SICKE CELL DISEASE

Sickle cell disease is a genetically inherited disorder that causes red blood cells to be sickle shaped instead of round. Due to their shape, these red blood cells tend to clot blood vessels including those of the retina. The blockage of retinal blood vessels through sickle cell clots can lead to vitreous hemorrhage and ischemia, both of which can seriously diminish eyesight.

Treatment of sickle cell disease symptoms involves diligently monitoring the patient’s ocular condition using OCT testing, fluorescein angiography, and/or microperimetry in order to employ preventative measures. While the prevention techniques of thermal laser and cryotherapy are not guaranteed to work, they can improve the patient’s visual condition by halting the progression of ischemia.

WHAT IS THE CONDITION?

Sickle cell disease is caused by a mutation in a gene called Hb SS. This gene leads to the development of abnormally structured hemoglobin, which in turn causes red blood cells to be sickle-shaped. Only people who have inherited these genes will have sickle cell disease. Moreover, those with two of the sickle cell genes will experience symptoms of increased severity compared to those with one copy of the gene. While the sickle shaped red blood cells can function, their shape leads to many complications including the greater risk of clotting. A clot occurs when the sickle shaped cells pile up against each other until they block the blood stream. This is a serious complication that can cause blood vessels, including those of the retina, to burst.

The development of ocular complications begins with the bursting of retinal blood vessels due to a blood clot. When this occurs, blood pools into the vitreous body from the retinal vessel and blocks light from reaching the retina. This immediately causes the eyesight of the patient to diminish, but not permanently. Next, the persistent leakage of blood can give rise to ischemia, a condition in which retinal cells absorb the leaked blood until they are unable to dispose cell waste and uptake cell nutrients from the blood stream. As a result of ischemia, retinal vessels can not only die but stimulate the growth of abnormal choroidal neovascular membranes over the retina. Although the abnormal choroidal neovascular membranes are blood vessels meant to revive dying retinal cells, their fragility causes them to quickly break and bleed and thus worsen ocular ischemia and perpetuate retinal cell death. All in all, sickle cell disease can cause the severe loss of eyesight if not properly diagnosed and managed in time.

PREVENTION

RETINAL EXAMINATION

While there is no prevention for the development of sickle cell retinopathy, patients who are at risk for developing sickle cell retinal disease are advised to have screening examinations by their eye care professionals. Early screening allows for earlier intervention including laser treatments which can prevent the most aggressive forms of sickle cell disease that can lead to ultimate blindness. OCC Eyecare also utilizes numerous investigative techniques including Fluorescein Angiography, OCT, Retinal Topography, and Retinal Microperimetry measurements to determine whether peripheral retinal changes in patients with sickle cell disease warrant laser or Cryotherapy treatments

LASER

The use of laser or Cryotherapy treatments as a preventative measure to minimize the development of neovascular issues in the peripheral retina in patients with advanced sickle cell disease is controversial.

However, in patients who have clearly been shown to demonstrate extensive areas of peripheral retinal ischemia on peripheral angiography, several studies have suggested the efficacy of earlier interventional laser treatments. These techniques, while difficult to perform technically, have been used by OCC for the management of patients with advanced sickle cell risks. These risks are determined on a patient-by-patient basis and are best discussed with your surgical team.

TREATMENT

Once the mutated genes are inherited, the patient is always at risk of experiencing retinal complications due to sickle cell disease. In order to minimize retinal damage caused by sickle cell disease, the patient’s retinal condition must be regularly checked by their ophthalmologist. This includes a comprehensive diagnostic protocol such as OCT testing, fluorescein angiography, and microperimetry. This allows the ophthalmologist to understand the patient’s current condition and determine whether preventative thermal laser treatment or cryotherapy is required.

Both thermal laser treatments and cryotherapy stop the retinal blood vessels or abnormal choroidal neovascular membranes from bleeding into the vitreous body. When they are effective, these treatments can preserve the patient’s eyesight and prevent the progression of vitreous hemorrhage and ischemia in the eye. However, if preventative treatments are not applied in time or are ineffective, a patient’s sickle cell disease can lead to severe long-term vision loss.