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Biomedical subjects

H R Taylor

Publications and source records attributed to H R Taylor.

At least 91 records · Page 5Linked to original sources
PubMed1999

The VECAT study: methodology and statistical power for measurement of age-related macular features. Vitamin E, Cataract, and Age-related Maculopathy Study.

PURPOSES: (1) To develop the methodology for the grading of macular one-frame stereoslides and to assess the reliability of the system. (2) To determine the prevalence of soft drusen (> 63 microm) and pigment abnormalities synonymous with age-related maculopathy (ARM) at baseline, in a clinical trial of volunteers aged between 55 and 80 years of age. (3) To ascertain the power of the study to detect the 4-year incidence and progression of ARM in vitamin E versus placebo treated participants, given the baseline prevalence. METHODS: The 1204 participants enrolled in the Vitamin E, Cataract, and Age-related Maculopathy Study (VECAT) had colour stereoslides of their fundus taken using the Nidek 3-DX mydriatic fundus camera. The stereoslides were graded by two masked graders according to the "International Classification System for ARM and AMD". Assessment of inter- and intra-observer reliability was carried out on a regular basis on 15% of randomly selected slides. Anticipated rates of incidence and progression were based on results reported by the Beaver Dam Eye Study and the Chesapeake Bay Waterman Study. Power estimations were determined using the "nQuery Advisor" software program. Analyses were carried out on the worse affected eye. RESULTS: Inter-observer reliability was moderate to substantial (Kappa 0.5-0.88) whilst intra-observer agreement was high (0.6-1.0). The prevalence of any soft drusen was 32%. Significant associations were found between soft large indistinct drusen, hypopigmentation, hyperpigmentation and age (p = 0.0001, 0.024 and 0.0001, respectively). The study has at least 87% power to detect an odds ratio equal to two for the progression of soft distinct, soft indistinct, hyperpigmentation and hypopigmentation. CONCLUSIONS: The VECAT study methodology appears to be highly reliable and to have sufficient power to detect the differences in the four-year progression of soft distinct and indistinct drusen and pigment abnormalities between the treatment groups.

Aged↗
PubMed1999

Methodology of the VECAT study: vitamin E intervention in cataract and age-related maculopathy.

Cataract is the leading cause of blindness in the world today, while age-related macular degeneration is responsible for the majority of new cases of visual impairment in the Western world. There is a growing body of evidence suggesting a role for antioxidant therapy to prevent the progression of these conditions. A 4-year prospective, randomised, controlled trial of an antioxidant versus placebo in a population of healthy volunteers aged 55-80 years at enrolment is described. This paper outlines the primary aims of the Vitamin E, Cataract and Age-related Macular Degeneration (VECAT) Study, the methodology, and the recruitment rates. Additional data on the toxicity and non-ocular effects of vitamin E will also be collected. Standardised clinical grading of macular and lens features, and comparison of serial macular photographs and digital lens photographs will form the basis for assessment of primary study outcomes. Information collected in this study will assist in the assessment of the potential value of antioxidants in preventing the enormous burden imposed on developed communities by age-related eye disease. In addition, important data on prevalence and progression rates of cataract and macular degeneration will be collected.

Aged↗
PubMed1999

The need for cataract surgery: projections based on lens opacity, visual acuity, and personal concern.

AIM: To assess the projected needs for cataract surgery by lens opacity, visual acuity, and patient concern. METHODS: Data were collected as part of the Melbourne Visual Impairment Project, a population based study of age related eye disease in a representative sample of Melbourne residents aged 40 and over. Participants were recruited by a household census and invited to attend a local screening centre. At the study sites, the following data were collected: presenting and best corrected visual acuity, visual fields, intraocular pressure, satisfaction with current vision, personal health history and habits, and a standardised eye examination and photography of the lens and fundus. Lens photographs were graded twice and adjudicated to document lens opacities. Cataract was defined as nuclear greater than or equal to standard 2, 4/16 or greater cortical opacity, or any posterior subcapsular opacities. RESULTS: 3271 (83% response) people living in their own homes were examined. The participants ranged in age from 40 to 98 years and 1511 (46.2%) were men. Previous cataract surgery had been performed in 107 (3.4%) of the participants. The overall prevalence of any type of cataract that had not been surgically corrected was 18%. If the presence of cataract as defined was considered the sole criterion for cataract surgery with no reference to visual acuity, there would be 309 cataract operations per 1000 people aged 40 and over (96 eyes of people who were not satisfied with their vision, 210 eyes of people who were satisfied with their vision, and three previous cataract operations). At a visual acuity criterion of less than 6/12 (the vision required to legally drive a car), 48 cataract operations per 1000 would occur and people would be twice as likely to report dissatisfaction with their vision. CONCLUSIONS: Estimates of the need for cataract surgery vary dramatically by level of lens opacity, visual acuity, and patient concern. These data should be useful for the planning of health services.

