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Biomedical subjects

M Leyland

Publications and source records attributed to M Leyland.

At least 19 recordsLinked to original sources
PubMed2006

Multifocal versus monofocal intraocular lenses after cataract extraction.

BACKGROUND: Good unaided distance visual acuity is now a realistic expectation following cataract surgery and intraocular lens (IOL) implantation. Near vision however still requires additional refractive power usually in the form of reading glasses. Multiple optic (multifocal) IOLs are available which claim to allow good vision at a range of distances. It is unclear whether this benefit outweighs the optical compromises inherent in multifocal IOLs. OBJECTIVES: The objective of this review was to assess the effects of multifocal IOLs, including effects on visual acuity, subjective visual satisfaction, spectacle dependence, glare and contrast sensitivity, compared to standard monofocal lenses. SEARCH STRATEGY: We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (which includes the Eyes and Vision Group Trials Register) on The Cochrane Library (2006, Issue 3), MEDLINE (1966 to July 2006), EMBASE (1980 to July 2006), NRR (2006, Issue 3) and PUBMED searched on 25 July 2006, limit: 90 days (entry date). We searched the reference lists of relevant articles and contacted investigators of included studies and manufacturers of multifocal intraocular lenses for information about additional published and unpublished studies. SELECTION CRITERIA: All randomised controlled trials comparing a multifocal IOL of any type with a monofocal IOL as control were included. Both unilateral and bilateral implantation trials were included. DATA COLLECTION AND ANALYSIS: Data were collected and trial quality was assessed. Where possible, statistical summary measures were calculated otherwise data were tabulated. MAIN RESULTS: Ten trials were identified, and a further three are pending review. There was significant variability between the trials in which outcomes were reported. Unaided distance acuity was similar in multifocal and monofocal IOLs (standardised mean difference (SMD) 0.03, 95% Confidence Interval (CI) -0.13 to 0.19). There was no statistical difference between multifocal IOLs and monofocals with respect to the proportion of participants achieving 6/6 best corrected visual acuity (Peto odds ratio (OR) 1.05, 95% CI 0.67 to 1.63). Unaided near vision was improved with the multifocal IOLs. Total freedom from use of glasses was achieved more frequently with multifocal than monofocal IOLs (OR for spectacle dependence 0.17, 95% CI 0.12 to 0.24). Adverse effects included reduced contrast sensitivity and the subjective experience of haloes around lights. AUTHORS' CONCLUSIONS: Multifocal IOLs are effective at improving near vision relative to monofocal IOLs. Whether that improvement outweighs the adverse effects of multifocal IOLs will vary between patients. Motivation to achieve spectacle independence is likely to be the deciding factor.

Cataract Extraction↗
PubMed2004

Epidemiological and molecular evidence of a monophyletic infection with Staphylococcus aureus causing a purulent dermatitis in a dairy farmer and multiple cases of mastitis in his cows.

An epidemiological and molecular investigation of a cutaneous suppurative infection with Staphylococcus aureus in a dairy farmer, occurring concurrently with an outbreak of clinical mastitis in his herd, was carried out. A common aetiology for the diseases in the farmer and his cows was established by combining clinical evidence with a molecular genomic analysis of the bacterial isolates using pulsed field gel electrophoresis of DNA macro-restriction fragments. This case indicates the possibility of the emergence and circulation of anthropozoonotic clones of S. aureus in dairy herds. It also provides further evidence of the severe impact of infection with highly virulent clones on dairy lactating cattle.

Abscess↗
PubMed2004

Validation of Orbscan II posterior corneal curvature measurement for intraocular lens power calculation.

