Journal ArticleDOI
Improvements on Littmann's method of determining the size of retinal features by fundus photography.
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TLDR
Three new methods of determining Littmann's factor q become available: simply reducing the axial length by a constant 1 · 82 mm; constructing a personalized schematic eye, given additional data; and ray tracing through this eye to extend calculations to peripheral retinal areas.Abstract:
Littmann's formula relating the size of a retinal feature to its measured image size on a telecentric fundus camera film is widely used. It requires only the corneal radius, ametropia, and Littmann's factor q obtained from nomograms or tables. These procedures are here computerized for practitioners' convenience. Basic optical principles are discussed, showing q to be a constant fraction of the theoretical ocular dimension k′, the distance from the eye's second principal point to the retina. If the eye's axial length is known, three new methods of determining q become available: (a) simply reducing the axial length by a constant 1 · 82 mm; (b) constructing a personalized schematic eye, given additional data; (c) ray tracing through this eye to extend calculations to peripheral retinal areas. Results of all these evaluations for 12 subjects of known ocular dimensions are presented for comparison. Method (a), the simplest, is arguably the most reliable. It shows good agreement with Littmann's supplementary procedure when the eye's axial length is known.read more
Citations
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Visualization of Radial Peripapillary Capillaries Using Optical Coherence Tomography Angiography: The Effect of Image Averaging.
Shelley Mo,Shelley Mo,Erika Phillips,Brian D Krawitz,Brian D Krawitz,Reena Garg,Reena Garg,Sarwat Salim,Lawrence S. Geyman,Lawrence S. Geyman,Eleni Efstathiadis,Eleni Efstathiadis,Joseph Carroll,Richard B Rosen,Richard B Rosen,Toco Yuen Ping Chui,Toco Yuen Ping Chui +16 more
TL;DR: OCTA image registration and averaging is a viable and accessible method to enhance the visualization and quantification of the radial peripapillary capillary (RPC) network, with significant improvements in image quality and RPC quantitative parameters.
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The foveal position relative to the optic disc and the retinal nerve fiber layer thickness profile in myopia.
TL;DR: The intrinsic foveal position relative to the optic disc was an essential determinant of normal RNFL thickness in myopia and was associated with the vertical asymmetry of RNFL distribution.
Journal ArticleDOI
Quantitative assessment of the retinal microvasculature and choriocapillaris in myopic patients using swept-source optical coherence tomography angiography.
Li Su,Li Su,Yong-Sok Ji,Yong-Sok Ji,Nianting Tong,David Sarraf,David Sarraf,Xiangui He,Xiaodong Sun,Xun Xu,Srinivas R. Sadda +10 more
TL;DR: The retinal microvasculature may demonstrate alterations in highly myopia eyes and the CC in macular regions shows greater impairment in eyes with high myopia compared with eyes with lesser degrees of myopia, and these deficits are already present in the absence of features of pathologic or degenerative myopia.
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Automatic detection of cone photoreceptors in split detector adaptive optics scanning light ophthalmoscope images.
David Cunefare,Robert F. Cooper,Brian P. Higgins,David F. Katz,Alfredo Dubra,Joseph Carroll,Sina Farsiu +6 more
TL;DR: In this paper, a fully automatic adaptive filtering and local detection (AFLD) method was proposed for detecting cones in split detector AOSLO images. But, this method was not applied to split detector images.
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Evaluation of retinal haemodynamics and retinal function after application of dorzolamide, timolol and latanoprost in newly diagnosed open-angle glaucoma patients.
TL;DR: It is suggested that dorzolamide treatment significantly shortened AVP times in newly diagnosed open-angle glaucoma patients, whereas timolol and latanoprost had no significant effect.
References
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Journal ArticleDOI
Determination of the real size of an object on the fundus of the living eye
TL;DR: A method is described which allows the real diameter of an object on the fundus to be determined by means of a system of curves which are the result of trigonometrical calculations and which give an approximate value.
Book
Clinical Visual Optics
TL;DR: The eye's optical system visual acuity and contrast sensitivity spherical ametropia astigmatism subjective refraction accommodation and near vision ocular motility and binocularVision convergence anomalies of binocular vision - heterophoria and heterotropia stereopsis and the stereoscope.
Journal ArticleDOI
Determining the true size of an object on the fundus of the living eye
TL;DR: The result was represented by curves which enable factors used in calculating the true diameter to be determined, but instead of the curves a quadratic equation is used to produce the same factors.
Journal ArticleDOI
A method of determining the equivalent powers of the eye and its crystalline lens without resort to phakometry
TL;DR: If the positions of the principal points of the crystalline lens are conjectured, its equivalent power and that of the eye can be calculated as described from ocular dioptrics.