Correlation of Photoreceptor Integrity with Retinal Vessel Density and Choriocapillaris in Eyes with Diabetic Retinopathy

Severity of Disorganization of Retinal Layers and Visual Function Impairment in Diabetic Retinopathy

PURPOSE

To evaluate best-corrected visual acuity (BCVA), retina sensitivity (RS), and fixation impairment by microperimetry (MP) due to the presence and severity of disorganization of retinal inner and outer layers (DRIL/DROL) and ischemia in OCT/OCT angiography (OCTA) in diabetic retinopathy (DR).

DESIGN

Retrospective case-control study.

SUBJECTS

Seventy-six eyes (65 patients) with DR were analyzed. Major exclusion criteria were: center-involving diabetic macular edema (DME), significant media opacity, nondiabetic macular pathology, and active proliferative DR. Patients with DRIL and DROL within central 3 mm were enrolled as cases. Patients with DR and no retina disorganization were considered as controls.

METHODS

A detailed grading of MP and OCT/OCTA images using Image J software, and specific Image Manipulation Program was applied to colocalize the presence of retina disorganization and RS. Best-corrected visual acuity and RS were correlated with the disorganization of retina layers' characteristics and grading (grade 1-DRIL; grade 2-DROL; grade 3-DROL plus, with involvement of the ellipsoid zone). The same procedure of colocalization was applied to the vascular layers on OCTA using MATLAB.

MAIN OUTCOME MEASURES

Correlation between BCVA and MP parameters with disorganization of retina layers grading and OCTA parameters.

RESULTS

Best-corrected visual acuity, mean RS within 1 mm and central 3 mm (overall RS [oRS]), perfusion density, vessel density, and geometric perfusion deficit in intermediate and deep capillary plexuses were lower in cases versus controls (P < 0.001). Mean RS within 1 mm (21.4 decibels [dB] ± 2.4 vs. 13.8 dB ± 5.4, P = 0.002), oRS (22.0 dB ± 2.1 vs. 14.4 dB ± 4.6, P < 0.001), and BCVA (76.1 ± 7.4 vs. 61.2 ± 20.4 ETDRS letters; P = 0.02), had a significant decrease from grade 1 to grade 3 retina disorganization. Choriocapillaris flow voids (CC-FVs) increased from grade 1 to grade 3 (DROL plus) (P = 0.004). Overall retina sensitivity and CC-FV were identified as significant predictors of retina disorganization grade with an adjusted coefficient of determination, R2 = 0.45. Cases had more dense scotomas (P = 0.03) than controls with a positive correlation between the worsening of fixation stability and the severity of DRIL/DROL (P = 0.04).

CONCLUSIONS

Microperimetry and BCVA documented a reduction in visual function in patients with DR and disorganization of retina layers at different grades, with greater functional impairment when outer retina layers and photoreceptors are involved. The severity of retina disorganization and the presence of ischemia could serve as a potential biomarker of functional impairment.

FINANCIAL DISCLOSURES

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Parapapillary Choroidal Microvasculature Predicts Diabetic Retinopathy Progression and Diabetic Macular Edema Development: A Three-Year Prospective Study

PURPOSE

To determine the predictive value of the microcirculation of the optic nerve head by swept-source optical coherence tomography angiography for identifying individuals with high risk of diabetic retinopathy (DR) progression and diabetic macular edema (DME) development.

DESIGN

Prospective observational cohort study.

METHODS

A total of 946 patients (1879 eyes) with type 2 diabetes mellitus were recruited who had no DR or mild nonproliferative DR at baseline, and no DME. All subjects underwent 3 × 3 mm swept-source optical coherence tomography angiography centered on the optic nerve head to generate angiograms in 4 layers: radial peripapillary plexus, superficial retinal capillary plexus (SCP), deep retinal capillary plexus, and choriocapillaris (CC). The CC flow deficit percentage (CC FD%), vessel density (VD), and perfusion density (PD) were quantified.

RESULTS

During the 3 consecutive years of follow-up, 312 eyes (16.60%) experienced DR progression and 115 eyes (6.12%) developed DME. The DR progression was related to a lower VD of the SCP (relative risk per standard deviation decrease, 95% confidence interval): 1.30, 1.14-1.48; P < .001), a lower PD of the SCP (1.41, 1.24-1.60; P < .001), a lower VD of the radial peripapillary plexus (1.23, 1.08-1.40; P = .002), and an elevated CC FD% (1.62, 1.40-1.88; P < .001). The DME occurrence was associated with a lower VD of SCP (1.35, 1.09-1.66; P = .005), a lower PD of SCP (1.29, 1.05-1.59; P = .016), and a higher CC FD% (1.29, 1.03-1.61; P < .001). The CC FD% significantly improved the predictive power, with the increase of the C-statistic for DR progression and DME occurrence by 3.83% (P = .002) and 5.24% (P < .001), respectively.

CONCLUSIONS

This study provides the first longitudinal evidence suggesting that peripapillary CC FD% can improve the prediction of DR progression and DME development beyond traditional risk factors.

Evaluation of Ring Amplitude and Factors Affecting Ring Amplitude in Multifocal Electroretinography in Diabetic Eyes

PURPOSE

The aim of this paper was to evaluate the ring amplitudes in diabetic patients and to evaluate the effect of the risk factors for diabetic retinopathy on the ring amplitudes. We also aimed to investigate the success of ring amplitudes in classifying diabetic retinopathy.

METHODS

The study included 32 eyes of 32 diabetic patients without retinopathy (DM), 34 eyes of 34 patients with mild non-proliferative diabetic retinopathy (NPDR) without macular edema, and 62 eyes of 62 age- and sex-matched controls (CG). All subjects were evaluated using mfERG. The relationship between age, diabetes duration, HbA1c and ring amplitudes and the effect of diabetes and hypertension on ring amplitudes were evaluated. Three-way ROC analysis was performed to evaluate the discrimination power of the ring amplitudes.

RESULTS

In the comparison of the ring amplitudes, the amplitudes of the DM and NPDR groups were statistically significantly decreased compared to the CG (p < .05). A moderate to strong correlation was found between the duration of diabetes, HbA1c and ring amplitudes (p < .05). The effect of diabetes decreased towards the peripheral rings and hypertension did not affect ring amplitudes. Volume under the ROC surface of R1 = 0.65 had p < .05 and 95% CI [0.50-0.72], and the best cut-off point pair to differentiate the three classes was found to be c₁ = 217.3, c₂ = 151.2 in three-way ROC analysis.

CONCLUSION

In conclusion, the effects of diabetes are unevenly distributed on the retina topographically. Diabetes affects the central rings more than peripheral rings in multifocal ERG. Both ring densities and ring ratios are effective ways to identify early changes in retinal function.