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Table 2 Number of patients with ischemia, neurodegeneration, and subclinical edema by BCVA and ETDRS severity groups

From: Visual acuity is correlated with ischemia and neurodegeneration in patients with early stages of diabetic retinopathy

  Normal BCVA (n = 88) Decreased BCVA (n = 44) P value ETDRS 20 (n = 56) ETDRS 35 (n = 52) ETDRS 43–53 (n = 24) P value
No % (95% CI) No % (95% CI) No % (95% CI) No % (95% CI) No % (95% CI)
Ischemia
 VD SRCP decrease 11 12.5 (5.6–19.4) 10 22.7 (10.3–35.1) 0.130 4 7.1 (0.4–13.9) 10 19.2 (8.5–29.9) 7 29.2 (11.0–47.4) 0.031
 VD DRCP decrease 12 13.6 (6.5–20.8) 19 43.2 (28.5–57.8)  < 0.001 6 10.7 (2.6–18.8) 9 17.3 (7.0–27.6) 16 66.7 (47.8–85.5)  < 0.001
 FAZ area increase 2 2.3 (0–5.4) 3 6.8 (0–14.3) 0.333 1 1.8 (0–5.3) 2 3.8 (0–9.1) 2 8.3(0–19.4) 0.333
 VD decrease or FAZ area increase 17 19.3 (11.1–27.6) 21 47.7 (33.0–62.5) 0.001 8 14.3 (5.1–23.5) 13 25.0 (13.2–36.8) 17 70.8 (52.6–89.0)  < 0.001
Neurodegeneration
 RNFL thinning 0 0 2 4.5 (0–10.7) 0.109 1 1.8 (0–5.3) 0 0 1 4.2 (0–12.2) 0.485
 GCL-IPL thinning 0 0 4 9.1 (0.6–17.6) 0.011 1 1.8 (0–5.3) 2 3.8 (0–9.1) 1 4.2 (0–12.2) 0.672
 RNFL or GCL-IPL thinning 0 0 5 11.4 (2.0–20.7) 0.004 2 3.6 (0–8.4) 2 3.8 (0–9.1) 1 4.2 (0–12.2) 1.000
Subclinical edema
 INL thickening 3 3.4 (0–7.2) 2 4.5 (0–10.7) 1.000 2 3.6 (0–8.4) 0 0 3 12.5 (0–25.7) 0.031
 OPL thickening 14 15.9 (8.3–23.6) 7 15.9 (5.1–26.7) 1.000 10 17.9 (7.8–27.9) 5 9.6 (1.6–17.6) 6 25 (7.7–42.3) 0.201
 Total retinal thickening 0 0 0 0 NA 0 0 0 0 0 0 NA
 INL or OPL or total retinal thickening 16 18.2 (10.1–26.2) 7 15.9 (5.1–26.7) 0.746 11 19.6 (9.2–30.0) 5 9.6 (1.6–17.6) 7 29.2 (11.0–47.4) 0.094
  1. BCVA best-corrected visual acuity; ETDRS Early Treatment Diabetic Retinopathy Study; CI confidence interval; NA not applicable; VD vessel density; SRCP superficial retinal capillary plexus; DRCP deep retinal capillary plexus; FAZ foveal avascular zone; RNFL retinal nerve fiber layer; GCL-IPL ganglion cell layer plus inner plexiform layer; INL inner nuclear layer; OPL outer plexiform layer
  2. Pathological changes in ischemia, neurodegeneration, and subclinical edema were accepted if the differences between the normal values, i.e., the mean value of healthy the control population and the DR group values were more than 1.96 standard deviation (SD) units. Thus, ischemia was diagnosed if the value of DR group was 1.96 SD less than the normal value of the control group. Neurodegeneration was diagnosed if the value of DR group was 1.96 SD less than that of the control group. Subclinical edema was diagnosed if the value of DR group was 1.96 SD more than normal value. P-values were based on the Chi-squared test result of the ratio of each group. Bold font indicates significance of P < 0.05