AIMS: To validate the use of Orbscan II slit-scanning topography for measuring posterior corneal curvature, by comparing corneal power calculations using this value with the standard keratometric method of corneal power calculation. METHOD: Corneal measurements were taken from both eyes of 15 normal subjects using the Javal-Schiotz keratometer and the Orbscan II topographer. Corneal power was calculated using standard keratometric indices of 1.337.5 or 1.331.5 and Javal-Schiotz keratometry. Corneal power was then recalculated using the thick-lens formula, with anterior corneal curvature from the Javal-Schiotz or Orbscan II and posterior measurements from the Orbscan II; in addition, the 3.0 mm 'Mean Power' value from the Orbscan II software was noted. Six comparisons were then made using mean-difference plots. RESULTS: The smallest difference and therefore the most predictable agreement was between Javal-Schiotz keratometry using a refractive index of 1.331.5 and the thick-lens formula using Javal-Schiotz anterior curvature and Orbscan II posterior curvature. The mean difference was 0.27 D with a confidence interval of 0.02-0.52 D. CONCLUSIONS: In normal eyes, data on posterior corneal curvature from the Orbscan II can be used to calculate corneal power in close agreement with the standard keratometric method. This suggests the use of the Orbscan II in eyes that have previously undergone refractive surgery, for calculation of intraocular lens power prior to cataract surgery.

Biometry↗
PubMed2004

Salmonella Brandenburg - emergence of a new strain affecting stock and humans in the South Island of New Zealand.

AIMS: To report information on the spread of a new strain of Salmonella Brandenburg, which affected livestock and humans in the South Island of New Zealand, and a series of small case studies designed to investigate potential transmission of infection. METHODS: Information on the occurrence and spread of S. Brandenburg in livestock was gathered from laboratory diagnostic submissions, from case studies on the faecal excretion rate in ewes, carrier status of black-backed gulls (Larus dominicanus), spread of S. Brandenburg organisms in sheep yards, infection in lambs going to meat plants, and from post-abortion pathological changes in the reproductive tract of ewes. RESULTS: A newly recognised strain of S. Brandenburg was first diagnosed in aborting sheep from a flock in mid Canterbury in the South Island in 1996. Subsequently, the disease spread to other farms in mid and south Canterbury in 1997 and to Southland and Otago in the lower half of the South Island in 1998-2003. In 1999, the same strain was responsible for abortions in cattle and gastroenteritis in calves and adult cattle. The same strain of bacterium also caused disease in horses, goats, deer, pigs and humans. Spread of the disease on farms was strongly associated with aborting ewes, which resulted in considerable environmental contamination. During the abortion season, black-backed gulls appeared to spread the disease to other farms. Other potential sources of infection were carrier sheep, contaminated water sources and contaminated sheepyard dust. Damage to the reproductive tract may affect the ability of surviving ewes to conceive. CONCLUSION: Important features of this disease are its high morbidity and mortality within a flock or herd, rapid local spread and its role as an occupational, health and safety risk to farm workers and their families.

Journal Article↗
PubMed2004

Duration of infection and strain variation in Streptococcus uberis isolated from cows' milk.

The duration of infection and pulsed-field gel electrophoresis (PFGE) types of bovine intramammary Streptococcus uberis isolates were examined. Milk samples were collected in duplicate from all 4 glands of 503 cows from 5 herds within 1 to 3 d of parturition and from 113 cows with clinical mastitis in the same herds throughout lactation. Glands from which S. uberis was isolated were resampled at 28-d intervals.The prevalence of S. uberis was 12% for cows around parturition, and the median duration of infection was 16 d. Cows >2 yr old had a longer duration of infection than 2 yr old cows, and duration varied among herds. A total of 173 different PFGE types were identified from a total of 234 S. uberis isolates. Each farm had a unique set of PFGE types. Only 3 PFGE types were common to each of 3 pairs of cows, and these occurred on the same farm. Where S. uberis was isolated on more than one occasion from a gland, only 55% of the PFGE types were the same across time. For cows with multiple glands infected, only one-half (9 of 18) had the same PFGE type in more than one gland. No predominant PFGE type was identified in any herd. It is concluded that there was wide heterogeneity of PFGE types, that the environment rather than other cows was the likely source of S. uberis infections, and that glands may be infected with multiple S. uberis PFGE types over a lactation.

Animals↗
PubMed2001

Multifocal versus monofocal intraocular lenses after cataract extraction.

