Outcomes of Corneal Collagen Crosslinking Treatment
Ninety-six eyes of ninety-six patients who had unilateral CXL treatment for progressive keratoconus were included in this retrospective study. The study group consisted of 39 (40.6%) male and 57 (59.4%) female with a mean age of 29.42±9.34 years (Table 1). All patients had 1-year follow-up. In the entire cohort, mean CDVA significantly improved from 0.39±0.29 logMAR (20/49 Snellen) to 0.28±0.22 logMAR (20/38 Snellen; Table 2, P<0.001) and the maximum K significantly decreased from 54.54±5.50 D to 53.52±5.18 D between baseline and 1 year after CXL treatment (Table 2, P<0.001).
The effects of preoperative patient characteristics on changes in CDVA and maximum K after CXL treatment were assessed.
Age Patients With <30 Years of Age (n=54). The mean CDVA significantly improved from baseline 0.34±0.23 logMAR (20/43 Snellen) to 0.21±0.15 logMAR (20/32 Snellen) at 1-year after CXL treatment (P<0.001), whereas improvement in maximum K (from 53.62±4.90 D to 53.06±5.03 D) was not statistically significant (P=0.61).
Patients With ≥30 Years of Age (n=42). The improvement in mean CDVA was not statistically significant (from 0.44±0.35 logMAR, 20/55 Snellen, to 0.36±0.27 logMAR, 20/45 Snellen, P=0.074) between baseline and 1 year, whereas maximum K significantly decreased after CXL treatment (from 55.72±6.12 D to 54.12±5.37 D, P<0.001).
Comparison of the Postoperative Changes in CDVA and Maximum K Between Groups. After CXL treatment, the patients with ≥30 years of age experienced more flattening in maximum K compared with that of the patients with <30 years of age (P=0.024), whereas there was no significant difference between two groups in terms of change in CDVA (P=0.442).
Gender Males (n=39). The mean CDVA (from 0.35±0.25 logMAR, 20/44 Snellen, to 0.27±0.22 logMAR, 20/37 Snellen, P=0.034) and maximum K (from 53.95±6.04 D to 53.28±6.06 D, P=0.005) significantly improved between baseline and 1 year after CXL treatment.
Females (n=57). There were significant improvements in mean CDVA (from 0.41±0.32 logMAR, 20/51 Snellen, to 0.28±0.22 logMAR, 20/38 Snellen, P=0.001) and maximum K (from 54.94±5.18 D to 53.69±4.53 D, P=0.001) after CXL treatment.
Comparison of the Postoperative Changes in CDVA and Maximum K Between Groups. There were no significant differences regarding the changes in CDVA and maximum K between males and females (P=0.501, P=0.183, respectively).
Preoperative CDVA CDVA <0.3 logMAR (n=39). The mean CDVA did not show significant improvement (from 0.16±0.06 logMAR, 20/28 Snellen, to 0.16±0.13 logMAR, 20/28 Snellen, P=0.905), whereas the decrease in maximum K was statistically significant (from 52.42±4.12 D to 51.66±3.92 D, P=0.002).
CDVA ≥ 0.3 logMAR (n=57). The mean CDVA (from 0.54±0.29 logMAR, 20/69 Snellen, to 0.36±0.23 logMAR, 20/45 Snellen, P<0.001) and maximum K significantly improved after CXL treatment (from 55.98±5.94 D to 54.80±5.57 D, P=0.001).
Comparison of the Postoperative Changes in CDVA and Maximum K Between Groups. The patients with a worse baseline visual acuity (CDVA ≥0.3 logMAR) showed significant improvement in CDVA 1 year after CXL treatment compared with that of the patients with a better baseline visual acuity (CDVA<0.3 logMAR; P<0.001). However, comparing two groups, the change in maximum K was not statistically significant at 1 year (P=0.316).
Preoperative Maximum Keratometry Maximum K <54 D (n=52). The baseline CDVA (from 0.28±0.17 logMAR, 20/38 Snellen, to 0.21±0.17 logMAR, 20/32 Snellen, P=0.009) and maximum K significantly improved (from 50.54±2.10 D to 49.74±2.31 D, P=0.003) after CXL treatment.
Maximum K ≥54 D (n=44). After CXL treatment, mean CDVA (from 0.51±0.35 logMAR, 20/64 Snellen, to 0.35±0.25 logMAR, 20/44 Snellen, P=0.002) and maximum K significantly improved (from 59.26±4.51 D to 58.00±3.89 D, P=0.003).
Comparison of the Postoperative Changes in CDVA and Maximum K Between Groups. There were no significant differences between two groups in terms of change in CDVA and maximum K after CXL treatment (P=0.099, P=0.332, respectively).
Preoperative Cone Location. The study group comprised only eyes with central and paracentral cones.
