Recent developments in vision research: light damage in cataract.
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Antioxidants↗
Biomedical subjects
H R Taylor
Publications and source records attributed to H R Taylor.
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↗
A simplified screening test for identifying people with low vision in developing countries.
Simple but effective tests have been produced for screening subjects with low vision in developing countries. These tests of distance and near vision, based on the E test, were evaluated and validated in trials with people aged 4-90 years, and have been field tested in the health, education and rehabilitation services in 32 developing countries. Their sensitivity and specificity as screening tools for low vision have been calculated; sensitivity of 85% and specificity of 96% for the distance vision test, and sensitivity of 100% and specificity of 84% for the near vision test. The content and format of the tests have been demonstrated to be appropriate for developing countries, and their effectiveness for screening for low vision has been confirmed.
Adolescent↗
Early detection of diabetic retinopathy.
Diabetic retinopathy remains a leading cause of blindness in Australia. Most cases can be prevented by timely laser photocoagulation and this requires early detection of asymptomatic retinopathy. The Australian Diabetes Society recommends regular retinal examinations through dilated pupils, either at diagnosis of diabetes (onset over 30 years), or five years after diagnosis (onset under 30 years). Examination should be repeated at least every two years, or more frequently in the presence of visual symptoms, pregnancy or other risk factors. Diabetic patients and primary care physicians should be better informed about the effectiveness of timely treatment of diabetic retinopathy and the need for regular eye examinations, either by general practitioners or through referral to ophthalmologists.
Adult↗
Chlamydia trachomatis conjunctivitis. Prevalence and association with genital tract infection.
OBJECTIVES: To determine the prevalence of Chlamydia trachomatis in acute conjunctivitis (non-trachoma) in Australia and to examine the source of transmission. DESIGN: A prospective survey of 400 consecutive patients presenting with acute conjunctivitis to the Royal Victorian Eye and Ear Hospital Emergency Department, Melbourne, from May to November 1991. Patients identified with chlamydial conjunctivitis during the survey period and in the following two months were assessed for concomitant genital infection. RESULTS: Chlamydia was the causative organism in 2% of patients with acute conjunctivitis. Of 15 patients with chlamydial conjunctivitis, 11 presented with disease in one eye only, and the same number had had symptoms for longer than two weeks. Many had been seen previously by experienced ophthalmologists, yet there were long delays in making a definitive diagnosis. Ten of the 12 adult patients who were assessed had signs of concomitant genital tract infection, although none had past or current genital tract symptoms. Serotyping of chlamydial isolates from the genital tract and eye showed concordance in individual patients. CONCLUSION: Most cases of ocular chlamydia infection have a genital source. Therefore, it is essential that all patients with chlamydial conjunctivitis and their sexual partners are examined and treated for concomitant genital infection.
Acute Disease↗
Impact of face-washing on trachoma in Kongwa, Tanzania.
Observational studies have suggested that the prevalence of trachoma is lower in children with clean faces than in those with ocular or nasal discharge or flies on the face. We carried out a community-based randomised trial in three pairs of villages to assess the impact on trachoma of a face-washing intervention programme following a mass topical antibiotic treatment campaign. Six villages in Kongwa, Tanzania, were randomly assigned mass treatment plus the face-washing programme or treatment only. 1417 children aged 1-7 years in these villages were randomly selected and followed up for trachoma status and observations of facial cleanliness at baseline and 2, 6, and 12 months. At 12 months, children in the intervention villages were 60% more likely to have had clean faces at two or more follow-up visits than children in the control villages. The odds of having severe trachoma in the intervention villages were 0.62 (95% Cl 0.40-0.97) compared with control villages. A clean face at two or more follow-up visits was protective for any trachoma (odds ratio 0.58 [0.47-0.72]) and severe trachoma (0.35 [0.21-0.59]). This community-based participatory approach to face-washing intervention had variable penetration rates in the villages and was labour intensive. However, we found that, combined with topical treatment, community-based strategies for improving hygiene in children in trachoma-endemic villages can reduce the prevalence of trachoma.
Administration, Topical↗
Five-year incidence and disappearance of drusen and retinal pigment epithelial abnormalities. Waterman study.
