Analysis of the Outcomes of Combined Cross-Linking with Intracorneal Ring Segment Implantation for the Treatment of Pediatric Keratoconus

Figures & data

Figure 1. The graphical presentation of the refractive and visual outcomes: (A) the cumulative logMAR visual acuity; (B) the postoperative UDVA versus the preoperative CDVA; (C) the postoperative SE refraction; (D) the postoperative refractive cylinder; (E) the postoperative refractive sphere; (F) the scatterplot of the attempted preoperative SE refraction versus the achieved postoperative SE refraction; (G) the stability of the postoperative SE refraction; and (H) the stability of the postoperative refractive cylinder.

Table 1. CXL-Plus preoperative and postoperative data summary of the results during the follow-up period.

Parameters	Preoperative data Mean ± SD Median [range]	Postoperative data 6 months Mean ± SD Median [range]	Postoperative data 12 months Mean ± SD Median [range]	Postoperative data 18 months Mean ± SD Median [range]	P value within subject (time)	P value between subject (surgeon)	Difference 18 months vs. pre Mean ± SD [95% CI]
Visual outcomes
Mean UDVA (logMAR)	0.89 ± 0.33 1 [0.22–1.52]	0.52 ± 0.290.48 [0.18–1.52]	0.47 ± 0.33 0.4 [0–1.52]	0.40 ± 0.28 0.3 [0–1.52]	< 0.0001	0.23	−0.49 ± 0.35 [−0.58 to –0.41]
P1 < 0.0001, P2 < 0.0001, P3 < 0.0001, P4 = 0.001, P5 < 0.0001, P6 = 0.03
Mean CDVA (logMAR)	0.35 ± 0.31 0.22 [0–1.30]	0.31 ± 0.26 0.22 [−0.10 to 1.12]	0.28 ± 0.26 0.22 [−0.10 to 1.10]	0.25 ± 0.24 0.22 [−0.10 to 1.10]	0.07	0.27	−0.09 ± 0.28 [−0.16 to –0.02]
P1 = 1.00, P2 = 1.00, P3 = 0.004, P4 = 0.02, P5 = 0.15, P6 = 0.83
Topographic outcomes
Mean K1 reading	46.51 ± 4.11 46.50 [39.99–57.50]	45.21 ± 3.72 45.00 [38.00–54.92]	45.15 ± 3.91 44.75 [37.25–54.78]	44.56 ± 3.53 44.50 [37.03–53.25]	0.006	0.08	−1.94 ± 1.99 [−2.44 to –1.44]
P1 = 0.03, P2 = 0.009, P3 < 0.0001, P4 = 1.00, P5 = 1.00, P6 = 0.66
Mean K2 reading	51.03 ± 4.65 50.50 [42.01–63.12]	49.05 ± 4.57 48.25 [41.50–60.50]	49.10 ± 4.72 48.25 [41.25–60.75]	48.74 ± 4.53 48.00 [40.75–61.05]	< 0.0001	0.07	−2.26 ± 2.51 [−2.89 to –1.62]
P1 < 0.0001, P2 < 0.0001, P3 < 0.0001, P4 = 1.00, P5 = 1.00, P6 = 1.00
Mean K average reading (D)	48.75 ± 4.25 47.88 [41.50–58.29]	47.13 ± 3.97 46.71 [39.88–57.24]	47.12 ± 4.13 46.63 [39.25–57.23]	46.65 ± 3.89 46 [39.25–57.13]	< 0.0001	0.08	−2.10 ± 1.76 [−2.54 to –1.66]
P1 = 0.001, P2 < 0.0001, P3 < 0.0001, P4 = 1.00, P5 = 1.00, P6 = 1.00
Mean corneal thickness at thinnest location (µm)	447.76 ± 31.12 450 [380–517]	435.14 ± 35.46 432 [365–502]	438.63 ± 36.87 432 [358–506]	442.33 ± 36.79 435 [351–514]	0.002	0.14	−5.43 ± 17.70 [−9.89 to –0.97]
P1 = 0.006, P2 = 0.03, P3 = 0.02, P4 = 1.00, P5 = 0.79, P6 = 0.89
Refractive outcomes
Mean spherical component	−3.69 ± 3.07 –2.75 [−17.00 to –0.75]	−1.58 ± 2.43 –1.00 [−13.25 to 1.50]	−1.50 ± 2.31 –0.75 [−13.00 to 1.50]	−1.52 ± 2.41 –1.00 [−13.50 to 1.25]	< 0.0001	0.11	2.17 ± 2.19 [1.62–2.72]
P1 < 0.001, P2 < 0.0001, P3 < 0.0001, P4 = 0.34, P5 = 1.00, P6 = 1.00
Mean cylindrical component	−4.65 ± 1.78 –5.00 [−8.25 to –1.50]	−3.34 ± 1.64 –3.00 [−9.25 to –0.75]	−3.14 ± 1.92 –3.25 [−9.00 to 3.50]	−3.20 ± 1.67 –3.00 [−9.00 to –0.50]	< 0.0001	0.65	1.44 ± 2.07 [0.92–1.96]
P1 < 0.0001, P2 < 0.0001, P3 < 0.0001, P4 = 0.28, P5 = 0.64, P6 = 1.00
Mean SE	−6.01 ± 2.97 –5.50 [−20.00 to 2.25]	−3.25 ± 2.83 –2.50 [−16.25 to 0.50]	−3.07 ± 2.79 –2.50 [−15.88 to 0.63]	−3.13 ± 2.78 –2.50 [−16.50 to 0.50]	< 0.0001	0.22	2.89 ± 2.32 [2.31–3.47]
P1 < 0.0001, P2 < 0.0001, P3 < 0.0001, P4 = 0.052, P5 = 0.24, P6 = 1.00

