Correlation between corneal stromal demarcation line depth and topographic outcomes after two pulsed-light-accelerated crosslinking protocols

Figures & data

Table 1 Baseline demographic, clinical and topographic parameters for two pulsed-light-accelerated CXL protocols

	A-CXL (30*8)	A-CXL (45*5:20)	p-value
N (patients)	12	15
N (eyes)	22	28
Age (years)	19.04±4.71	20.32±4.57	0.338
Gender	9F (75%)	7F (46%)	0.165
AK Stage	2.09 (Med 2)	2.36 (Med 2)	0.345
UDVA (LogMAR)	1.15±0.55	0.95±0.58	0.135
CDVA (LogMAR)	0.11±0.11	0.08±0.08	0.162
SE (D)	−6.88±4.79	−7.61±5.71	0.635
Kmin (D)	49.42±6.74	48.64±5.12	0.644
Kmax (D)	53.54±7.20	54.80±6.66	0.897
Km (D)	51.48±6.71	51.22±5.74	0.882
Astigmatism (D)	4.81±2.60	5.16±3.04	0.672
ECD (cells/mm^2)	2594.18±368.28	2552.25±340.60	0.781
CCT (µm)	471.86±62.29	466.96±49.78	0.758
TCT (μm)	453.27±68.19	451.60±51.11	0.994

Notes: None of the measurements was significantly different when comparing between groups [A-CXL (30*8) and A-CXL (45*5:20)] (unpaired two sample t-test, normal distribution assessed with Shapiro-Wilk test).

Abbreviations: AK Stage, Amsler-Krumeich keratoconus stage; UDVA, uncorrected distance visual acuity; CDVA, corrected distance visual acuity; SE, spherical equivalent; Astigmatism, topographic astigmatism; K_min, minimum keratometry; K_max, maximum keratometry; K_m, mean keratometry; CCT, central corneal thickness; TCT, thinnest corneal thickness; ECD, endothelial cell density (central).

Table 2 Visual, topographic and functional outcomes for two different pulsed-light-accelerated CXL modalities at 12 months follow-up

	Baseline		Month 1		Month 3		Month 6		Month 12
	A-CXL (30*8)	A-CXL (45*5:20)	A-CXL (30*8)	A-CXL (45*5:20)	A-CXL (30*8)	A-CXL (45*5:20)	A-CXL (30*8)	A-CXL (45*5:20)	A-CXL (30*8)	A-CXL (45*5:20)
UDVA (LogMAR)	1.15±0.55	0.95±0.58	1.11±0.59	0.93±0.49	0.83±0.39	0.80±0.39	1.04±0.75	0.66±0.42^†	0.98±0.58	0.77±0.52^†
CDVA (LogMAR)	0.11±0.11	0.08±0.08	0.08±0.10	0.06±0.06	0.07±0.10	0.04±0.05	0.08±0.09^†	0.04±0.07^†	0.06±0.06^†	0.04±0.06^†
SE (D)	6.88±4.79	7.61±5.71	6.52±4.08	7.85±4.25	5.70±3.69	5.64±3.05^†	5.66±2.92^†	4.90±2.32^†	6.09±3.38^†	5.89±3.14^†
Astigmatism (D)	4.81±2.60	5.16±3.04	4.55±2.66	4.91±3.22	4.01±1.31^†	4.18±1.47^†	4.22±2.96^†	4.03±2.84^†	3.84±2.28^†	4.00±2.48^†
Kmin (D)	49.42±6.74	48.64±5.12	48.27±4.85	48.08±5.12^†	46.76±3.11	46.93±4.74	47.80±5.29^†	46.44±4.22^†	47.01±4.58^†	45.64±3.86^†
Kmax (D)	53.54±7.20	54.80±6.66	52.64±6.18	52.93±6.46^†	50.79±4.78	51.96±5.64^†	51.51±6.50^†	50.03±4.39^†	51.09±6.12^†	49.98±4.95^†
Km (D)	51.48±6.71	51.22±5.74	50.45±5.16	50.50±5.59^†	48.77±3.82	48.95±5.10^†	49.65±5.83^†	48.23±4.22^†	48.69±5.01^†	47.89±4.24^†
CCT (μm)	471.86±62.29	466.96±49.78	466.26±51.27^†	451.96±51.40^†	476.11±54.06^†	457.55±41.57	466.26±71.23^†	468.20±43.13	468.05±59.51	470.80±35.33
TCT (μm)	453.27±68.19	451.60±51.11	451.61±46.52^†	446.03±50.53^†	461.94±50.35^†	442.05±40.12	450.46±71.98	449.80±42.16	449.25±64.09	458.85±40.71
ECD (cell/mm^2)	2594.18±368.28	2552.25±340.60			2494.55±432.27	2591.53±475.75	2539.60±261.70	2566.15±268.02	2562.33±230.70	2543.61±336.29