PURPOSE: To obtain 5-year longitudinal data on age-related macular degeneration (AMD) that might be useful for disease prognosis, public health planning, and clinical trial development. PATIENTS AND METHODS: Baseline (1985) and 5-year follow-up (1990) fundus photographs of 483 watermen over 30 years of age who participated in a cohort study conducted on the eastern shore of Maryland were graded independently in a reliable, standardized fashion. Eyes in which AMD appeared or disappeared also were graded in a side-by-side fashion. RESULTS: Development of definite choroidal neovascularization and/or disciform scarring occurred in one of 50 participants over 70 years of age, specifically one of 15 participants over 70 years of age with AMD-3 (defined as large or confluent drusen focal hyperpigmentation of the retinal pigment epithelium [RPE], and/or nongeographic atrophy of the RPE). Appearance of large drusen, focal hyperpigmentation, or AMD-3 was age related, occurring in 5%, 1%, and 7%, respectively, of participants aged 50 to 59 years; 17%, 3%, and 14%, respectively, of participants aged 60 to 69 years; and 17%, 9%, and 26%, respectively, of participants aged 70 years or more. Disappearance of large drusen, hyperpigmentation, or AMD-3 occurred in 16 (34%) of 47 participants, 11 (58%) of 19 participants, and 17 (28%) of 61 participants, respectively, who had each feature photographically present in 1985. Among the 47 eyes identified in which AMD-3 developed by independent gradings, 38 cases of AMD-3 (81%) were confirmed on side-by-side grading. Among the 16 eyes identified as having AMD-3 that disappeared, nine disappearances (56%) were confirmed. Borderline differences in appearance of pigment, drusen size, drusen location, or photographic quality may have accounted for disappearance in seven cases (44%). CONCLUSIONS: Prospective studies on the nonneovascular features of AMD (including large drusen and abnormalities of the RPE) must account for the appearance and disappearance of these features and support the idea that side-by-side gradings can complement independent gradings identifying appearance or disappearance of features of AMD.
Adult↗
Excimer laser treatment for high and extreme myopia. The Melbourne Excimer Laser and Research Group.
OBJECTIVE: The excimer laser allows the controlled ablation of corneal tissue to correct refractive error. We assessed the efficacy of excimer laser treatment for persons with high (spherical equivalent between -5 and -10 diopters) and extreme (spherical equivalent greater than -10D) myopia. METHODS: Patients were assessed 1, 3, and 6 months postoperatively. A VisX Twenty/Twenty laser was used. Visual acuity, refraction, corneal clarity, and adverse reactions were evaluated at each visit. RESULTS: Six month follow-up data were available for 194 high myopes and 53 extreme myopes. Postoperative healing was similar for the two groups. Six months postoperatively, 89.2% of high myopes and 49% of extreme myopes were within 2D of planned refraction. At 6 months, 28% of high myopes had an uncorrected visual acuity of 20/20 and 71% had an uncorrected visual acuity of 20/40. Of extreme myopes, 4% had an uncorrected visual acuity of 20/20 and 30% had an uncorrected visual acuity of 20/40. Significantly more corneal haze was observed in the extreme myopes. Loss of 2 or more lines of best corrected visual acuity was observed in 13% of high myopes and 13% of extreme myopes at 6 months. CONCLUSIONS: Excimer laser photorefractive keratectomy is an alternative means of treating high and extreme myopia and can cause a significant reduction in myopia. There is a need to gather further information as more patients are followed up for greater time.
Adult↗
One-year evaluation of excimer laser photorefractive keratectomy for myopia and myopic astigmatism. Melbourne Excimer Laser Group.
OBJECTIVE: To evaluate prospectively the efficacy and safety of excimer laser photorefractive keratectomy in the treatment of myopia and myopic astigmatism. METHODS: Up to 15 diopters (D) of myopia with or without astigmatism of less than 6 D was treated with an excimer laser (VISX Twenty/Twenty). One hundred fifty procedures have been followed up for more than 12 months. RESULTS: Postoperative refractions were generally stable after 3 months without significant early overcorrection. Of those eyes treated with spherical equivalents of 5 D or less, 96% were within 1 D of the targeted refraction after photorefractive keratectomy and 88% had uncorrected visual acuities of 20/40 or better. At 12 months, 77% of all 150 eyes treated achieved an uncorrected visual acuity of 20/40 or better and 81% were within 1 D of the intended correction. Nine eyes (6%) lost 2 or more lines of best corrected visual acuity and 14 (9%) gained 2 or more lines. Adverse reactions were reported in 12 patients (8%) during the postoperative period. CONCLUSIONS: Photorefractive keratectomy is capable of correcting low and moderate myopic errors with a relatively high degree of accuracy and safety. The predictability and stability of the postoperative refraction during the first 12 months seem to be good.
Adult↗
Cigarette smoking and risk for progression of nuclear opacities.
OBJECTIVE: To examine the relationships between smoking and the 5-year incidence of new nuclear opacities and between smoking and the progression of nuclear opacities in a prospective study of a cohort of Chesapeake Bay watermen. METHODS: A total of 442 men (age, > or = 30 years in 1985) with paired, gradable lens photographs in at least one eye in both 1985 and 1990 were studied. Photographs were graded by two readers who used the grading scheme of the Wilmer Institute, Baltimore, Md, with severity ranging in decimal units between 0.0 and 4.0. Data on the smoking history of the subjects were collected by personal interviews that were conducted in 1985 and updated in 1990. RESULTS: The incidence and progression of opacities increased with age. A nonsignificant association was observed between smoking (for both current and ex-smokers) and the incidence of a nuclear opacity. The risk of progression of nuclear opacities of less than grade 3 at baseline to grade 3 or worse was 2.4-fold higher among current smokers in 1985, compared with that among ex-smokers and nonsmokers (95% confidence limits: 1.0, 6.0) after adjustment for age, baseline opacity status, and alcohol use. An 18% increased risk of progression was significantly associated with each pack-year that a subject smoked between 1985 and 1990. CONCLUSION: These data confirm previous findings that smoking is associated with a nuclear opacity, particularly with progression to severe opacities.
