The inner workings of the human eye are complex, but at the same time, fascinating. Have you wondered how exactly they do work or what are the major parts of the eyeball involved in creating vision? Let’s find out.

These tiny cameras spend every day processing millions of pieces of information at lightning fast speeds, and turn them into the simple images we see almost instantly.

In reality, this process is anything but simple. The eye has several distinct parts, each of which has specific responsibilities that work together like a machine.

The eyeball is just like a camera. In fact, human eyes are part of a classification known as “camera-type eyes.” And just like a camera, it can’t function without the presence of light.  As light hits the eyes, it’s focused by the eye in a way similar to a camera lens. This process allows the images we see to appear clear and sharp rather than blurry.

There are specific parts of the eye that make this focusing process possible. Each beam of light that hits the eye goes through a series of steps:

Step 1: Light passes through a thin layer of moisture

Step 2: Light hits the cornea.  The cornea is transparent, and is the first layer to begin focusing light within the eye. The cornea is connected to the sclera, which is a tough fiber on the outside of the eye that acts as protection.

Step 3: Behind the cornea is another liquid layer known as the aqueous humor, and its job is to maintain pressure levels in the front of the eye as light is passing through.

Step 4: Once light has passed through the aqueous humor, it has finally reached the pupil. The pupil is the round entryway of the colored iris.

Step 5: Once the pupil determines how much light it will let inside your eye, the job passes to the lens. The lens factors in the amount of light the pupil lets in, and figures out how far away you are from the object that the light is reflecting off of, or the object you’re trying to see. From there, the lens focuses your image into an accurate view of what you’re looking at. Part of this process is controlled by muscles in the lens called ciliary muscles, which expand and contract to pull on the lens and allow it to focus properly.

Step 6: As light reaches the center of the eye passes through another layer of moisture, called the vitreous, or vitreous humor. Then, it reaches the final stop in the process: The Retina.

The retina is the back of the eye. If the lens in your eye is most like a camera, the retina is most like its film – this is where the final product is projected. The retina has several parts:

  • Macula: The center of the retina. The center point of the macula is called the fovea, and it has the most photoreceptors and nerve endings of any part of the eye.
  • Photoreceptors: Split into two designations – rods and cones.
    • Cones are in the macula. When there is bright light, cones provide clear, sharp central vision and detect colors and fine details.
    • Rods are located outside the macula and extend all the way to the outer edge of the retina. They provide peripheral or side vision. Rods also allow the eyes to detect motion and help us see in dim light and at night.

  • Retinal pigment epithelium: Abbreviated RPE, this is a tissue layer below the rods and cones which absorbs any extra, unneeded light.
  • Choroid: The choroid is behind the retina, and is in charge of making sure the retina and RPE have enough nutrition flowing from small blood vessels.

Once the photoreceptors have converted light into an electronic signal, they send a signal to the brain’s visual command center and you have vision. It’s amazing what even small parts of our bodies can do.


How the Eye Works

January is Glaucoma Awareness Month

National Glaucoma Awareness Month reminds all of us to get regular eye exams and show support for those suffering from this conditionGlaucoma is one of the leading causes of vision loss and blindness.  Glaucoma is often called “the sneak thief of sight” because glaucoma has few symptoms or warning signs in its early stages. It can be diagnosed only by a full eye exam by an eye care practitioner.

Glaucoma is a disease where pressure builds up and damages the eye’s optic nerve. Types of this disease include the common Primary Open Angle Glaucoma, which causes peripheral eyesight to slowly diminish and is age-related. Angle Closure Glaucoma, where the fluid drainage system is narrow and closed so that the aqueous fluid remains in the front chamber of the eye and intraocular pressure rises; and Low Tension Glaucoma, where the optic nerve becomes damaged in spite of the intraocular pressures being within the normal range. There’s currently no way to restore vision lost from glaucoma because once the nerve cells become damaged, they do not regenerate.