Adult↗
PubMed1999

Variability in digital assessment of cortical and posterior subcapsular cataract.

To identify validity of the standardised Nidek EAS-1000 retroillumination image analysis, images of 450 consecutive patients were analysed for the standard 6.5 mm and for the maximal pupil size. The software allows for separation of cortical and posterior subcapsular opacities and defines threshold for cataract automatically at 12% below the brightest point of the histogram of pixel luminescence. The results were compared with clinical Wilmer cataract grading. Correlation between clinical and digital assessment was 0.48* for cortical opacities in maximal pupil size, 0. 47* in 6.5 mm pupil size analyses, and 0.71* for posterior subcapsular opacities (*p < 0.001). In 24.6% of maximal pupil size analyses and in 11.7% of standard pupil size analyses standardisation revealed confounding features, such as other opacities of media, refractive shadows etc., that masqueraded as cataract and interfered with the cortical opacity measurements. Automatic standardized analysis has reduced many sources of observer variation (level of illumination, pupil size and threshold adjustment), but the revealed range of confounding opacities and artifacts still requires observer interpretation.

Aged↗
PubMed1999

Comparison of clinical and digital assessment of nuclear optical density.

To compare the standardised Nidek EAS-1000 densitometric analysis of the lens with clinical assessment of the nucleus at an early stage of cataract development, 1,200 eyes of 1,204 participants of the VECAT study were assessed at the baseline using both subjective and objective lens grading. Standardisation of the automatic slit image analysis was achieved using a custom-designed EAS-1000 Software version 3.01c. Among 6 measurements of nuclear optical density, the mean pixel luminescence of integrated anterior nuclear density correlated best with clinical assessment (R = 0.662, p < 0.001). Variance components that interfere with the assessment are defined.

Aged↗
PubMed1999

Risk factors for pediatric presumed microbial keratitis: a case-control study.

PURPOSE: To evaluate risk factors for pediatric presumed microbial keratitis and to describe the clinical picture, microbiologic spectrum, treatment modalities, posttreatment sequelae, and visual outcome in cases of pediatric presumed microbial keratitis. METHODS: A case-control study design was used to identify the risk factors associated with pediatric presumed microbial keratitis. Fifty cases of fresh corneal ulceration aged 12 years or younger were compared with 50 controls. The study variables included were age, gender, immunization status, nutritional status (weight for height), and socioeconomic status. The clinical presentation of the cases with corneal ulceration, microbiologic spectrum, and treatment modalities also were evaluated. All the cases were followed up for a minimum of 3 months, and the posttreatment sequelae and visual outcome were analyzed. RESULTS: The mean (+/- standard deviation) age of children with corneal ulceration and controls was 4.8 (+/-3.8) years and 5.1 (+/-2.8) years, respectively. Incomplete immunization status (AOR [95% confidence interval (CI)], 1.34 [0.62-2.9]) and poor nutritional status [AOR (95% CI) 1.06 (0.68-1.6)] were not found to be the predictors of corneal ulceration. Lower socioeconomic status was significantly associated with the occurrence of corneal ulceration [AOR (95% CI) 1.52 (1.1-2.3)]. Corneal trauma (38%) and systemic illness (24%) were the most often associated predisposing factors. Seventy percent of the cases were culture positive. Staphylococcus (70%) species was the most frequently isolated, followed by Pseudomonas aeruginosa (10%). Fungi were isolated in five eyes. Postresolution visual acuity at 3 months could be recorded only in 31 eyes and a visual acuity of 6/18 or better was achieved in 22% of these cases. CONCLUSION: Corneal ulceration in pediatric age group in India is associated with poverty.

Body Height↗
PubMed1998

Prevalence and risk factors for diabetic retinopathy in the multiethnic population of Mauritius.

