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Biomedical subjects

C A McCarty

Publications and source records attributed to C A McCarty.

At least 109 records · Page 6Linked to original sources
PubMed1997

Visual impairment in Australia: distance visual acuity, near vision, and visual field findings of the Melbourne Visual Impairment Project.

PURPOSE: To describe the age-specific and gender-specific rates of blindness and visual impairment in urban adults aged 40 years and older. METHODS: A population-based sample of residents was recruited. Presenting and best-corrected distance visual acuities were assessed. Functional near vision was measured at each participant's preferred distance. Visual field examination was performed with a Humphrey Field Analyzer (HFA); those unable to perform the field analyzer test attempted a Bjerrum screen or confrontation field. RESULTS: The study population comprised 3,271 residents (83% of eligible) from ages 40 to 98 years; 54% were women. Overall, 56% of the study population wore distance correction; this was significantly lower in men but higher in the older age groups. Age-adjusted rates of blindness were 0.066% in men and 0.170% in women. Vision with current correction improved after refraction by gender and age. Direct age-standardized rates of functional near vision did not vary significantly by gender. Forty-six people had significant visual field loss in their better eye. The proportion of participants with constriction of the visual field to within 20 degrees of fixation was similar for men and women when controlled for age (odds ratio, 0.81; 95% confidence interval, 0.44 to 1.49) but increased significantly with age controlled for gender. Visual field abnormalities were detected in 548 right eyes (17%) and 533 left eyes (16%). CONCLUSIONS: Although overall rates of blindness because of visual acuity loss were relatively low, nearly three times more people had visual impairment because of visual field loss than visual acuity loss. These results highlight the need to target blindness prevention programs to the aging population, with a special emphasis on women.

Adult↗
PubMed1997

Visual impairment and socioeconomic factors.

BACKGROUND: Information about socioeconomic factors associated with visual impairment can assist in the design of intervention programmes. Such information was collected by the Melbourne Visual Impairment Project (Melbourne VIP). METHODS: The Melbourne VIP was a population based study of non-institutionalised permanent residents in nine suburbs of the Melbourne metropolitan area aged 40 years of age and older. A standardised eye examination was provided to eligible residents which included a structured interview. Variables of interest for this analysis were age, sex, country of birth, language spoken at home, education level, use of private health insurance, employment status, and living arrangements. Visual impairment was defined as a best corrected visual acuity < 6/18 and/or visual field constriction to within 20 degrees of fixation. RESULTS: A total of 3271 (83%) residents participated. Participants ranged in age from 40 to 98 years; 54% were female. Forty four (1.34%) were classified as visually impaired due to visual acuity and/or visual field loss. To evaluate the independent association of the significant sociodemographic variables with visual impairment, a regression model was constructed that included age, retirement status, use of private health insurance, and household arrangement. The results showed that age was the significant predictor of visual impairment (OR: 3.19; CI: 2.29-4.43), with the mean age of people with visual impairment significantly older (75.0 years) compared with people without visual impairment (58.2 years) (t test = 9.71; p = 0.0001). Of the 44 visually impaired people, 39 (87%) were aged 60 years of age and older. CONCLUSION: The results indicate that age is the most significant factor associated with visual impairment. Of some importance was the finding that people with visual impairment were less likely to have private health insurance. With the aging of the population, the number of people affected by visual impairment will increase significantly. Intervention programmes need to be established before the onset of middle age to offset the escalation of visual impairment in the older population.

Adult↗
PubMed1997

A comparison of participants with non-participants in a population-based epidemiologic study: the Melbourne Visual Impairment Project.

PURPOSE: Adequate participation in population-based studies in essential to ensure that the sample is representative of the population under investigation. Participants may differ from non-participants on important variables such as age, sex socioeconomic status, and general health factors. The Melbourne Visual Impairment Project (Melbourne VIP) is a population-based study designed to increase understanding of the prevalence and severity of common ocular disorders affecting people 40 years of age and over. AIM: The aim of this study was to determine the potential for any non-response bias by comparing data from participants and non-participants of the Melbourne VIP. METHODS: Specific demographic and general variables were compared between the two groups. The variables included age, sex, education level, and social status. The reason for non-attendance was also recorded. RESULTS: A total of 3271 (83%) eligible residents from the 9 sample areas were screened; 46% males and 54% females. Language spoken at home was significantly associated with participation. Residents whose main language at home was not English were less likely to attend the screening centre. (OR: 0.60; CI: 0.44-0.81). The main reasons given for non-attendance by eligible residents were lack of interest (6%), too busy to attend (4%), personal illness (2%), and attend own eye specialist (2%). CONCLUSION: We believe these results will not impact significantly on the interpretation of gender and age-specific data from the Melbourne VIP.