A few important facts you should know about Glaucoma in adults:

  • More patients than ever are affected – Over 3 million people in the U.S. have glaucoma, and the number is rising.
  • Glaucoma can affect people of all ages – The most common form of glaucoma, Primary Open Angle Glaucoma, becomes more prevalent with increasing age. However, glaucoma can strike anyone, even infants and children but it is rare.
  • Demographics do play a role – Glaucoma is a leading cause of blindness among African Americans; it’s also highly prevalent in Hispanics over the age 65.
  • Is glaucoma hereditary? The risk of developing Primary Open–Angle Glaucoma is up to nine times more likely if parents or siblings have the disease.
  • Hope for future glaucoma patients – Although there is no cure for any form of glaucoma, early diagnosis and treatment help control the disease and slow the process of vision loss or blindness.

Newer Glaucoma Treatments 

Glaucoma treatment usually begins with the use of topical (eye drop) medications which lower the intraocular pressure. Within the past two years, two new topical medications have been approved for the treatment of glaucoma: VYZULTA® and Rhopressa®. VYZULTA® is a modification of a class of medications currently used to treat glaucoma – the prostaglandin analogs. This drug helps lower intraocular pressure by increasing the drainage of fluid (aqueous humor) from the eye.

Rhopressa® is part of a new class of drugs used to treat glaucoma called Rho kinase inhibitors. Rhopressa®, like VYZULTA®, also lowers intraocular pressure by increasing aqueous outflow. Both Rhopressa® and VYZULTA® are dosed once daily and pose few, if any, systemic safety concerns.


Using a laser to make a small opening in the iris to help with fluid drainage usually cures Angle-Closure Glaucoma.  This procedure is called a laser peripheral iridotomy.

For Primary Open Angel Glaucoma, when eye drops are not enough to reduce the pressure then a procedure called Selective Laser Trabeculoplasty (SLT) can be used. The SLT reduces intraocular pressure by stimulating increased outflow of fluid from the eye. SLT offers an improved safety profile compared to older glaucoma laser therapies and may lower eye pressure by as much as 20 to 30 percent. It is typically used as the next step in patients whose glaucoma is uncontrolled on medical therapy. Because of its excellent benefit-to-risk profile, however, SLT can sometimes be used in place of medications, especially in patients who have difficulty with their eye drops.


When other treatments fail, there are many surgical therapies to lower the eye pressure. These surgical approaches, which are riskier than medical therapy or lasers, are usually employed when non-surgical means do not work well enough to stop vision loss.


The goal of Minimally Invasive Glaucoma Surgery (MIGS) is to reduce intraocular pressure by enhancing the eye’s own internal aqueous humor drainage system. Some MIGS can be performed as stand-alone procedures, while others are typically done along with cataract surgery in patients with visually significant cataracts and mild to moderate glaucoma.

There are now a variety of recently FDA approved MIGS available for use in this country. MIGS typically are performed through a small incision in the eye with minimal tissue trauma and offer a favorable safety profile as well as more rapid visual recovery than traditional glaucoma surgery. There are many well qualified glaucoma specialists that perform the MIGS procedure.


Glaucoma Treatment Overview


National Glaucoma Awareness Month reminds all of us to get regular eye exams. Don’t let glaucoma steal your sight!  The best way to protect your sight is to get an annual comprehensive eye examination.

Thanks to funding from private philanthropists, DEF’s research continues to make great strides toward cures and treatment for glaucoma.  If you would like to support DEF’s sight saving research please donate today!


A Vision of Christmas

A special holiday message from our beloved blind Ambassador of VisionTom Sullivan

My wife Patty loves every aspect of the Christmas season, and she begins celebrating the yule tide even before Thanksgiving.  The transforming of our house with traditional decorations brings her a marvelous sense of family and holiday season.  She loves to look at every ornament remembering how we acquired it.  As the lights turn on outside our house, she is busy making sure that every bulb on our tree is placed just so to give the room a warmth that in every way reflects her commitment to the true spirit of the season.

