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Biomedical subjects

A M Hamilton

Publications and source records attributed to A M Hamilton.

At least 37 records · Page 2Linked to original sources
PubMed1995

Is the first day postoperative review necessary after cataract extraction?

BACKGROUND: In current ophthalmic practice day-case surgery cataract patients are conventionally discharged and then reviewed the following morning thus limiting the advantages of what 'true' day-case surgery strives to achieve. The aim of this study was to see if there was a difference in outcome between 'true' day-case cataract surgery and non-day-care surgery. METHODS: A total of 387 consecutive cataract operations were followed, comprising 122 local anaesthetic day-cases, 149 local anaesthetic non-day-cases, 63 general anaesthetic non-day-cases, and 53 general anaesthetic day-cases. RESULTS: Although not randomised the groups were comparable with respect to age, operator grade, sex, presence of diabetes, anaesthetic type, pre and postoperative visual acuities, and time to first planned outpatient visit. There were 10 early postoperative complications in the day-case group (5.71% of total) and 14 in the non-day-case group (6.6% of total), the commonest complications in both groups were raised intraocular pressure, corneal oedema, and wound leaks. One patient in each group had an early complication that necessitated attending the casualty department. The visual outcomes in both groups were comparable. CONCLUSIONS: These findings suggest that there were no preventable complications within the constraints of the number of operations studied and that no additional risk is attached to 'true' day-case surgery relative to non-day-case surgery.

Aged↗
PubMed1994

Color contrast sensitivity and pattern electroretinographic findings after diode and argon laser photocoagulation in diabetic retinopathy.

The retinal depth at which photocoagulation is maximal varies with wavelength. We compared visual function of eyes undergoing photocoagulation by the near-infrared diode laser to the argon green laser. We treated 14 patients with diabetic retinopathy requiring bilateral panretinal photocoagulation with the diode laser on the right eye and the argon system on the left eye. Before and after treatment visual acuity, central and peripheral color contrast sensitivity, and pattern electroretinograms were recorded. No difference was noted in the clinical response or visual acuity outcome, but a tendency was observed for less decline in color contrast sensitivity and pattern electroretinogram recordings after diode laser photocoagulation. Although P values (.05 to .5) did not reach significance, a mean of 8.4 of 14 patients per test had better test results after diode laser treatment. Diode laser photocoagulation seems to be a viable alternative to argon laser treatment and may be a more gentle mode of treatment.

Adult↗
PubMed1994

Posterior capsule opacification following diabetic extracapsular cataract extraction.

Review was performed of extracapsular cataract extraction with posterior chamber lens implantation in 90 diabetic patients and 263 non-diabetic patients. There was a higher incidence of posterior capsular opacification as judged by the requirement for Nd:YAG posterior capsulotomy in patients with non-proliferative (12/35, 34%) or quiescent proliferative diabetic retinopathy (8/18, 44%) than in non-diabetic patients (48/263, 18%) (Mantel-Haenszel p = 0.04). Although subgroup analysis showed a higher incidence of posterior capsule opacification in diabetics with non-proliferative or quiescent proliferative retinopathy than in diabetics without retinopathy, this was not statistically significant (Mantel-Haenszel p = 0.19 and p = 0.07, respectively). Following cataract surgery in diabetics with retinopathy, frequent review and prompt management of posterior capsular opacification is recommended, to maintain adequate fundus visualisation at a time when deterioration of retinopathy is likely.

Aged↗
PubMed1994

Orbital ultrasound in the ocular ischaemic syndrome.

The ocular ischaemic syndrome illustrates well the effects of hypoperfusion of the globe and is a useful model for studying disorders of the orbital circulation. Recent advances in orbital ultrasound techniques have provided a non-invasive method of examining flow velocities in the orbital vessels, particularly the ophthalmic artery. Orbital ultrasound studies were performed on 3 cases of the ocular ischaemic syndrome. Continuous or intermittent reversal of blood flow in the ophthalmic artery was seen in all cases. How this phenomenon relates to the symptoms and signs in affected patients, and the role of orbital ultrasound in the investigation of the ocular ischaemic syndrome, are discussed.

