Search PubMed⌕ Search

Biomedical subjects

P K Leaver

Publications and source records attributed to P K Leaver.

At least 19 recordsLinked to original sources
PubMed1992

Four-quadrant local anaesthesia technique for vitreoretinal surgery.

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.

Anesthesia, Local↗
PubMed1992

Mathematical modelling of retinal tear formation: implications for the use of heavy liquids.

When force is applied to detached retina it elevates, stretches, and becomes irreversibly deformed. Finally it tears, and the timing and location of tear formation are determined by the distribution of stress within the retina. This stress distribution is dependent upon the retinal contour. We have tested this using retinas of freshly enucleated bovine eyes. A suture was attached to isolated retinal tissue using butylacrylate (Histoacryl) glue and traction was applied to this suture so stretching the retina. We present a mathematical model of the in vitro data obtained, with predictions for local retinal internal tensions. We show that these are altered by the addition of hydrostatic forces due to the presence of heavy liquids. These findings have implications for epiretinal membrane dissection during surgery and for the use of heavy liquids during membrane peeling.

Animals↗
PubMed1991

Removal of silicone oil--rewards and penalties.

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.

Adult↗
PubMed1990

Extended criteria for vitrectomy and fluid/silicone oil exchange.

The results of vitrectomy combined with fluid/silicone oil exchange at six months after surgery in 39 eyes with complex retinal detachments without (initially) severe proliferative vitreoretinopathy, proliferative diabetic retinopathy or giant retinal tears, are reported. Eyes with detachments as a result of macular holes, large multiple or posterior breaks, and eyes which had undergone previous, unsuccessful vitreoretinal surgery are included. In 90% the retina remained reattached, with functional improvement in 72%. These findings, together with the relatively low incidence of complications observed, lead us to recommend this technique in the management of selected detachments falling outside the parameters within which its use is generally accepted.

Cataract↗
PubMed1989

Vitrectomy and fluid/silicone-oil exchange for giant retinal tears: 5 years follow-up.

A series of 64 eyes, in 64 patients with giant retinal tears, treated by vitrectomy and fluid/silicone-oil exchange, has been reviewed after 5 years. Anatomical success was achieved in 73% of cases and visual function in successful cases ranged from 6/6 to NPL; 66% achieved acuities of 6/60 or better and 32% had vision of 6/18 or better. These results compare favourably with those in a previous series reported after 6 months and 18 months. Epiretinal membrane proliferation and shortening accounted for the majority of retinal redetachments while macular abnormalities, especially pucker, were responsible for a poor visual outcome. Glaucoma is the most serious long-term complication of the surgical method and occurs most frequently in aphakic eyes. Retention of the crystalline lens, whenever possible, the creation of a 6 o'clock iridectomy in aphakic eyes, early removal of silicone oil and a conservative approach to the use of scleral buckles are recommended.

Adolescent↗
PubMed1989

Retinal detachments--when to refer? Identifying the complicated case.

Cases of retinal detachment are usually referred by one ophthalmologist to another, because of their complexity. The complicated nature of such cases can be judged by their likely response to conventional methods of retinal reattachment surgery. When the causative retinal breaks cannot be identified or closed by conventional means, it is reasonable to call detachments complicated. The prompt identification of such cases and their referral, if appropriate facilities and expertise to undertake them are not at hand, are essential steps in the correct management of rhegmatogenous retinal detachments.

Humans↗
PubMed1989

Silicone oil in the aphakic eye: the influence of a six o'clock peripheral iridectomy.

Complications after six months, in a series of 44 aphakic eyes treated by vitrectomy and fluid/silicone-oil exchange with six o'clock (Ando) peripheral iridectomy, are reported. Comparisons are made with the complications after six months in a similar series treated prior to the introduction of the six o'clock iridectomy. It is concluded that a patent six o'clock iridectomy is effective in reducing the complications of intraocular silicone oil in the aphakic eye.

Adolescent↗
PubMed1988

Behaviour of intraocular gases.

The changes in volume of intraocular bubbles of air, sulphur hexafluoride, perfluoropropane and mixtures of these gases, were studied in human eyes, following vitrectomy for treatment of retinal detachment. The implications of these findings, for the provision of optimal internal tamponade in the treatment of retinal detachment, are discussed.

Air↗
PubMed1987

Intraocular argon laser photocoagulation.

Intraoperative photocoagulation using an endolaser delivery system is an important recent development in the field of vitreous microsurgery. Endolaser photocoagulation is indicated in a wide variety of vitreoretinal disorders and offers important advantages over previous techniques of endophotocoagulation using xenon energy. We review our experiences of argon laser endophotocoagulation to identify the role of this technique, the potential hazards and stringent precautions required for theatre personnel.

Animals↗
PubMed1987

Closed microsurgery for the sequelae of neovascularisation from veno-occlusive retinopathies.

Our experience of closed microsurgery for vitreous haemorrhage and/or traction retinal detachment complicating extraretinal neovascularisation after retinal vein occlusion or Eales' and Behçet's periphlebitis is discussed. Many of these eyes represented a relatively simple management problem, but the visual outcome was often compromised by intrinsic macular damage. Some eyes had complicated vitreoretinal relationships which presented unexpected technical difficulties, while persisting retinal ischaemia posed the risk of rubeosis iridis or post-operative vitreous haemorrhage unless scatter endophotocoagulation was used.

Cataract Extraction↗
PubMed1979

Silicone oil in the treatment of massive preretinal retraction. I. Results in 105 eyes.

A study of 105 eyes in which intraocular injection of silicone oil was used to treat retinal detachment with massive preretinal retraction showed that early results were encouraging, and anatomical and visual results correlated well. Operative complications had little influence on the immediate outcome, the reasons for failure being poor case selection or inadequate surgical technique. When a deterioration occurred during the postoperative period it was found to be associated with late complications, particularly cataract; redetachment occurred in only a small number (12%) of cases.

Humans↗
PubMed1979

Silicone oil injection in the treatment of massive preretinal retraction. II. Late complications in 93 eyes.

Long-term assessment of eyes in which silicone oil injection had been used in the treatment of retinal detachment with massive preretinal retraction was undertaken in 92 consecutive patients. While a high incidence of complications, particularly cataract, was confirmed, this study showed that they were probably caused not by any toxic effect of silicone oil but by obstruction of normal metabolic exchange at the silicone-tissue interface. The incidence of complications causing deterioration of vision or serious symptoms was not found to be high, and navigating vision was well preserved.

Adult↗
PubMed1978

Macular abnormalities in the reattached retina.

Sixty-six patients in whom the macula was detached before surgery were observed for at least 1 year after retinal reattachment. Macular abnormalities were recognised clinically in most patients with severely reduced vision. Failure of retinal receptor regeneration or receptor misalignment may account for visual reduction in a minority of patients but may be less important as a cause of reduced visual acuity than was previously supposed. This study confirms that the visual prognosis is related to the duration of the detachment before surgery, and patients with a macular detachment for 2 months or longer are likely to suffer persistently reduced vision.

Fluorescein Angiography↗