While I am listening to football upstairs, she’s singing along with Celine Dion as she completes the visual picture that for Patty confirms that there really are important traditions that make our home a place of love, beauty, and peace.  For the record, let me say that I really do enjoy Christmas even though I offer half-hearted complaints that Patty plays carols starting even before Turkey Day.  The truth is…I love them just as much as she does.

For over thirty years we went to Colorado every Christmas to ski, and those experiences were wonderful to just be in the mountains and feel the cold nipping at your nose as you fly down a ski slope.  We often would take a sleigh ride on Christmas Eve with hot chocolate spiced with peppermint schnapps.  Listening to a children’s choir and being with people we love always seems to make things a little more right with the world.  So I really do love Christmas, but when I consider Patty’s ebullient joy in the visuals of the holiday, I admit it makes me just a little sad to know that I’ll never be able to see them.

I realize that people go to extraordinary lengths in their decorating zeal and that certainly some of their elaborate choices that brighten the neighborhood could be considered over the top, but when Patty’s carols are playing and she’s enjoying the happiness of singing along with the decorations just so, I know that what she’s reflecting is her true commitment to her faith and the celebration of the season that she treasures. 

So open your hearts and your eyes and take in the true experience of the Christmas spirit.  It’s my hope that you’ll consider supporting Discovery Eye Foundation’s commitment to preserving vision allowing more people every year to enjoy not just the smell of a Christmas tree, or the taste of a Christmas toast, the touch of a hug from a loved one on Christmas morning, or the beautiful sounds of Silent Night sung by the voice of a child.

From all of us at Discovery Eye, we wish you a Merry Christmas and Happy Holidays!


Tom Sullivan
DEF’s Ambassador of Vision


Common Eye Problems in Winter

Winter time is here!! And as most people would expect, the holidays are a very popular time of the year. But the winter also comes with extreme temperatures, humidity and precipitation, so don’t let it affect your vision!

Be on the lookout for these common eye conditions this winter and hopefully, you will comfortably enjoy the season without any problems.



Cold outdoor air and heated indoor air often have less moisture than other seasonal environments. In the winter, you may experience dry skin, chapped lips, and dry eyes due to this low humidity. Cold winter winds may also dry your eyes out. To learn more about dry eyes, visit the linked website at Dry Eyes.

To minimize the drying ability of winter air, keep yourself hydrated. Use non-preserved artificial tears several times a day. Running an humidifier in your home to improve the quality of your indoor air will help as well.



While some people experience a lack of tears in the winter, others have the opposite problem. Excess tearing and runny eyes can occur due to cold air, biting winds, or seasonal allergies. Pay attention to when your eyes tear up to determine the cause. If your eyes start to water when you step outside or when the wind blows your way, wear sunglasses or goggles to protect your eyes. Although it seems strange using additional artificial tears for teary eyes, nonetheless they can lessen this reflex tearing.

If you experience excess tearing and itching while indoors, try an allergy medication and appropriate eye drops to reduce the effect of seasonal allergies. If you cannot determine the cause of your watery eyes or if over-the-counter treatments have no effect, especially if the wateriness alters your vision, see an eye doctor.



Winter skies can seem dark and gloomy, but snowfall and ice create many reflective surfaces that can dramatically increase the amount of light that reaches your eyes. If you have sensitive eyes, you may experience even more blinking, discomfort, tearing and other symptoms in bright winter light.

Some individuals develop new light sensitivity during winter due to a condition known as “snow blindness”.  Always protect your eyes with UV filtering glasses or ski goggles when going outdoors for long periods of time, including when walking, shoveling snow, or other winter activities.



Harsh winter conditions can cause redness, tenderness, and inflammation in the eye area. You may have swollen eyelids or redness over the normally-white part of the eye (the conjunctiva which covers the white sclera).

