Low-Cost Standard-Field Fundus Camera Viable for Proliferative Sickle Cell Retinopathy Screening

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The cost-effective standard-field fundus camera demonstrated viability in screening for proliferative sickle cell retinopathy but not for non-proliferative sickle cell retinopathy, according to new research.¹

Led by Andrew DesLauriers, BA, from Larner College of Medicine at University of Vermont, the study aimed at finding a cheaper tool to screen sickle cell retinopathy screening. Thus, the team evaluated the standard-field fundus camera in a Ghana population through a cross-sectional study in Accra, Ghana. The findings were presented at the 127th Annual American Academy of Ophthalmology (AAO) in San Francisco.

The camera studied is a Forus Health 3Nethra—45 degrees, an optical resolution of 8 – 14 microns, an image sensor of 3 megapixel, and equipped with a gaze target for 8 peripheral fields. According to Forus Health, the camera provides non-mydriatic retinal imaging, multifunctional imaging of posterior segment, anterior segment, and dry eye, peripheral retinal imaging, short eye examination time, compact design, and telemedicine compatible.²

Although ultra-wide field cameras serve as another option for screening (granted, one study noted this type of imaging may not carry clinical significance to all patients), a standard-field camera is more cost-effective.³

The investigators wrote that the standard-field fundus camera may improve screening in West Africa, a region with the highest volume of disease. Also, Ghana has a population of > 30 million people, and of that population, 2% have sickle cell disease. Among that 2%, 40% have the milder HbSC genotype, and 60% have the severer HbSS genotype.1

Currently, Ghana has no sickle cell retinopathy screening programs or standardized protocols. The only accepted standard for diagnosis in the country is a dilated fundus exam. Also, the low number of ophthalmologists (n = 120) and retina specialists (n = 7) presents as a diagnosis challenge—this equates to 250,000 patients per ophthalmologist and 4.3 million per retina specialist. Thus, having lower cost screening camera such as the standard-field fundus camera could help Ghana screen patients.

The study included 16 patients (30 eyes) from Komfo Anokye Teaching Hospital (KATH), with a mean age was 33 years old. The sample had 38% of females. Patients all had a HbSC genotype, except 1 patient, who did not know the genotype.

The team found 50% of Ghanian patients with sickle cell disease had sickle cell retinopathy, while 12.9% had proliferative sickle cell retinopathy. Moreover, with the fundus camera, 10 patients (14 eyes) were diagnosed with proliferative sickle cell retinopathy at Goldberg Stage 3 or worse. Five of the patients with proliferative sickle cell had previously undergone laser photocoagulation. Also, 4 eyes were diagnosed with regular sickle cell retinopathy at Goldberg Stage 1 or 2.

Furthermore, one patient recruited from the sickle cell clinic—who had never seen an eye doctor before—got diagnosed with Goldberg Stage 5 disease. Without the screening study, the patient may have never sought treatment.

The investigators found the image-grading performed well for screening proliferative diseases, with a sensitivity of 92.9% and a specificity of 100%. Though, the image-grading performed poorly for non-proliferative diseases. The image-based grading could not detect patients with non-proliferative sickle cell retinopathy (Goldberg Stage 1 and 2), and therefore it gave non-proliferative diseases a sensitivity of 0%.

“This study provides sufficient evidence for a larger study to confirm the efficacy of our low-cost imaging-based protocol,” the investigators wrote. “Current treatment options are directed toward proliferative disease, making it an appropriate screening target, however future research should investigate methods to detect non-proliferative disease as well.”

References

1. ^{Deslauriers, A, Brant, A, Mruthyunjaya, P, et al. A Novel Method for Cost-Effective Sickle Cell Retinopathy Screening in Kumasi, Ghana. American Academy of Ophthalmology. November 3, 2023.}
2. ^{3nethra classic. Forus Health. https://www.forushealth.com/3nethra-classic.html. Accessed November 17, 2023.}
3. ^{Linz MO, Scott AW. Wide-field imaging of sickle retinopathy. Int J Retina Vitreous. 2019;5(Suppl 1):27. Published 2019 Dec 12. doi:10.1186/s40942-019-0177-8}