Adult↗
PubMed1997

Reliability of a food frequency questionnaire to assess dietary antioxidant intake.

OBJECTIVE: Epidemiologic evidence of a role for antioxidants in the prevention of chronic disease has been inconclusive, in part due to the difficulty of measuring past diets of free-living populations. The purpose of the current study was to examine the reliability of a 19-item, self-administered, semiquantitative, food frequency questionnaire to assess intake of the major dietary antioxidants. METHODS: Reliability was established by administering the food frequency questionnaire a second time by telephone. The subjects comprised 151 participants in the Melbourne Visual Impairment Project, a study of the distribution and determinants of eye disease in Melbourne residents aged 40 and over. RESULTS: Spearman correlation coefficients ranged from 0.39 for spinach to 0.76 for yoghurt, and all were highly significant (all p = 0.001). The reliability of the instrument was not influenced by gender, English speaking ability, or the number of days between the first and second administration of the questionnaire. CONCLUSION: In conclusion, we have shown this 19-item food frequency questionnaire to be highly reliable. It should be useful for anyone involved in the study of the relationship of dietary antioxidant intake to health outcomes in large populations where limitations of time and money prohibit the collection of more detailed dietary intake information.

Adult↗
PubMed1997

Design of a population-based study of visual impairment in India: The Andhra Pradesh Eye Disease Study.

Reliable population-based epidemiologic data regarding vision and ocular morbidity, as well as those about the perceptions of people regarding visual impairment and eye care, are lacking for the most part in the developing world including India. These data are the basis on which effective eye care services can be developed. To meet this need we designed the Andhra Pradesh Eye Disease Study, a population-based epidemiology study of 10,000 people in the Indian state of Andhra Pradesh. The design of this study is described in this paper. Various options for the sample size, study areas, sampling procedure, and recruitment of subjects were considered. A sample size of 10,000 people, 5,000 each in the < or = 30 and > 30 years age groups, was determined to obtain reasonable confidence in estimating the prevalence of diseases and odds ratios for risk factors of interest. A multistage sampling strategy was chosen for the study which was assumed to give a design effect of 1.5 for the estimates. One urban area, Hyderabad, and three rural areas, West Godavari, Adilabad and Mahbubnagar districts, were selected in Andhra Pradesh. Interview instruments were developed to obtain detailed information about demographic data, diet, ocular and systemic history, risk factors for eye diseases, visual function, quality of life, barriers to eye care, and knowledge about eye diseases. A detailed examination procedure was devised to obtain a broad range of normative and abnormal data related to eyes and vision. A protocol was developed for doing automated visual fields, slitlamp and fundus photography. Computer databases were made in FoxPro for data entry and subsequent analysis with SPSS. Pilot studies were done to test the instruments, procedures, and logistics of the study in urban and rural areas. Information from the Andhra Pradesh Eye Disease Study is expected to help in planning and implementation of effective long-term preventive, curative, and rehabilitative eye care services in Andhra Pradesh.

Blindness↗
PubMed1996

Diabetic retinopathy: examination practices and referral patterns of general practitioners.

OBJECTIVE: To investigate general practitioners' (GPs') examination and referral practices for diabetic retinopathy. METHODS: A questionnaire survey of a random stratified sample of 500 Victorian GPs. RESULTS: The response rate was 88%. 53% of GPs examined none or less than half of their patients with diabetes for diabetic retinopathy. Those who did examine for retinopathy rarely performed funduscopy through a dilated pupil and 65% reported that they never did. Only 37% had dilating drops in their surgery. Only 45% often or always tested visual acuity. 88% often or always referred patients at the recommended frequency to an ophthalmologist. CONCLUSIONS: Although most GPs do not perform dilated fundus examinations, they report referring their patients with diabetes for assessment by an ophthalmologist at an early stage to prevent vision loss. Referral chain breakdown may explain the discrepancy between GPs' reported referral rates and the lower rates of ophthalmic examination reported in the Melbourne Visual Impairment Project.

