Retinal detachment is an ocular condition that involves the retina being separated from the underlying layer of cells, including the retinal pigment epithelium (RPE). This separation often results in the death of key retinal cells, including photoreceptors, which can lead to vision impairment and/or loss.
There are approximately 50,000 retinal detachments each year in the U.S. These retinal detachment cases are categorized in two different ways:
- Rhegmatogenous vs. Non-Rhegmatogenous: This categorization pertains to the root cause of the detachment. Rhegmatogenous detachments, the most common type of retinal detachment, are caused by a retinal break. In these cases, the vitreous (the gel which fills the eye behind the lens) contracts and pulls the retina away from the RPE causing a tear or chronic retinal atrophy results in a retinal hole. Non-rhegmatogenous detachments are not affiliated with a retinal break and are caused by one of two triggers. The first type, tractional, occurs when the vitreous contracts and pulls the retina away from the RPE without cause an actual tear. The second type, exudative, occurs when there is damage to the underlying RPE, which allows fluid to collect beneath the retina and push it away from the RPE.
- Macula On vs. Macula Off: The categorization pertains to the degree of detachment. Retinal detachments can be considered macula off (the macula has detached completely from the RPE) or macula on (the macula has not yet detached from the RPE).
Due to variations in the root cause and the degree of detachment, retinal detachments can be referred to as any one of the following:
- Rhegmatogenous Macula On
- Rhegmatogenous Macula Off
- Non-rhegmatogenous Macula On
- Non-rhegmatogenous Macula Off
For most retinal detachments, surgery represents the only treatment option for patients. However, in cases of non-rhegmatogenous exudative detachments, therapeutic intervention is focused on identifying and treating of any inflammatory disease or underlying mass.
While surgery results in a successful reattachment of the retina in more than 90 percent of retinal detachment cases, these procedures are unable to prevent vision loss associated with the detachment. This is due to the fact that key retinal cells, including photoreceptors, begin to die once the detachment takes place and cell death continues up to the time of surgery (sometimes as long as a week). Studies show retinal detachment results in vision worse than 20/60 for one-third of patients. Studies show retinal detachment results in vision worse than 20/60 for one-third of patients.
ONL believes that its lead therapeutic candidate, ONL1204, can protect against the vision impairment and/or loss associated with retinal detachments.