Central Cone (n=72). There were significant improvements in mean CDVA (from 0.43±0.32 logMAR, 20/53 Snellen, to 0.30±0.23 logMAR, 20/39 Snellen, P<0.001) and maximum K (from 55.75±5.68 D to 54.54±5.36 D, P<0.001) 1 year after CXL treatment.
Paracentral Cone (n=24). There were no significant improvements in mean CDVA (from 0.24±0.09 logMAR, 20/34 Snellen, to 0.21±0.18 logMAR, 20/32 Snellen, P=0.239) and maximum K (from 50.90±2.92 D to 50.47±3.05 D, P=0.057) at 1-year follow-up.
Comparison of the Postoperative Changes in CDVA and Maximum K Between the Groups. The changes in mean CDVA and maximum K after CXL treatment did not show significant differences between two groups (P=0.176, P=0.160, respectively).
Preoperative Thinnest Pachymetry Thinnest Pachymetry <450 μm (n=45). The baseline mean CDVA (from 0.44±0.35 logMAR, 20/55 Snellen, to 0.32±0.23 logMAR, 20/41 Snellen, P=0.012) and maximum K (from 57.79±5.52 D to 56.10±5.17 D, P<0.001) significantly improved after CXL treatment.
Thinnest Pachymetry ≥450 mm (n=51). The mean CDVA (from 0.34±0.23 logMAR, 20/43 Snellen, to 0.24±0.21 logMAR, 20/34 Snellen, P=0.001) significantly improved, whereas maximum K (from 51.67±3.67 D to 51.25±4.02 D, P=0.124) did not show significant improvement after CXL treatment.
Comparison of the Postoperative Changes in CDVA and Maximum K Between Groups. The maximum K significantly decreased in thinner corneas (pachymetry <450 μm) compared with that of the relatively thicker corneas (pachymetry ≥450 μm; P=0.005), whereas there was no significant difference between the groups with respect to improvement in CDVA (P=0.627).
Postoperative changes in mean CDVA and maximum K according to the preoperative factors are demonstrated in Figures 1 and 2.
(Enlarge Image)
Figure 1.
Change in mean corrected distance visual acuity (CDVA) between baseline and year after CXL treatment in subgroups (*indicates statistically significant difference between two groups, P<0.05).
(Enlarge Image)
Figure 2.
Mean decrease in maximum keratometry between baseline and 1 year in subgroups (*indicates statistically significant difference between two groups, P<0.05).
Results
Ninety-six eyes of ninety-six patients who had unilateral CXL treatment for progressive keratoconus were included in this retrospective study. The study group consisted of 39 (40.6%) male and 57 (59.4%) female with a mean age of 29.42±9.34 years (Table 1). All patients had 1-year follow-up. In the entire cohort, mean CDVA significantly improved from 0.39±0.29 logMAR (20/49 Snellen) to 0.28±0.22 logMAR (20/38 Snellen; Table 2, P<0.001) and the maximum K significantly decreased from 54.54±5.50 D to 53.52±5.18 D between baseline and 1 year after CXL treatment (Table 2, P<0.001).
The effects of preoperative patient characteristics on changes in CDVA and maximum K after CXL treatment were assessed.
Subgroup Analyses According to the Preoperative Patient Data
Age Patients With <30 Years of Age (n=54). The mean CDVA significantly improved from baseline 0.34±0.23 logMAR (20/43 Snellen) to 0.21±0.15 logMAR (20/32 Snellen) at 1-year after CXL treatment (P<0.001), whereas improvement in maximum K (from 53.62±4.90 D to 53.06±5.03 D) was not statistically significant (P=0.61).
Patients With ≥30 Years of Age (n=42). The improvement in mean CDVA was not statistically significant (from 0.44±0.35 logMAR, 20/55 Snellen, to 0.36±0.27 logMAR, 20/45 Snellen, P=0.074) between baseline and 1 year, whereas maximum K significantly decreased after CXL treatment (from 55.72±6.12 D to 54.12±5.37 D, P<0.001).
Comparison of the Postoperative Changes in CDVA and Maximum K Between Groups. After CXL treatment, the patients with ≥30 years of age experienced more flattening in maximum K compared with that of the patients with <30 years of age (P=0.024), whereas there was no significant difference between two groups in terms of change in CDVA (P=0.442).
Gender Males (n=39). The mean CDVA (from 0.35±0.25 logMAR, 20/44 Snellen, to 0.27±0.22 logMAR, 20/37 Snellen, P=0.034) and maximum K (from 53.95±6.04 D to 53.28±6.06 D, P=0.005) significantly improved between baseline and 1 year after CXL treatment.
Females (n=57). There were significant improvements in mean CDVA (from 0.41±0.32 logMAR, 20/51 Snellen, to 0.28±0.22 logMAR, 20/38 Snellen, P=0.001) and maximum K (from 54.94±5.18 D to 53.69±4.53 D, P=0.001) after CXL treatment.
