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Disc Ratio (disc + ratio)
Selected AbstractsTechnical Note: Grading the vertical cup:disc ratio and the effect of scalingOPHTHALMIC AND PHYSIOLOGICAL OPTICS, Issue 6 2007Ruth Bennett Abstract Purpose:, To evaluate the effect of scaling on sensitivity to change for grading the vertical cup:disc ratio (CDR). Methods:, Vertical CDR was assessed by six observers (three ophthalmologists and three optometrists) on 43 stereo disc photographs. Repeated observations were made for both 0.1 and 0.05 interval scales. Paired differences were calculated for all observers and each observer separately. Mean and standard deviation of differences and agreement statistics were used to compare scales. Results:, Five observers demonstrated a reduction in the spread of differences (mean difference 0.19 to 0.15) and all observers demonstrated a reduction in concordance using the finer scale (mean concordance 54% to 39%). Conclusion:, The use of a finer scale reduces test,retest variability and increases sensitivity to change when estimating the vertical CDR. Use of this scale does not require any additional resource and it may be easily implemented in routine clinical practice. [source] 2453: Optic disc in the picture: novel imaging techniquesACTA OPHTHALMOLOGICA, Issue 2010W DREXLER Purpose Advances in light sources and detection technologies enabled a paradigm shift in retinal OCT imaging performance. ,Snap-shot OCT' enabling isotropic sampling over 512x512x1024 voxels with 600 frames/second in less than a second is now possible. Methods The resolution advantage in conjunction with full volumetric sampling has enabled the development of more informative indices of axonal damage in glaucoma compared with measurements of RNFL thickness and cup to disc ratio provided by other devices. A novel mapping method was developed, the three-dimensional minimal distance (3D-MDM) as the optical correlate of true retinal nerve fiber layer thickness around the optic nerve head region. In a preliminary study relation between the cross-sectional areas of the retinal nerve fiber layer and the optic nerve was found to be a sensitive measure of axon loss. Results In addition to all the major layers of the retina, the entire choroid down to the lamina cribrosa and sclera can now be visualized. This enables unprecedented information about choroidal vasculature without any contrast agents, choroidal thickness and will enable quantification of choroidal blood flow in the near future. Furthermore this technique allows tissue to be imaged in vitro with an image resolution better than 1-2 µm, allowing to image single cells and detect pre-apoptotic signatures using OCT. RGC-5 cells were imaged using a sampling rate 1024x512x1024 voxel at 800 nm central wavelength and a bandwidth of 230 nm, enabling the detection of optical signatures at different pre-stages of programmed cell death. Conclusion Significantly increased OCT imaging speed and tissue penetration might enable novel insights and diagnostic opportunities in the diagnosis and therapy monitoring of glaucoma. Commercial interest [source] Effect of phacoemulsification on the primary open angle glaucoma control after trabeculectomy: a case-control studyACTA OPHTHALMOLOGICA, Issue 2009S AZIZ Purpose In this retrospective and comparative study, we analyzed the influence of phacoemulsification (PE) on the glaucoma control in case patients (trabeculectomy-phacoemulsification [CE]) compared with the control that underwent trabeculectomy (T) alone in eyes with primary open angle glaucoma (POAG). Methods Twenty one patients who underwent PE subsequent to T were identified, and 41 who underwent T alone were matched. Visual acuity (VA), intraocular pressure (IOP), bleb appearance, vertical cup disc ratio (VCDR), visual field (VF), glaucoma medications, iris manipulation and complications were documented. Mean follow up was 12 months. Success was defined when IOP , 21 mmHg with the abscense of glaucoma medication and/or further surgical intervention. Results Patients in CE group had no significant change in IOP from pre-operative measures to 12 months post-operative (p=0.001). The mean IOP reduced from 15.3 mm Hg to 14.7 mmHg postoperatively. The control group showed an average IOP reduction of 6 mm Hg in the last visit. In CE group, 19% required 1 or 2 glaucoma medications at one year fellow-up vs 19.5% in the control group. In CE group 9.5% showed flattening of previously formed bleb in the last visit (P<0.001), 9.7 % ended with flat bleb in the T group. The increase in VCDR for the CE group was statistically significant when compared to the control group (p<0.001). Patients in CE group were more likely to exhibit a change in VF (47.6% versus 7.3% respectively). The study is limited by the small number of cases available. Conclusion Corneal PE in eyes with filtering blebs does not adversely affect long-term glaucoma control in patients with POAG. [source] A prospective longterm study of primary chronic angle closure glaucomaACTA OPHTHALMOLOGICA, Issue 2 2004Ramanjit Sihota Abstract. Purpose:, To prospectively evaluate the longterm outcome of therapy for chronic primary angle closure glaucoma (PACG) and to assess the efficacy of medical and surgical treatment in terms of intraocular