Biomedical subjects
Publications and source records attributed to W A Franks.
Prions have emerged in the past 5 years as serious transmissible infective agents. Ocular tissue transplantation has come under scrutiny after potential infected tissue was transplanted into healthy patients. In this review we examine the evidence for the risk of transmission of prions after scleral transplantation and explore alternative materials that may be used in ocular surgery.
AIMS/BACKGROUND: In the past 5 years there has been a dramatic increase in the use of radiotherapy to treat subfoveal neovascular membranes (NVMs) in both Europe and the USA despite the high cost. An alternative, more cost effective method of delivery using x ray simulation and bite block head fixation is described. METHOD: 15 patients were recruited with classic subfoveal NVMs. Head fixation was achieved with a customised Perspex mask for eight patients and a bite block for seven. An x ray simulator was used to check the field of irradiation. No computerised tomography (CT) was performed. All patients received a total dose of 13.3 Gy ionising radiation. Visual acuities were charted before and after treatment over a 24 month period. RESULTS: After 24 months, 5/8 (67%) in the mask group showed stable visual acuities (less than two line change on Snellen chart) compared with 3/7 (43%) in the bite block group. This difference may be attributed to a variation in the pretreatment visual acuities in the two groups. From several studies it has been estimated that 24 months after diagnosis 28% untreated individuals would have stable vision compared with 53% patients in this study. CONCLUSIONS: These results compare favourably with other studies and show that teletherapy can be safe and effective form of treatment for subfoveal NVMs. The authors have described an alternative method of head fixation and shown that CT scanning is not essential. This method of delivery is considerably less costly than that traditionally used and may allow greater numbers of patients to benefit from radiotherapy treatment.
Chronic simple glaucoma is a common disease in old age and lowering intraocular pressure is the treatment strategy. Although this can be achieved surgically, medical treatment with eye drops is more often prescribed. Beta-antagonists are the class of drug most often chosen, although other medical therapies are available. Systemic absorption of beta-antagonist eye drops can cause unsuspected respiratory impairment. Physicians should be alert to the possibility of respiratory side-effects of topical therapy with beta-antagonists and whenever such side-effects occur should use alternative treatments.
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This paper addresses the molecular basis of interactions between leucocytes, other cells in the vitreoretinal environment and extracellular matrix that may underlie the pathogenesis of proliferative vitreoretinopathy. In this study we report the expression of adhesion molecules (CD11a, CD11c, CD18 and ICAM-1), lymphocyte surface markers (CD3, CD4, CD8 and CD22) and HLA-DR molecules in 25 epiretinal membranes obtained from eyes undergoing vitrectomy for the treatment of retinal detachment complicated by epiretinal membrane formation. Retinas from normal cadaveric eyes were used as controls. The results showed that cells expressing the adhesion molecules CD11a, CD11c and CD18 were present in 5 of 25, 17 of 25 and 11 of 23 membranes, respectively. Cells stained with antibodies against intracellular adhesion molecule 1 (ICAM-1) were observed in 24 of 25 membranes, whilst HLA-DR positive cells were seen in all membranes investigated. Immunohistochemical staining revealed that the molecules ICAM-1 or HLA-DR were not only expressed on inflammatory cells but also distributed within the extracellular matrix in several specimens. Lymphocytes expressing CD3 markers were present in 12 of 25 membranes, whilst T lymphocytes expressing CD4 and CD8 markers were observed in 5 of 18 and 12 of 24 membranes, respectively. In contrast, B lymphocytes expressing CD22 molecules were not found in any of the membranes. Leucocyte surface molecules were not expressed in control cadaveric retinas, although occasional cells expressing ICAM-1 were identified in the inner plexiform layer.(ABSTRACT TRUNCATED AT 250 WORDS)
We have investigated the expression of mRNA for interleukin 6 (IL-6) in cells infiltrating 12 epiretinal membranes, and the presence of biologically active IL-6 in vitreous humour available from five corresponding eyes. The results showed that nine of the 12 membranes (75%) contained cells expressing mRNA for this cytokine. Although in two of the specimens pigmented cells were identified as some of the cells expressing mRNA for IL-6, we did not identify the nature of IL-6 mRNA-producing cells infiltrating the membranes. Interestingly, two vitreous samples from eyes whose membranes did not contain cells with mRNA for IL-6 exhibited significant concentrations of IL-6 (315 and 28 micrograms/ml). Parallel study of mRNA for IL-6 in PVR biopsies and of IL-6 levels in corresponding vitreous may indicate how cytokine-mediated pathways of inflammation are involved in the pathogenesis of epiretinal membrane formation.
