This lens is thicker in the middle and narrows out towards the edges.

There lies a lens behind the pupil of the eye.

The amount of light entering the eyes is controlled by the iris by changing the pupil size.

Under dim light, the iris contracts to increase the pupil size so as to increase the amount of light entering the eyes.

This is done to decrease the amount of light entering the eyes.

When light is shone onto a person’s eye, the iris relaxes and the pupil size decreases.

The iris has a small circular opening called the pupil, whose size is controlled by the iris.

The color of the eyes of a person is the color of the iris of their eyes.

There are colored muscular structures behind the cornea called the iris.The transparent part at the front is called the Cornea.The outer white coat called sclera is tough in order to prevent it from injuries and accidents.A human eye has a roughly spherical shape.The following are the characteristics of a human eye: We will also look at the ways to take care of our eyes and the alternative for visually impaired people. In this section we will learn about the human eye, its structure and function of its various parts. Therefore, our eyes are essential for us to see everything around us. When light getting reflected from the surrounding objects enters our eyes, we see the objects. An alternative to visually impaired people.Please get in touch for more information. In addition to high-end quality lenses, an inverter and a BIOM, are used for fundus observation.įor fundus observation devices adaptations, OM-19 is compatible with Oculus BIOM and Haag Streit EIBOS. We are able to observe the retina thanks to the cutting-edge Takagi OM-19 Operating Microscope, that uses exceptional quality objective lenses and eyepieces made in Japan. The video showcases the incredible retina, just before a vitreoretinal surgery procedure, where the optic disc that connects to the optical nerve and the blood vessels are visible. In this video, we can observe another way of visualising the retina, with an operating microscope. But we will talk more on the most common retinal diseases in our future posts. Ophthalmologists and optometrists examine the retina in order to detect signs of damage or abnormalities, which could cause retinal diseases.

There are a few ways to examine the retina, by using different devices such as an ophthalmoscope, a slit lamp, a retinal camera or an OCT, for a distinct view of the retina’s layers. One of the nerve fibres in the ganglion cells called axon, together with glial cells forms the optical nerve, which transmits the visual signals to the brain. Based on their location in the retina, these cells can receive inputs from 100 rods and cones. At this stage the ganglion cell, another type of neuron, once the information has been received from the photoreceptors, it transmits it to the brain through the optical nerve.

The bipolar cells are a type of neuron that connects the rods and cones with the ganglion cells, this is called synaptic connection. For this reason, looking at an object in the dark, it’s easier to focus if looking slightly to the side of the object and not directly at it. The peripheral part of the retina is composed of approx. This allows the human eye to achieve a sharp and visually detailed colour vision, crucial for reading for example. Whereas, the most important one part of the macula is its centre called the fovea, where the highest concentration of cones are located. The part with a high concentration of cones is called the macula, which is around 5.5mm. 7 million cones located predominantly in the central part. These retinal layers are connected by synapses and supported by the outer layer of pigment epithelium which provides nutrients to the retina. Reception of light rays, transmission to the bipolar cell layer and ganglion cell layer and finally transmission through the optic nerve. It’s made of neuron layers that can be divided into 4 main groups based on the stages of processing the light that enters the eye, as such: The retina in human adults is 0.5mm thick and 22mm in diameter and is considered to be the most important part of the eye. However, the retina and the camera sensor, both play the same role in transforming light photons into electrical impulses. The impressive layers of tissue that form the retina are more complex than any camera sensor on the market, be it an analogue film or digital CCD/CMOS sensor. Now we are going to focus on the retina and its functions. In our previous post, we have introduced the main similarities between the eye and the camera. Retina and Its Functions – The Role of 150 Million Receptors and 1 Million Optic Nerve Fibres

Function of retina in human eye