Femtosecond Laser Implantation of a 355-Degree Intrastromal Corneal Ring Segment in Keratoconus: A Three-Year Follow-Up

Table 2

Comparison between preoperative and postoperative UCVA and BCVA measures.

	Preoperative	3 months postoperative	6 months postoperative	12 months postoperative	24 months postoperative	36 months postoperative	value	P1	P2
UCVA (logMAR)
Mean ± S.D.	0.93 ± 0.21	0.46 ± 0.18	0.47 ± 0.18	0.49 ± 0.18	0.54 ± 0.18	0.63 ± 0.21	<0.001	<0.001	0.001
Median (range)	0.9 (0.5–1.3)	0.4 (0.2–0.8)	0.45 (0.2–0.8)	0.45 (0.2–0.8)	0.6 (0.2–0.8)	0.6 (0.3–1.1)
BCVA (logMAR)
Mean ± S.D.	0.67 ± 0.22	0.29 ± 0.16	0.29 ± 0.15	0.37 ± 0.23	0.39 ± 0.24	0.43 ± 0.26	<0.001	0.248	0.052
Median (range)	0.6 (0.3–1.1)	0.25 (0.1–0.8)	0.3 (0.1–0.8)	0.3 (0.1–0.9)	0.3 (0.1–0.9)	0.3 (0.1–1)

value compared the six repeated measures and was calculated by Friedman’s two-way ANOVA test. P1 compared 12 months postoperative and 24 months postoperative measures and was calculated by using Wilcoxon signed-rank test. P1 compared 24 months postoperative and 36 months postoperative measures and was calculated by Wilcoxon signed-rank test. value <0.05 is statistically significant Notes: UCVA: uncorrected visual acuity; BCVA: best-corrected visual acuity; D: diopters; logMAR, logarithm of the minimum angle of resolution; SD: standard deviation.