Subconjunctival injection of 2% lignocaine at the 12 o'clock position was used as the local anaesthetic in 19 eyes undergoing a primary trabeculectomy for open angle glaucoma. The appearance of the bleb and mean post-operative intraocular pressure (IOP) were compared with those in 29 eyes with the same diagnosis undergoing trabeculectomy under general anaesthesia by the same surgeons over the same time period. The two groups of eyes were similar with regard to treatment with beta blockers (p > 0.1), miotics (p > 0.25), sympathomimetics (p > 0.25), carbonic anhydrase inhibitors (p > 0.5), or no treatment (p > 0.25). Seventy-seven per cent of the local anaesthetic group and 25% of the general anaesthetic group developed avascular, thin-walled drainage blebs (p < 0.001). The mean post-operative IOP was significantly lower in the group receiving local anaesthetic (p < 0.001). The reasons for and significance of these observations are discussed, and the merits and disadvantages of thin-walled blebs are evaluated.
A consecutive series of 114 eyes (112 patients) undergoing pars plana vitrectomy for rhegmatogenous retinal detachment not complicated by severe proliferative vitreoretinopathy is presented (follow up 1 to 4 years; mean 19 months). The indications for vitrectomy fell into two main groups: (1) where the retinal view was poor and vitrectomy was required to clear media opacities to allow identification of retinal breaks (n = 62); and (2) where technically difficult breaks existed and vitrectomy with internal tamponade was used to relieve vitreoretinal traction and facilitate retinal break closure (n = 44). In some of these cases the need for scleral buckling was eliminated. A smaller third group (n = 8) existed where the position of the break(s) was uncertain in the presence of an adequate view. The success rate with one procedure was 74% and with further surgery retinal reattachment was achieved in 92%. At 6 months after further surgery, beyond which interval no new failures were encountered, best corrected visual acuity was improved in 92 eyes (81%), unchanged in 14(12%), and worse in eight (7%). We conclude that pars plana vitrectomy is an effective method for treatment of selected cases of rhegmatogenous retinal detachment not complicated by proliferative vitreoretinopathy.
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We studied a cohort of 165 eyes that had undergone tube implant surgery for glaucoma, with a minimum follow-up of 12 months (range, 12 to 72 months). Of the 57 cases (34.5%) in which surgery failed to control intraocular pressure (less than 22 mm Hg), 15 (26%) occurred by 3 months, 36 (63%) by 12 months, and 46 (80%) by 24 months. Cox regression modeling was used to evaluate independent risk factors in the absence of additional therapy. The use of a two-piece (anterior chamber-to-encircling band) tube system was associated with a 2.4 times higher risk of failure (P less than .001) compared with a one-piece system. Neovascular glaucoma was associated with a 2.1 times higher risk of failure (P less than .037) than other types of glaucoma. Late failure of tube implant surgery is common and there is a steady attrition rate over a 2-year follow-up period.