CXL, cross-linking; SD, standard deviation; CI, confidence interval; UDVA, uncorrected distance visual acuities; CDVA, corrected distance visual acuities; P1, pre compared with 6 months; P2, pre compared with 12 months; P3, pre compared with 18 months; P4, 6 months compared with 12 months; P5, 6 months compared with 18 months, P6, 12 months compared with 18 months; K, keratometry; SE, spherical equivalent.

Table 2. Summary of the preoperative and postoperative data of a 14-year-old female patient.

Parameters	Preoperative data	Postoperative data at 6-month follow-up	Postoperative data at 12-month follow-up	Postoperative data at 18-month follow-up
Visual outcomes
UDVA (logMAR)	1.52	0.40	0.40	0.40
CDVA (logMAR)	1.00	0.18	0.22	0.22
Topographic outcomes
K1 reading	51.10	44.39	44.53	44.65
K2 reading	52.70	47.51	47.45	47.34
K average reading (D)	51.90	45.95	45.99	46.00
Corneal thickness at thinnest location (µm)	438	429	421	423
Refractive outcomes
Subjective refraction
Sphere cylinder (axis)	−11.00 –6.25 (162°)	−6.00 –3.75 (139°)	−6.25 –3.50 (148°)	−5.75 –4.00 (145°)
SE	−14.13	−7.88	−8.00	−7.75

UDVA, uncorrected distance visual acuities; CDVA, corrected distance visual acuities; K, keratometry; SE, spherical equivalent.

Figure 2. Corneal topography of a 14-year-old female patient with KC: (A) preoperatively; (B) at the 6th follow-up month postoperatively with an improvement in the K readings; and at the 12th (C) and 18th (D) follow-up month postoperatively with stabile K readings.

Figure 3. Corneal topography of a 9-year-old male patient with KC: (A) preoperatively; (B) at the 6th follow-up month postoperatively; (C) at the 12th follow-up month postoperatively; and (D) at the 18th follow-up month postoperatively.

Figure 4. Corneal topography of a 17-year-old female patient with KC: (A) preoperatively; (B) at the 6th follow-up month postoperatively; (C) at the 12th follow-up month postoperatively; and (D) at the 18th follow-up month postoperatively.

Table 3. Visual, topographic, and refractive pathways of the eight eyes with complications preoperatively and after 18 months.

Eye	No. 1	No. 2	No. 3	No. 4	No. 5	No. 6	No. 7	No. 8
Complication	Segments’ migration	Segments’ extrusion	Segments’ extrusion	Segments’ extrusion	KC progression	KC progression	KC progression	KC progression
Management	Segments’ explantation	Segments’ explantation	Segments’ explantation	Segments’ explantation	Standard CXL retreatment	Standard CXL retreatment	Standard CXL retreatment	Standard CXL retreatment
Visual rehabilitation	Spectacles	Spectacles	Spectacles	Spectacles	Spectacles	Spectacles	Spectacles	Spectacles
UDVA (logMAR)
Preoperative	1.30	0.50	0.48	0.60	0.78	1.22	1.12	1.00
Postoperative	0.80	0.52	0.52	0.78	1.12	1.52	1.48	1.48
CDVA (logMAR)
Preoperative	0.80	0.10	0.18	0.30	0.40	0.52	0.60	0.70
Postoperative	0.70	0.22	0.30	0.48	0.60	1.00	0.90	1.00
K average reading (D)
Preoperative	46.13	49.47	51.85	48.43	52.34	55.38	52.35	49.51
Postoperative	46.75	50.26	53.21	49.17	56.23	57.13	54.18	51.02
Corneal thickness at thinnest location (µm)
Preoperative	439	421	442	409	471	439	412	380
Postoperative	431	413	434	395	433	401	385	351
Spherical component
Preoperative	−5.00	−0.75	−0.75	−1.25	−1.50	−3.50	−2.00	−3.00
Postoperative	−6.00	−1.00	−0.50	−2.00	−3.75	−6.50	−4.00	−4.25
Cylindrical component
Preoperative	−3.00	−7.00	−6.50	−5.50	−3.25	−8.00	−6.00	−5.00
Postoperative	−0.50	−9.00	−8.50	−7.50	−5.50	−5.00	−6.50	−5.50
SE
Preoperative	−6.50	−4.25	−4.00	−4.75	−3.125	−7.50	−5.00	−5.50
Postoperative	−6.25	−5.50	−4.75	−5.75	−6.50	−9.00	−7.25	−7.00

KC, keratometry; CXL, cross-linking; UDVA, uncorrected distance visual acuities; CDVA, corrected distance visual acuities; K, keratometry; SE, spherical equivalent.