Anatomy of the Eye
PVR is the most common complication following a rhegmatogenous retinal detachment, i.e., a retinal detachment associated with a retinal hole or break. Rhegmatogenous detachment occurs when liquid from the vitreous cavity enters the area below the retina through the retinal break and dislodges the retina. This condition can be treated with retinal re-attachment surgery. However, in 10% of the patients undergoing re-attachment surgery, PVR occurs. PVR occurs during the healing process after surgery when scar tissue forms on both sides of the retina and in the vitreous cavity. The scar tissue contracts and causes a second detachment and distortion of the retina. When the retina is detached it is not in the correct position to send messages to the brain and the patient’s vision is profoundly decreased. Retinal detachment caused by PVR requires another specialized surgery called a vitrectomy. Vitrectomy involves the removal of scar tissue on or under the retina. Unfortunately, PVR is a complicated disease and even with vitrectomy, vision loss occurs.
PVR also occurs with greater frequency in patients undergoing cataract surgery and those with myopia. As the baby boom generation ages, the number of people requiring cataract surgery will increase and the number people at risk for PVR will increase.
PVR is caused by the formation of scar tissue on the surface of the retina and in the vitreous cavity. The scar tissue forms when cells that reside under the retina migrate through the retinal break onto the surface of the retina and into the vitreous cavity. These migrating cells divide and increase in number and form sheets of cells (scar tissue) on the retina. The sheets of cells contract and pull the retina off. There are no procedures to prevent PVR.
LD22-4 is under development as a preventative treatment for PVR. Since the scar tissue formation that causes PVR requires cell migration onto the surface of the retina and into the vitreous cavity, stopping cell migration with LD22-4 will stop scar tissue formation and prevent PVR.