We report our experience of a recently described local anaesthetic technique which seeks to avoid risk of perforation of the globe, damage to the optic nerve, or injection into the subarachnoid space, whilst providing prolonged and reliable anaesthesia. A prospective series of 19 patients who underwent vitreoretinal surgery using this technique were compared with 19 patients who had retrobulbar anaesthesia for cataract extraction. The vitreoretinal group had excellent akinesia and very good anaesthesia, allowing prolonged retinal reattachment surgery lasting up to 3 hours. Patient evaluation of discomfort or pain experienced in the two groups was assessed using a visual analogue pain score chart. The pain scores for the two groups were not significantly different (p = 0.03) and 16 of 19 patients in each group (84%) experienced only slight pain or less. Satisfaction with local anaesthesia, in both groups, was also assessed by asking patients which method of anaesthesia they would prefer if future surgery were to be performed. In the vitreoretinal group, 18 of 19 patients expressed a preference for local anaesthesia and in the cataract group 17 ot 19 also favoured local anaesthesia. The vitreoretinal patients' median pain score was 0 compared with 1 for the cataract patients. This study demonstrates that local anaesthesia provides pain relief for vitreoretinal surgery which is comparable to the experience of patients undergoing cataract surgery by retrobulbar anaesthesia. The technique described can provide successful local anaesthesia for vitreoretinal procedures. The success of this technique for pain relief and akinesia calls for a reappraisal of the number of patients suitable for vitreoretinal surgery under local anaesthesia.
The presence of interleukin 6 (IL-6), interleukin 1 (IL-1), interleukin 2 (IL-2) and tumour necrosis factor (TNF) was investigated in vitreous and aqueous aspirates from eyes undergoing vitrectomy for the treatment of different inflammatory conditions. Cadaveric vitreous from 10 normal subjects were used as controls. IL-6 was observed in 5 specimens from eyes with idiopathic uveitis (range = 26-264 pg/ml), in 2 specimens from eyes with uveitis complicated with retinal detachment (28 and 279 pg/ml, respectively), in 6 samples from eyes with diabetic retinopathy (range = 5-480 pg/ml), in one sample from an eye with phacolytic glaucoma (1190 pg/ml) and in one specimen from an eye with Behçet's disease (366 pg/ml). Although IL-1 was detected in 80% of all the samples investigated, concentrations of this cytokine greater than 3 pg/ml were only observed in 2 specimens from eyes with uveitis (5 and 20 pg/ml, respectively) and 2 samples from eyes with diabetic retinopathy (3 and 31 pg/ml, respectively). TNF was present in 3 specimens from eyes with uveitis (range = 2-24 pg/ml) and 1 sample from eyes with diabetic retinopathy (4 pg/ml), but was not detected in the eyes with phacolytic glaucoma or Behçet's disease. IL-2 (less than 0.1 U/ml) was detected in one sample from an eye with uveitis, one specimen from an eye with uveitis complicated with retinal detachment and 2 samples from eyes with diabetic retinopathy. None of the cytokines measured were detected in any of the control vitreous. The present observations suggest that cytokines, particularly IL-6 and IL-1, may act as local amplification signals in pathological processes associated with chronic eye inflammation.
This study determined the presence of interleukin 1 (IL-1), interleukin 6 (IL-6), tumour necrosis factor alpha (TNF alpha), tumour necrosis factor beta (TNF beta), interferon gamma (IFN gamma), transforming growth factor beta 2 (TGF beta 2) and fibroblast proliferation activity (FPA) in vitreous aspirates from eyes undergoing vitrectomy for the treatment of retinal detachment complicated by proliferative vitreoretinopathy (PVR) or uncomplicated retinal detachment (RD). Cadaveric vitreous from normal subjects were used as controls. The results showed that IL-1 and IL-6 predominated in vitreous from eyes with PVR or RD, and that concentrations of IL-6 greater than 20 pg/ml were more frequently found in PVR than in RD (p = 0.031) or control specimens (p = 0.006). Low levels of TNF alpha were observed in 4/18 eyes with PVR, 1/15 eyes with RD and 1/15 control vitreous, and small concentrations of TNF alpha were seen in 3/18 eyes with PVR, 1/15 eyes with RD and 2/15 control vitreous. IFN gamma was detected in 12/18 eyes with PVR, but only in 5/15 eyes with RD (p = 0.048) and 6/15 control specimens. TGF beta 2 was present in all vitreous samples at concentrations ranging from 100 to 4,500 pg/ml with no significant differences among the three groups. Control vitreous possessed the greatest FPA when compared with vitreous from eyes with PVR (p = 0.031) or RD (p = 0.048). These observations provide further evidence that cytokine-mediated pathways of inflammation are involved in the pathogenesis of PVR and point to the possible involvement of IL-1, IL-6 and IFN gamma in cellular interactions leading to chronicity.
