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A comparative study of optical coherence tomography and slit-lamp based grading of cataractPurpose:Established methods of grading cataract are susceptible to error due to their subjective nature as well as variation in slit-lamp settings during assessment. Furthermore, grading systems such as the Lens Opacities Classification System III (LOCS III) are only applicable to age-related forms of the condition. Optical coherence tomography (OCT) offers the potential to provide an objective method of imaging and grading all forms of cataract. An observational clinical study was performed to compare anterior segment OCT imaging with traditional, slit-lamp based grading. Methods:Crystalline lens images of 60 eyes from 38 adults aged 50 to 79 years (mean 62.97+/-9.99) were captured using a Nikon FS-3 slit-lamp photo-biomicroscope and a Zeiss Visante anterior segment OCT. Prior to imaging, participants were assessed for habitual visual acuity (logMAR), contrast sensitivity (Pelli-Robson), and straylight scatter (Oculus C-Quant). Pupils were then dilated with 1% tropicamide to obtain optimum images of the crystalline lens. The slit-lamp images were graded for age-related cataract (nuclear colour and opalescence) using the LOCS III. Raw OCT data were analysed in MATLAB to determine a pixel intensity ratio for the nucleus of each crystalline lens (see figure). Linear regression compared LOCS III nuclear opalescence and nuclear colour scores to OCT pixel intensity ratios.Results: Age-related nuclear cataract was the predominant cataract type, with LOCS III mean scores of 2.04+/-0.63 for nuclear opalescence and 1.65+/-0.71 for nuclear colour. Cortical and posterior subcapsular cataract were present at low levels (0.32+/-0.51; 0.12+/-0.12 respectively). Mean OCT nuclear pixel intensity ratio was 1.077+/-0.04. Regression analyses revealed significant relations between pixel intensity ratio and nuclear opalescence (F(1,58)=8.24, p<0.006) as well as pixel intensity ratio and nuclear colour (F(1,58)=4.37, p<0.041).Conclusion:OCT can provide an objective method of imaging and grading the severity of cataract. OCT may be an effective means of profiling cataract in populations who do not exhibit typical age-related forms of crystalline lens opacities.2781305486400Figure: Panel A. Raw OCT image of the anterior crystalline lens. Panels B-E. Images depicting the selection of the anterior chamber and nucleus. The pixel intensity ratio is defined as the quotient of mean nuclear pixel intensity (E) divided by mean anterior chamber pixel intensity (C).00Figure: Panel A. Raw OCT image of the anterior crystalline lens. Panels B-E. Images depicting the selection of the anterior chamber and nucleus. The pixel intensity ratio is defined as the quotient of mean nuclear pixel intensity (E) divided by mean anterior chamber pixel intensity (C). ................
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