Ocular tumours or neoplasms are benign and malignant. However, all benign tumours are not completely innocent, just as all malignant ones are not dangerous or fatal. Chemical carcinogens, radiant energy, oncogenic viruses and genes are capable of altering the growth behaviour of normal cells of the ocular tissues. In the recent past, substantial advances have been made in the diagnosis and treatment of ocular tumours. At the same time considerable controversies are generated in ocular oncology. These controversies are indeed interesting as well as thought provocative.
| Retinoblastoma|| |
Retinoblastoma, a most common intra ocular tumour of childhood has its origin in the neuroreceptor cells of the retina. The incidence of the tumour is approximately 1 in 18000 births. It occurs both in hereditary and nonhereditary forms and is relatively often bilateral (8 to 35 percent) For the first time D group chromosome deletion in the skin fibroblast or a retinoblastoma patient was reported in 1963. Later it was hypothesised that majority of unilateral retinoblastomas are phenocopies due to somatic mutation, while all bilateral ones are genetically determined . Recently, an oncogene predisposing to retinoblastoma in the autosomal dominant inherited cases has been identified. The genetic locus determining retinoblastoma susceptibility was asigned to band q 14 chromosome 13 along with the gene for the polym,orphic marker enzyme esterase -D, by examination of cytogenetic deletion. It is proposed that inactivation of both alleles of a gene located in the region of 13,g 14 resulted in retinoblastoma. Lee et.al. has now sequenced the gene of retinoblastoma isolated earlier. Incidently, it is the first human cancer gene isolated and sequenced .
The newer diagnostic modalities such as hypocyclodial polytomography, computerised trans-axial tomography, Nuclear magnetic resonance, A and B ultrosonography radionucleide scintigraphy with technitium diphosphate are more sensitive in the clinical diagnosis of retinoblastoma. Besides A and B scans, M-scan Kinetic ultrosonography is also advocated as spontaneous vascular pulsations within the mass can be easily seen as box shaped .The estimation of Lactic dehydrogenase (LDH) activityin the tear, aqueous humour and serum of retinoblastoma patients may be helpful. Perhaps the determination of LDH isoenzymes might even be more rewarding.
It is depressing that retinoblastoma survivors are prone to develop secondary primary neoplasms (2 to 15 percent) irrespective of their treatment modalities. These primaries are often histologically distant from retinoblastoma; most commonly osteosarcomas. The patients with the genetic form of retibnoblastoma are particularly sensitive to the carcinogenic effect of radiation.
Enucleation, Cobalt plaque irradiation, photocoagulation, cryo therapy and systemic chemotherapy are well established modalities for the management of retinoblastoma. The identification of the oncogene will certainly open new vistas for more appropriate preventive and therapeutic protocols for retinoblastomas. The day is not far when biotechnologists would understand the basic biochemical alteration that influence the retinal cells to proceed to form retinoblastoma. Hopefully, the retinoblastoma can be prevented by the biotechnological gene correction in the future.
| Malignant melanoma of the uvea|| |
Malingnant melanoma of the uvea is not a common intra ocular tumour in our population. It originates from melanocytes which are derived from the neural crest. Malignant melanomas of choroid are frequent, comprising of 85% melanomas of the uveal tract, while ciliary body and iris melanomas occur only in 9 percent and 6 percent of cases respectively. The tumour poses diagnostic problems. Inspite of the availability of sophisticated procedures 2 to 5 percent cases remain misdiagnosed even at major ophthalmic centres.  Monoclonal antibodies (MoAb) have more affinity for melanoma cells in vitro. It is speculated that in the recent future the application of monoclonal antibodies is likely to increase diagnostic as well as therapeutic possibilities in malignant melanoma . 
Malignant melanoma of the uveal tract has become a topic of great controversy. The clinicians seem to be divided in their opinion on prognosis and treatment protocols. Some ophthalmologists advocated that malignant melanoma of iris should not be dealt with by radical excision but be periodically followed with meticulous clinical documentation as the tumour rarely metastasises and the mortality is much less than in the tumours of ciliary body and choroid. The better outlook of iris melanomas is attributed to their tendency to present at an early stage in their development and remain localised for a long duration. On the other hand, the large tumour size, epitheloid cell type, and relative tendency for delayed presentation are the main factors for a poor prognosis for the patients of melanomas of the ciliary body and choroid than that of the iris . 
Owing to the poor prognosis of the melanomas of the posterior uvea, enucleation of the eye was the classical treatment of the disease. Recently, the value of enucleation was questioned and it was suggested that perhaps the operation facilitates metastasis of the tumour cells and thus might worsen the prognosis.  To minimise the dissemination of neoplastic cells "no touch technique" of enucleation or radiation treatment prior to enucleation was introduced. However, a number of clinicians strongly advocate and prefer using alternative methods of management of malignant melanoma.  Indeed each case must be treated on individual basis and generalisation be strictly avoided. Size, location, extent of melanoma, status of the other eye, age and general health of the patient must be taken into consideration before the modality of therapy is worked out. An eye with large tumour without useful vision warrant enucleation while conservative procedures be applied in eyes with small tumours and salvagable vision. The alternative modalities of management includes periodic follow-up, supported with steroscopic coloured photographs, photocoagulation, radidtherpy and local resections.Most patients with systemic metastasis need palliative radiation and chemotherapy. May be the immunotherapy provides an effective management of the malignant melanoma of the uvea in the near future.
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