3 resultados para imagej
em Aston University Research Archive
Resumo:
Purpose. To evaluate the repeatability and reproducibility of subfoveal choroidal thickness (CT) calculations performed manually using optical coherence tomography (OCT). Methods. The CT was imaged in vivo at each of two visits on 11 healthy volunteers (mean age, 35.72 ± 13.19 years) using the spectral domain OCT. CT was manually measured after applying ImageJ processing filters on 15 radial subfoveal scans. Each radial scan was spaced 12° from each other and contained 2500 A-scans. The coefficient of variability, coefficient of repeatability (CoR), coefficient of reproducibility, and intraclass correlation coefficient determined the reproducibility and repeatability of the calculation. Axial length (AL) and mean spherical equivalent refractive error were measured with the IOLMaster and an open view autorefractor to study their potential relationship with CT. Results. The within-visit and between-visit coefficient of variability, CoR, coefficient of reproducibility, and intraclass correlation coefficient were 0.80, 2.97% 2.44%, and 99%, respectively. The subfoveal CT correlated significantly with AL (R = -0.60, p = 0.05). Conclusions. The subfoveal CT could be measured manually in vivo using OCT and the readings obtained from the healthy subjects evaluated were repeatable and reproducible. It is proposed that OCT could be a useful instrument to perform in vivo assessment and monitoring of CT changes in retinal disease. The preliminary results suggest a negative correlation between subfoveal CT and AL in such a way that it decreases with increasing AL but not with refractive error.
Resumo:
Purpose: Autofluorescence of ultraviolet (UV) light has been shown to occur in localised areas of the bulbar conjunctiva, which map to active cellular changes due to UV and environmental exposure. This study examined the presence of conjunctival UV autofluorescence in eye care practitioners (ECPs) across Europe and the Middle East and its associated risk factors. Method: Images were captured of 307 ECPs right eyes in the Czech Republic, Germany, Greece, Kuwait, Netherlands, Sweden, Switzerland, United Arab Emirates and the United Kingdom using a Nikon D100 camera and dual flash units through UV filters. UV autofluorescence was outlined using ImageJ software and the nasal and temporal area quantified. Subjects were required to complete a questionnaire on their demographics and lifestyle including general exposure to UV and refractive correction. Results: Average age of the subjects was 38.5±12.2 years (range 19-68) and 39.7% were male. Sixty-two percent of eyes had some conjunctival damage as indicated by UV autofluorescence. The average area of damage was higher (p=0.005) nasally (2.95±4.52mm2) than temporally (2.19±4.17mm2). The area of UV damage was not related to age (r=0.03, p=0.674), gender (p=0.194), self-reported sun exposure lifestyle (p>0.05), geographical location (p=0174), sunglasses use (p>0.05) or UV-blocking contact lens use (p>0.05), although it was higher in those wearing contact lenses with minimal UV-blocking and no spectacles (p=0.015). The area of UV damage was also less nasally in those who wore contact lenses and spectacles compared to those with no refractive correction use (p=0.011 nasal; p=0.958 temporal). Conclusion: UV conjunctival damage is common even in Europe, Kuwait and UAE, and among ECPs. The area of damage appears to be linked with the use of refractive correction, with greater damage nasally than temporally which may be explained by the peripheral light focusing effect.
Resumo:
PURPOSE: To examine the optimum time at which fluorescein patterns of gas permeable lenses (GPs) should be evaluated. METHODS: Aligned, 0.2mm steep and 0.2mm flat GPs were fitted to 17 patients (aged 20.6±1.1 years, 10 male). Fluorescein was applied to their upper temporal bulbar conjunctiva with a moistened fluorescein strip. Digital slit lamp images (CSO, Italy) at 10× magnification of the fluorescein pattern viewed with blue light through a yellow filter were captured every 15s. Fluorescein intensity in central, mid peripheral and edge regions of the superior, inferior, temporal and nasal quadrants of the lens were graded subjectively using a +2 to -2 scale and using ImageJ software on the simultaneously captured images. RESULTS: Subjectively graded and objectively image analysed fluorescein intensity changed with time (p<0.001), lens region (centre, mid-periphery and edge: p<0.05) and there was interaction between lens region with lens fit (p<0.001). For edge band width, there was a significant effect of time (F=118.503, p<0.001) and lens fit (F=5.1249, p=0.012). The expected alignment, flat and steep fitting patterns could be seen from approximately after 30 to 180s subjectively and 15 to 105s in captured images. CONCLUSION: Although the stability of fluorescein intensity can start to decline in as little as 45s post fluorescein instillation, the diagnostic pattern of alignment, steep or flat fit is seen in each meridian by subjective observation from about 30s to 3min indicating this is the most appropriate time window to evaluate GP lenses in clinical practice.