This redness could result from dry eye or seasonal allergies. Use non-preserved artificial tears every 2-3 hours.  To reduce the discomfort of inflamed eyes, apply a cool compress, such as a damp washcloth and take an over-the-counter oral pain medication.  If your symptoms persist, see an eye doctor to determine the cause of the irritation.



While many winter eye health problems result from increased light or decreased moisture, you can also experience eye conditions caused by cold temperatures.

If you notice vision changes while out in the cold, move to a warm area as soon as possible. Use non-preserved artificial tears every 2-3 hours to to keep your eyes moist. If your normal vision doesn’t return after 30 minutes or so, seek medical attention.


If you experience any of the seasonal problems listed above for a prolonged period, consult your eye doctor.

Thanks – Giving

It’s Holiday season and I’m reminded that between Thanksgiving and Christmas I very much prefer America’s turkey day.  Somewhere over the course of my life I began to think of Thanksgiving in two distinct parts – Thanks and Giving.  There is so much I am grateful for – family, friends, good health, and most of all a sense of real purpose.  I treasure my role as an Ambassador of Vision for the Discovery Eye Foundation.  Our work supporting research that preserves and enhances vision is most rewarding in every way, and the stories of patients who maintain their sight because of breakthroughs provided by our Foundation and its on-going research is incredibly rewarding for all of us who work tirelessly to make a difference.  On this special holiday I’m sure that every person who has benefitted from our dedication is saying “Thank You” as they enjoy a day surrounded by family and friends. 

The link between the two words “Thanks” and “Giving” is obvious.  When you say “thank you” the desire to give seems to go hand and hand.   We are so grateful to everyone who has supported the important work of Discovery Eye through your generous donations over all these years.  At this Holiday season, please know that we will continue to search for answers that will guarantee many more people with the gift of vision.  We are thankful for your support and grateful that you choose to give us the opportunity to make a difference.

Happy Holidays from everyone in the Discovery Eye Family.


Tom Sullivan
DEF’s Ambassador of Vision



As autumn takes on the majestic beauty of its fall colors, school children remind us of the explorer Columbus on his October holiday.  We remember how much courage it must have taken for men to set sail from Spain and cross the Atlantic in search for new lands and treasure.  As the days became months, the sailors on the three small ships began to believe that they were about to fall off the face of the earth convinced that the world was flat and that monsters were waiting on the other side of the horizon.

In many ways the search for breakthroughs in vision have been just as frightening and just as surprising.  It wasn’t that long ago when cataract surgery required patients to be hospitalized for days at a time lying perfectly still while their new lenses gradually settled.  When I was a baby suffering from glaucoma, there were no drugs available to ease the crippling headaches I’ll never forget.  Diabetic retinopathy and wet macular degeneration had no possibility for control until gifted researchers began to apply stem cells, gene therapy, and nutraceuticals.  Much like the exploration of Columbus, most forms of blindness are moving toward remarkable and dynamic breakthroughs.

Research supported by Discovery Eye Foundation is now on the cutting edge of unlimited possibilities that someday may dynamically improve the vision and the lives of patients and their families.  Our work can only continue with your support.  Please join us as we explore and discover new worlds of vision and hope.


Tom Sullivan
DEF’s Ambassador of Vision


September is Healthy Aging Month

Healthy Aging Month is an annual health observance designed to focus national attention on the positive aspects of growing older.  Aging is a process that brings many changes. Vision loss and blindness, however, do not have to be one of them. There are several simple steps you can take to help keep your eyes healthy for the rest of your life.