This study examines the prevalence of, and risk factors for, diabetic retinopathy in Asian Indian, Chinese, and Creole Mauritians in whom there is an increasing prevalence of non-insulin-dependent diabetes mellitus (NIDDM). As part of a population-based survey on the Indian Ocean island of Mauritius in 1992, glucose tolerance was classified using a 75-g oral glucose tolerance test on 6,553 persons. Subjects with newly diagnosed (n = 358) or known diabetes (n = 388), and a random sample of one in four subjects with impaired glucose tolerance (n = 165), had stereoscopic 45 degrees retinal photographs taken of three fields in the right eye after mydriasis. Photographs were graded according to a modified version of the Airlie House criteria. The prevalence of nonproliferative and proliferative retinopathy was: 14.5% and 0.3%, respectively, in newly diagnosed diabetic subjects; 42.0% and 2.3%, respectively, in known diabetic subjects; and 9.1% and 0%, respectively, in persons with impaired glucose tolerance. Muslim Indians had the lowest prevalence of retinopathy (10.8% and 34.0% for new and known diabetes, respectively), but after adjusting for other factors, this was significantly different only to Creoles (18.8% and 53.8%, respectively). Univariate analysis revealed significant differences between diabetic subjects with and without retinopathy in mean age, body mass index, fasting and 2-hour plasma glucose levels, systolic and diastolic blood pressure, fasting triglycerides, serum creatinine, and urinary albumin levels. For known diabetes, mean duration of diabetes and the proportion using insulin were also greater in those with retinopathy. Multivariate analysis using logistic regression confirmed that increasing duration of diabetes, fasting plasma glucose, systolic blood pressure, and urinary albumin concentration, and decreasing body mass index, were independently associated with retinopathy. The high prevalence of diabetic retinopathy observed in all major ethnic groups in Mauritius portends a serious public health problem, given the relative recency of the NIDDM epidemic in that country and the limited resources for laser photocoagulation. Strategies to minimize this problem among those already known to have diabetes should include strict control of plasma glucose and blood pressure.

Age Factors↗
PubMed1998

The prevalence of glaucoma in the Melbourne Visual Impairment Project.

PURPOSE: The purpose of the study was to determine the prevalence of glaucoma in Melbourne, Australia. METHODS: All subjects were participants in the Melbourne Visual Impairment Project (Melbourne VIP), a population-based prevalence study of eye disease that included residential and nursing home populations. Each participant underwent a standardized eye examination, which included a Humphrey Visual Field test, applanation tonometry, fundus examination including fundal photographs, and a medical history interview. Glaucoma status was determined by a masked assessment and consensus adjudication of visual fields, optic disc photographs, intraocular pressure, and glaucoma history. RESULTS: A total of 3271 persons (83% response rate) participated in the residential Melbourne VIP. The overall prevalence rate of definite primary open-angle glaucoma in the residential population was 1.7% (95% confidence limits = 1.21, 2.21). Of these, 50% had not been diagnosed previously. Only two persons (0.1%) had primary angle-closure glaucoma and six persons (0.2%) had secondary glaucoma. The prevalence of glaucoma increased steadily with age from 0.1% at ages 40 to 49 years to 9.7% in persons aged 80 to 89 years. There was no relationship with gender. The authors examined 403 (90.2% response rate) nursing home residents. The age standardized rate for this component was 2.36% (95% confidence limits = 0, 4.88). CONCLUSION: The rate of glaucoma in Melbourne rises significantly with age. With only half of patients being diagnosed, glaucoma is a major eye health problem and will become increasingly important as the population ages.

Adult↗
PubMed1998

The epidemiology of dry eye in Melbourne, Australia.