Clinical Competence↗
PubMed1996

Predictability of excimer laser treatment of myopia. Melbourne Excimer Laser Group.

OBJECTIVE: To prospectively examine the predictability of excimer laser photorefractive keratectomy and photoastigmatic refractive keratectomy for myopia that ranged from -1 to -18 diopters (D). METHODS: Patients were treated with an excimer laser and followed up prospectively for 12 months. Low myopia was treated in one ablation zone (6.0 mm), high myopia in two ablation zones (5.0 and 6.0 mm), and extreme myopia in three ablation zones (4.5, 5.0, and 6.0 mm) with a maximum treatment of 15 D. Data were analyzed to determine the distribution of the various postoperative outcomes by preoperative myopia. RESULTS: Two hundred seventy-four low myopes, 189 high myopes, and 41 extreme myopes were available for 12-month follow-up. The re-treatment rate increased with preoperative myopia. The predictability of refraction and uncorrected and best corrected visual acuity progressively decreased with increasing myopia. The likelihood of losing lines of best corrected visual acuity and corneal haze increased with increasing myopia. CONCLUSION: These data should help in the counseling of patients about the likely outcome if they have excimer laser surgery to correct myopia.

Adult↗
PubMed1996

Overcorrection after excimer laser treatment of myopia and myopic astigmatism. Melbourne Excimer Laser Group.

OBJECTIVE: To study the incidence and associations of overcorrection after excimer laser treatment of myopia and myopic astigmatism. METHODS: The study cohort consisted of 645 patients who had photorefractive or photoastigmatic refractive keratectomy done by an excimer laser during a 2-year period. Patients were assessed 1,3,6, and 12 months postoperatively. The variables evaluated were visual acuity, refraction, keratometry, and corneal clarity. RESULTS: At 1 month, overcorrection of more than +1 diopter spherical equivalent (SEQ) was seen in 22% of the eyes. This progressively regressed so that only 8.6% of the 140 eyes that were overcorrected at 1 month were overcorrected at 1 year. Overall, 2.2% of eyes were overcorrected at 1 year. The magnitude of attempted correction and use of topical nonsteroidal anti-inflammatory drugs disclosed a notable association with occurrence of overcorrection at 1, 3, and 6 months. The use of bandage contact lenses also was associated with overcorrection at 1 and 3 months. After controlling for myopia and use of contact lenses, the odds of overcorrection for use of topical nonsteroidal anti-inflammatory drugs at 1,3, and 6 months were 2.21 (95% confidence limits [CL]=1.49, 3.44), 1.69 (95% CL=0.88, 3.24), and 2.01 (95% CL=0.88, 4.56), respectively. The odds of overcorrection with bandage contact lenses were 1.79 (95% CL=1.05, 3.05) at 1 month and 2.42 (95% CL=1.23, 4.75) at the end of 3 months. No associations were seen between overcorrection and age, gender, surgical technique, or simultaneous astigmatic corrections. CONCLUSIONS: Overcorrection is common during the early postlaser treatment period and is associated with degree of myopia, use of nonsteroidal anti-inflammatory drugs, and bandage contact lens wear.

Adult↗
PubMed1996

Retreatment after excimer laser photorefractive keratectomy. The Melbourne Excimer Laser Group.

PURPOSE: To determine the risk factors for undercorrection of myopia after photorefractive keratectomy and to evaluate the efficacy and safety of retreatment. METHODS: A VISX Twenty/Twenty excimer laser was used to treat myopia and myopic astigmatism of up to -15.00 diopters (spherical equivalent) at the corneal plane. Retreatments were performed primarily for undercorrection with or without coexistent corneal haze or abnormalities on videokeratoscopy. Not every patient who was undercorrected requested retreatment. RESULTS: Of 645 eyes (440 patients) followed up for more than 12 months, 58 eyes (9%) required retreatment. The retreatment rate increased with increasing myopia: 17 (5%) eyes with myopia of less than -5.00 diopters, 30 (13%) eyes with myopia of -5.01 to -10.00 diopters, and 11 (19%) eyes with myopia of greater than -10.00 diopters required a second procedure. A higher retreatment rate was observed after astigmatic corrections than after spherical corrections. Corneal haze after retreatment was no greater than that observed after initial procedures. Twelve months after primary procedures, 378 (75%) of 504 eyes were within 1.00 diopter of emmetropia, whereas 27 (69%) of 39 eyes attained this result after retreatment. A total of 383 (76%) of 504 eyes attained uncorrected visual acuity of 20/40 or better after primary procedures, compared with 25 (64%) of 39 eyes after retreatment. CONCLUSIONS: The risk of undercorrection requiring retreatment after photorefractive keratectomy increases with the magnitude of the primary treatment. Although less successful than initial procedures, retreatment appears to enhance the results of photorefractive keratectomy.