pressure (IOP) and visual field stabilization. Methods:, Seventy consecutive patients with chronic PACG, whose IOP remained > 21 mmHg despite a patent iridotomy, had their IOP controlled by medications or trabeculectomy performed without antimetabolites. They were followed over a 6-year period. Best corrected visual acuity, IOP (mean of annual diurnal variation readings), cup : disc ratio and visual fields were recorded. A trabeculectomy was performed if the IOP was not adequately controlled on maximal tolerable medical therapy or if there was a progression of the glaucomatous defect. Data from one eye of each patient were analysed; if both eyes met the inclusion criteria, one was randomly selected for the analysis. The baseline parameters were compared with those at the end of 6 years. Results:, A total of 46 eyes (65%) were controlled medically throughout the 6-year follow-up period, while 24 eyes (35%) required surgery. The mean IOP was 25.4 ± 4.9 mmHg at baseline and 15.6 ± 4.6 mmHg at 6 years follow-up (p < 0.001). Stereoscopic evaluation of the cup : disc ratio did not show a significant change from a mean of 0.6 ± 0.18 at baseline to a mean of 0.64 ± 0.2 at 6 years (p = 0.12). Progression of visual field defects was seen in seven eyes (10%), which had statistically larger cup : disc ratios (p = 0.04) and more extensive visual field deficits at the initial assessment (p = 0.04), and which also maintained higher levels of IOP (p = 0.03) over the 6 years of follow-up. Conclusions:, Stable visual fields and good longterm IOP control were seen in 90% of chronic primary angle closure glaucoma eyes on medical/surgical therapy over 6 years. [source] Fred Hollows lecture: Digital screening for eye diseaseCLINICAL & EXPERIMENTAL OPHTHALMOLOGY, Issue 3 2000Ij Constable ABSTRACT The purpose of this study was to explore progress, in the adaptation to community screening for blinding eye disease, of digital imaging devices and technology for storage and transmission. Available imaging systems were compared to gold standard clinical photography in terms of sensitivity and specificity for diagnosis of common blinding eye conditions. Since the use of expensive non-portable imaging devices is likely to be limited for widespread community screening purposes, a portable fundus camera (Nidek, Chiyoda-ku, Japan) and a prototype monocular digital indirect ophthalmoscope constructed at the Lions Eye Institute (LEI) were selected for comparative trials for the screening of optic disc cupping, glaucoma and clinical signs of diabetic retinopathy. Fifty-one eyes of 27 consecutive patients being assessed at the LEI clinic for glaucoma were dilated and photographed with a Zeiss retinal camera, and digital images were taken with the portable Nidek NM100 fundus camera (Carl Zeiss, Oberkochen, Germany) or with a prototype digital monocular indirect ophthalmoscope. Vertical cup : disc ratios (VCDR) were measured on the disc photographs by one ophthalmologist while three other clinicians were presented with compressed digital images in random order to estimate VCDR. Field trials were also carried out to demonstrate the practicality of compression, local storage and then transmission by mobile telephone ISDN lines and satellite, of optic discs and fundus images of patients with diabetes in either rural Western Australia or Surabaya, Indonesia. Kappa values of correlations of measurement of agreement between measured and estimated VCDR were 0.87, 0.45 and 0.84, respectively, for the three observers, corresponding to a specificity of 79,97% and a sensitivity of 70,95%. The portable Nidek fundus camera was also assessed for specificity and sensitivity in the diagnosis of diabetic retinopathy in comparison to standard Zeiss fundus camera photographs. Of 49 eyes in 25 consecutive patients attending the LEI clinic for assessment of diabetic retinopathy, three ophthalmologists assessed photographs and images in random order. When used for screening diabetic retinopathy, the digital images of the Nidek camera were graded as adequate quality in only 56% of eyes compared to 93% of the photographs. The kappa value of agreement in analysis of diabetic retinopathy was only 0.30. The prototype digital monocular indirect ophthalmoscope compared favourably with the Nidek camera. At 1:5 compression, images of size 36 kB transmitted from Surabaya to Perth took 29 s on the mobile telephone, while uncompressed images took 170 s. Images compressed 1:5 were transmitted in 60 s using the satellite telephone, while the uncompressed images took 240 s. Satellite transmission was more expensive but the lines were more stable than telephone connections from Indonesia. Digital imaging is becoming a powerful tool for ophthalmology in clinical records, teaching and research, and interoffice diagnostic opinions. It also has enormous potential for community screening for blinding eye diseases, such as glaucoma and diabetic retinopathy. Inexpensive portable imaging devices that are easy to use, and on which local health workers might be trained, must be developed and validated in terms of sensitivity and specificity of performance. The technology of image capture, image compression, transmission, data base storage and analysis is rapidly evolving and becoming less expensive. [source] | ||||||||||