Comparison of the nerve fiber layer of type 2 diabetic patients without glaucoma with normal subjects of the same age and sex

Figures & data

Table 1 Demographic features of enrolled subjects

Feature	Normal subjects		Diabetics with no retinopathy		Diabetics with mild retinopathy
Patients/eyes (n)	25		27		24
Male/female (n)	10/15		10/17		9/15
	Mean ± SD	Range	Mean ± SD	Range	Mean ± SD	Range	P-value (ANOVA)
Age (years)	62.80 ± 9.9	44–82	65.4 ± 6.9	50–80	62.9 ± 9.8	38–77	0.48
Duration of diabetes (years)	0	0	12.8 ± 5.9	5–30	15.75 ± 7.9	5–35	0
IOP (mmHg)	17.3 ± 1.7	13–21	16.8 ± 2	14–21	16.38 ± 1.9	12–19	0.19
CCT (μm)	532.2 ± 28	500–600	532.3 ± 27.9	495–580	538 ± 29.3	490–595	0.71
C/D ratio	0.2 ± 0.05	0.1–0.3	0.17 ± 0.07	0.1–0.3	0.2 ± 0.07	0.1–0.3	0.06
HbA1c (%)	–	–	7.2 ± 1.6	5.2–11.5	7.6 ± 1.7	5.1–10.7	0.41

Abbreviations: ANOVA, analysis of variance; CCT, central corneal thickness; C/D, cup to disc; HbA_1c, glycosylated hemoglobin; IOP, intraocular pressure; SD, standard deviation.

Table 2 GDx VCC parameters of enrolled subjects

Parameter/group	Normal subjects	Diabetics without retinopathy	Diabetics with mild retinopathy	ANOVA test for three groups	Mann–Whitney U test for diabetic groups
	Mean ± SD	Mean ± SD	Mean ± SD	P-value	P-value
TSNIT average (μm)	58.8 ± 4.5	56.7 ± 6.8	55.9 ± 7.0	0.27	0.89
Superior average (μm)	68.5 ± 6.5	64.8 ± 9.7	64.5 ± 8.8	0.18	0.69
Inferior average (μm)	68.3 ± 7.4	61.6 ± 10.1	62.6 ± 8.4	0.02	0.79
TSNIT SD (μm)	22.3 ± 4.9	18.9 ± 5.4	18.8 ± 4.5	0.02	0.58
NFI	15.3 ± 5.4	21.7 ± 11.9	20.8 ± 9.6	0.04	0.57
Inter-eye symmetry	0.9 ± 0.1	0.7 ± 0.2	0.7 ± 0.2	0.01	0.16

Abbreviations: ANOVA, analysis of variance; NFI, nerve fiber indicator; SD, standard deviation; TSNIT, temporal-superior-nasal-inferior-temporal.

Table 3 Percentage and cumulative percentage explained by each factor (R-mode) for normal, no retinopathy, and with retinopathy groups

Factor	Percent of variance			Cumulative percent of variance
	Normal	No retinopathy	With retinopathy	Normal	No retinopathy	With retinopathy
1	28.34	22.35	30.52	28.34	22.35	30.52
2	19.11	20.91	17.89	47.45	43.26	48.41
3	16.92	17.30	13.59	64.37	60.56	62.00
4	13.93	12.23	12.68	78.30	72.79	74.68

Figure 1 Varimax rotated factor loadings for the normal group of the four factors. NFI shows negative correlation with TSNIT, superior and inferior average, as it is expected, and shows no relation with other ocular parameters, such as CCT and normal IO.

Abbreviations: CCT, central corneal thickness; C/D, cup to disc; F1, first factor; F2, second factor; F3, third factor; F4, fourth factor; IOP, intraocular pressure; NFI, nerve fiber indicator; SD, standard deviation; TSNIT, temporal-superior-nasal-inferior-temporal.

Figure 2 Varimax rotated factor loadings for the “no retinopathy” group of the four factors (A). Varimax rotated factor loadings for the “with mild retinopathy” group of the four factors (B). The results for F1 of the mild retinopathy group are similar to F1 of the normal group analysis and resample those of the “no retinopathy” group.

Abbreviations: CCT, central corneal thickness; C/D, cup to disc; F1, first factor; F2, second factor; F3, third factor; F4, fourth factor; IOP, intraocular pressure; NFI, nerve fiber indicator; SD, standard deviation; TSNIT, temporal-superior-nasal-inferior-temporal; Yod, years of diabetes.