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Trevor Sherwin

Publications and source records attributed to Trevor Sherwin.

8 recordsLinked to original sources
PubMed2006

Ophthalmology and vision science research: part 5: surfing or sieving--using literature databases wisely.

Literature databases are an ever-expanding resource available to the field of medical sciences. Understanding how to use such databases efficiently is critical for those involved in research. However, for the uninitiated, getting started is a major hurdle to overcome and for the occasional user, the finer points of database searching remain an unacquired skill. In the fifth and final article in this series aimed at those embarking on ophthalmology and vision science research, we look at how the beginning researcher can start to use literature databases and, by using a stepwise approach, how they can optimize their use. This instructional paper gives a hypothetical example of a researcher writing a review article and how he or she acquires the necessary scientific literature for the article. A prototype search of the Medline database is used to illustrate how even a novice might swiftly acquire the skills required for a medium-level search. It provides examples and key tips that can increase the proficiency of the occasional user. Pitfalls of database searching are discussed, as are the limitations of which the user should be aware.

Biomedical Research↗
PubMed2006

Laser scanning in vivo confocal microscopy of the normal human corneoscleral limbus.

PURPOSE: To elucidate the structure of the human corneoscleral limbus by in vivo laser scanning confocal microscopy and to correlate limbal epithelial dimensions and density with the central epithelium and in relation to age. METHODS: Fifty adult subjects were recruited into one of two age groups: younger (age<45 years) and older (age>or=45 years). Fifty left eyes of these 50 healthy subjects were examined by laser scanning in vivo confocal microscopy, to assess the basal epithelium of the central cornea and inferior limbus. Mean epithelial cell diameter, area, and density were calculated for the central basal epithelium, limbus-corneal basal epithelium, and limbus-palisade epithelium. RESULTS: Data were analyzed in relation to the two age groups, group A, 30+/-6 years (n=25; mean+/-SD), and group B, 60+/-11 years (n=25; P<0.01). Mean epithelial density in the limbus-cornea and limbus-palisade regions decreased significantly with age: limbus-cornea group A=7253+/-1077 cells/mm2 group B=6614+/-987 cells/mm2, P=0.03; limbus palisade group A=5409+/-799 cells/mm2, group B=5055+/-722 cells/mm2, P=0.03). Central corneal epithelial density did not change with age: group A=6162+/-503 cells/mm2, group B=6362+/-614 cells/mm2, P=0.08. Mean epithelial density was greatest at the limbus-cornea (7010+/-1081 cells/mm2) and lowest at the limbus-palisades (5289+/-847 cells/mm2). The mean width of palisade ridges was 25.0+/-6.3 microm. CONCLUSIONS: This is the first study to image clearly the living human corneal limbus by laser scanning in vivo confocal microscopy and to demonstrate quantitative changes in the basal epithelium with age.

Adult↗
PubMed2005

The New Zealand National Eye Bank study 1991-2003: a review of the source and management of corneal tissue.

PURPOSE: To evaluate donor demographics and source, donor tissue processing and storage, biologic contamination, and the utilization and distribution of corneal tissue procured by the New Zealand National Eye Bank. METHODS: As part of a prospective longitudinal study, the electronic records of the NZNEB for the 13-year period 1991-2003 were analyzed for each year with respect to donor demographics, donor source and cause of death, death-to-preservation interval, storage methods, endothelial assessment, biologic contamination, corneal tissue utilization, and distribution. RESULTS: During the study period, 3221 corneas were retrieved from 1628 donors (69.8% male, 30.2% female), with the mean age of donors 59.4 years (SD 18.3 years) and range 4 to 95 years. No significant correlation was identified between donor age group (using 10-year intervals) and the proportion of corneas suitable for transplantation. Donors were procured from the Coroner's service (67.6%), public hospitals, (23.5%) and multiorgan donors (7.1%). The most common causes of donor death were cardiovascular disease, trauma, and cerebrovascular disease. Average storage duration increased from 3.5 to 11.8 days when organ culture replaced hypothermic storage in 1992. Biologic contamination occurred in 5% of all donor corneas. The most common bacterial and fungal isolates were coagulase-negative staphylococci and Candida spp, respectively. A significant decrease in contamination rate over the years of the study was identified. Overall, 79.4% of corneal tissue procured was used for corneal transplantation (75.8% for penetrating keratoplasty, 2.1% for lamellar keratoplasty, and 1.5% for unspecified transplants), and 21.6% was discarded. Most common reasons for discarding tissue were biologic contamination, abnormal serology, and failed endothelial assessment. CONCLUSION: Analysis of the NZNEB database provides valuable information in relation to eye banking and corneal transplantation in New Zealand. Significant trends were identified in donor demographics, donor procurement source, improved donor tissue processing and storage, decreased biologic contamination, and increased utilization of corneal tissue.