Aged↗
PubMed1994

Immunofluorescence analysis of B-1 cell ontogeny in the mouse.

In order to further understand the developmental aspects of B-1 cells, we characterized the ontogeny of this B cell population in the spleen and peritoneal cavity of BALB/c mice. Although there are B-1 cells in the spleen within the first 1-3 weeks after birth, they do not at any stage represent the majority of splenic B cells. Splenic B-1 cells reach peak levels at approximately 9 days after birth. The mesenteric lining that covers the small intestine of 7-day-old mice contains a population of IgM+ B cells, while at the same age, there are few lymphoid cells in the peritoneal cavity. Between 7 and 8 days after birth there is an influx of B cells into the peritoneal cavity. At 8 days, the first detectable peritoneal B cells appear to be of the B-1 type based on expression of IL-5 receptor and CD5. However, these peritoneal B-1 cells do not express Mac-1. This antigen is not expressed by the majority of peritoneal B-1 cells until 3 weeks. This study indicates that the majority of early splenic B cells are not B-1 cells and it suggests that the mesenteric tissues surrounding the gut contain B lymphocytes which traffic into the peritoneal cavity where they then reside.

Aging↗
PubMed1994

Adult Coats' disease in branch retinal vein occlusion.

We report a case of adult Coats disease secondary to a branch retinal vein occlusion. Angiograms show the relationship of the peripheral telangiectasis, aneurysm formation and vascular incompetence to the peripheral retinal ischaemia. The possible role of vascular remodelling in the pathogenesis of this uncommon complication of a common condition is discussed.

Exudates and Transudates↗
PubMed1994

Effects of IgM allotype suppression on serum IgM levels, B-1 and B-2 cells, and antibody responses in allotype heterozygous F1 mice.

IgM allotype heterozygous F1 mice were independently suppressed for Igh6a or Igh6b to evaluate the contribution of B-1 and B-2 cells to natural serum IgM levels and Ab responses. B-2 B cells expressing IgM of the suppressed allotype were evident in the spleens of suppressed mice 4 to 6 weeks after cessation of the suppression regimen, whereas B-1 B cells of the suppressed allotype were undetectable for up to 9 months. Although serum IgM of the suppressed allotype was initially depleted in mice suppressed for either allotype, by 7 months of age, there were detectable levels of IgM of the suppressed allotype in the serum; however, the levels were significantly below that found in nonsuppressed mice. When mice were immunized with either the T-independent or T-dependent form of phosphorylcholine, those suppressed for either allotype, and consequently depleted of B-1 B cells of that allotype, did not respond with phosphorylcholine-specific IgM of the suppressed allotype. In contrast, when mice were immunized with alpha 1-3 dextran, the Igh6a allotype-suppressed mice were able to produce dextran-specific IgM of that allotype. These results show that allotype-bearing B-1 cells of both allotypes can be effectively suppressed by this suppression protocol and this produces long-lasting effects on B-1 cell levels and serum IgM of the suppressed allotype. These observations reflect the derivation of the majority of B-1 cells from fetal-neonatal precursors, which cannot be replaced by newly emerging B-2 cells of adult origin. Their ablation by antibody treatment results in permanent alterations to the adult B-cell repertoire.

Alleles↗
PubMed1993

Long-term follow-up of diode laser trabeculoplasty for primary open-angle glaucoma and ocular hypertension.

