Tear Mediators NGF along with IL-13 Predict Keratoconus Progression

Figures & data

Table 1. Demographic and Pentacam data of participants at baseline

	Non-progressive keratoconus group (N = 29 eyes)	Progressive keratoconus group (N = 16 eyes)	p
Age (years)	37.3 (11.3)	33.5 (13.4)	0.386^a,c
Sex (female/male)	11 (37%)/18 (63%)	4 (25%)/12 (75%)	0.728^c
Follow-up time (days)	419 (352–1004)	418 (378–555)	0.610^b
K1	44.9 (40.9–59.5)	46.6 (39.4–57.9)	0.302^b
K2	48.9 (43.6–64.1)	51.7 (45.7–60.1)	0.035^b
Kmax	52.9 (44.4–86.8)	59.4 (48.9–75.4)	0.014^b
D-index	7.55 (4.17)	10.79 (4.14)	0.016^a
Astig	3.57 (0.3–6.6)	4.65 (1.8–10.87)	0.055^b
PachyMin	453 (288.3–534)	443.5 (332.7–560)	0.569^b
KI	1.22 (0.15)	1.31 (0.14)	0.077^a
CKI	1.03 (0.99–1.18)	1.08 (0.97–1.18)	0.117^b

Significant differences are highlighted in bold; ^at test, values are presented as mean (SD); ^bWilcoxon’s rank-sum test, values are presented as p50 (min-max); ^cTest excludes thee patients with eyes in both groups

Pentacam readings: K1 and K2, simulated keratometry 1 and 2 of the front surface (diopters); Kmax, maximal keratometry of the front surface; Astig, corneal astigmatism of the front surface; PachyMin, thinnest corneal thickness; KI, keratoconus index; CKI, center keratoconus index.

Table 2. Pentacam data of participants at end of follow-up

	Non-progressive keratoconus group (N = 29 eyes)	Progressive keratoconus group (N = 16 eyes)	p
K2	48.6 (43.6–61.9)	52.3 (46.2–61.2)	0.007^b
Kmax	53.9 (6.1)	61.2 (7.2)	0.0008^a
D-index	8.18 (4.81)	11.27 (4.44)	0.0396^a
Astig	3.2 (0.6–5.9)	4.7 (0.5–12.3)	0.027^b
PachyMin	453.7 (281–535.3)	441.3 (349–538.3)	0.538^b
KI	1.23 (0.15)	1.31 (0.15)	0.109^a

Significant differences are highlighted in bold; ^at test, values are presented as mean (SD); ^bWilcoxon’s rank-sum test, values are presented as p50 (min-max)

Pentacam readings: K2, simulated keratometry 2 of the front surface (diopters); Kmax, maximal keratometry of the front surface; Astig, corneal astigmatism of the front surface; PachyMin, thinnest corneal thickness; KI, keratoconus index.

Table 3. Significant (p value is <0.05) differences in released mediator quantities (pg) between the two groups at the end of follow-up

	Non-progressive keratoconus group (N = 29 eyes)	Progressive keratoconus group (N = 16 eyes)	p
IFNγ	34.3 (0–179.9) (29)	60.6 (18.2–223.1) (13)	0.020 ^b
IL-13	21.0 (0–152.5) (29)	43.7 (6.1–171.3) (13)	0.018 ^b
IL-17A	36.9 (0.2–145.3) (29)	51.4 (15.3–197.8) (13)	0.022 ^b
CCL5/RANTES	2.71 (0.55–15.14) (18)	7.38 (0.94–23.62) (13)	0.041^b
MMP-13 (log transformed)	−0.40 (0.97) (26)	0.42 (1.33) (14)	0.031^a
PAI-1	0.010 (0–0.200) (29)	0.043 (0.003–0.463) (15)	0.027^b

^at test, mean (SD), eye counts are presented as (n); ^bWilcoxon’s rank-sum test, p50 (min-max), eye counts are presented as (n).

IFNγ, gamma interferon; IL, interleukin; CCL5, chemokine (C–C motif) ligand 5 or RANTES (regulated on activation, normal T cell expressed and secreted); MMP-13, matrix metalloproteinase-13; PAI-1, plasminogen activator inhibitor-1.

