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- Abrahamsson, Maths, 1953, et al.
(författare)
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[Dim the light! Glare problems in a world with ever increasing demands on visual acuity] : Blända av!
- 1997
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Ingår i: Läkartidningen. - 0023-7205. ; 94:41, s. 3607-11
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Ocular tissue transparency is dependent on the regular lattice configuration of lens and corneal fibres of uniform diameter. Ageing is associated with degeneration of both lens and cornea, which lose some of their structural order and eventually their transparency, though this process is not uniform. The structural changes are local and result in ocular media opacities. When the opacities increase in number and extension, they begin to affect visual acuity. As the loss of acuity becomes clinically significant, we speak of clinically relevant cataract. Retinal exposure to light diffused by intraocular light scattering induces optical glare, one of two forms of glare. The other form is transient glare--i.e., glare due to adaptation problems in an environment with rapidly changing ambient luminance. Contemporary society is characterised by increasing emphasis on visual information in such forms as texts, icons, signs and symbols. The computer revolution has been accompanied by further stress on the importance of the detection and interpretation of written instructions.
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| 2. |
- Abrahamsson, Maths, 1953, et al.
(författare)
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Inheritance of strabismus and the gain of using heredity to determine populations at risk of developing strabismus.
- 1999
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Ingår i: Acta ophthalmologica Scandinavica. - : Wiley. - 1395-3907. ; 77:6, s. 653-657
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: In the Nordic countries 2 to 4% of the population squint or have been squinting. Since strabismus is one of the major causes of amblyopia early detection and treatment is important for preventing this development. For centuries it has been recognized that strabismus is hereditary. Identifying individuals with a family history of squinting could give access to a risk population for a selective screening. METHODS AND RESULTS: 1,571 children were selected for this study. All children that took part in a voluntary eye examination at one year of age (born 1978-1983) in the city of Vasteras, Sweden and that had a family history of strabismus were selected together with controls. The study was a 6-year follow-up from 1 to 7 years of age. Parental knowledge of squint among relatives and measured high hyperopia (>3.0 D) present at 1 year of age were each and in combination evaluated as a risk indicator for development of strabismus between 1 to 7 years of age. CONCLUSION: The study indicates that a family history of squint in combination with measured high hyperopia can be used in a selective screening to identify a population with an increased risk of 4 to 6 times for developing strabismus. Among the children with parental knowledge of squint among several relatives of both the parents, those with high hyperopia developed strabismus in almost every second case while this was the case in only approximately 10% of those with low hyperopia. Finally, heredity is an important risk indicator that can be used for selective screening purpose. Its potential as a risk indicator is substantially increased when combined with a high hyperopia.
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| 3. |
- Abrahamsson, Maths, 1953, et al.
(författare)
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The occurrence of congenital cataract in western Sweden
- 1999
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Ingår i: Acta Ophthalmologica Scandinavica. - : Wiley. - 1395-3907. ; 77:5, s. 578-580
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To estimate the occurrence of congenital cataract in a Nordic country. Methods: In 1980, we constructed a database in the Department of Ophthalmology Goteborg University, containing basic data from all cases in western Sweden diagnosed with congenital cataract. By collecting and processing these data from 1980 onwards, we hoped to improve the management of congenital cataract treatment and to optimize the outcome of the treatment. Results: In this study, the incidence of congenital cataract in the four western counties of Sweden was evaluated. The occurrence rate of all cases with congenital cataract during the study period was 36 cases per 100 000. The occurrence rate for dense bilateral and all unilateral cases were both 14 per 100 000 each. Conclusion: There were no time-related changes in incidence of congenital cataract from 1980 until today, although there was a large variation in the yearly incidence.
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| 4. |
- Magnusson, Gunilla, 1968, et al.
(författare)
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Changes in visual acuity from 4 to 12 years of age in children operated for bilateral congenital cataracts.
