RESEARCH DIGEST

sCD200 expression and PDR

In this study, researchers found that expression of sCD200, the soluble form of the immunosuppressive molecule CD200, could be interacting with VEGF-mediated inflammatory response and therefore could be contributing to retinal angiogenesis. The finding could signify a possible new therapy for those with proliferative diabetic retinopathy (PDR).

Using an enzyme-linked immunosorbent assay, known as ELISA, the researchers set out to learn the expression levels of sCD200 in the vitreous of PDR patients. They also wanted to ascertain its connection with VEGF and its receptors, proinflammatory cytokines and other vitreoretinal conditions, including diabetic macular edema (DME). The vitreous from patients with various vitreoretinal diseases was sampled.

They found that vitreous levels of sCD200 were significantly higher in those with PDR; those with PDR who also had DME or traction retinal detachment; and that, statistically, the sCD200 levels and VEGF levels were associated.

In those with PDR, for example, the results were 182.2 ± 17.63 pg/mL; in the control group, they were 56.86 ± 6.573 pg/mL; P < 0.0001. In those with DME, the levels were 266.9 ± 28.82 pg/mL; in the control group, 136.9 ± 15.13 pg/mL; P < 0.0001.

DR, CVD link

In this study, researchers concluded that a correlation exists between DR and cardiovascular disease (CVD) risk in those with type 2 diabetes. They concluded: yes.

The 188 enrolled diabetic patients — none of whom had heart disease at baseline — were subsequently classified, according to fundoscopic findings: without diabetic retinopathy (NDR), with nonproliferative diabetic retinopathy (NPDR) and with proliferative diabetic retinopathy (PDR). Their risk of developing CVD in 10 years’ time was based on the United Kingdom Prospective Diabetes Study risk engine. Patients were then classified as high, moderate or low risk: >20%; 10%-20%; <10%, respectively. The total DR prevalence was 30.5%.

For those with PDR vs. NDR, their risk of developing CVD was significantly higher (18.7±10.0% vs. 11.3±8.4%, p=0.01). The prevalence of NPDR (32% vs. 17.8%, p=0.002) and PDR (20% vs. 4.1%, p=0.04) was higher in the CVD high-risk group as compared with the CVD low-risk group. Even after adjustments were made for traditional risk factors for CVD, the CVD risk stayed convincingly higher in the presence of DR.

OCTA and the macula

Using optical coherence tomography angiography (OCTA), researchers observed retinal microcirculation impairment in the macula before retinopathy had developed. They conclude that en face OCTA is a valuable noninvasive tool that can locate microcirculatory problems in diabetic patients. Their retrospective chart review involved patients who had a fundus exam that included en face OCTA. The researchers evaluated the foveal avascular zone that had been captured by the OCTA. Using ImageJ software, they measured and assessed those areas located in the superficial and deep plexus layers.

In the superficial layer, the foveal avascular zone was 0.25 ± 0.06 mm in healthy eyes (n = 19); 0.37 ± 0.07 mm in diabetic eyes without retinopathy (n = 24) and 0.38 ± 0.11 mm in eyes with DR (n = 20). Regardless of a diagnosis of retinopathy, diabetic eyes (P < 0.01) had statistically significant foveal avascular zone enlargement compared to their healthy counterparts. This area in the deep plexus location also was significantly bigger in diseased eyes (P < 0.01).

Early retina thinning with DR

Using spectral-domain optical coherence tomography (SD-OCT), researchers found that the inner retina thins even before visible signs of damage to the vasculature emerge because of DR. The researchers concluded that diabetic patients’ eyes are experiencing neurodegeneration and require intervention. Also, SD-OCT could be a vital tool for locating these early neurodegenerative signs.

The retrospective study involved 62 diabetics (76 eyes) and a control group of 66 age-matched healthy people. The diabetic group was divided into those with no DR (20); NPDR (43); and PDR (13). An ANOVA test compared the thickness measurements taken for the retinal nerve fiber layer (RNFL) and the ganglion cell-inner plexiform layer (GCIPL).

Average and minimum GCIPL showed exceptional thinning compared with their healthy counterparts at all DR stages (P < 0.05). But, this thickness was similar between the divisions. While there was no particular difference in sectoral or average RNFL thicknesses among the divisions, the least RNFL thickness was lower in those with diabetes than among the controls.