Figure 1. Significant (p value is <0.05) differences in released mediator quantities (pg) between the two groups at the end of follow-up eye counts are presented as (n); INF?, interferon gamma; IL, interleukin; CCL5, chemokine (C–C motif) ligand 5 or RANTES (regulated on activation, normal T cell expressed and secreted); MMP-13, matrix metalloproteinase-13; PAI-1, plasminogen activator inhibitor-1.

Table 4. Significant, groupwise heterogeneous correlations between baseline to follow-up changes in the levels of different tear mediators and changes in Pentacam parameters

		INFγ (pg/ml)		IL-13 (pg/ml)		IL-17A (pg/ml)		CXCL8/IL-8 (pg/ml)		CCL5/RANTES (pg/ml)		TIMP-1 (ng)		t-PA (pg/ml)
		non-prog	prog	non-prog	prog	non-prog	prog	non-prog	prog	non-prog	prog	non-prog	prog	non-prog	prog
K1												r = 0.16 p = .47	r = 0.58 p = .05
	*											p = .034
Kmax								r = −0.25 p = .28	r = 0.55 p = .05
	*							p = .013
Astig		r = 0.20 p = .30	r = 0.57 p = .03	r = 0.27 p = .16	r = 0.57 p = .03	r = 0.13 p = .50	r = 0.70 p = .005
	*	p = .017		p = .018		p = .001
KI								r = −0.08 p = .73	r = 0.68 p = .01	r = −0.04 p = .89	r = 0.64 p = .07			r = −0.30 p = .23	r = 0.54 p = .07
	*							p = .015		p = .035				p = .020
CKI												r = 0.23 p = .30	r = 0.63 p = .03
	*											p = .021

*significant differences between the non-progressive (n = 29 eyes) and the progressive (n = 16 eyes) group.

Tear mediators (concentration, pg/ml): INFγ, gamma interferon; IL, Interleukin; CXCL8, chemokine (C-X-C motif) ligand 8 or IL-8; CCL5, chemokine (C–C motif) ligand 5 or RANTES (regulated on activation, normal T cell expressed and secreted); t-PA, tissue plasminogen activator; tear mediator (release, ng): TIMP-1, tissue inhibitor of metalloproteinase-1.

Pentacam readings: K1, simulated keratometry 1 of the front surface; Kmax, maximal keratometry of the front surface; Astig, corneal astigmatism of the front surface; KI, keratoconus index; CKI, center keratoconus index.

Figure 2. Significant, groupwise heterogeneous correlations between baseline to follow-up changes in the levels of interleukin-17 (IL-17/A) concentration (pg/ml) and changes in corneal astigmatism of the front surface (Astig F) measured with Pentacam between the non-progressive (n=29 eyes) and the progressive (n=16 eyes) group (one representative example of Table 4 for significant correlation).

Figure 3. Non-significant correlation between baseline to follow-up changes in the levels of interleukin-8 (IL-8) concentration (pg/ml) and changes in corneal astigmatism of the front surface (Astig F) measured with Pentacam between the non-progressive (n=20 eyes) and the progressive (n=13 eyes) group (one representative example of Table 4 for non-significant correlation).

Table 5. Diagnostic performance indicators of pairs of baseline tear mediator release levels in predicting keratoconus progression

	Sensitivity 95%CI	Specificity 95%CI	PPV (%) 95%CI	NPV (%) 95%CI	p value of the model
INFγ and NGF	60% (14.7–94.7)	84.6 % (54.6–98.1)	60% (14.7–94.7)	84.6 % (54.6–98.1)	0.0058
IL-13 and NGF	80% (28.4–99.5)	100% (75.3–100)	100% (39.8–100)	92.9 % (66.1–99.8)	0.0008

Tear mediators (release (pg), square root transformed): IFNγ, gamma interferon; IL-13 = interleukin-13; NGF, nerve growth factor; PPV, positive predictive value; NPV, negative predictive value.

