Researchers at the University of Tennessee Health Science Center have conducted a study to uncover more about sickle cell disease and its impact on vision in children. They found one in three children with sickle cell disease had retinopathy, damage to the retina because of disease.
Sickle cell disease is a group of inherited red blood cell disorders that blocks blood flow because the cells become crescent or sickle shaped and do not move easily, according to the National Heart, Lung, and Blood Institute. The blockage in blood flow can lead to vision problems and other health issues.
“The red blood cell tends to become a sickle shape instead of a disc shape. Those cells aren’t very flexible. Rather than passing through the small blood vessels in different organ systems, in this case we’re talking about the eye, they will cause blockages and can cause bleeding,” said Mary Ellen Hoehn, MD, professor in the UT Health Science Center College of Medicine’s Department of Ophthalmology. “If there are enough blockages of those blood vessels, then you have areas of the retina that aren’t getting the oxygen and the nourishment that they need. New, abnormal blood vessels can grow which can bleed and cause retinal detachment.”
With the lack of clarity in research for treating adults with sickle cell retinopathy, Dr. Hoehn sought to find the answers on the best treatments for children with sickle cell retinopathy. Dr. Hoehn is the lead author of the study, “Evaluation of Pediatric Patients with Sickle Cell Retinopathy Enrolled in a Cohort Study at One of the Largest Sickle Cell Programs in the Country.” Dr. Hoehn and Barbara Smith, MD, resident in the Department of Ophthalmology, presented the research during the 127th annual meeting of the American Academy of Ophthalmology (AAO). The study is currently in process for publication.
In addition to the American Academy of Ophthalmology, their research presentation has been shared nationally from various medical media outlets including Medscape, Ophthalmology Times, Sickle Cell Disease News, and others.
To conduct this study, the team analyzed medical records for 652 patients enrolled in a cohort study at St. Jude Children’s Research Hospital between ages 10 and 25 who completed eye exams, 2,240 visits, over a 12-year time frame.
“St. Jude enrolls patients with sickle cell disease in the study and follows them longitudinally. When we approached the hematologist working with these patients about doing the study, they were excited because they didn’t have any eye data yet. They gave us the names of the patients and medical record numbers and we were able to go through all those visits for all those patients and include the eye data,” Dr. Hoehn said.
Their findings included one in three children with sickle cell disease experienced retinopathy, of which nine percent required treatment. They also found that 33% had nonproliferative retinopathy, or leaking of blood vessels in the retina, and six percent had proliferative retinopathy, the growth of new blood vessels in the retina.
“It showed a higher rate of retinopathy in the pediatric age group than prior studies. Our rate of retinopathy was more in keeping with what’s been reported in the adult literature,” Dr. Hoehn said.
They also assessed the effectiveness of treatments for sickle cell retinopathy and discovered that hydroxyurea, a treatment to improve the flexibility of red blood cells, and chronic blood transfusions were associated with decreased rates of retinopathy.
“Hydroxyurea tended to decrease the rate at which patients developed retinopathy. The same for chronic blood transfusions,” Dr. Hoehn said.
More findings included vision loss following complications from sickle cell in one patient with a central retinal artery occlusion, retinal detachment and retinal artery occlusion in two patients, 33 eyes were treated with panretinal photocoagulation, a laser procedure, and five eyes with proliferative retinopathy received intravitreal anti-VEGF therapy.
With this research, they hope to emphasize the importance of frequent vision exams for children with sickle cell disease. “I am hoping that it will help us to do what I started out to do, which is learn how to take better care of our patients. Hopefully it will encourage physicians to stress the need for screenings in pediatric patients with sickle cell, not just waiting until they are adults,” Dr. Hoehn said. “I also hope this will promote education for eye complications with the disease and the treatments available to try to decrease the risk of vision loss.”
Dr. Hoehn also serves as a pediatric ophthalmologist and director of Eye Clinics at St. Jude Children’s Research Hospital, and as a pediatric ophthalmologist at Le Bonheur Children’s Hospital.
Dr. Hoehn earned her bachelor’s degree in biology from Vanderbilt University in 1993 and earned her medical degree from the UT Health Science Center in 1997. She completed her residency in ophthalmology at UT Health Science Center in 2001, and a pediatric ophthalmology fellowship at Manhattan Eye, Ear and Throat Hospital in New York in 2002.
Dr. Hoehn is also one of the 2023 recipients of the Research to Prevent Blindness and American Academy of Ophthalmology Award for IRIS Registry Research for a different study that focuses on establishing the best timing for strabismus surgery in patients that have strabismic amblyopia.
Strabismus refers to a misalignment of the eye, and amblyopia is decreased vision in one eye that is anatomically normal, Dr. Hoehn said.
“Strabismic amblyopia is decreased vision in an eye due to a misalignment of the eye. The eye doesn’t develop good vision because the brain is not using that eye as well,” Dr. Hoehn said. “There is not a consensus on when to do eye muscle surgery in those patients. The standard teaching is that you treat the amblyopia with patching or do things to try to make the vision as good as you can, and then do surgery. My question is, what if you try to improve the vision with these treatments, and you can’t. When is the best time to do the surgery?”
The $35,000 grant supports use of the IRIS Registry database and analytics to advance population-based research in ophthalmology and blindness prevention, according to the AAO.