PURPOSE To determine the extent of rod and cone photoreceptor dysfunction in patients with cone dystrophy using psychophysical and electrophysiological tests. METHODS Ten patients with cone dystrophy participated. Rod and cone system psychophysical thresholds were measured as a function of retinal eccentricity. Bright-flash full-field electroretinograms were obtained under dark-adapted (rod-m...

OBJECTIVE To demonstrate the progression of electroretinographic (ERG) findings in mucolipidosis IV. METHODS Two patients with mucolipidosis IV were examined clinically and their condition was followed up for ophthalmic manifestations of the disease. Electroretinograms were performed on both patients, and conjunctival biopsy specimens were analyzed for characteristic ultrastructural inclusion...

PURPOSE This study tests whether cones in the rhodopsin-mutant transgenic P23H-3 retina are damaged by ambient light and whether subsequent light restriction allows repair of damaged cones. METHODS P23H-3 rats were raised in scotopic cyclic (12 hours of 5 lux, 12 hours of dark) ambient light. At postnatal day 90 to 130, some were transferred to photopic conditions (12 hours of 300 lux, 12 hou...

BACKGROUND Mice with a function-blocking mutation in the Scn8a gene that encodes Na(v)1.6, a voltage-gated sodium channel (VGSC) isoform normally found in several types of retinal neurons, have previously been found to display a profoundly abnormal dark adapted flash electroretinogram. However the retinal function of these mice in light adapted conditions has not been studied. METHODOLOGY/PRI...

We show that if (u,K) is a minimizer of the Mumford-Shah functional in an open set Ω of R, and if x ∈ K and r > 0 are such that K is close enough to a minimal cone of type P (a plane), Y (three half planes meeting with 120◦ angles) or T (cone over a regular tetrahedron centered at the origin) in terms of Hausdorff distance in B(x, r), then K is C equivalent to the minimal cone in B(x, cr) where...

Zebrafish are tetrachromats with red (R, 570 nm), green (G, 480 nm), blue (B, 415 nm), and UV (U, 362 nm) cones. Although neurons in other cyprinid retinas are rich in color processing neural circuitry, spectral responses of individual neurons in zebrafish retina, a genetic model for vertebrate color vision, are yet to be studied. Using dye-filled sharp microelectrodes, horizontal cell voltage ...

A cone-beam algorithm which provides a practical implementation of B D Smith's cone-beam inversion formula is presented. For a cone-beam vertex orbit consisting of a circle and an orthogonal line. This geometry is easy to implement in a SPECT system, and it satisfies the cone-beam data sufficiency condition. The proposed algorithm is in the form of a convolution-back projection, and requires a ...

We quantified rod- and cone-related electroretinogram (ERG) responses following subretinal injections of the human-derived retinal pigment epithelial (hRPE) cell line ARPE-19 at age P23 to prevent progressive photoreceptor loss in the Royal College of Surgeons (RCS) rat. Culture medium-injected eyes served as sham controls. At P60, in comparison with sham-injected eyes, all recordings from hRPE...

PURPOSE To examine the S-cone ERG in subjects with and without L and M-cone function. METHODS Ganzfeld spectral flashes in the presence of strong Ganzfeld adapting fields are used to elicit S-cone ERGs. RESULTS The S-cone ERG b-wave ranges from 0.2 to 4 mV in amplitude and 38-45 msec in implicit time. There is a progressive decrease in amplitude with age. The response is similar in subjects...

The mechanism of contraction in motile models of teleost retinal cones has been examined by using N-ethylmaleimide (NEM)-modified myosin fragments (NEM-S-1 and NEM-heavy meromyosin [HMM]) to prevent access of native myosin to actin filaments during reactivation of contraction. In the diurnal light/dark cycle, retinal cones of green sunfish (Lepomis cyanellus) and bluegill (lepomis macrochirus) ...