Figure 4. Logistic regression-predicted and observed progression of keratoconus in relation to baseline released quantities of tear mediator pairs (INF?+NGF, IL-13+NGF). Curves indicate model-derived location of probability threshold ensuring equal number of predicted and observed progressive cases. INF?, gamma interferon; IL-13, interleukin-13; NGF, nerve growth factor.

Table 6. Diagnostic performance indicators of pairs of baseline Pentacam data to predict keratoconus progression

	Sensitivity 95%CI	Specificity 95%CI	PPV (%) 95%CI	NPV (%) 95%CI	p value of the model
Astig and CKI	38% (15–65)	86% (68–96)	60% (26–88)	71% (54–85)	0.003
Astig and D-index	38% (15–65)	90% (73–98)	67% (30–93)	72% (55–86)	0.002
Astig and K1	38% (15–65)	86% (68–96)	60% (26–88)	71% (54–85)	0.007
Astig and K2	44% (20–70)	83% (64–94)	58% (28–85)	73% (55–87)	0.024
Astig and KI	44% (20–70)	90% (73–98)	70% (35–93)	74% (57–88)	0.011
Astig and Kmax	50% (25–75)	86% (68–96)	67% (35–90)	76% (58–89)	0.005
Astig and Pachy Min	19% (4–46)	93% (77–99)	60% (15–95)	68% (51–81)	0.014
CKI and D-index	25% (7–52)	86% (68–96)	50% (16–84)	68% (50–82)	0.113
CKI and K1	31% (11–59)	90% (73–98)	63% (25–92)	70% (53–84)	0.237
CKI and K2	31% (11–59)	86% (68–96)	56% (21–86)	69% (52–84)	0.298
CKI and KI	31% (11–59)	93% (77–99)	71% (29–96)	71% (54–85)	0.259
CKI and Kmax	44% (20–70)	90% (73–98)	70% (35–93)	74% (57–88)	0.089
CKI and Pachy Min	38% (15–65)	90% (73–98)	67% (30–93)	72% (55–86)	0.126
D-index and K1	31% (11–59)	86% (68–96)	56% (21–86)	69% (52–84)	0.077
D-index and K2	63% (35–85)	83% (64–94)	67% (38–88)	80% (61–92)	0.063
D-index and KI	25% (7–52)	83% (64–94)	44% (14–79)	67% (49–81)	0.098
D-index and Kmax	44% (20–70)	86% (68–96)	64% (31–89)	74% (56–87)	0.089
D-index and Pachy Min	56% (30–80)	83% (64–94)	64% (35–87)	77% (59–90)	0.001
K1 and K2	38% (15–65)	86% (68–96)	60% (26–88)	71% (54–85)	0.068
K1 and KI	25% (7–52)	93% (77–99)	67% (22–96)	69% (52–83)	0.355
K1 and Kmax	44% (20–70)	83% (64–94)	58% (28–85)	73% (55–87)	0.030
K1 and Pachy Min	6 % (0–30)	100% (88–100)	100% (3–100)	66% (50–80)	0.745
K2 and KI	44% (20–70)	90% (73–98)	70% (35–93)	74% (57–88)	0.190
K2 and Kmax	69% (41–89)	76% (57–90)	61% (36–83)	82% (62–94)	0.037
K2 and Pachy Min	44% (20–70)	83% (64–94)	58% (28–85)	73% (55–87)	0.040
KI and Kmax	25% (7–52)	93% (77–99)	67% (22–96)	69% (52–83)	0.164
KI and Pachy Min	25% (7–52)	86% (68–96)	50% (16–84)	68% (50–82)	0.175
Kmax and Pachy Min	56% (30–80)	83% (64–94)	64% (35–87)	77% (59–90)	0.002

PPV, positive predictive value; NPV, negative predictive value. Pentacam readings: K1 and K2, simulated keratometry 1and 2 of the front surface; Kmax, maximal keratometry of the front surface; Astig, corneal astigmatism of the front surface; KI, keratoconus index; CKI, center keratoconus index; PachyMin, thinnest corneal thickness.