BACKGROUND: Good unaided distance visual acuity is now a realistic expectation following cataract surgery and intraocular lens implantation. Near vision however still requires additional refractive power, usually in the form of reading glasses. Multiple optic (multifocal) intraocular lenses are available that are claimed to allow good vision at a range of distances. It is unclear whether this benefit outweighs the optical compromises inherent in multifocal intraocular lenses. OBJECTIVES: The objective of this review is to assess the effects of multifocal intraocular lenses, including effects on visual acuity, subjective visual satisfaction, spectacle dependence, glare and contrast sensitivity, compared to standard monofocal lenses. SEARCH STRATEGY: We searched the Cochrane Controlled Trials Register - CENTRAL (which includes the Cochrane Eyes and Vision Group specialised register), MEDLINE and EMBASE. The reference lists of relevant articles were searched. Investigators of included studies and manufacturers of multifocal intraocular lenses were contacted for information about additional published and unpublished studies. SELECTION CRITERIA: All randomised controlled trials comparing a multifocal intraocular lens of any type with a monofocal intraocular lens as control were included. Both unilateral and bilateral implantation trials were included. DATA COLLECTION AND ANALYSIS: Data were collected and trial quality assessed. Where possible, statistical summary measures were calculated, otherwise data were tabulated. MAIN RESULTS: One ongoing and six completed trials were identified. There was significant variability between the trials in the outcomes reported. Unaided distance acuity was similar in multifocal and monofocal intraocular lenses (Peto odds ratio 1.27 (95% Confidence Interval (CI) 0.76 to 2.11)), with a small increase in the proportion of multifocal intraocular lens participants achieving less than 6/6 best corrected visual acuity (Peto odds ratio 1.64 (95% CI 1.10 to 2.42)). Unaided near vision tended to improve with the multifocal intraocular lenses. This resulted in decreased spectacle dependence with use of the multifocal intraocular lenses (Peto odds ratio 0.16 (95% CI 0.11 to 0.23)). Adverse effects included reduced contrast sensitivity and the subjective experience of haloes around lights. REVIEWER'S CONCLUSIONS: Multifocal intraocular lenses are effective at improving near vision relative to monofocal intraocular lenses. Whether that improvement outweighs the adverse effects of multifocal intraocular lenses will vary between patients, with motivation to achieve spectacle independence likely to be the deciding factor.

Cataract Extraction↗
PubMed2001

Prospective evaluation of a plate haptic toric intraocular lens.

PURPOSE: Standard intraocular lenses (IOL) only correct the spherical component of aphakic refractive error. This study describes clinical experience with a foldable, injectable, toric IOL. METHODS: Keratometric, refractive and visual data were collected on patients listed for cataract surgery. Toric IOLs were offered where keratometric cylinder was greater than 1.5 dioptres. Small-incision phacoemulsification surgery was performed and the IOL implanted with its long axis along the steep corneal axis. Post-operative refractive data were compared with pre-operative and expected refraction using vector analysis software. RESULTS: Results of 22 eyes of 16 consecutive patients implanted with toric IOLs are reported. Two IOLs rotated more than 30 degrees in the first 24 h and were re-dialled surgically. Two further IOLs (9%) rotated more than 30 degrees during follow-up. In 21 of 22 eyes (95%) the refractive astigmatism was reduced, with a mean 73% of planned correction (vector analysis) achieved. CONCLUSIONS: The toric IOL is a useful surgical tool to reduce the refractive effects of pre-existing corneal astigmatism. Design modification to prevent IOL rotation would make results more predictable.

Adult↗
PubMed2001

Single intraoperative application of 5-Fluorouracil versus placebo in low-risk trabeculectomy surgery: a randomized trial.

PURPOSE: Trabeculectomy is the procedure of choice for the surgical control of glaucoma, and is often augmented by intraoperative 5-fluorouracil application to reduce scarring. This study aims to assess the validity of this technique with a randomized placebo-controlled trial. METHODS: Patients without risk factors for bleb failure other than previous drop use who were undergoing trabeculectomy surgery as their first ocular procedure were randomized to receive fluorouracil or placebo. The main outcome measures were intraocular pressure and bleb morphology. RESULTS: Results from 40 eyes of 36 patients are presented; 23 eyes were treated with fluorouracil, and 17 eyes were treated with placebo. Mean intraocular pressure at 1 year and at the final follow-up examination was significantly lower than preoperatively, but was not different between fluorouracil and placebo groups. Kaplan-Meier survival analysis also failed to show any difference, though there was a trend toward better survival of an intraocular pressure of 16 mm Hg or lower. Bleb morphology was examined postoperatively in 24 patients, with no differences found between fluorouracil and placebo groups. CONCLUSIONS: No significant difference was found in trabeculectomy outcome between fluorouracil-treated and placebo-treated eyes. The study was too small to state definitively that no such difference exists, but suggests that any treatment effect is likely to be small.