OBJECTIVE: To describe the epidemiology of dry eye in the adult population of Melbourne, Australia. DESIGN: A cross-sectional prevalence study. PARTICIPANTS: Participants were recruited by a household census from two of nine clusters of the Melbourne Visual Impairment Project, a population-based study of age-related eye disease in the 40 and older age group of Melbourne, Australia. Nine hundred and twenty-six (82.3% of eligible) people participated; 433 (46.8%) were male. They ranged in age from 40 to 97 years, with a mean of 59.2 years. MAIN OUTCOME MEASURES: Self-reported symptoms of dry eye were elicited by an interviewer-administered questionnaire. Four objective assessments of dry eye were made: Schirmer's test, tear film breakup time, rose bengal staining, and fluorescein corneal staining. A standardized clinical slit-lamp examination was performed on all participants. Dry eye for the individual signs or symptoms was defined as: rose bengal > 3, Schirmers < 8, tear film breakup time < 8, > 1/3 fluorescein staining, and severe symptoms (3 on a scale of 0 to 3). RESULTS: Dry eye was diagnosed as follows: 10.8% by rose bengal, 16.3% by Schirmer's test, 8.6% by tear film breakup time, 1.5% by fluorescein staining, 7.4% with two or more signs, and 5.5% with any severe symptom not attributed to hay fever. Women were more likely to report severe symptoms of dry eye (odds ratio [OR] = 1.85; 95% confidence limits [CL] = 1.01, 3.41). Risk factors for two or more signs of dry eye include age (OR = 1.04; 95% CL = 1.01, 1.06), and self-report of arthritis (OR = 3.27; 95% CL = 1.74, 6.17). These results were not changed after excluding the 21 people (2.27%) who wore contact lenses. CONCLUSIONS: These are the first reported population-based data of dry eye in Australia. The prevalence of dry eye varies by sign and symptom.

Adult↗
PubMed1998

Evaluation of axis alignment system for correction of myopic astigmatism with the excimer laser.

PURPOSE: To evaluate the efficacy of in situ axis alignment for the treatment of myopic astigmatism with an excimer laser. METHODS: In this prospective clinical trial, 71 eyes with stable astigmatism of -1.00 to -6.00 diopters (D) with or without stable myopia of up to 10.00 D were randomized to receive excimer treatment of their astigmatic component aligned to the axis determined by subjective refraction (control group) or to have the alignment verified and altered is necessary by in situ alignment (axis alignment group). A VISX Twenty-Twenty excimer laser was used for the treatment. Patients were followed for 6 months. RESULTS: In 85% of eyes in the axis alignment group, the axis of cylinder was different from that calculated by routine refraction. Pretreatment mean cylinder was -1.81 D +/- 0.91 (SD) in the axis alignment group and -1.75 +/- 0.60 D in the control group. At 6 months, an undercorrection of cylinder was seen in both groups; the mean residual cylinder was -0.70 +2- 0.56 D in the axis alignment group and -0.59 +/- 0.50 D in the control group. More than 80% of all eyes were within +/- 1.00 D of plano and achieved an uncorrected visual acuity of 6/12 or better. A loss of two or more lines of best corrected visual acuity was recorded in three eyes. CONCLUSION: The in situ alignment technique did not produce better results of photoastigmatic refractive keratectomy than the routine axis alignment technique.

Adult↗
PubMed1998

Excimer laser correction of astigmatism with multipass/multizone treatment. The Melbourne Excimer Laser Group.

PURPOSE: To evaluate the accuracy of excimer laser correction of myopic astigmatism by multipass/multizone photoastigmatic refractive keratectomy (PARK). SETTING: Tertiary referral ophthalmic hospital with an associated private laser facility. METHODS: This study comprised a consecutive series of 332 eyes of 289 patients who were followed for 6 months. All patients were 18 years or older, had stable myopic astigmatism (up to a -19.0 diopters [D] spherical equivalent [SE] at the spectacle plane), and had a best corrected visual acuity of at least 20/60 in both eyes. All eyes were treated with a VISX Twenty-Twenty excimer laser. The correction was divided between ablation zones using a multipass/multizone treatment paradigm based on the amount of myopia and astigmatism. Patients were examined 1 week, and 1, 3, and 6 months after surgery. RESULTS: Analysis of the mean percentage of spherical correction across the range of myopic preoperative SEs treated demonstrated 90% correction for most amounts of myopic astigmatism. Eyes with low myopia (mean preoperative SE < or = -5.0 D) treated with < or = -1.0 diopter cylinder (DC) of astigmatism achieved a mean percentage of spherical correction of 91% versus 93% in eyes with high myopia (> -5.0 D mean preoperative SE). Eyes with low myopia treated with > -1.0 DC of astigmatism achieved a mean percentage spherical correction of 90% versus 89% in eyes with high myopia. The differences between the two groups were not statistically significant. Patients with high relative cylinder (> 80% of total sphere treated) achieved comparable results. Analysis of the astigmatic component of the treatment, independent of the spherical result, showed a trend toward overcorrection in the high myopia group with less than -1.0 DC and a mean astigmatic correction of 89 and 98%, respectively, in the low and high myopic astigmatism groups. The mean angle of error was +2.0 degrees. CONCLUSION: Multipass/multizone PARK for myopic astigmatism demonstrated a high degree of predictability and stability with desirable results for low and high levels of astigmatism across the range of myopic astigmatism treated by surface ablation.

