| 1. |
- Bjerager, Jakob, et al.
(författare)
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Long-term development of lens fluorescence in a twin cohort : Heritability and effects of age and lifestyle
- 2022
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 17:5 May
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Tidskriftsartikel (refereegranskat)abstract
- The blue-green autofluorescence of the ocular lens increases with age, glycemia and smoking, as the irreplaceable structural proteins of the lens slowly accumulate damage from the encounter with reactive molecular species. We have conducted a prospective study of lens autofluorescence over two decades in a twin cohort. The study included 131 phakic, non-diabetic adult twins (median age at follow-up 58 years, range 41–66 years) who were examined twice at an interval of 21 years. Change in anterior lens peak autofluorescence was analyzed in relation to age, current and baseline glycemia, cumulative smoking and heritability. The level of lens autofluorescence in the study population increased as a function of age and smoking (p ≤.002), but not as a function of glycemia (p ≥.069). Lens autofluorescence remained a highly heritable trait (90.6% at baseline and 93.3% at follow-up), but whereas the combined effect of age and cumulative smoking explained 57.2% of the variance in lens autofluorescence at baseline in mid-life, it only accounted for 31.6% at followup 21 years later. From mid to late adulthood, the level of blue-green fluorescence remained overwhelmingly heritable, but became less predictable from age, smoking habits and glycemic status. Presumably, as the lens ages, its intrinsic characteristics come to dominate over environmental and systemic factors, perhaps in a prelude to the development of cataract.
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| 2. |
- Hougaard, Jesper Leth, et al.
(författare)
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Glaucomatous retinal nerve fibre layer defects may be identified in Stratus OCT images classified as normal.
- 2008
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Ingår i: Acta Ophthalmologica. - : Wiley. - 1755-3768 .- 1755-375X. ; 86:5, s. 569-575
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: We aimed to compare the retinal nerve fibre layer (RNFL) in different Stratus optical coherence tomography (OCT) images in glaucoma eyes with RNFL thickness values within normal limits. Methods: We studied the Stratus OCT high-resolution standard protocol for assessment of peripapillary RNFL thickness. The four glaucoma eyes presented (with reproducible visual field defects, mean deviations from - 3.49 dB to - 0.49 dB and structural loss on RNFL and/or disc photography) had results within the 95% normal limits for all OCT parameters (full circle, quadrant or clock hour mean RNFL thickness). We qualitatively compared the RNFL in pseudo-colour and grey-scale images defined by the Stratus OCT software with what appeared to be the RNFL when not defined automatically (and in raw data OCT images). Results: A localized RNFL defect was identified in conventional 495-nm RNFL photographs in all four patients. Obviously, in these selected eyes, the atrophy was not picked up by the OCT RNFL border algorithm, and at the corresponding location a localized RNFL atrophy (narrowing of the high signal intensity RNFL) was either not or just barely detectable in pseudo-colour OCT. However, defects seemed to be present in OCT grey-scale and raw data images in all four eyes. Conclusions: Our observations suggest that OCT images obtained in glaucoma eyes that are misclassified by the standard statistical analyses of Stratus OCT may contain information indicating RNFL defects. Thus, the current diagnostic ability of OCT in glaucoma can probably be extended.
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| 3. |
- Hougaard, Jesper Leth, et al.
(författare)
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The nerve fibre layer symmetry test: computerized evaluation of human retinal nerve fibre layer thickness as measured by optical coherence tomography
- 2004
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Ingår i: Acta Ophthalmologica Scandinavica. - : Wiley. - 1395-3907 .- 1600-0420. ; 82:4, s. 410-418
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To present and test a new interpretative concept, the nerve fibre layer symmetry test (NST), for computerized evaluation of retinal nerve fibre layer thickness (RNFLT) as measured by optical coherence tomography (OCT) in glaucoma. Methods: The NST concept was constructed and tested in a pilot study. A total of 32 healthy and 40 age-matched glaucomatous eyes were included and examined by OCT, computerized perimetry, RNFL/disc photography, tonometry and a general ophthalmologic examination. Results: The observed NST sensitivity and specificity were high, at 38/40 eyes (95%) and 32/32 eyes (100%), respectively, and 40/40 eyes (100%), and 31/32 eyes (97%), respectively, when correcting the OCT RNFLT measurement for the influence of variability in image signal/quality. The NST sensitivity was 8-10% higher than the single most sensitive traditional OCT RNFLT parameter; this difference was not statistically significant in this small sample. Conclusion: The NST showed high specificity and sensitivity for detection of RNFLT attenuation indicating early to severe glaucoma. Although promising, the NST needs to be further developed and validated in larger study samples and in patients with various stages of glaucomatous damage.
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| 4. |
- Vergmann, Anna Stage, et al.
(författare)
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Heritability of retinal vascular fractals : A twin study
- 2017
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Ingår i: Investigative Ophthalmology and Visual Science. - : Association for Research in Vision and Ophthalmology (ARVO). - 0146-0404. ; 58:10, s. 3997-4002
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE. To determine the genetic contribution to the pattern of retinal vascular branching expressed by its fractal dimension. METHODS. This was a cross-sectional study of 50 monozygotic and 49 dizygotic, same-sex twin pairs aged 20 to 46 years. In 50º, disc-centered fundus photographs, the retinal vascular fractal dimension was measured using the box-counting method and compared within monozygotic and dizygotic twin pairs using Pearson correlation coefficients. Falconer’s formula and quantitative genetic models were used to determine the genetic component of variation. RESULTS. The mean fractal dimension did not differ statistically significantly between monozygotic and dizygotic twin pairs (1.505 vs. 1.495, P = 0.06), supporting that the study population was suitable for quantitative analysis of heritability. The intrapair correlation was markedly higher (0.505, P = 0.0002) in monozygotic twins than in dizygotic twins (0.108, P = 0.46), corresponding to a heritability h2 for the fractal dimension of 0.79. In quantitative genetic models, dominant genetic effects explained 54% of the variation and 46% was individually environmentally determined. CONCLUSIONS. In young adult twins, the branching pattern of the retinal vessels demonstrated a higher structural similarity in monozygotic than in dizygotic twin pairs. The retinal vascular fractal dimension was mainly determined by genetic factors, which accounted for 54% of the variation. The genetically predetermination of the retinal vasculature may affect the retinal response to potential vascular disease in later life.
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