Note: †Significantly different compared with baseline measurement (Paired t-test, p<0.05).

Abbreviations: UDVA, uncorrected distance visual acuity; CDVA, corrected distance visual acuity; LogMAR, Logarithm of the Minimum Angle of Resolution; SE, spherical equivalent; Astigmatism, topographic astigmatism; K_min, minimum keratometry; K_max, maximum keratometry; K_m, mean keratometry; CCT, central corneal thickness; TCT, thinnest corneal thickness; ECD, endothelial cell density (central).

Figure 1 AS-OCT of corneal stromal demarcation line at postoperative month 1 in after pulsed-light-accelerated CXL with 30 mW/cm² (A) and 45 mW/cm² (B) irradiances.

Abbreviation: CXL, corneal crosslinking.

Table 3 Postoperative change in visual acuity, refractive error and topography at 12 months

	A-CXL (30*8)	A-CXL (45*5:20)
Δ UDVA (LogMAR)	−0.22±0.51	−0.25±0.39
Δ CDVA (LogMAR)	−0.06±0.11^†	−0.04±0.05^†
Δ SE (D)	1.04±2.91^†	2.04±3.67^†
Δ Astigmatism (D)	−1.48±2.78^†	−0.81±2.07^†
Δ Kmin (D)	−1.94±3.01^†	−2.08±2.76^†
Δ Kmax (D)	−2.98±3.09^†	−2.99±2.98^†
Δ Km (D)	−2.68±2.72^†	−2.54±2.21^†
Δ CCT (μm)	−6.25±17.63	−7.30±18.94
Δ TCT (μm)	−6.60±20.74	−6.14±22.05

Notes: †Significantly different compared with baseline measurement (Paired t-test, p<0.05); None of the measurements was significantly different when comparing between groups [A-CXL (30*8) and A-CXL (45*5:20)] through the follow-up period (unpaired two sample t-test).

Abbreviations: SE, spherical equivalent; K_min, minimum keratometry; K_max, maximum keratometry; K_m, mean keratometry; CCT, central corneal thickness; ECD, endothelial cell density (central).

Table 4 Percentage of regression (>1D decrease in K_max in 12 months), stabilization (no more than 1D change in K_max) and progression (>1D increase in K_max in 12 months) of keratoconus

Group	Number (%)
	Regression	Stabilization	Progression
A-CXL (30*8)	16 (73)	3 (13.5)	3 (13.5)
A-CXL (45*5:20)	19 (68)	7 (25)	2 (7)

Note: No statistical difference between groups was observed (chi-square test).

Abbreviation: A-CXL, accelerated crosslinking.

Figure 2 Pearson´s correlation between baseline CCT and (A) ΔK_min (r=0.381, p=0.014), (B) ΔK_max (r=0.473, p=0.002) and (C) ΔK_m (r=0.517, p=0.001).

Abbreviation: CCT, central corneal thickness.