Trabeculectomy: effect of varying surgical site.

Trabeculectomy reduces intraocular pressure by fistula formation into a subconjunctival bleb. The operation site traditionally has been at the superior corneo-scleral junction with a failure rate of 10-30%. The causes of trabeculectomy failure can be broadly classified into intraocular, scleral and extraocular. Extraocular factors account for the majority of failures, the main cause being increased subconjunctival fibrosis. Hitherto the effect of varying the site of filtration surgery on intraocular pressure control has not been studied. We therefore carried out a prospective study to evaluate the optimum site for trabeculectomy. Sixty patients were randomised to undergo a superior, nasal or temporal trabeculectomy. Patients who underwent a nasal trabeculectomy had significantly lower intraocular pressures 18 months after surgery (p < 0.05), with 30% having an intraocular pressure of < or = 10 mmHg.

A comparison of prophylactic, topical and subconjunctival treatment in cataract surgery.

Prophylactic subconjunctival antibiotics and steroids have been used in cataract surgery since the early 1950s. However despite their widespread acceptance, there has, to date, been no direct comparison of subconjunctival and topical routes of administration. We therefore carried out a prospective comparison of the effects of subconjunctival and topical administration of antibiotics and steroids in sixty patients undergoing elective, uncomplicated, extracapsular cataract extraction and posterior chamber lens implantation. The patients were examined by a single observer on the first and third post-operative days and two and six weeks following surgery. The observer was blinded to the patient treatment group. Significantly higher degrees of conjunctival injection and anterior chamber activity were noted in those who received subconjunctival injections compared with those who received topical treatment. There were no significant differences between the two groups in best corrected visual acuity, central corneal oedema, cystoid macular oedema, intraocular pressure and infection. We conclude that prophylactic subconjunctival therapy in uncomplicated cataract surgery is not necessary.

Marfan syndrome affecting four generations of a family without ocular involvement.

Thirty eight relatives of a patient with Marfan syndrome were screened for the presence of this disorder. Marfan syndrome was newly diagnosed in living members of 4 generations in this family without evidence of ocular abnormality in any. After screening, 10 relatives were newly diagnosed as having definite, and 5 relatives as having possible, Marfan syndrome. Family screening has drawbacks as well as benefits for the patients. The main benefit is the identification and treatment of previously undiagnosed patients at risk of cardiac complications which are the major cause of mortality. The drawbacks include employment problems created for patients with Marfan syndrome as a direct consequence of our screening programme and the anxiety induced in previously asymptomatic family members who did not realize that they could be at risk. Also, the 4 adult patients with possible Marfan syndrome found it difficult to accept that a definite diagnosis could not be reached after they had been invited to attend a screening programme for a serious genetic disorder. This report illustrates the importance of screening all the relatives of a patient with Marfan syndrome to identify previously undiagnosed cases. However, before screening a family, the physician should be aware that a clear diagnosis may not be reached in all patients, and financial, psychological or social problems may arise as a result of the screening programme.

Oxidative effects of laser photocoagulation.

Diabetic proliferative retinopathy is a common and sight-threatening condition. Oxidative stress is an integral and possibly causative part of the pathogenesis. Although laser photocoagulation is usually a beneficial treatment it remains unclear how it works. The possibility that it induces a sudden, temporary increase in free radical activity either by direct thermal damage or by oxygen reperfusion is explored in this clinical study by measuring the oxidative status in the peripheral blood of 13 patients undergoing panretinal photocoagulation. There were significant increases at one hour in malondialdehyde-like material (MDA-LM), 8.1 (6.9-9.6) nmol/mL, to 9.1 (7.6-9.8) nmol/mL, (less than 0.005); plasma thiols (PSH), 423 (352-457) microns/L, to 444 (382-478) microns/L, (p less than 0.005) and red cell reduced glutathione (GSH), 1357 (1295-1655) microns/L, to 1480 (1305-1760) microns/L, (p less than 0.01). Diene conjugates rose over the first hour 0.55 (0.36-0.79) od/mL, to 0.58 (0.34-0.85) od/mL falling to 0.56 (0.36-0.79) od/mL at 2 h but these changes were not significant. At 2 h, MDA-LM 8.4 (6.7-9.6) nmol/mL and PSH 404 (379-462) microns/L had returned to baseline but GSH remained significantly elevated 1500 (1325-1675) microns/L, (p less than 0.005 compared to baseline). This is a new observation and in some circumstances such generation of free radicals could explain the mechanism behind the complications of photocoagulation by direct or indirect damage to vascular endothelium leading to increased vascular permeability manifest as macular oedema or choroidal effusions.

Videofluoroscopy in macular disease.

Fluorescein Angiography has contributed immensely to our understanding and management of macular disease. Ridley first introduced the concept of television ophthalmoscopy and in 1973 Van Heuven and Schaffer reported the value of videofluoroscopy using a low light level system and an image intensifier. Major advances in electronic imaging technology since then have permitted high quality videofluoroscopy to be developed in particular the integral silicone intensified tube (SIT) allowed ultra low light levels to be recorded. A videofluorography system has been in routine use in our department for the last six years and we have found it to have certain advantages over conventional photography in macular disease. In this presentation we demonstrate some of these.

Orbital mucormycosis with survival.

Orbital mucormycosis is reported in a healthy patient with maturity onset diabetes who was treated with orbital exenteration, amphotericin B, and ketoconazole. A six-year follow-up shows no evidence of recurrence.

Penicillamine-induced ocular myasthenia gravis.

Two patients with rheumatoid arthritis (two women, 58 and 62 years old) developed reversible penicillamine-induced ocular myasthenia gravis. Both had the HLA-DR1 antigen, unlike most patients with idiopathic myasthenia gravis who show HLA-DR3, suggesting that penicillamine-induced myasthenia gravis and its idiopathic counterpart occur in patients with different genetic backgrounds. In both cases, cessation of drug treatment led to resolution of the symptoms.

Video funduscopy and fluoroscopy.

A system of television ophthalmoscopy has been developed using commercially available colour television cameras and a specially designed high-sensitivity monochrome television camera. Funduscopy and fluoroscopy can be performed at low light levels and recorded on standard video tape for clinical evaluation and also as a teaching aid. A computerised television stereo ophthalmoscope image processor is being developed for real-time volumetric recording the volume of the optic disc cup in glaucoma.