Adult↗
PubMed1996

Undercorrection after excimer laser refractive surgery. Excimer Laser Group.

PURPOSE: The incidence and correlations of undercorrection were studied for 1 year after excimer laser surgery for myopia or myuopic astigmatism. METHODS: A consecutive series of 645 eyes of 440 patients were studied. Eyes were examined preoperatively and at 1, 3, 6, and 12 months after surgery. The parameters evaluated were visual acuity, refraction, and corneal clarity. RESULTS: Following excimer laser surgery, undercorrection of > or = -1.00 diopters gradually increased from 10% at 1 month to 40% at 12 months. Increasing degree of preoperative myopia was significantly associated with increasing occurrence of undercorrection at 3 months (chi 2 = 17.3, P < .001), 6 months (chi 2 = 53.6, P < .001), and 12 months (chi 2 = 64.8, P < .001). Undercorrection was more common in eyes that had had photorefractive keratectomy than in those that had had photoastigmatic refractive keratectomy (odds ratio, 0.40; 95% confidence interval, 0.25 to 0.60). At 1 year, a loss of 2 or more lines of best-corrected visual acuity was recorded in 38% of undercorrected patients. Loss of 2 or more lines of best-corrected visual acuity was more common in patients undercorrected by -1.00 diopter or more (odds ratio, 8.8; 95% confidence interval, 5.4 to 14.6). No relationship was seen between corneal haze and loss of best-corrected visual acuity. Undercorrection was not associated with age, gender, use of nonsteroidal anti-inflammatory drugs, bandage contact lens wear, or corneal haze. Patients with lower degrees of myopia reached a stable refraction more quickly. At 6 months, 71% were within +/- 0.5 diopter of 1-year refraction. Of 17 patients with undercorrection who were treated with topical corticosteroids, only one patient showed a permanent beneficial change. CONCLUSION: Occurrence of undercorrection is more common in patients with severe myopia and when simultaneous astigmatic corrections are undertaken.

Adult↗
PubMed1996

Comparison of results of excimer laser correction of all degrees of myopia at 12 months postoperatively. The Melbourne Excimer Laser Group.

UNLABELLED: To examine prospectively the efficacy and safety of photorefractive keratectomy and photoastigmatic refractive keratectomy. METHODS: We treated 645 eyes (440 patients) with a VisX Twenty/Twenty excimer laser and followed them up for 12 months. RESULTS: The percentage of eyes with myopia between -5.01 and -10.00 diopters spherical equivalent within 1 and 2 diopters of emmetropia at 12 months was 65% (123 of 189) and 90% (170 of 189), respectively, whereas the corresponding percentages for eyes with myopia greater than -10.00 diopters spherical equivalent were 39% (16 of 41) and 56% (23 of 41), and for eyes with myopia of -5.00 diopters spherical equivalent or less, 87% (238 of 273) and 99% (270 of 273), respectively. Uncorrected visual acuity of 20/20 and 20/40 or better at 12 months was attained in 47% (129 of 273) and 87% (237 of 273) of the eyes with myopia -5.00 diopters spherical equivalent or less, respectively. At 12 months, 48 (25%) of the 189 eyes with myopia between -5.01 and -10.00 diopters spherical equivalent had uncorrected visual acuity of 6/6 or better and 135 (71%), 6/12. At 12 months, one eye (2%) with myopia greater than -10.00 diopters spherical equivalent had uncorrected visual acuity of 6/6 and 11 (27%) of 41 eyes, 6/12. Ten (4%) of the 273 eyes with myopia of -5.00 diopters spherical equivalent or less, 15 (8%) of the 189 eyes with myopia between -5.01 and -10.00 diopters spherical equivalent, and nine (22%) of the 41 eyes with myopia greater than -10.00 diopters spherical equivalent had lost two or more LogMAR lines of best-corrected visual acuity at 12 months. CONCLUSION: Excimer laser surgery is highly reliable for myopia of -5.00 diopters spherical equivalent or less and is less reliable for greater myopia.

