What Is the Retina?

Pediatric retinoblastoma is a rare form of children’s eye cancer that develops in the retina of the eye. To understand pediatric retinoblastoma, it is important to first understand the retina and its purpose. The retina is a layer of light-sensitive tissue that lines the back of the eye’s inner surface. It plays a significant role in vision.

Role of the Retina

The role of the retina can be compared to film in a camera. This is because light projects through the lenses of the eyes and becomes focused onto light-sensitive cells in the retina called photoreceptors. The photoreceptors then convert the projected images into electrical signals, which are sent to the brain through the optic nerve. The brain then interprets these signals into sight.

Retina Anatomy

The retina consists of several structures that work together to project light and interpret vision. There are two main types of retinal photoreceptors, which are referred to as rods and cones. The macula is a yellow-colored spot near the retina’s center. Near the center of the macula is the fovea, which contains a large concentration of cones.

Retina Rods

On average, there are roughly 120 million rods in the retina. The rods in the retina are particularly sensitive to changes in lightness, darkness, shape, and movement. Rods only contain one type of pigment, and are not effective for color vision. An example of when rods are most effective is vision in a dark room. The individual can sense shape and movement, but essentially sees in black and white.

Retina Cones

Cones are less numerous than rods, with roughly six-to-seven million in the human retina. While not as sensitive to light as rods, each cone is most sensitive to red, green, or blue. Cones are not effective for vision in the dark. This explains the phenomenon of seeing in “black and white” in a dim room. Color blindness occurs when the affected individual lacks one type of retinal cone.

Retina Macula

The macula acts as natural “sunglasses” for the eyes. This is because the macula absorbs excess harmful ultraviolet and blue light entering the eye. The macula contains structures which are specialized to provide high-acuity vision.

Retina Fovea

The fovea is a small pit near the center of the macula. The fovea contains a high density of retinal cones. The fovea provides high-acuity vision due to the high acuity, or sharpness, of vision that cones provide.

Pediatric Retinoblastoma in the Retina

Due to the key role of the retina in vision, children with pediatric retinoblastoma may experience vision symptoms. In severe cases of pediatric retinoblastoma, the child may suffer permanent vision damage or blindness. For this reason, it is important to diagnose and treat pediatric retinoblastoma as soon as the child exhibits any potential symptoms.