BACKGROUND: Initial studies of laser trabeculoplasty using infrared energy (810 nm) emitted by diode semi-conductor lasers have been encouraging. A 2-year study of diode laser trabeculoplasty (DLT) in the control of primary open-angle glaucoma (POAG) and ocular hypertension has been completed. METHODS: Patients with uncontrolled POAG or ocular hypertension were treated with DLT to one half of the trabecular meshwork using a trabeculoplasty lens. Spot size was 100 microns, exposure time was 0.2 second, and mean power was 1096 mW (+/- 46.5 mW). The desired endpoint was a mild blanching of the meshwork only. RESULTS: Twenty-five eyes of 16 patients were treated. Mean intraocular pressure reduction was 9.24 mmHg (+/- 3.4 mmHg) at 6 weeks, 9.32 mmHg (+/- 3.6 mmHg) at 3 months, 9.34 mmHg (+/- 3.8 mmHg) at 6 months, 8.42 mmHg (+/- 2.62 mmHg) at 12 months, 8.14 mmHg (+/- 3.42 mmHg) at 18 months, and 7.9 mmHg (+/- 3.63 mmHg) at 24 months. No pressure peaks (> 5 mmHg) were recorded after therapy. Inflammation and discomfort were minimal after laser treatment. Of 16 eyes examined at 2 years, there were no peripheral anterior synechiae. During the course of the study, six eyes became uncontrolled, despite one session of DLT. Four eyes regained control with a further session of DLT, but two required trabeculectomy. CONCLUSION: Diode laser trabeculoplasty is an effective form of therapy in POAG and ocular hypertension. Hypotensive effects and success rates are comparable with argon laser trabeculoplasty (ALT). Reduced inflammation after laser treatment may be due to reduced absorption of infrared energy by the melanin of the anterior segment. The portable nature of these lasers may allow for laser delivery in developing countries and remote situations.

Aged↗
PubMed1993

No-needle one-quadrant sub-tenon anaesthesia for panretinal photocoagulation.

Panretinal photocoagulation (PRP) is tolerated well by most patients using topical anaesthesia alone, though there are a significant number of patients who experience pain. Additional local anaesthesia alternatives for these patients include retrobulbar, peribulbar or subconjunctival injection. Deep introduction of a sharp needle may rarely cause damage to orbital structures, whereas no-needle sub-Tenon irrigation of local anaesthetic solution to the posterior Tenon's space theoretically avoids these risks. A one-quadrant, inferior-nasal, sub-Tenon delivery of 1.5-2 ml plain 2% lignocaine was administered and PRP performed on 12 eyes of 12 patients who were previously intolerant of PRP by topical anaesthesia alone. To assess the efficacy of anaesthesia, patients were asked to score pain, using a visual analogue score chart graded from 0 to 10. If patients were unable to see the chart, or read the accompanying text, a verbal explanation and description of the scoring chart was performed. Where PRP was performed with topical amethocaine 1% alone, pain scores were graded as median 8, mean 8.5 and range 6-10. The administration of sub-Tenon anaesthesia was well tolerated with a median pain score of 1.5, mean 1.9 and range 0-5. PRP after sub-Tenon administration was successfully completed in 11 of the 12 patients with a median pain score of 1.5, mean 1.8 and range of 0-9. The range was wide due to one patient with a high pain score who was intolerant of PRP in spite of the sub-Tenon delivery.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Topical↗
PubMed1993

Factors influencing the natural history of diabetic retinopathy.

Despite recent improvements in the management of blood glucose control and in modern technology such as laser treatment and vitreoretinal surgery, diabetes mellitus is the major systemic cause of blindness in the Western world. The study of the natural history of diabetic retinopathy is difficult because of the variability of the disease, and the numerous factors that may influence its course and outcome. In the many studies available of the natural history of diabetic retinopathy, there is a failure to identify these factors. This article tries to identify and to classify the influences that may modify the outcome and the natural course of diabetic retinopathy, and gives some advice on how to deal with them. They can be subdivided into external, internal and ocular factors. Any future studies of the natural history of diabetic retinopathy are marred by the fact that effective treatment is now established and the guidelines for when to commence treatment and the techniques of treatment are well documented.

Diabetic Retinopathy↗
PubMed1993

Photocoagulation of choroidal neovascular membranes with a diode laser.

