Retina

What is Diabetic Retinopathy?

It is an advanced stage of the disease process in which the blood vessels in the retina are damaged and leak fluid or blood. It has been seen that 25 per cent of all diabetics develop this complication after 10 years of diabetes and 50 per cent develop it after 20 years of diabetes. People with type I diabetes [diabetes since childhood] are more likely to develop diabetic retinopathy at a younger age.

Diabetics also have a higher incidence of cataract and glaucoma and those with poorly controlled blood sugar and blood pressure are at a higher risk of losing vision.

What are the symptoms of diabetic retinopathy?

Early diabetic retinopathy usually has no symptoms. Gradual blurring of vision may occur if fluid leaks in the central part of the retina [the macula]. In late diabetic retinopathy [proliferative stage], new abnormal blood vessels begin growing on the surface of the retina or the optic nerve. These vessels have weak walls and leak blood out into the retina and vitreous [jelly that fills most of the eye]. Presence of blood in the path of light entering the eye blocks vision.

What is the macula?

The macula is a small area at the center of the retina that allows us to see fine details such as central vision, activities such as reading and writing and appreciating colour vision.

What causes Macular Degeneration?

Sometimes the delicate cells of the macula are damaged and stop functioning. The exact cause is not known although it tends to happen as people age and get older. This is called age-related macular degeneration. The most common types of macular degeneration are the dry (atrophic) and the wet (exudative).

The dry type is caused by aging and thinning of the tissues of the macula. The wet type results from the formation of abnormal blood vessels under the macula which leak fluid or blood and blur the central vision. Children and young people can also suffer from an inherited form of macular degeneration called macular dystrophy, which can sometimes affect several members from the same family

Symptoms of macular degeneration:

  • Blurred or distorted central vision
  • Words on a page look blurred
  • Straight lines appear distorted or wavy
  • Dark or shadowy areas appear in the center of vision
  • This makes activities like reading, writing and recognizing small objects or faces very difficult

ARMD TREATMENTS

There is NO TREATMENT for dry AMD, although high dose multivitamin combination has been shown to decrease the risk of visual loss.
There are a few treatment options for wet AMD although the best outcomes occur when this disease is detected early.

  •  Laser
  • Photodynamic therapy (PDT)
  • Anti-VEGFs (Lucentis, Avastin, Macugen)
  •  Combinations of the above mentioned

What is the retina?

The retina is a nerve layer at the back of the eye that senses light and sends images to the brain.

What is a retinal detachment ?

The retina is attached to the inner back surface of the eye. Detachment is the pulling away of the retina from its normal position. The separation of the retina from the wall of the eye impairs its normal functioning, resulting in blurred vision.

What causes retinal detachment ?

The vitreous is a clear gel that fills most of the space in the eye. It is located in front of the retina. With age, the vitreous pulls away from its attachments to the retina, usually without causing problems. Sometimes the vitreous pulls hard enough to tear the retina. Fluid may then pass through the retinal tear and lift the retina off the wall of the eye.

Risk factors for retinal detachment:

  • Myopia or near-sightedness
  • Injury to the eye
  • Previous retinal detachment in the other eye
  • Family history of retinal detachment
  • Areas of thin/weak retina
  • Complicated cataract surgery

Warning symptoms of retinal detachment:

  • Flashes of light
  • New, or increase in, floaters [black dots in your vision]
  • A gray curtain noticed in the field of vision

TREATMENTS

When a retinal tear or hole hasn’t yet progressed to detachment, your eye surgeon may suggest one of the following procedures to prevent retinal detachment and preserve vision.

  • Laser surgery (photocoagulation): The surgeon directs a laser beam into the eye through the pupil. The laser makes burns around the retinal tear, creating scarring that usually “welds” the retina to underlying tissue.
  • Freezing (cryopexy): After giving you a local anaesthetic to numb your eye, the surgeon applies a freezing probe to the outer surface of the eye directly over the tear. The freezing causes a scar that helps secure the retina to the eye wall.
  • Retinal Surgery as soon as possible to put the retina back in its proper position. The longer the retina stays detached, the less the visual improvement after surgery.
  • Injecting air or gas into your eye: In this procedure, called pneumatic retinopexy, the surgeon injects a bubble of air or gas into the center part of the eye (the vitreous cavity). If positioned properly, the bubble pushes the area of the retina containing the hole or holes against the wall of the eye, stopping the flow of fluid into the space behind the retina.
  • Indenting the surface of your eye: This procedure, called scleral buckling, involves the surgeon sewing (suturing) a piece of silicone material to the white of your eye (sclera) over the affected area. This procedure indents the wall of the eye and relieves some of the force caused by the vitreous tugging on the retina.
  • Draining and replacing the fluid in the eye: In this procedure, called vitrectomy, the surgeon removes the vitreous along with any tissue that is tugging on the retina. Air, gas or silicone oil is then injected into the vitreous space to help flatten the retina.
  • Eventually the air, gas or liquid will be absorbed, and the vitreous space will refill with body fluid. If silicone oil was used, it may be surgically removed months later. Vitrectomy may be combined with a scleral buckling procedure.