Thinning of the peripapillary retinal nerve fiber layer (pRNFL) and impairment of  choroidal circulation, shown by the thinning of the peripapillary choroidal thickness (pCT), are independently associated with the development and progression of diabetic retinopathy (DR), according to a published in Investigative Ophthalmology & Visual Science. The researchers relied on swept source optical coherence tomography (SS-OCT) to monitor the participants’ retinal structures. 

“These results illuminate a strong connection between neurodegeneration and DR incidence and suggest that pRNFL thickness and pCT are potential components of a future predictive model,” according to the investigators.

Researchers monitored 895 patients (aged 65.0±7.9 years) with type 2 diabetes mellitus (duration of 9.2±7.2 years) and assessed DR  severity for 2 years. The patients (748 without DR  at baseline) underwent comprehensive ocular examinations and SS-OCT imaging. Researchers measured the patients’ blood pressure, artery pressure, body mass index (BMI), HbA1c, cholesterol, and triglycerides.


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At 2 years, 80 patients had incident DR and 11 patients with DR had experienced progression of the complication.

Hb1Ac levels and BMI were higher among patients who developed DR or whose DR progressed, compared with those who did not experience DR development or progression. Women were more likely to have experienced DR progression than men, according to the findings.

Patients with DR had thinner pRNFL (nasal, inferior, and superior quadrants) compared with those without DR (111.4±12.9 μm vs 103.0±8.8 μm, P <.001). 

Average pCT was thinner in each quadrant among patients with DR (114.4±52.6 μm vs 91.1±33.4 μm P <.001).

Reduced pRNFL thickness and pCT were negatively associated with higher risk of incident DR  (average pRNFL RR 0.55 average pCT RR, 0.49), except for in the temporal quadrant, researchers found after adjusting for possible confounding factors. 

Area under the curve analysis for predictive models increased with the addition of pRNFL and pCT to the standard model both individually (pRNFL 11.80% increase, P <.001; pCT 7.80% increase, P =.014) and together (15.38% improvement, P <.001). 

“The pRNFL thickness and pCT should be considered as components in the development of more accurate DR predictive models as the noninvasive OCT becomes more available in the future,” researchers explain. “This will reduce the cost-effectiveness ratio of DR screening by prolonging the screening interval for patients at low risk of developing DR.”

Baseline values of pRNFL thickness and pCT in the peripapillary region were not associated with increased risk of DR within 2 years. The researchers said this could be due to small sample size of patients with DR or low progression rate.

Limitations of the study include selection bias, relatively small sample size, length of follow-up, and variation in time of scan.

Reference

Gong X, Wang W, Xiong K, et al. Associations between peripapillary retinal nerve fiber layer and choroidal thickness with the development and progression of diabetic retinopathy. Invest Ophthalmol Vis Sci. 2022;63(2):7. doi:10.1167/iovs.63.2.7