Regulation of Light through the Pupil
The pupillary opening appears to occupy a central location, but if carefully measured, it is actually situated slightly inferior and nasal to the center of the cornea. Thus, the pupil…
Ganglion-Cell Photoreceptors and Non-Image-Forming Vision
Overview In the past decade, compelling evidence has emerged for a novel class of photoreceptors in the mammalian retina. These neurons are ganglion cells that express the photopigment melanopsin and…
Signal Processing in the Inner Retina
The inner plexiform layer (IPL) is the second synaptic layer of the retina ( Fig. 23.1 ) and the final stage for processing visual information before it leaves the eye….
Signal Processing in the Outer Retina
Light-evoked hyperpolarizing signals in rods and cones are transmitted to and processed by neurons in the rest of the retina through a complex, but highly organized network of electrical and…
Photoresponses of Rods and Cones
Retinal rods and cones are highly specialized neurons that respond to light with an electrical signal (see Chapter 18 ) and provide the sensory input for vision. In contrast to…
The Synaptic Organization of the Retina
The basic architecture, signal flow, and neurochemistry of signaling through the vertebrate retina is well-understood: photoreceptors, bipolar cells (BCs), and ganglion cells (GCs) are all thought to be glutamatergic neurons…
Light Adaptation in Photoreceptors
1 Vision from starlight to sunlight The human visual system operates effectively over an enormously wide range of intensities, of at least a billion-fold, from around 10 −4 cd m −2…
Sensory Innervation of the Eye
Introduction The sensory innervation of the eye is provided by the peripheral axons of primary sensory neurons located in the trigeminal ganglion. The sensory nerves enter the eyeball mainly through…
Biochemical Cascade of Phototransduction
Overview Phototransduction is the series of biochemical events that lead from photon capture by a photoreceptor cell to its hyperpolarization and slowing of neurotransmitter release at the synapse. This overall…
Outward-Directed Transport
Introduction In ocular therapeutics, the current literature describes drug delivery limitations posed by outward directed transport mechanisms of the eye. Drug delivery to ocular tissues is restricted by various factors…