Adult↗
PubMed1996

Astigmatic change 1 year after excimer laser treatment of myopia and myopic astigmatism. Melbourne Excimer Laser Group.

PURPOSE: To evaluate the surgically induced astigmatism (SIA) 1 year after excimer laser photorefractive astigmatic keratectomy (PARK) and photorefractive keratectomy (PRK). SETTING: Royal Victorian Ear and Eye Hospital, Melbourne, Australia. METHODS: This study comprised 333 PARK patients and 155 PRK patients treated with a VISX 20/20 excimer laser and followed prospectively for 12 months. Vector analysis of the change in astigmatism was used to calculate the SIA in the PRK group and the percentage of astigmatism corrected in the PARK group. RESULTS: Among patients with low cylinders astigmatic correction varied greatly, particularly in those treated for large amounts of myopia. The spherical PRK treatments yielded a mean induced postoperative astigmatism of 0.47 diopter. There was a linear relationship between this inadvertent SIA and increasing myopia. CONCLUSION: Excimer laser surgery for myopia creates a low degree of random, unpredictable SIA that may be the result of irregular epithelial thickening during postoperative healing. This creates a background noise of astigmatic change upon which the targeted astigmatic correction is superimposed.

Adult↗
PubMed1996

Relation of hormone and menopausal status to outcomes following excimer laser photorefractive keratectomy in women. Melbourne Excimer Laser Group.

PURPOSE: To examine the effect of hormone use, pregnancy and menopausal status on clinical outcomes following excimer laser surgery for myopia and myopic astigmatism. METHODS: Participants comprised all female patients of the Melbourne Excimer Laser Group (MELG). A standardised surgical protocol was followed by the 27 MELG members, using the VisX 20/20 excimer laser and included the prospective collection of the following information preoperatively and one, three, six and 12 months after the procedure: uncorrected and best corrected visual acuity with a LogMAR chart; best manifest refraction; and subjective assessment of corneal clarity. A survey that elicited information about oral contraceptive (OC) use, pregnancy history, surgical and natural menopause, and use of hormone replacement therapy (HRT) was mailed to all the women. RESULTS: A 77% response to the mailed survey was achieved. Two women were pregnant at the time of surgery, one became pregnant during the first month after surgery, and all three women were excluded from further analyses, although a review of two of the case histories revealed suboptimal clinical outcomes. Women taking OC were included in the control group after OC use was shown not to be associated with outcome. Women were grouped accordingly: control, n = 225, pre-menopausal on HRT, n = 7, post-menopausal not on HRT, n = 34; and post-menopausal on HRT, n = 21. The groups differed significantly with regard to age and preoperative spherical equivalent. After controlling for age and preoperative spherical equivalent, the mean number of uncorrected LogMAR letters read one year after surgery was significantly lower for the post-menopausal women on the HRT in comparison with the control group. Best corrected acuity and corneal clarity were not significantly different among the groups. DISCUSSION: These preliminary results suggest that the interaction of menopausal and HRT status could decrease the effectiveness of PRK and PARK, but require confirmation with a further study in a prospective manner using objective measures of corneal epithelial healing and serum hormone levels.

Adult↗
PubMed1996

Ocular exposure to UV-B in sunlight: the Melbourne visual impairment project model.

Quantification of ocular exposure to ultraviolet-B radiation (UV-B) has become an important public health issue, with reports that the ozone layer is being depleted worldwide. Ocular exposure to UV-B is determined by ambient UV-B levels, the duration of outdoor exposure, the proportion of ambient UV-B that reaches the eye, and the use of ocular protection. We have developed a simplified model for quantifying lifetime ocular UV-B exposure that can be used in large epidemiological surveys. Exposure to UV-B is assessed and quantified using a model based on personal exposure over the six summer months. Data available for a population-based sample of 1150 people in the age range 40-98 years revealed a distribution in average annual lifetime ocular UV-B exposure similar to that reported in a previous study on which this model is based, and also demonstrate that people can recall lifetime personal behaviour related to ocular protection. It takes 12 minutes on average to collect these data. This model can be employed by researchers worldwide for uniform assessment of ocular UV-B exposure.

Adult↗