The eye is one of the most amazing organs in the body. It is responsible for perceiving images and transmitting that information to the brain.
Basic Anatomy
The Visual Pathway
As light passes into the eye the first structure it hits is the tear film. The tear film is composed of 3 parts an outer lipid layer, an intermediate aqueous layer, and an inner mucus layer. This tripartite tear film is produced by the meibomian glands of the eyelid margin, the lacrimal glands and the goblet cells of the inner conjunctiva.
Did you know that even if one of these layers is inadequate you can develop dry eye syndrome?
Based on which gland is dysfunctional you can be treated accordingly to help alleviate your dry eye disease.
Did you know that the tear film is crucial in providing adequate vision?
If you have a poor tear film besides having irritated eyes you can develop blurry vision. This is because the tear film is responsible for more refraction or focusing power than your natural lens.
Did you know that patients with autoimmune diseases often suffer from Dry Eye disease ?
If you suffer from autoimmune related dry eye disease you may benefit from topical Cyclosporine or Restasis.
The next structure encountered is the Cornea. The normal cornea is composed of 5 layers. Starting from the front we have the Epithelium, Bowmans layer, Stroma, Descemet’s membrane and the endothelium. Each layer serves an important role in allowing crisp clear vision. The epithelium protects the internal structures and protects the eye from getting infections. The Stroma has a very high tensile strength due to the orientation of its fibers and allows light to pass through undisturbed. Finally Descemet’s membrane is responsible to pump out excess fluid that might build up in the cornea.
Did you know that LASIK/LASEK and most refractive surgeries are performed on the cornea ?
Refractive surgeons use special lasers with eye tracking software to modify the shape of the cornea making it into a “natural contact lens.”
Did you know that the cornea has the highest concentration of nerve endings ?
They say that a corneal abrasion is one of the few ways a man can experience the pains of childbirth without an epidural. The good thing is that it is quick to heal, most abrasions in healthy individuals will heal within 24 hours.
Did you know that historically corneal transplants needed to be full thickness but no longer ?
Now with DSEAK technology Descemet’s membrane can be replaced with the need for full penetrating keratoplasty. With DSEAK a patient has a quicker visual recovery time and does not have to deal with unexpected post-operative astigmatism.
After light passes through the cornea the next structure it hits is the Lens. The Lens is composed of 3 main parts the lens capsule, epithelium and the lens fibers. It is responsible for focusing near and far images on the retina. This is called accommodation. With time, as we age, our lens loses the ability to accommodate and the need for reading glasses or bifocals arises. The natural lens is what is replaced in cataract surgery.
Did you know that the lens is only responsible for approximately a third of the focusing power of the eye?
The other 2/3 are supplied by the tear film and the cornea.
Did you know that there has never been a diagnosed case of Lens cancer?
Cancer cells can develop throughout the eye but there has never been a case of lenticular cancer described in the literature.
Did you know that not all Cataracts are the same?
There are different types of cataracts; Nuclear sclerosis, Cortical, Posterior Subcapsular are the 3 most common. Each of them present with different symptoms. The doctors at Eye Surgeons NYC can determine what type of cataract you have and recommend the appropriate course of action.
After passing through the lens and the vitreous cavity light finally hits the Retina. The Retina is composed of specialized photoreceptors that are capable of perceiving an image and transmitting this information to the brain. There are 2 major categories of photoreceptors the Rods and the Cones. The Rods are mainly responsible for vision in low light situations while the Cones are responsible for color perception.
Did you know that there are over 120 million photoreceptors in the eye?
Interestingly the Rods responsible for scotopic, or dark-adapted vision outnumber the Cones by a ratio of about 20:1.
Did you know that an Ophthalmologist can see your brain without any invasive techniques?
The Retina is a direct extension of the brain and can be seen with specialized lens by an Ophthalmologist. With this exam skill ophthalmologists can often detect some of the earliest signs of CNS pathology.
Did you know that your car isn’t the only thing with a blind spot?
Your Retina has a normal physiologic blind spot at the optic nerve the site were all the the nerves leave the eye transmitting information to the brain.
Did you know that some of the earliest signs of a systemic disease can be detected on a complete eye exam?
There are times that your Ophthalmologist at Eye Surgeons of NYC can detect the beginning signs of hypertension, diabetes, systemic infection, cancer, or autoimmune diseases on an eye exam prior to it being diagnosed by your general practitioner. Obviously this can help in initiating therapy before it is to late.
