Contact angles of substances used for internal tamponade in retinal detachment surgery.

In order to ascertain the tamponade effect of air and silicone oil we examined the contact angles subtended by ex vivo human retina, Teflon and Perspex to find a suitable experimental material which would mimic the surface properties of the retina at a three-phase interface. Using the captive bubble technique to measure the contact angle, it was found that air subtended a larger contact angle (38.8 degrees) with the retina than did silicone oil (18.2 degrees). On coating the Perspex surface with protein (PCP), it was observed that the surface properties were modified such that PCP subtended contact angles with air (43.0 degrees) and silicone oil (16.4 degrees) similar to those subtended by ex vivo human retina. Using PCP as an experimental material that mimics ex vivo human retina, spherical chambers were employed in order to examine qualitatively and to quantify the arc of contact obtained with air and silicone oil. It was found that air gave a greater arc of contact for the same percentage fill than silicone oil.

Merkel cell carcinoma of the eyelid.

The clinical and pathological features of two Merkel cell carcinomas of the eyelid skin are reported. Both tumours occurred in the upper lid in elderly women and enlarged rapidly to form smooth, round nodules which projected from the lid surface anterior to the grey line. In one case the primary excision biopsy was followed by a wider excision in 1982, and the patient has been free from recurrence or metastases in the intervening period. In the second more recent case, the tumour was inadequately excised in 1984 and the lid was treated by radiotherapy: this patient is at present free from recurrence. Histological examination of each tumour revealed an identical morphology - characterised by the presence of uniform polyhedral cells with multiple nucleoli lying in nests and lobules within the dermis: mitotic figures were prominent. Immunohistochemical studies showed the cells to react positively with antisera against neurone-specific enolase, epithelial membrane antigen and met-enkephalin. Electron microscopy revealed only rare neuroendocrine granules in one tumour, and numerous granules in the other. Intranuclear rodlets were not identified and there was paucity of cell membrane attachment modifications.

The prevalence of carotid artery disease in patients presenting with amaurosis fugax.

Ninety-five patients with amaurosis fugax were investigated for extracranial carotid artery disease. A doppler system combining imaging with spectrum analysis was used. Stenosis (greater than 25 per cent) and occlusion of the ipsilateral extracranial internal carotid artery occurred in 30 per cent and 26 per cent of patients respectively. The association of amaurosis fugax with ipsilateral carotid disease is highly significant. The role of this Doppler technique in the investigation of patients with amaurosis fugax is considered.