Retinal Anatomy

The retina is the light-sensitive layer of the back of the eye that makes focused light into an electrical signal that is carried to our brains through the optic nerve.  Light travels through different parts of the eye to become focused light on the retina.  The cornea, iris and lens are in the front of the eye and help to focus the light. The center part of the eye is made up of a clear gel called the vitreous (vi-tree-us).  The vitreous is attached to the retina.  Sometimes the gel forms clumps, called floaters, that cast shadows on the retina which are seen as dark specks in our vision.  These changes in the vitreous often lead to the gel pulling away from the back of the eye. When this happens it is called a Posterior Vitreous Detachment (PVD).  If the gel pulls too hard on the retina, you can notice flashing lights. Rarely, the vitreous can pull hard enough to create a small retina hole or tear.  Fluid may pass through the retinal tear and lift the retina off the back of the eye and create a retinal detachment.  This will often be noticed as a dark curtain in your peripheral vision.  A retinal detachment can cause loss of vision if left untreated.

Retinal Detachments

Nearsightedness, previous eye surgery, trauma or family history does increase risk of a retinal detachment.  Symptoms of a retina tear or detachment include:

  • Worsening floaters
  • New or repetitive flashing lights
  • A new peripheral curtain (dark shadow) in your vision
  • Decreased vision or darkened vision

An eye care specialist can help you.  By dilating the pupil, the retina can be better seen and tears or detachments visualized.  Additionally, an ultrasound of the eye can help confirm if the retina is detached.

A tear or hole in the retina can often be corrected with an in-office procedure by a retina specialist.  Laser surgery or cryotherapy (a freezing treatment) is often used to correct the problem.  Sometimes, gas is injected into the eye to support the retina during this time.  If gas is used, it is important to remember not to fly on an airplane or go above 3,000’ in altitude, because the gas could expand and cause a dangerous rise in eye pressure.

If a large amount of the retina is detached from the back of the eye, you may require a surgical repair.  A retina specialist may use a scleral buckle or vitrectomy in the operative room.  A scleral buckle uses a flexible band to surround and support the retina tears from the outside of the eye to close the hole in the retina.  A vitrectomy is when the vitreous is removed and the retina is re-attached with a gas bubble.  Sometimes an oil bubble is used instead of gas.

Once the retina detachment is fixed, the vision can continue to improve for many months. However, the vision may never return fully.  Most retinal detachment surgeries are successful (greater than 75%).  However, some retinal detachments require multiple surgeries to correct and some are not able to be fixed.

Posterior Vitreous Detachment

The gel of the center of the eye is called the vitreous (vi-tree-us) and is attached to the retina in the back of the eye.  As we get older, the gel can pull away from the back of the eye.  When this happens it is called a Posterior Vitreous Detachment (PVD).  As the vitreous is separating from the retina, we may see floaters of vitreous clumps or flashing lights from retina traction.

Epiretinal Membrane

A thin layer can grow across the surface of the macula, the center of the retina that is responsible for our best vision.  If the membrane becomes thick enough, the retina can become “wrinkled” causing the central retina to resemble a piece of cellophane.  “Warping” or distortion of images along with decreased vision are the most common symptoms.

There are many causes of an epiretinal membrane, but it is not due to medical problems external to the eye.

Some common causes include:

  • Eye inflammation
  • Eye trauma
  • Retina vein occlusion
  • Retina tears or detachments
  • Posterior vitreous detachments

Macular Hole

If a hole develops in the center of the retina, or macula, it is called a macular hole.  Since the macula is responsible for our best vision, a macular hole often results in poor vision.  There are many causes of macular holes, but the two most common causes involve traction from an epiretinal membrane or posterior vitreous detachment at the very center of the macula, or fovea.  The fovea is the thinnest part of the macula and is most easily injured by traction.

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