- 2002
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Ingår i: The British journal of ophthalmology. - 0007-1161. ; 86:12, s. 1385-9
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Tidskriftsartikel (refereegranskat)abstract
- AIMS: To investigate the long term effects of age at surgery on the development of visual acuity (VA) by measuring VA from preschool age to puberty. Furthermore, to report the VA levels at 12 years of age in a geographically based cohort of operated congenital bilateral cataracts. METHODS: All children born in four western counties of Sweden between January 1980 and December 1993 who were diagnosed with congenital cataracts were included in a longitudinal prospective study. The monocular VA of the better eye in 38 subjects was analysed at 4, 7, 10, and 12 years of age, with 20 total and 18 partial cataracts. The mean follow up time was 9.3 years after surgery. RESULTS: The final value of VA was 0.4 or above for approximately 50% of the subjects at 12 years of age. Visual acuity improved to a considerable extent after school age, especially in children who underwent surgery between the ages of 7 weeks and 1 year. Results for partial cataracts were favourable compared to those for total cataracts, reaching a mean of approximately 0.5 at age 12. The mean VA in the group of total congenital cataracts operated on before 7 weeks of age achieved higher values of VA at 4 years of age compared to children with total cataracts operated on between 7 weeks and 1 year of age. However, no statistically significant difference in VA results among these groups could be proved. CONCLUSION: Visual acuity improves to a considerable extent after school age in children with delayed visual development caused by congenital cataracts. Surgery within 7 weeks results in a more rapid development of VA, initially.
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| 5. |
- Magnusson, Gunilla, 1968, et al.
(författare)
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Glaucoma following congenital cataract surgery: an 18-year longitudinal follow-up.
- 2000
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Ingår i: Acta ophthalmologica Scandinavica. - 1395-3907. ; 78:1, s. 65-70
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: To report the occurrence of postoperative glaucoma and to evaluate risk factors. METHODS: Children born in four of the western counties of Sweden who were diagnosed with congenital cataracts formed a cohort (n=137). The following parameters were evaluated: age at cataract surgery; type of surgery; visual outcome; postoperative IOP; optic disc abnormalities; date of onset of the complication; number of reoperations, including treatment for secondary cataract; presence of systemic anomalies; microphthalmus; and eye-related anomalies. RESULTS: A diagnosis of glaucoma was recorded for 12% of the eyes. The mean follow-up time was 9.6 years. There is a relationship between surgery before the age of 10 days and development of glaucoma. Microphthalmus is an important risk factor as well. CONCLUSIONS: Despite modern surgical techniques the incidence of aphakic glaucoma is 10% or higher. No time-dependent increase in the incidence of late-onset glaucoma between the 1980s and the 1990s could be proven.
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| 7. |
- Sjöström, Anders, 1951, et al.
(författare)
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Subnormal visual acuity (SVAS) and albinism in Mexican 12-13-year-old children.
- 2004
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Ingår i: Documenta ophthalmologica. Advances in ophthalmology. - 0012-4486. ; 108:1, s. 9-15
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: In a previous study the vision of 1046 12-13-year-olds in Sweden was examined. Of those 67 had some kind of visual disturbances and in 20 no obvious cause was found. In this group, defined as children with subnormal visual acuity syndromes (SVAS), albinism was shown to be a major cause to the visual dysfunction giving a prevalence of about 1%. This is about 100 times higher than previous figures. Albinism can therefore be the cause in many cases of unexplained low visual acuity, at least in Sweden. Subnormal visual acuity is usually found in 2-4% in a pediatric population and is often called 'amblyopia'. The Swedish study showed that in many cases 'amblyopia' should be replaced by 'SVAS' and further investigation. The present Mexican study was designed identically to the Swedish study. The objective was to describe the distribution of visual acuity and the prevalence of ocular disorders, including incidence of subnormal visual acuity (SVAS) and the occurrence of albinism in a Mexican population of 12-13-year-olds. SUBJECTS AND METHODS: Altogether 1035 children, 12-13 years of age, were examined. A total number of 344 children were referred to the university pediatric eye clinic for further examination. 272 of these had simple refractive errors, 59 were diagnosed with an ophthalmological disorder and 13 children could not be pathologically classified. These were referred to a second ophthalmological examination, including VEP (Visual Evoked Potential) recordings. VEP reveals an asymmetric (right vs. left) cortical response after monocular stimulation in albinism. RESULTS: No child showed iris translucency or any other typical albinoic sign. VEP was recorded from 11 children. Three children showed an asymmetric VEP and were classified as albinos. The VEP response was normal in 8 of the children. CONCLUSIONS: The results indicate that albinism is common in Mexico, although not as common as in a similar Swedish population. A prevalence of albinism of approximately 0.3% was found in the Mexican population, compared to approximately 1% in the Swedish study group. The number of albinos was much higher in both study groups than to be expected from previous estimates. The difference between the Swedish and the Mexican figures may be explained by the general difference in pigmentation between Sweden and Mexico and thus probably by the subsequent lower number of commonly occurring albino foci in the Mexican heritage. It is emphasised that in investigations of children with SVAS, also in countries with a generally high pigmentation level, electro-physiological examinations are important, to be able to reveal albinism, but also to exclude or verify other conditions in the SVAS group, for example neurometabolic conditions.