Nine eyes with parafoveal choroidal neovascular membranes due to age-related macular degeneration or angioid streaks were treated with a diode laser and were followed up to 40 weeks (mean 26 weeks). Angiographically proved closure of the membrane was achieved in seven eyes. Four lesions needed a second treatment for growth of subretinal neovascular tissue. Post-treatment visual acuity ranged from 6/9 to 6/60. Two eyes developed subfoveal membranes resulting in poor visual acuity. The morphology of the diode laser lesions differed from that of the argon green laser and was more similar to that of the krypton laser, producing a 'black hole' on the fluorescein positive print. In one particular eye fluorescein angiography revealed subfoveal choroidal non-perfusion next to the site of the diode lesion suggesting choroidal vascular closure.

Aged↗
PubMed1993

[Comparative use of diode and argon laser for panretinal photocoagulation in diabetic retinopathy].

The recently introduced semiconductor diode laser is portable, more compact, and cheaper to maintain than other laser systems. It is unclear whether its wavelength characteristics in the near infrared (810 nm) lead to different clinical results of retinal photocoagulation. In a prospective study ten diabetics (3 type I and 7 type II) ranging in age from 26 to 72 years with bilateral proliferative or severe nonproliferative diabetic retinopathy and visual acuity better than 6/18 in both eyes underwent panretinal photocoagulation. One eye was treated with the diode laser, the fellow eye with argon green (514 nm). Follow-up was documented by best-corrected visual acuity, fundus photography and fluorescein angiography. Mean duration of follow-up was 12 months. In neither group was there a significant difference in the response of retinopathy and neovascularization to the treatment, or in the course of visual acuity. Fluorescein angiography revealed the more profound effects of the diode laser in the choroid. Compared to argon laser treatment, patients found diode laser treatment more painful, but appreciated the absence of bright flashes during therapy. Photocoagulation for diabetic retinopathy using the diode laser was as effective as using the argon system in this initial pilot study.

Adult↗
PubMed1992

Encephalitis and chorioretinitis associated with neurotropic African horsesickness virus infection in laboratory workers. Part II. Ophthalmological findings.

Four laboratory workers developed uveitis-chorioretinitis, associated with encephalitis in 3 cases. The retinitis was characterised by haemorrhages and areas of retinal oedema, most marked over the posterior polar regions, and was associated with exudative retinal detachments. The lesions progressed over weeks and showed a severe retinal arterial vasculopathy with arteriolar narrowing, ghost vessel formation and the development of optic atrophy. The picture in 2 of the patients resembled that of the acute retinal necrosis syndrome (ARN). Antibodies to African horsesickness (AHS) virus were detected. The serology for AHS virus was positive in all 4 patients as well as in 5 of 15 laboratory workers from the same facility who were clinically and ophthalmologically normal. This is to our knowledge the first description of subclinical and probable clinical neurotropic AHS virus infection in man. AHS is a hitherto-unrecognised possible cause of viral retinitis and the ARN syndrome.

Adolescent↗
PubMed1992

Macular oedema and retinal neovascularisation in juvenile diabetics.

Thirteen young diabetic patients with peripheral capillary non perfusion who presented with symptoms of mild maculopathy were reviewed retrospectively. In this group, peripheral retinal ischaemia was often overlooked and a rapidly progressive proliferative retinopathy developed. Fluorescein angiography of the peripheral retina showed capillary closure, but with preservation of arterioles and venules. In this series, half of the eyes lost vision. In seven eyes where the peripheral ischaemia was treated by pan retinal photocoagulation, the maculopathy resolved without any specific laser treatment to the macula. In young diabetics presenting with maculopathy, the peripheral retina should be examined for ischaemia, and if present, pan retinal laser photocoagulation should be performed. Focal treatment for the macular disease can be delayed until after the peripheral photocoagulation, as the maculopathy may remit.

Adolescent↗
PubMed1992

Acute tear of the retinal pigment epithelium.

The fluorescein angiographic findings immediately following a tear of the retinal pigment epithelium are presented and the mechanisms of fluid movement from the retina to the choroid are discussed. Our case represents a clinical correlate to recent experimental reports on fluid movement across the retinal pigment epithelium-Bruch's membrane complex.

Acute Disease↗