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CONJUNCTIVAL TUMOURS: UNUSUAL BUT DANGEROUS
Conjunctival melanomas are rare. Nevertheless, Anastassiou and co-workers review their 28 year experience with 69 patients with conjunctival melanoma. They report a 32% tumour related mortality at 5 years and nearly a 50% recurrence rate of the tumour. In the accompanying editorial Shields points out that many of the tumours in this study were incompletely excised and the tumour extended to the margin of resection. Shields emphasises that incisional biopsy for these tumours is contraindicated and that a “no touch” technique with supplemental alcohol corneal epitheliectomy and conjunctival cryotherapy provides the most benefit to the patients.
Squamous cell carcinoma of the conjunctiva has, heretofore, also been considered a rarity. However, in their study of this tumour McKelvie and co-workers emphasise that this tumour may be much more common than was previously thought since they collected a series of 26 cases in just over 7 years. As in previous series most patients with this tumour were male and elderly. The tumours primarily occurred at the limbus. Even in a relatively short clinical follow up period one third of the patients developed recurrence of the tumours. Two of these patients died of metastatic disease. In this study impression cytology did not reliably distinguish in situ from minimally invasive disease. See 127, 163, and 168
NEW DISINFECTING SOLUTIONS FOR CONTACT LENSES ARE NOT ALL EFFECTIVE AGAINST ACANTHAMOEBA
Acanthamoeba keratitis remains a serious problem primarily related to soft contact lens wear with contamination of the contact lens storage case. In order to prevent contamination of the case and the development of biofilm, frequent microwave treatment or boiling of the storage case, mechanical cleansing and use of intensive cleaning solutions, and avoidance of the contact with contaminated water are effective treatments. Recently, new storage solutions have been developed in an effort to disinfect contact lenses. Hiti and co-workers compare three commercially available disinfectant solutions and their effectiveness in preventing possible Acanthamoeba infection. The hydrogen peroxide 0.6% solution showed very good amoebicidal effects after a soaking time of 8 hours whereas the 3% hydrogen peroxide one step solution could not effectively destroy the cysts of the pretested species. A new multipurpose disinfecting solution demonstrated amoebicide effects; however, cysts of two strains persisted after 8 hours of soaking. The Titmus H2O2 (0.6% hydrogen peroxide) appears to be the most effective contact lens disinfectant solution in preventing Acanthamoeba. See 144
VASCULAR DYSFUNCTION AND NORMAL PRESSURE GLAUCOMA
The pathophysiology of normal pressure glaucoma remains unclear. It has been proposed that vascular dysfunction contributes to this disorder in which normal eye pressure is maintained. It has been suggested that widespread cerebral vascular and systemic cardiovascular disease are associated with normal tension glaucoma. In a unique study O'Brien and co-workers have convinced not only patients with normal pressure glaucoma but also some of their non-affected relatives and friends to undergo gluteal fat biopsies. The authors then studied the contractile and relaxant functions of the arteries dissected from these biopsies. Vascular endothelium modulates contractile responses to 5-hydroxytryptamine and endothelin-1. This modulating effect of the vascular endothelium was lost in the patients with normal pressure glaucoma in this study. This is similar to results that have been reported in studies of vascular endothelium in hypertensive patients. This is one more bit of information suggesting that normal pressure glaucoma may indeed be related to factors affecting vascular stability. See 227