The retina

Is the light sensitive tissue located in the back of the eye. It records the images we see and sends them via the optic nerve from the eye to the brain. The retina instantly converts light images into electrical impulses through a chemical reaction. The retina then sends these impulses or signal, to the brain, where we interpret what we see, process the visual information, and relate what we see to the rest of our environment. Having a healthy retina is fundamental for a clear vision.

The eyes’ principal function, as the organs of vision, is to take an image and transform it into electric impulses and subsequently transfer them to the brain -a superior organ- in order to be interpreted. The ability to let light pass through and the fact that it’s a hollow organ with transparent structures (the lens, the cornea and the intraocular fluids that act as the aqueous and vitreous humors), make it unique. These transparencies of its structure make it the only bodily organ of which its interior we can contemplate and approach directly.

Macular degeneration:

Is an age-related condition, acting as the principal cause of blindness for those 50 years and older. It is caused due to damages to the MACULA, the central part of the retina. The macula is responsible for central vision (straight-ahead vision) and provides the ability to see fine detail in your direct line of sight. We use the macula of each eye to have the clear vision that allows us to read, drive a car, and recognize faces or colors.

There exist two forms of macular degeneration: “dry” and “wet.” Wet macular degeneration occurs when abnormal blood vessels grow from the choroid (the layer of blood vessels between the retina and the outer firm coat of the eye called the sclera) under and into the macular portion of the retina. In some cases, these vessels leak blood or certain liquids, leading to a distorted or blurry vision. Without the proper treatment, this condition can lead to severe and rapid visual loss.
A VITRECTOMY is a surgical procedure that removes the vitreous gel of the eye and replaces it with silicone oil, intraocular gases or special liquids in order to reattach the retina. When the vitreous gel is opaque or there is a retinal disorder, this procedure allows access to the vitreous cavity of the eye (the interior space with the largest dimension within the organ) with the objective of removing the gel.

Posterior Vitrectomy surgery with retinopexy, silicone oil injection and endolaser

This procedure requires general, local or mixed anesthesia and is ambulatory, or outpatient surgery. The purpose of this procedure is to remove the vitreous gel from the ocular cavity so that it does not produce more friction or damage to the retina. Posteriorly, this gel is replaced with special liquids, intraocular gases or silicone oil. With time, the gases and liquids will be reabsorbed by the body, with only the silicone oil having to be removed at a later date after de first procedure, according to the nature of the case and each patient’s needs.

This procedure dramatically improve the patient’s vision by elimination of the opaque gel and its accumulation in the vitreous cavity. This procedure allows direct treatment to the retina to correct damages such as the removal of membranes, traction, retinal displacement, or hemorrhages, and in this way, improve vision.

Which disorders or diseases require a vitrectomy?

This procedure is highly beneficial for those with diabetic retinopathy, especially when patients suffer from hemorrhages in the eye’s interior, develop membranes on the retina’s surface, or have a detached retina. In the case of ocular injuries, traumas or, macular diseases, such as the recurrent formation of membranes over the retina’s surface, macular holes or degeneration with the formation of new vessels, this procedure can be beneficial. Additionally, those that suffer from recurrent inflammation of the eye or have complications post a cataract surgery can require a vitrectomy.

Postoperative controls

- First check-up the day after the surgery - Second check up 3-6 days following the surgery - Third check-up about a month after the surgery - Recurring check-ups depending on the patient’s evolution

What are some pre-operative guidelines?

Usually, these include a physical exam prior to the surgery and a complete ophthalmologic exam. Here, the patient’s health is thoroughly evaluated via a variety of exams and appointments with different health specialists, when necessary. The day of the surgery, the patient is asked to fast for 6 hours and should arrive at the clinic with all the exam results that have been issued prior to the surgery. Unless stated, there is not other need for any other pre-operative procedures.
This condition occurs in persons with long-term diabetes mellitus, and it is the result of the damage to the tiny blood vessels that nourish the retina, causing progressive impairment. It is a serious sight-threatening complication of diabetes.
People with this type of diabetes frequently suffer from prolonged periods of hyperglycemia and other complications as a result of diabetes, such as hypertension. Some early signs of retinopathy include micro aneurisms and round or oval intraretinal hemorrhages. If left untreated, these symptoms can progress to a vascular disease, where the vessels will harden, white spots and growths will arise, and more intraregional micro vascular abnormalities will appear.

TYPES OF DIABETIC RETINOPATHY

There are two types of diabetic retinopathy, Non-proliferative diabetic retinopathy (NPDR) and Proliferative diabetic retinopathy (PDR). 1: NPDR:
This type is commonly known as background retinopathy, is the first stage of diabetic retinopathy during which the small blood vessels in the retina leak blood or fluids, causing the retina to swell or to form deposits called exudates. Many people with diabetes have a minor case of NPDR that, in general, does not affect eyesight. When vision is affected, it is due to a macular edema, Macular ischemia, or both. Macular edema: refers to the swelling, or thickening, of the macula, a small area in the center of the retina that allows us to see fine details clearly. The swelling is caused by fluid leaking from retinal blood vessels. It is the most common cause of visual loss in diabetes. Vision loss may be mild to severe, but even in the worst cases, peripheral (side) vision continues to function. Laser treatment can be used to help control vision loss from macular edema.

