Jay M. Enoch

Bio: Jay M. Enoch is an academic researcher from University of California, Berkeley. The author has contributed to research in topics: Hyperacuity & Vernier acuity. The author has an hindex of 28, co-authored 171 publications receiving 2481 citations. Previous affiliations of Jay M. Enoch include University of California, San Francisco.

Vertebrate photoreceptor optics

Abstract: 1. Introduction.- 2. The Retinal Receptor: A Description.- 3. The Stiles-Crawford Effects.- 4. Retinal Receptor Orientation and Photoreceptor Optics.- 5. Waveguide Properties of Retinal Receptors: Techniques and Observations.- 6. Theoretical Considerations of the Retinal Receptor as a Waveguide.- 7. Theoretical Consideration of Optical Interactions in an Array of Retinal Receptors.- 8. The Visual Receptor as a Light Collector.- 9. Microspectrophotometry and Optical Phenomena: Birefringence, Dichroism, and Anomalous Dispersion.- 10. Tapeta Lucida of Vertebrates.- 11. A Comparison of Vertebrate and Invertebrate Photoreceptors.- Additional References with Titles.

Quantitative layer-by-layer perimetry.

Abstract: The receptive field properties of retinal neurons are briefly and simply considered. Psychophysical tests (or tests of vision) are described which exhibit functional characteristics similar to those described in electrophysiological studies of retinal neurons. The special properties of these tests of vision are reviewed. Then an orderly attempt is made to localize the major components of these vision test functions along the visual pathways by making use of dichoptic test techniques and by analyzing alterations in function observed in pathology with known sites of action. A sustained-like response function, believed to be organized at the retinal outer plexiform layer and a transient-like function probably organized at the inner plexiform layer are considered. Both are apparently dominantly sampled at the inner plexiform layer. The former function seems affected by pathology affecting both layers, the latter function seems influenced by events occurring only in the inner plexiform layer. N'either function is altered in nerve conduction anomalies affecting only the myelinated portion of the optic nerve. The latter cause time-based losses in visual sensitivity revealed by the flashing repeat static perimetric test. These tests of vision allow point-by-point, layer-by-layer analysis of visual response and effectively extend our quantitative perimetric capabilities. They aid the clinician by providing finer localization and differentiation of different forms of anomaly and by allowing evaluation of the effects of therapy and lor progression of the disease process. Because these techniques are noninvasive, they help the basic scientist understand the organization of the human visual system. Special analyses and differentiations are provided, relating to senile macular degeneration, open-angle glaucoma, and diabetic retinopathy (here used as a model of a disease causing microvascular changes in the retina).

The effects of blur upon perimetric thresholds. A method for determining a quantitative estimate of retinal contour.

Abstract: Introduction This paper serves a twofold purpose. Some of the effects of blur of the retinal image upon perimetric thresholds are considered, and a clinical procedure is presented which utilizes these characteristics in order to provide a quantitative estimate of retinal contour. The method does not provide a measure of the true contour, but rather provides a precise reference or relative contour which may be compared with that obtained in other portions of the retina, or which may be compared with a similar set of determinations obtained at a different time. The procedure is based upon the assumption that the contrast or luminous increment threshold is lowest when the perimetric test target, imaged upon its corresponding retinal area, is focused upon the retina. The clinical method permits quantitative determination of shifts in a fore-and-aft direction of the retinal receptors in that part of the visual field usually studied with a

Anatomical correlates to the bands seen in the outer retina by optical coherence tomography: literature review and model.

Abstract: Optical coherence tomography (OCT) made possible noninvasive visualization of the microscopic anatomy of the retina, a nearly transparent structure. Understanding what is visualized requires proper identification of the layers and substructures within the retina. Comparatively low resolution early OCT devices detected one highly reflective band (or “line”) in the posterior ocular fundus. This band was ascribed to more than one structure depending on the authority.1–6 Introduction of commercial OCT devices occurred in 1996, and initially the retinal thickness was measured from the inner retina to the top of the highly reflective posterior band.4,5 Development of higher-bandwidth illumination in research devices increased attainable resolution to 3 μm to 4 μm and was called “ultrahigh-resolution” OCT. With the newer OCTs, the formerly single highly reflective band was resolved as either three or four separate bands. Various publications attributed diverse anatomical correlates to these bands; the discordance existed not only between different author groups but also between papers from the same group.7–9 The 2007 entry into the commercial market and subsequent widespread adoption of high-resolution spectral-domain OCT created the opportunity for practicing ophthalmologists to have a nearly cellular level of resolution of the retina.10 A practical need for terminology of various layers of the retina arose and an ad hoc nomenclature, based on an amalgamation of previous OCT papers, was adopted by the ophthalmic community. Commercial spectral-domain OCT instruments conventionally resolve 4 bands in the outer retina outside of the central fovea (Figure 1). The innermost band has been attributed to the external limiting membrane (ELM),8 a linear confluence of junctional complexes between Muller cells and photoreceptors. This band typically is thinner and much fainter than the others. The second of the four bands has been commonly ascribed to the boundary between the inner segments (IS) and outer segments (OS) of the photoreceptors.9,11 The third band is commonly referred to as either the OS tips12 or as Verhoeff membrane.13,14 The outermost highly reflective band has been thought to represent the retinal pigment epithelium (RPE), Bruch membrane, and possibly the choriocapillaris.2,6,8,14,15 Fig. 1 Drawing of the outer hyperreflective bands overlaid on a representative spectral-domain OCT scan of a normal macula. Each of the bands has had different anatomical correlations proposed over time, with varying designations by research group and time period. ... Close inspection of these four bands raises questions about some of these assignments. For both foveal cones and rods, the length of the OSs is roughly the same as the ISs,16,17 so one would expect the boundary between the IS and OS to lie at the midpoint between the ELM and RPE. However, the second reflective band lies much closer to the ELM than it does to the RPE. Further, the word “boundary” implies a narrow line as a reflection, while the “IS/OS boundary” image typically is nearly as thick as the RPE band. Finally, although the third band is called Verhoeff membrane, what Verhoeff described was an anatomical structure girdling RPE cells,18,19 known now as junctional complexes between RPE cells.20,21 Therefore, a reflective band physically separated from the RPE cannot be Verhoeff membrane. Over the last century a wealth of information about the anatomical structure of the retina has been published, complete with meticulous measurements. Assembling this information into a database would allow comparisons between known measurements and the structures seen by OCT. We assembled this information and constructed a scale model drawing of the outer retina to enable visual comparisons. Using this model for analysis, we find that the designation of the ELM for the first band is correct and that the fourth band at least contains the RPE, but current assignments of the middle two bands are more problematic.