Comparison of the Postoperative Changes in CDVA and Maximum K Between Groups. There were no significant differences regarding the changes in CDVA and maximum K between males and females (P=0.501, P=0.183, respectively).
Preoperative CDVA CDVA <0.3 logMAR (n=39). The mean CDVA did not show significant improvement (from 0.16±0.06 logMAR, 20/28 Snellen, to 0.16±0.13 logMAR, 20/28 Snellen, P=0.905), whereas the decrease in maximum K was statistically significant (from 52.42±4.12 D to 51.66±3.92 D, P=0.002).
CDVA ≥ 0.3 logMAR (n=57). The mean CDVA (from 0.54±0.29 logMAR, 20/69 Snellen, to 0.36±0.23 logMAR, 20/45 Snellen, P<0.001) and maximum K significantly improved after CXL treatment (from 55.98±5.94 D to 54.80±5.57 D, P=0.001).
Comparison of the Postoperative Changes in CDVA and Maximum K Between Groups. The patients with a worse baseline visual acuity (CDVA ≥0.3 logMAR) showed significant improvement in CDVA 1 year after CXL treatment compared with that of the patients with a better baseline visual acuity (CDVA<0.3 logMAR; P<0.001). However, comparing two groups, the change in maximum K was not statistically significant at 1 year (P=0.316).
Preoperative Maximum Keratometry Maximum K <54 D (n=52). The baseline CDVA (from 0.28±0.17 logMAR, 20/38 Snellen, to 0.21±0.17 logMAR, 20/32 Snellen, P=0.009) and maximum K significantly improved (from 50.54±2.10 D to 49.74±2.31 D, P=0.003) after CXL treatment.
Maximum K ≥54 D (n=44). After CXL treatment, mean CDVA (from 0.51±0.35 logMAR, 20/64 Snellen, to 0.35±0.25 logMAR, 20/44 Snellen, P=0.002) and maximum K significantly improved (from 59.26±4.51 D to 58.00±3.89 D, P=0.003).
Comparison of the Postoperative Changes in CDVA and Maximum K Between Groups. There were no significant differences between two groups in terms of change in CDVA and maximum K after CXL treatment (P=0.099, P=0.332, respectively).
Preoperative Cone Location. The study group comprised only eyes with central and paracentral cones.
Central Cone (n=72). There were significant improvements in mean CDVA (from 0.43±0.32 logMAR, 20/53 Snellen, to 0.30±0.23 logMAR, 20/39 Snellen, P<0.001) and maximum K (from 55.75±5.68 D to 54.54±5.36 D, P<0.001) 1 year after CXL treatment.
Paracentral Cone (n=24). There were no significant improvements in mean CDVA (from 0.24±0.09 logMAR, 20/34 Snellen, to 0.21±0.18 logMAR, 20/32 Snellen, P=0.239) and maximum K (from 50.90±2.92 D to 50.47±3.05 D, P=0.057) at 1-year follow-up.
Comparison of the Postoperative Changes in CDVA and Maximum K Between the Groups. The changes in mean CDVA and maximum K after CXL treatment did not show significant differences between two groups (P=0.176, P=0.160, respectively).
Preoperative Thinnest Pachymetry Thinnest Pachymetry <450 μm (n=45). The baseline mean CDVA (from 0.44±0.35 logMAR, 20/55 Snellen, to 0.32±0.23 logMAR, 20/41 Snellen, P=0.012) and maximum K (from 57.79±5.52 D to 56.10±5.17 D, P<0.001) significantly improved after CXL treatment.
Thinnest Pachymetry ≥450 mm (n=51). The mean CDVA (from 0.34±0.23 logMAR, 20/43 Snellen, to 0.24±0.21 logMAR, 20/34 Snellen, P=0.001) significantly improved, whereas maximum K (from 51.67±3.67 D to 51.25±4.02 D, P=0.124) did not show significant improvement after CXL treatment.
Comparison of the Postoperative Changes in CDVA and Maximum K Between Groups. The maximum K significantly decreased in thinner corneas (pachymetry <450 μm) compared with that of the relatively thicker corneas (pachymetry ≥450 μm; P=0.005), whereas there was no significant difference between the groups with respect to improvement in CDVA (P=0.627).
Postoperative changes in mean CDVA and maximum K according to the preoperative factors are demonstrated in Figures 1 and 2.
(Enlarge Image)
Figure 1.
Change in mean corrected distance visual acuity (CDVA) between baseline and year after CXL treatment in subgroups (*indicates statistically significant difference between two groups, P<0.05).
(Enlarge Image)
Figure 2.
Mean decrease in maximum keratometry between baseline and 1 year in subgroups (*indicates statistically significant difference between two groups, P<0.05).
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