Eye diseases often have no early symptoms, but can be detected during a comprehensive dilated eye exam A comprehensive dilated eye exam is different from the basic eye exam or screening you have for glasses or contacts. By dilating the pupils and examining the back of the eyes, your eye care professional can detect eye diseases in their early stages, before vision loss occurs. By performing a comprehensive eye exam, your eye care professional can check for early signs of –

Here are some other tips to help maintain healthy vision and body now and as you age:

  • Eat a healthy, balanced diet. Loading up on fruits and vegetables can help keep your eyes healthy and disease free.
  • Maintain a healthy weight. Being overweight increases your risk for heart disease and diabetes. Complications from diabetes, such as diabetic retinopathy or glaucoma, can eventually lead to vision loss.
  • Don’t smoke. Smoking increases your risk for age-related macular degeneration, cataract, and other systemic diseases, including cancer. Wear protective eyewear when outdoors. Protecting your eyes from the sun’s ultraviolet rays when you are outdoors is important for your eye health. Choose sunglasses that block 99 to 100 percent of both UV-A and UV-B radiation.

Even if you are not experiencing vision problems, visiting an eye care professional regularly for a comprehensive dilated eye exam is the most important thing you can do to reduce your risk of vision loss as you age.


Download “Everyone’s vision can change with age”
A handout with explanation on how vision can change with age.

Children’s Eyes

It’s said that the “eyes are the windows to the soul.”  If that is true, looking into the eyes of a child, it’s easy to see the beauty and innocence that all of us wish could be more a part of the world they will live in.

I’ve also heard that there is a wonder found in those eyes – a curiosity that opens the child’s brain and heart to all of life’s joys and potentials. 

The thought that those eyes could be threatened through accident or disease is a painful reality that all of us at Discovery are working to prevent through all of our cutting-edge research with your on-going support.

All too often I have been present in an ophthalmologist’s office when a caring doctor is forced to tell a family that there is a major problem with their baby’s vision.  Diseases of the retina such as glaucoma, or retinitis pigmentosa, are joined by diseases of the cornea like keratoconus.  It’s even worse when a family has to hear the diagnosis is retinoblastoma – or a cancer of the eye.  In these personal and painful moments, a family’s entire life is forever changed and their child’s struggle with vision will remain on-going and difficult.

August is “Children’s Eye Safety” month, and I can’t think of anything else more important to protect.  The eyes of a child are beautiful, full of innocence and love.  So, let’s make sure that they will continue to see the world with beauty and clear vision. 

The Discovery Eye Foundation is committed to finding the answers that will preserve the vision of millions of people.  Our groundbreaking research needs your help to move forward! 

To learn how you can help, click here Ways to Help DEF or click the button below to donate online. 

Tom Sullivan
DEF’s Ambassador of Vision


Cancer in the EYE: Unexpected Thought

When you think of cancer, most of us do not think about the eye or vision. Though rare, cancer can start inside or outside of the eye. If cancer starts inside the eyeball it’s called intraocular and if it starts outside the eye (eyelid or in the eye socket) then it’s called extraocular tumor. It can occur in both children and adults. Most major eye centers have specialists who are trained in the diagnosis and treatment of eye cancers.

Here are a few types of cancer in eye:

  • Eye Cancer in Children: The most common cancer seen in the eye of children is retinoblastoma. This occurs in children at very early age so these are the youngest cancer patients. This cancer starts inside the eye and affects the retinal cells. This is a cancer that presents very quietly, the child has no pain, no complaints and plays happily without any problem until one day parents notice that the pupil of the eye has some abnormal ‘White Glow’ (leukocoria) rather than the usual ‘red-eye’ reflection seen in a photo—that can be the first sign of retinoblastoma. So, it requires prompt evaluation by an ophthalmologist. Retinoblastoma is a curable cancer but if it is not treated on time, it can grow quickly and fill the eyeball. It can lead to loss of vision and life-threatening problems.

At the later stage of this cancer, the only one way to survive is to remove the eyeball (enucleation). Like many of other types of cancer, retinoblastoma has a genetic component so genetic testing needs to be done. The tumor begins with the RB1 gene mutation that stimulates retinal cells to develop into a tumor called a retinoblastoma. The RB1 mutation can be inherited from the parents, but in some cases it is sporadic and not inherited. There are various treatments such as surgery, chemotherapy, radiotherapy etc. to cure retinoblastoma cancer. Rarely it can spread beyond the eye. 

