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Skin Color
Published in Enzo Berardesca, Peter Elsner, Klaus-P. Wilhelm, Howard I. Maibach, Bioengineering of the Skin: Methods and Instrumentation, 2020
The remitted light is transferred to three photodiodes. Before each diode, a color filter ensures a specific spectral sensitivity with peaks at 450 nm (blue), 550 nm (green), and 610 nm (red). The sensitivity of the photodiodes is adjusted according to a “Standard Observer” as defined by the CIE in 1931. These photodiodes therefore simulate the human eye with its three blue-, green-, and red-sensitive cones in the central foveola. The light reaching the sensors is transformed into electrical signals that are used by the microprocessor for the calculation of the color values in the chosen color space.
Vitreoretinal surgical anatomy
Published in A Peyman MD Gholam, A Meffert MD Stephen, D Conway MD FACS Mandi, Chiasson Trisha, Vitreoretinal Surgical Techniques, 2019
Controversy exists regarding retinal nomenclature. Clinicians refer to the 6 mm area within the arcades as the posterior pole, whereas anatomists refer to it as the area centralis (Fig. 1.4b). The clinical macula or anatomic fovea is a central circular area 1.5 mm in diameter. It is centered 3.4 mm temporal to the optic disc margin and 0.8 mm below the center of the nerve head.13 The center of the macula is the clinical fovea or anatomic foveola, measuring 350μm in diameter. It appears in profile as a pit because of the absence of inner retinal layers.
ENTRIES A–Z
Published in Philip Winn, Dictionary of Biological Psychology, 2003
A visual scene that is to be inspected may often, in laboratory experiments, contain an explicit mark or target to which the observer is instructed to direct their gaze. This fixation point will become imaged on the FOVEOLA, the region of the RETINA with the most acute vision. It is to be noted that even with steady fixation there still exist small EYE MOVEMENTS which prevent the fading of an image that is associated with the perfect stabilization of a visual target.
Stargardt disease and progress in therapeutic strategies
Published in Ophthalmic Genetics, 2022
Di Huang, Rachael C. Heath Jeffery, May Thandar Aung-Htut, Samuel McLenachan, Sue Fletcher, Steve D. Wilton, Fred K. Chen
In children with no abnormalities on clinical examination, FAF has demonstrated discrete hyperautofluorescent dots confined to the foveola and even mild hyperautofluorescence in the perifoveal region (43). Furthermore, a broader and more diffuse band of hyperautofluorescence with increasing retinal eccentricity has also been demonstrated (43). FAF abnormalities have been reported in most patients with normal fundoscopy (43). A thickened external limiting membrane (ELM) as seen on SD-OCT may provide an early biomarker for childhood-onset disease (43,44). This thickening demonstrated a maximal prominence at the foveola and decreased symmetrically with increasing eccentricity. These changes may represent disruption of the outer nuclear layer (ONL) within the cones and this is consistent with cone photoreceptor nuclei residing close to the ELM in the perifoveal region (45). Sequential OCT images have illustrated focal collapse of the inner retinal layers, secondary to loss of the outer retinal structures (43). These changes appear to preferentially affect perifoveal areas as the foveola photoreceptors are more resistant to degenerative processes (43). Intraretinal pigmentations have been correlated to hyperreflective deposits in the inner layers of the fovea.
The Influence of Crescent-Shaped Selective Internal Limiting Membrane Staining on Vital Dye Toxicity in Temporal Inverted Flap Technique
Published in Current Eye Research, 2021
Remzi Avci, Aysegul Mavi Yildiz, Sami Yilmaz
The mechanism of MH closure with the inverted flap technique is thought to be multifactorial. The ILM provides a regular scaffold that determines the front limits of the glial proliferation underneath. Neurotrophic factors produced by activated Müller cells on the surface of the ILM may contribute to MH closure.18 Furthermore, Muller cell seems to play a critical role for the recovery of the central 1.5° visual field of the foveola after MH surgery.12 Since ILM is formed by the end feet of Müller cells, some kind of toxicity to the macular Müller cells might occur following the use of vital dye. Accordingly, several studies in the literature revealed cases with postoperative paracentral scotomas corresponding precisely to the size and location of the iatrojenic retinotomies where the ICG made contact with the RPE.34,35
Influence of one or two horizontal muscle surgeries on OCT findings
Published in Strabismus, 2021
Meryem guler alis, Abdulkadir alış
The choroid is the part of the body that has the most blood circulation, and 85% of all the blood delivered to the eye feeds the choroid. The choroid layer provides oxygenation, nutrition, and heat regulation for the retinal outer layers, which have the highest metabolic activity in the eye.1 The foveola (central macula) is devoid of retinal vessels, presumably to enhance visual acuity, and therefore, it is nourished solely by the choroid. Changes in choroidal nutrition can cause damage to the retina, retinal pigment epithelium (RPE), and optic nerve.2 Intraocular surgeries such as cataract surgery and retinal surgery and conditions such as retinal vascular diseases and ocular inflammation may affect the macula.3–6 Choroid was a vascular structure in close relation to the retina in the eye, and changes in choroid thickness might also be predicted.