Correlation between glycemic control and peripapillary retinal nerve fiber layer thickness in Saudi type II diabetics

Quantitative measurement of retinal nerve fiber layer thickness and its correlation with optical coherence tomography angiography vascular biomarker changes in preclinical diabetic retinopathy

PURPOSE

The present study was done to assess the use of optical coherence tomography angiography (OCTA) in detecting earlier stages of diabetic retinopathy and for the early management and effective blood glucose control in preclinical diabetic patients for preventing retinal nerve fiber layer (RNFL) thinning.

METHODS

A tertiary care center-based prospective observational study was conducted from the year 2021 to 2022 in the Department of Ophthalmology. The study included 50 cases and 50 controls. The parameters analyzed by using OCTA (Topcon 3D OCT-1 Maestro2) were RNFL thickness and peripapillary vessel density.

RESULTS

We found that the RNFL thickness in the temporal and superior disc in patients with preclinical diabetic retinopathy was significantly (0.041 and 0.044, respectively) decreased. The duration of diabetes and glycated hemoglobin (HbA1c) were the risk factors for peripapillary vessel density reduction in patients with preclinical diabetic retinopathy (P < 0.001).

CONCLUSION

RNFL thinning is an early sign of retinal neurodegeneration and is associated with peripapillary vessel density reduction. Early management and effective blood glucose control in diabetes patients may be beneficial for preventing RNFL thinning in superior and temporal disc.

Relationship between anthropometric and biochemical changes of metabolic syndrome with retinal nerve fiber layer and macular thickness

Objective

To evaluate the retinal nerve fiber layer (RNFL) and macular thicknesses and identify systemic risk factors for thinning of these layers in patients with metabolic syndrome (MetS).

Methodology

A cross-sectional observational study was performed on patients diagnosed with MetS and compared to normal controls. All patients underwent ophthalmic and anthropometric examination, serological and biochemical blood investigations; and ocular imaging using spectral-domain optical coherence tomography. Patients with ocular pathology were excluded. Unpaired t-test was used to compare mean thickness between the two groups. One-way ANOVA with Bonferroni correction for multiple comparisons was used to compare mean thickness between different tertiles of MetS parameters, and a generalized estimating equation was used to correct for inter-eye correlation and to assess association between mean thickness and covariates.

Results

Two hundred and forty-eight eyes from 124 participants (1:1 ratio of MetS patients to controls) were included. Age ranged between 30 to 50 years old, and mean age was 40 ± 6.6 years. RNFL thickness was lower globally (93.6 ± 9.9 μm vs 99.0 ± 9.3, p<0.001) and in the inferior (124.5 ± 17.5 μm vs 131.0 ± 16.4 μm, p = 0.002), superior (117.2 ± 16.0 μm vs 126.3 ± 14.4 μm, p<0.001) and temporal (65.5 ± 10.2 μm vs 69.5 ± 9.8, p = 0.002) sectors in MetS patients compared to controls. Only the central (237.0 ± 14.0 μm vs 243.6 ± 18.0 μm, p = 0.002) and inferior parafoveal (307.8 ± 20.9 vs 314.6 ± 14.6, p = 0.004) area of the macula was significantly thinner. The inferior RNFL sector had the most difference (mean difference = 9.1 μm). The Generalized Estimating Equation found that, after adjusting for age, diastolic blood pressure, BMI, HDL and obesity; the number of MetS components and elevated triglyceride levels were independent risk factors for reduced thickness in global RNFL (β = -4.4, 95% CI = -7.29 to -1.5, p = 0.003) and inferior parafovea (β = -6.85, 95% CI = -11.58 to -2.13, p = 0.004) thickness respectively.

Conclusion

RNFL thinning was seen more than macula thinning in MetS patients, suggesting RNFL susceptibility to neurodegeneration than the macula. A higher number of metabolic components and elevated triglyceride levels were independent risk factors for retinal thinning in this group of patients.