Adolescent↗
PubMed2004

Higher-order aberrations of lenticular opacities.

PURPOSE: To measure and quantify higher-order aberrations induced by different types of lenticular opacities. SETTING: Department of Ophthalmology, University of Auckland, and Department of Ophthalmology, Auckland Public Hospital, Auckland, New Zealand. METHODS: Patients with lenticular opacities were recruited from outpatient clinics of a major tertiary referral center for ophthalmology. Patients were included if they had clinically evident, mild to moderate lenticular opacity with no coexisting ocular pathology. Patients were examined using standard preoperative techniques with additional assessment by wavefront aberrometry (Zywave, Bausch & Lomb) and Scheimpflug photography (EAS-1000, Nidek). For comparison, 20 eyes of 10 subjects with no lenticular opacity (control group) were recruited and assessed in an identical manner. RESULTS: Thirty persons were recruited and 40 eyes assessed, 20 with lenticular opacities. Ten eyes had predominantly cortical opacification, and 10 had mainly nuclear opacification. In eyes with predominantly cortical opacification, the mean logMAR uncorrected visual acuity (UCVA) was 0.5 +/- 0.2 (SD) (6/18 Snellen equivalent) and the mean logMAR best spectacle-corrected visual acuity (BSCVA), 0.2 +/- 0.2 (6/9). Analysis of aberrometry data for a 6.0 mm pupil in this group revealed an increase in coma of cosine phase (Z(3), P =.06) and tetrafoil of cosine phase (Z(4), P =.07) compared to eyes in the control group. Eyes with predominantly nuclear opacification had a mean logMAR UCVA of 0.7 +/- 0.2 (6/30) and a logMAR BSCVA of 0.4 +/- 0.2 (6/15). Aberrometry data for this cohort for a 6.0 mm pupil showed a statistically greater amount of spherical aberration (Z(4)(0), P =.001) and tetrafoil of cosine phase (Z(4), P =.005; Z(4)(-4), P =.004). CONCLUSIONS: This pilot study suggests that different types of early lenticular opacities induce different wavefront aberration profiles. Predominantly cortical opacification produced an increase in coma and nuclear opacification induced an increase in spherical aberration compared to eyes without opacities. Both types of lenticular opacities also induced a higher amount of tetrafoil. This could explain the significant visual symptoms in patients with early cataract and relatively good high-contrast Snellen acuity.

Adult↗
PubMed2004

Is directed donation misguided?

The worldwide shortage of organs and tissue for transplant has led to many ethical discussions involving restrictions concerning organ and tissue donation, including living donations and payment for donation. Efforts are being made to increase the donor pool; however, it is timely to ask whether moral decisions such as the rejection of directed donations are defensible. In this Clinical Conundrum, six specialists delve into the ethical and practical issues surrounding directed donation of human organs and tissues with particular reference to its implications in the field of ophthalmology.

Cornea↗
PubMed2004

Morphological changes in keratoconus: pathology or pathogenesis.

Keratoconus was first discriminated from other corneal ectatic diseases in 1854. Since that time the morphological characteristics of keratoconic progression have been invaluable in the diagnosis of the condition. The key clinical features used to identify keratoconus have remained essentially the same since the introduction of the slit-lamp biomicroscope. Only relatively recently has the development of computerized corneal topography revolutionized the diagnosis of early keratoconus. Analysis of peer-reviewed literature databases revealed a steady chronological increase in pathological research into the progress of keratoconus. This overview describes the recent advances in our understanding of keratoconic pathology and highlights the interactions within the cornea that may be important in the pathogenesis of this condition.

Humans↗