Adult↗
Effect of ivermectin prophylaxis on antibody responses to Onchocerca volvulus recombinant antigens in experimentally infected chimpanzees.
Antibody responses to recombinant Onchocerca volvulus antigens were studied in experimentally infected chimpanzees. Sera from 3 groups of 6 animals were tested by ELISA with recombinant antigens OC 3.6 and OC 9.3. Groups I and II were treated with 200 micrograms/kg of ivermectin on the day of infection or on day 28, respectively. Group III were untreated controls. Antibodies to OC 3.6 developed during the prepatent period in all 3 groups. In contrast, antibodies to OC 9.3 were usually first detected around the time of onset of patency. Several animals had early antibody responses to OC 9.3, but these animals subsequently failed to develop microfilarial patency. Only 1 of 6 animals in group I produced a strong antibody response to OC 9.3 while all 12 animals in groups II and III developed antibodies to this antigen. Although there was some inconsistency in antibody responses observed in each treatment group, the results suggest that OC 9.3 may be more useful than OC 3.6 for monitoring the efficacy of prophylactic drugs or vaccines for onchocerciasis while OC 3.6 may be useful for detecting exposure to the parasite and early infection, regardless of the later outcome of the infection.
Animals↗
Excimer laser filtration surgery.
PURPOSE: In order to remove precisely scleral tissue overlying Schlemm's canal with minimal trauma as an outpatient procedure under local anesthetic, we used a VisX Twenty/Twenty excimer laser. METHODS: We performed excimer laser filtration in three enucleated pig eyes, seven enucleated human eyes, and seven eyes of seven patients with severe glaucoma. Precise ablation to Schlemm's canal was confirmed by scanning electron microscopy in the enucleated eyes. For the patients, a local anesthetic was used, and a custom-made holder was used to mobilize the conjunctiva and fix the eye. RESULTS: A functional sclerostomy was obtained with 1,780 to 5,965 pulses, using a 2 x 1-mm slit. In our mean follow-up of nine months (range, six to 12 months) the excimer laser filtration technique achieved controlled filtration in five of seven patients and minimized conjunctival trauma. One patient subsequently underwent cataract extraction. CONCLUSIONS: This study indicates that excimer laser filtration is an effective technique for achieving filtration in glaucoma. It may reduce the complications of glaucoma filtration surgery, particularly the incidence of shallow anterior chamber postoperatively, as it leaves the trabecular meshwork intact.
Aged↗
Prevalence of central islands after excimer laser refractive surgery.
We conducted a study to determine the prevalence of central islands after refractive excimer laser surgery and the factors associated with their occurrence. A VISX Twenty/Twenty excimer laser was used to perform 157 photorefractive keratectomy (PRK) and 263 photorefractive astigmatic keratectomy (PARK) procedures. Corneal topography was assessed in 156 patients three months postoperatively using a topographic analysis system. Central islands were seen in 67% of patients; 26% had islands of 3.0 diopters (D) or more in height. Occurrence was associated with the laser suction nozzle being fixed during the procedure (P < .05). There was no demonstrable effect of central islands on visual acuity or refractive outcome, nor was there any relation to the amount of attempted correction or type of procedure (PARK or PRK). Central islands with a curvature difference of less than 3.0 D were seen more frequently than an absence of islands, suggesting these may be a "normal" postoperative topographic variation. The effect of nozzle position on island formation suggests that plume removal or corneal hydration may be important, as is corneal epithelial healing.
Adult↗
Excimer laser lamellar keratoplasty.
PURPOSE: To evaluate a procedure using the excimer laser to perform lamellar keratoplasty to treat deep corneal scars in the central optical zone. To determine if excimer laser can safely prepare a smooth surface for the host bed and the donor button, assess the interface opacity and evaluate the effects of the ablation on the recipient's endothelial surface with the deeper ablation. METHODS: Nineteen rabbits underwent an excimer laser lamellar keratoplasty in one eye. The rabbits were followed for 9 to 12 weeks until they were sacrificed. RESULTS: Little opacity developed at the graft-host interface and scanning electron microscopy of the endothelial surface showed little difference between the treated and untreated areas or the endothelium of the untreated eyes. CONCLUSIONS: Our results suggest that the use of the excimer laser to treat corneas with deep stromal scars and normal endothelium is feasible. However, we have not proved that this technique will give a better result than conventional lamellar dissection methods.
Animals↗
Blindness and trachoma in South Australia.
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Australia↗
An ounce of prevention is worth a pound of cure.
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Australia↗