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| 8. |
- Thaung, Jörgen, 1965, et al.
(författare)
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A New Set-up for Contrast Sensitivity Testing at Very Small Glare Angles
- 2003
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Ingår i: Investigative Ophthalmology & Visual Science. ; 44:13
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Purpose: To investigate whether a small angle glare test in a clinical setting can produce and detect a significant decrease in contrast sensitivity with age in normal young and elderly eyes. Methods: Contrast sensitivity (CS), with and without glare, was measured in 20 subjects. The subjects were all fully corrected. CS was measured using the "Freiburg Visual Acuity & Contrast Test" (FrACT) software running on a Macintosh imac (CRT). In our set-up the software uses a 4AFC-method, and the test distance was 4 meters. Glare was induced by a Fostec DCR® II light source with a randomised fiberoptical bundle mirrored into the centre of a Landolt C test target. Full test symmetry was accomplished by using this glare set-up. The test target and the glare source subtended an angle of about 1.3° and 0.2° respectively, yielding a 0.5° glare angle. The target mean luminance was 61 cd/m2 and the illuminance at the eye was 15 lux with glare. Results: We measured 20 subjects (20 to 59 yrs) with no known eye disease. The results from the measurements were analysed seperately and also calculated as glare scores (CS without glare divided by CS with glare). CS data with and without glare produced low correlation with age, but the data showed large correlation with age when calculated as glare scores. The increase in glare score with age was about 2.5 in the tested group. The data was also compared with measurements of after cataract patients. For these patients the glare scores were about 10 to 20 times higher. Conclusions: The results indicate that this method is useful in studies of glare in normal and elderly eyes. The data also indicate a usefulness in quantifying the impact of cataract and after cataract.
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| 9. |
- Thaung, Jörgen, 1965, et al.
(författare)
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Evaluation of the effect of tinted night driving glasses on contrast sensitivity with and without glare
- 2001
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Ingår i: Journal of Vision. ; 1:3, s. 456-456
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Purpose: To evaluate claims of contrast improvement by tinted night driving glasses (TNDG) during mesonic luminance conditions. Methods: Contrast sensitivity functions (CSF) were measured in two trained myopic subjects, aged 20 and 34 years, with no known eye disease and normal foveal fusion. Both were fully corrected and their accommodative abilities were 13D and 8D, respectively. CSF with and without glare, induced by a Fostec DCR® II Light with four fiberoptical branches, was measured with the Morphonome® 4.2.4 image psychophysics software at two spatial frequencies (3 and 23 cod). All measurements were done with the subjects wearing prescribed glasses, TNDG (Zeiss Clarlet 1.5 GOLD ET 015), and ophthalmic test lenses, with TNDG and test lenses beeing of equal dioptric value. Results: TNDG were found to perform better than prescribed glasses, especially subjectively. CSF was improved both with and without the presence of glare sources. However, no significant difference was found between TNDG and test lenses, neither with nor without glare. Conclusion: CSF was not significantly improved by tinted night driving glasses. Subjectively, the TNDG were prefered by both test subjects. Our findings indicate that at the higher spatial frequency the major improvements are due to the correction of night myopia.
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