Aged↗
PubMed2000

Hepatitis C virus infection is not associated with a marked increase in the prevalence of ophthalmic morbidity.

BACKGROUND: Chronic infection with the hepatitis C virus has been reported to cause a wide variety of ophthalmic lesions. The incidence and significance of these lesions in an unselected population has not been assessed. METHODS: We studied a group of unselected patients with chronic hepatitis C and performed a full ophthalmic examination on each. As a control group we studied patients with chronic hepatitis B infection. RESULTS: In 25 patients with chronic hepatitis C we found no increase in the prevalence of significant ocular disease when compared with a cohort of patients with chronic hepatitis B. CONCLUSION: Chronic heptatitis C does not cause any marked increase in the incidence of ocular disease.

Adult↗
PubMed1997

Clinical assessment of a hand-held automated keratometer in cataract surgery.

PURPOSE: Pre-operative keratometry was performed on 32 eyes of 32 patients undergoing extracapsular cataract extraction with intraocular lens implantation, for calculation of intraocular lens power. In an additional 20 eyes of 20 patients post-operative keratometry was performed to guide selective suture removal. Readings from a manual keratometer and an automated hand-held keratometer were compared. METHODS: Pre-operative measurements were repeated three times on each subject to assess the repeatability of each machine. Mean-difference plots were performed to define the limits of agreement of the two machines. RESULTS: Repeatability was higher using manual keratometry (MK) than automated keratometry (AK). There was broad agreement between the two machines in pre-operative and post-operative assessment, although clinically significant differences are likely to occur in some cases. CONCLUSIONS: MK should continue to be used for routine pre-operative keratometry, with the AK providing a useful alternative when MK is not possible. AK is sufficiently accurate to allow its use in post-operative assessment of suture-induced astigmatism.

Astigmatism↗
PubMed1997

Trabeculectomy with intraoperative sponge 5-fluorouracil in Afro-Caribbeans.

AIM: To study the efficacy and safety of intraoperative 5-fluorouracil (5-FU) in Afro-Caribbean patients. METHODS: The results of trabeculectomy in 18 eyes of 18 Afro-Caribbean patients in whom a sponge soaked in 25 mg/ml solution of 5-FU was applied between Tenon's capsule and sclera for 5 minutes before excision of the trabecula were compared with 16 eyes of 16 Afro-Caribbean patients matched for age, quantity, and duration of preoperative medications, who underwent trabeculectomy without 5-FU. RESULTS: The mean postoperative intraocular pressure (IOP) at 1 month was 15.6 (SD 6.1) mm Hg in the 5-FU group and 18.0 (5.2) mm Hg in the control group (p = 0.15). There was no significant difference in the IOP at 6, 12, 15, 18, and 24 months in the two groups. Success rate at 18 months defined as an IOP less than or equal to 21 mm Hg with no adjunctive medication was 56% in the 5-FU group and 55% in the control group. No major complications were noted in either group. CONCLUSION: Intraoperative sponge 5-FU alone is safe but does not appear to decrease the risk of failure of trabeculectomy in Afro-Caribbeans.

Administration, Topical↗
PubMed1996

Structure-activity relationships in the peptide antibiotic nisin: antibacterial activity of fragments of nisin.

The post-translationally modified peptide antibiotic nisin has been cleaved by a number of proteases and the fragments produced purified, characterised chemically, and assayed for activity in inhibiting the growth of Lactococcus lactis MG1614 and Micrococcus luteus NCDO8166. These results provide information on the importance of different parts of the nisin molecule for its growth-inhibition activity. Removal of the C-terminal five residues leads to approximately a 10-fold decrease in potency, while removal of a further nine residues, encompassing two of the lanthionine rings, leads to a 100-fold decrease. There are some differences between analogous fragments of nisin and subtilin, suggesting possible subtle differences in mode of action. Cleavage within, or removal of, lanthionine ring C essentially abolishes the activity of nisin. The fragment nisin1-12 is inactive itself, and specifically antagonises the growth-inhibitory action of nisin. These results are discussed in terms of current models for the mechanism of action of nisin.

Amino Acid Sequence↗