Macular ischemia: occurs when small blood vessels (capillaries) close. Vision blurs because the macula no longer receives sufficient blood supply to work properly. 2: PDR:
This type exists when new, abnormal blood vessels (neovascularization), begin to grow on the retina’s surface or the optic nerve. The most common cause of PDR is the closing off of blood vessels, which limits the blood flow to the eye and therefore, the retina responds by growing now blood vessels. Unfortunately, these blood vessels do not provide adequate blood flow and many times grow along with a fibrous layer that can lead to the inflammation or the detachment of the retina, causing further complications. PDR can cause a more serve visual loss than can NPDR, in that it can affect not only the central vision, but the peripheral vision as well.
PDR can produce visual loss in the following ways:
A vitreous hemorrhage: where the new blood vessels are so delicate that they rupture or begin leaking blood within the vitreous cavity (the transparent and jelly-like gel that fills the center of the eye). If the hemorrhage is small, it is possible that the patient see only a few floating dark spots. However, a big hemorrhage can impede vision completely. Days, weeks, or months can pass before the blood is reabsorbed, depending on the vitreous cavity. If the eye does not discharge the blood within a reasonable amount of time, a vitrectomy may be recommended as the best option for treatment.
The hemorrhage in itself does not cause vision loss. When the blood disappears, the visual clarity can return to its prior state, as long as there has been no damage done to the macula.

When should you consider treatment for diabetic retinopathy?

The best kind time of treatment is the preventive one, before developing retinopathy. A strict control of blood-sugar levels will significantly reduce the long-term risk of visual loss due to diabetic retinopathy. If conditions such as hypertension of kidney problems exist, they should be treated immediately.
This condition occurs in premature babies and it is when there is an abnormal growth of blood vessels on the surface of the retina; the layer of light-sensitive cells that cover the posterior part of the eye and which helps us see.

The blood vessels on the retina begin to develop approximately during the third month of gestation and reach full development at the end of a normal gestation period of nine months. If a baby is born prematurely it is possible that the eyes may not develop properly. The blood vessels can stop growing or grow abnormally from the retina into the posterior part of the eye. The blood vessels are delicate and can have ruptures, causing blood to leak in the eye. In the same manner, scar tissue can form and detach the retina from the interior surface of the eye. In extreme cases, this condition can cause complete vision loss.

The most common methods used in ROP surgery are the following:

1: Laser surgery: Small lasers are used to seal or destroy abnormal, leaking blood vessels in the retina (also known as laser therapy or laser photocoagulation). This procedure lasts about 30- 45 minutes for each eye.

Laser photocoagulation is a treatment used to eliminate abnormalities present in the retina before they cause its detachment. The laser beam reaches the avascular retina through the pupillary hole, allowing the damage done to the retina and surrounding tissues to be minimal. The objective of this procedure is to reduce the risk of complete vision loss and diseases that poor vision can cause in a premature baby.

2: Cryotherapy: This procedure includes the use of freezing temperatures to seal the peripheral retina with the objective of reducing the growth of abnormal blood vessels. For many years, Cryoteraphy (aka. Cryosurgery) was the only accepted surgical method for treating ROP, but in recent years has been replaced by laser surgery.

CARING FOR THE CHILD

If hospital care is not necessary, you can take your child home about an hour after the procedure. Care post-surgery for ROP includes administering eye drops for about a week from the date of the procedure to prevent infections.
Retinal detachment is what occurs when the retina is torn and it detaches from the different parts of the eye, resulting in partial or total vision loss. A retinal detachment can occur when the vitreous fluid collects under the retina, exerting pressure until it causes it to detach from the eyeball. It can also occur when there is friction over the retina that causes it to list and detach.

When retinal detachment occurs, the person affected will see dark shapes and suffer progressive vision loss. Retinal detachments are common in people that have myopia or diabetes. It can also occur after ocular trauma, such as after a cataract surgery or treatment for other diseases.

RETINAL TEAR

The tear itself is not usually painful, but it is of concern. It left untreated, the tear can extend and allow fluid to enter through the tear, possibly leading to a retinal detachment. The detachment itself does not cause any pain either, but it leads to partial or even total vision loss.

When there is a tear in the retina, the person affected will begin to see flashes of light in one side of the eye, usually in dark places. The person will also begin to see floaters and lose vision due to the haemorrhage in the case of a severe tear.

Treatment for a retinal tear requires surgery to repair and prevent further damage, such as retinal detachment. Laser surgery or cryosurgery as the procedures commonly used and can be done in an ambulatory manner, without having to stay the night in the clinic/ hospital. The post-surgery process can take about a couple of week.