Adult↗
PubMed1998

Methods for the Hong Kong Vision Study: a pilot assessment of visual impairment in adults.

INTRODUCTION: The Hong Kong Vision Study (HKVS) was a pilot study to collect data on the prevalence of eye diseases and risk factors in Hong Kong using methodology comparable to that developed in America and Australia. AIM: The main goal was: to evaluate the application of the methodology in a different culture and language; and to determine the prevalence and risk factors of eye diseases in order to design a larger study of an ethnic Chinese population. METHOD: This study was patterned after the Melbourne Visual Impairment Project using the Chinese language in data collection and examinations. CONCLUSION: Well-designed methodology is transferable to different cultures, languages and continents. Use of similar methodology will enable better comparisons and analyses to be made from population-based data.

Adult↗
PubMed1998

Lattice corneal dystrophy: epithelial macroerosions in clear corneal grafts.

Two sisters, aged 33 and 35, underwent uncomplicated penetrating keratoplasty for lattice corneal dystrophy type 1. Both patients, as well as their younger brother, had experienced frequent recurrent epithelial erosions prior to undergoing corneal grafting. Each sister has subsequently experienced painful, corneal epithelial macroerosions in the corneal graft, in the absence of any signs of recurrence of the lattice corneal dystrophy in the grafted tissue. With treatment each episode of macroerosion has resolved without complication. To our knowledge, this is the first report of epithelial erosions in a corneal graft without clinical evidence of recurrent lattice corneal dystrophy.

Adult↗
PubMed1998

Pterygium surgery in Victoria: a survey of ophthalmologists.

AIM: To determine the surgical approaches and adjunctive therapy es currently used by Victorian ophthalmologists for the treatment of primary and recurrent pterygia. METHOD: Ophthalmologists practising in Victoria were asked to complete a written survey relating to their experience with pterygium surgery. RESULTS: Responses were received from 142 of 165 ophthalmologists surveyed (86%). Of these, 107 (75%) had performed at least one pterygium operation during the preceding 2 years. Excision followed by beta irradiation was the most commonly performed procedure for both primary (57%) and recurrent (35%) pterygia. The next most commonly performed procedure for primary pterygia was excision leaving bare sclera (15%) and, for recurrent pterygia, excision with autologous conjunctival transplantation (26%). Considerable variation was observed in surgical technique, choice of adjunctive therapy, postoperative care and in the surgeons' estimates of the frequency of major complications. CONCLUSION: Although there is little consensus regarding the surgical management of pterygium, beta irradiation remains the most commonly used adjunctive therapy in Victoria.

Chemotherapy, Adjuvant↗
PubMed1998

Patterns of glaucoma medication use in urban and rural Victoria.

PURPOSE: The purpose of the present study was to describe patterns of glaucoma medication use among people who self-report a history of glaucoma in a population-based study of age-related eye disease. METHODS: The present study was comprised of a population-based cluster stratified sample of 5000 Victorians aged 40 years and older. Participants completed an interview regarding demographic characteristics, medical history and use of medications. Participants also completed orthoptic and dilated fundus examinations, including measurement of intra-occular pressure (IOP) and visual fields. Glaucoma history and use of glaucoma medication was self reported. Glaucoma disease status was confirmed by a specialist consensus group. RESULTS: The most common glaucoma medications used were beta-adrenoceptor blocking agents (63%), followed by sympathomimetics (18%) and cholinergic agents (16%). There were no differences in glaucoma medication use by gender, age, years since diagnosis, rural or urban residence or a history of glaucoma surgery. Among participants using medication, 16.1% exceeded 21 mmHg IOP. CONCLUSION: The high prevalence of the use of beta-adrenoceptor blocking agent medication reflects the shift from the use of pilocarpine over the past 20 years. The prevalence of IOP greater than 21 mmHg highlights the difficulty in managing high IOP.

Adrenergic beta-Antagonists↗