  • Eye Cancer in Adults: The development of a tumor in the back of the eye in adults can be from a metastatic cancer from elsewhere in the body or can arise in the eye itself. The most common primary eye cancer is called uveal melanoma and is a cluster of rapidly growing cells underneath the retina, which can lead to vision loss. The tumor can also appear as a dark black spot on the iris. Ideally the uveal melanoma can be treated when the tumor is still only in the eye.However, unfortunately, in approximately 50% of patients the uveal melanoma spreads (metastasis) to other part of the body, making it the most dangerous eye cancer in adults. Depending upon its location the uveal melanoma may not cause early symptoms but the patient may experience blurred vision or large numbers of floaters. The uveal melanoma can be diagnosed only when an ophthalmologist or eye care specialist examines your eye. What is the main cause of uveal melanoma? How it starts, grow and spread? These questions are still unanswered. The risk of this cancer increases in persons having fair skin (white), light eye color and inability to tan. There are certain changes in the genes linked to uveal melanoma. Currently the most common are GNAQ and BAP-1 gene mutations that are associated with greater risk of metastasis, where it spreads to other parts of the body. The standard treatment of this tumor is fine-needle aspiration biopsy (FNAB), brachytherapy (radioactive material inside a small capsule placed next to the tumor), radiation therapy and possibly enucleation. 
  • Metastasis to Eye: Finally, the other types of cancers found in the eyes are because of the spreading of a primary cancer (from a distant site such as the breast, lung or liver) to the eye.  Sometimes an eye exam can identify a metastatic tumor before the primary tumor is recognized elsewhere in the body.  Examples of cancers that spread to the eye are breast cancer in women and lung cancer in men. Less commonly, the prostate, kidney, gastrointestinal and blood cancers (leukemia and lymphomas) can spread to the eye.  Treatment depends on the type of cancer involved. 
  • Eye Damage from Chemotherapy: Eye problems can also develop through the side effects of chemotherapy or hormone therapies given for tumors outside the eye. When a person has any type of cancer, they often must undergo treatments with chemotherapeutic drugs.  A commonly used cancer drug is called cisplatin.  When treated with cisplatin, there can be damage to the retinal pigment epithelial cells in the inner part of the retina. Hemorrhages or bleeding can occur within the retina itself and vision can decrease temporarily. If a person is undergoing cancer treatments, it is a good idea to have their eyes checked, especially if they are having any vision problems. The chemotherapy does not actually cause cancers but only side effects.

Therefore, if you are having any decreased vision, it is always makes sense to have a good eye examination to identify any problems at early stage.


As America celebrates its 243th birthday, I find myself thinking about what it means to be independent.  Because I was born blind, I was told early on that I would quite likely spend my life as a dependent person. I suppose it’s fair to say that I’ve proved I can be independent, and for that, I am very grateful.

I came to learn about the world as a blind person, and so I never thought very much about what I was missing without having the ability to see. In my role as the Ambassador of Vision for the Discovery Eye Foundation, I spend a lot of time talking to people who are losing or have lost their sight later in life. I am amazed to learn how truly dependent they are as they work to rehabilitate their lives after the loss of vision. They tell me that even the smallest tasks in daily life become major obstacles.

A woman recently told me, “there is a constant fear of falling, even in a familiar place like my own house.  I am just not sure of where the steps are.  I hate to have to ask people to put my clothes together in the right color combinations and learn to cook and be comfortable in my own kitchen.  It feels impossible to get anything done.”

The most touching thing I ever heard was when a loving grandfather told me that he was having trouble remembering what his grandchildren’s faces looked like.

Let me hasten to say that many people who lose their vision do make extraordinary adjustments, but for all of them, the road back to independence is difficult, arduous, and sometimes impossible. At the Discovery Eye Foundation, we remain committed to funding the research that will hopefully preserve vision and provide the independence that all of us wish for and deserve.


Tom Sullivan
DEF’s Ambassador of Vision