Silicone oil is a useful tool in retinal reattachment surgery in selected cases, but complications, particularly cataract, glaucoma and keratopathy, have led to worries about its use for prolonged internal tamponade. Removal of silicone oil has been recommended to preempt or reverse these complications. A retrospective review of 120 eyes in which temporary silicone oil tamponade had been employed is presented. One hundred and twelve eyes were examined six months and two years after removal of silicone oil. Retinal redetachment occurred in 21 eyes (19%). Cataract formation was delayed by early removal of silicone oil, but after two years the majority of eyes had undergone surgery for cataract or had developed lens opacities. Removal of silicone oil was ineffective in reversing an established pressure rise in nearly all cases. Three phakic eyes developed glaucoma after removal of silicone oil but no new cases occurred in phakic eyes in the two years following silicone oil removal. Keratopathy was uncommon and was arrested and occasionally reversed by silicone oil removal. Visual acuities improved in the majority of eyes after removal of silicone oil.
Trabeculectomy has a very high success rate, however, certain eyes are known to be at high risk of failure due to scarring of the conjunctival bleb. Such eyes include those with a previous failed filter, eyes with glaucoma secondary to uveitis and neovascularisation and the eyes of children and young adults. Trabeculectomy is generally accepted to have less successful results in patients of African race although good results are reported from some centres. The effectiveness of treatment with 5-fluorouracil in improving the results of trabeculectomy has been established in a number of pilot studies and clinical trials. Early studies used 100 mg of 5-fluorouracil in divided doses. Serious complications were recorded and lower dose regimes have been advised to improve the safety of the technique. Similar success in improving the chance of success to trabeculectomy has been found with doses of 40 mg with a lower incidence of side effects. We report complications associated with the use of 5-fluorouracil in a total dose of 50 mg in a group of 49 eyes undergoing trabeculectomy and postoperative 5-fluorouracil and describe the previously unreported increased incidence of thin cystic blebs in these eyes.
Peribulbar anaesthesia has been recommended as a safer alternative to retrobulbar anaesthesia. We report a case of perforation of the globe sustained during peribulbar anaesthesia which resulted in blindness. Orbital injections are potentially dangerous, be they peribulbar or retrobulbar. To minimise the risk, short, blunt needles are advocated for the peribulbar route.
Hypotony after fistulizing surgery is common, and most cases resolve without complications. Occasionally, a flat anterior chamber in phakic or pseudophakic eyes may lead to corneal decompensation or cataract formation. In aphakic eyes that have undergone previous vitreous surgery, flat anterior chambers will not develop, but large choroidal detachments and delayed suprachoroidal hemorrhage may occur while the eye is soft. To maintain intraocular pressure (IOP) in the early postoperative period, the authors used a technique to seal the drainage tube with a Vicryl tie, combined with injection of sodium hyaluronate, sulfur hexafluoride (SF6), or perfluoropropane (C3F8), perioperatively in 28 eyes undergoing glaucoma tube implant surgery. Eight eyes were treated with injection of sodium hyaluronate, 8 with SF6, and 12 eyes with C3F8. Hypotony was significantly less frequent in eyes treated with C3F8 compared with sodium hyaluronate (P less than 0.05). Mean IOP was significantly higher for eyes treated with C3F8 injection compared with sodium hyaluronate for the first 4 days after surgery (P less than 0.05).
Four women, from three families, are presented who developed severe bilateral optic nerve disease. A diagnosis of Leber's hereditary optic neuropathy (LHON) was made when male family members became affected. The disease ran a similar course in men and women with severe and permanent reduction in vision. Two women had been told that they suffered from multiple sclerosis. With recent advances in diagnostic techniques it should be possible to distinguish between these two conditions. Although LHON may be underdiagnosed in women, there does seem to be a male preponderance of the disease in most European pedigrees. Recent work supports the assumption that LHON is transmitted via cytoplasmic DNA; however, this does not explain why men are more likely to be affected, nor why only a minority of those carrying the defect develop the disease.