Treatment of ROP

Cryotherapy

The current standard for treatment involves a freezing process, called cryotherapy.  In the late 1980's a nationally organized clinical trial established that this therapy improved the outcome of the disease for infants who had reached Threshold Stage 3+ in 50% of cases.  That is, half of the treated eyes that would otherwise (i.e. without treatment) have progressed to retinal detachment and possible blindness did not do so.

The technique of cryotherapy involves freezing the retina by touching a cold probe to the outside of the eye and waiting to allow the freeze to reach the abnormal retina (i.e. the retina without a blood supply) inside the eye.  The treatment kills the abnormal retina thus eliminating its demand for oxygen.  The abnormal blood vessels disappear and the progression of scar tissue stops.

There are risks in performing cryotherapy.  Severe decreases in heart rate and breathing rate may occur.  For this reason heart rate and blood oxygen are monitored constantly during the cryotherapy procedure.  Sometimes infants need to be placed back on a ventilator after the procedure if they are having trouble breathing on their own.

Cryotherapy is performed under either local anesthesia or general anesthesia.  If local anesthesia is used, this can be administered and the procedure performed at the infant's bedside in the neonatal intensive care nursery.  Administration of general anesthesia may require that the infant is transferred to the operating room.  Neonatal staff also accompanies the baby to ensure constant monitoring of his or her condition.  Some phsicians prefer to give general anesthesia because they believe that cryotherapy is such a painful procedure that it is in the infant's best interest to be fully anesthetized.

After cryotherapy there is usually a large amount of swelling around the eyes, bloody tears and redness.  These effects go away in approximately one week.

A newer therapy, laser treatment, may achieve the same effects as cryotherapy with fewer side-effects, but to date cryotherapy is the only treatment proven in a large nationally-conducted clinical trial.  Additional trials are underway to clinically compare results of laser therapy with results of cryotherapy.

Lasers

Lasers have been used to successfully treat eye disorders in adults for over 20 years.  Diabetic retinopathy is a retinal disease afflicting diabetics which is like retinopathy of prematurity in that it involves growth of abnormal blood vessels in the retina.  Treatment of diabetic retinopathy was revolutionized by the advent of laser therapy.  Prior to laser therapy there was no way to prevent blindness in these people.

Due to a technical advance in the last few years, laser therapy can now be administered to newborn infants.  The same instrument that the doctor uses to examine the infant's retina - the indirect ophthalmoscope - can also deliver the laser treatment beam into the eye.  So if the doctor sees abnormal retina with the indirect ophthalmoscope, it can also be treated.

Laser treatment acts in the same way as cryotherapy by killing the abnormal retinal tissue and so eliminates the growth of abnormal blood vessels and ends the progression of scar tissue formation.

The potential benefits of laser treatment are:

• Less need for anesthesia

• Less pain

• Less swelling after the procedure

• Less likelihood of damage to the eye

• Less chance of decreases in heart and breathing rates during the treatment

The drawback of laser therapy is that it has only been proven effective in a few small clinical trials and not in a large nationwide trial.  Early trials indicate that laser therapy is at least as effective as cryotherapy and potentially better at preventing many infants progressing to retinal detachment.  Currently a large nationwide trial is being organized.

Traditional laser systems were large, immobile units that required moving the infant to the laser rather than bringing the laser to the baby.  Newer lasers - using semiconductors - are fully portable and can be taken to the nursery and attached to an indirect ophthalmoscope for treating ROP babies without disturbing their routine.

Surgery

If cryotherapy, or laser treatment at Stage 3 is unsuccessful in preventing progression to retinal detachment stages - Stage 4 and Stage 5 - there are some surgical treatment options.

If the detachment is shallow (i.e. there is not a lot of space between the retina and the eye wall) a technique called scleral buckling may be effective.  This involves placing a belt around the outside of the eye and tightening in until the retina is close enough to the wall to reattach itself.

Some studies have shown this technique to be effective in some cases of Stage 4a, Stage 4b and mild Stage 5.  Vision after successful scleral buckling tends to be better than after the more invasive surgical procedures discussed below.

If scleral buckling is not possible or is unsuccessful a more direct technique for reattaching the retina, called a vitrectomy, can be performed.

In this procedure the eye is opened up, the lens is removed and some or all of the vitreous humor is removed so the surgeon can access the detached retina.  The source of traction causing the detachment (i.e., the scar tissue or membrane that is tugging at the retina) is cut away from the retina and the retina is then laid back against the eye wall by injecting a gelatin-like material to replace the vitreous that was removed.

A vitrectomy is not always successful in reattaching the retina and even if the retina is reattached, only a fraction of the eyes achieve ambulatory vision, the ability to recognize faces.

Late Complications of Retinopathy of Prematurity

Most infants with mild retinopathy of prematurity (Stages 1 to mild 3) that spontaneously resolves itself will have no remaining scar tissue.  However, some infants who undergo regression may still suffer further complications later in life.  These later complications include:

Strabismus and Amblyopia

Strabismus (crossed eyes) and amblyopia (lazy vision in one eye) occur more frequently in infants with even the mildest stages of regressed ROP compared with premature infants who do not develop ROP.  Eye muscle surgery (for strabismus) and patching (for amblyopia) are often necessary.

Myopia

Myopia (near-sightedness) can occur with the mildest forms of regressed ROP.  The nearsightedness is usually more severe when a greater amount of scar tissue remains from regressed ROP.  Myopia is correctable with glasses.

Glaucoma

Different forms of glaucoma (increased pressure in the eye) may develop in eyes that have regressed or treated ROP.  Glaucoma may cause pain and does damage vision.  Laser, or other types of surgery, are sometimes necessary to help the eye drain off the build-up of the watery fluid (aqueous humor) that bathes the front of the eye and causes the increased pressure.

Late-onset Retinal Detachment

Late Retinal Detachment may rarely occur in the mid-teens or early adulthood as a result of traction from scar tissue as the eye grows or as the vitreous gel shrinks, pulling holes in the retina.  Surgery is usually necessary for repair.

Any person who experienced retinopathy of prematurity should therefore see a retina specialist and/or a pediatric ophthalmologist at least once a year during childhood and early adult years.