{'fraction_non_alphanumeric': 0.016495601173020527, 'fraction_numerical': 0.004032258064516129, 'mean_word_length': 4.650103519668737, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Melanoma of the iris.

The paper by McGalliard and Johnston in this month's issue (p 591) prompted me to read some of the literature on ocular melanomata. 'Iris tumours rarely metastasise, and the mortality is much less than in similar tumors of the ciliary body or choroid. They are easily seen and ordinarily are removed at an early stage." This statement was published in 1962, long before McLean and colleagues' bombshell suggesting that enucleation increased the chances of metastasis from malignant choroidal melanoma.2 The trouble is that the first statement is at variance with the second. If it is indeed true that metastasis from iris melanoma is less than from choroidal, the obvious assumption is that the lower frequency must be due to earlier diagnosis and hence earlier treatment. There is evidence that the chances of metastasis depend mainly on size' and histological type.4 Therefore, if we assume that melanomata of the iris behave in the same way as those of the choroid, it does seem reasonable to assume that removing the melanoma when it is small would give the patient a better chance of survival than leaving it until it was larger. And, in accordance with this line of argument, one can easily see that the patient with an iris melanoma is more likely to survive, since for one thing it is almost impossible to allow such a lesion to develop to anything like the size of the average 'mushroom' choroidal melanoma, which by the time it reached its usual size would be capable of filling the anterior chamber three times over. Hence early removal of iris melanomata is more or less automatic. The trouble is that if McLean and colleagues are right and enucleation of the eye predisposes to metastasis, one would have thought that excision of an iris melanoma ought to predispose to metastasis as well, but clinical experience, quite apart from any published reports, clearly indicates that it does not. As an ordinary ophthalmologist without pretension to particular expertise in oncology I certainly do not wish to get embroiled in controversy over enucleation versus radiation or observation, since, as readers of this journal will be aware, such matters can be debated with much energy with the resultant friction engendering some heat.54 I write merely as an ophthalmological 'man in the street' trying to make up my mind on such matters, according to what I read in the papers, in this case the ophthalmological papers. And I have to admit that so far I have not had it explained to me to my satisfaction why it should be a bad thing to enucleate for melanoma of the choroid but a good thing to excise a melanoma of the iris, at any rate so far as the long term survival of the patient is concerned.