Journal of Ophthalmology

Clinical Study

Corneal Cap Thickness and Its Effect on Visual Acuity and Corneal Biomechanics in Eyes Undergoing Small Incision Lenticule Extraction

Table 1

Baseline characteristics of all eyes preoperatively and at 3 months postoperatively. (mean ± SD or Q2 ± IQR).


	110 μm cap ()	150 μm cap ()	value

Pre-BCVA	0.1 ± 0.1	0.1 ± 0.1	0.16
Pre-sph (D)	−4.77 ± 1.26	−4.25 ± 1.31	<0.001
Pre-cyl (D)	−0.75 ± 0.43	−0.77 ± 0.48	0.88
Post-UCVA (LogMAR)	−0.10 ± 0.0	−0.10 ± 0.0	0.99
Post-sph (D)	0.31 ± 0.50	0.20 ± 0.61	0.41
Post-cyl (D)	0.11 ± 0.34	0.06 ± 0.45	0.73
Pre-CCT (µm)	549.8 ± 23.7	548.9 ± 24.7	0.48
Pre-K1 (D)	42.4 ± 1.1	42.4 ± 1.1	0.63
Pre-K2 (D)	43.5 ± 1.2	43.5 ± 1.2	0.74
OBL ≥ level 2 (eyes)	7	0	0.004^a
Pre-SR	0.24 ± 0.08	0.20 ± 0.07	0.18
Post-SR	0.19 ± 0.05	0.16 ± 0.04	0.08
Pre-OSI	0.68 ± 0.47	0.69 ± 0.42	0.09
Post-OSI	0.88 ± 0.54	0.99 ± 0.47	0.10
Pre-MTF cutoff (cpd)	36.85 ± 12.21	34.84 ± 12.08	0.64
Post-MTF cutoff (cpd)	33.82 ± 11.03	32.26 ± 8.63	0.49
Prephotopic contrast sensitivity at low frequency (cpd)^&	1.62 ± 0.04	1.62 ± 0.04	0.99
Postphotopic contrast sensitivity at low frequency (cpd)	1.66 ± 0.03	1.62 ± 0.03	0.25
Prephotopic contrast sensitivity at high frequency (cpd)^@	1.17 ± 0.04	1.11 ± 0.03	0.28
Postphotopic contrast sensitivity at high frequency (cpd)	1.24 ± 0.04	1.08 ± 0.04	0.001
Prescotopic contrast sensitivity at low frequency (cpd)	1.62 ± 0.04	1.60 ± 0.02	0.57
Postscotopic contrast sensitivity at low frequency (cpd)	1.66 ± 0.05	1.51 ± 0.04	0.004
Prescotopic contrast sensitivity at high frequency (cpd)	1.05 ± 0.05	1.09 ± 0.05	0.38
Postscotopic contrast sensitivity at high frequency (cpd)	1.18 ± 0.04	1.05 ± 0.03	0.009
Precorneal spherical aberration (µm)	0.17 ± 0.08	0.20 ± 0.08	0.10
Postcorneal spherical aberration (µm)	0.38 ± 0.19	0.32 ± 0.10	0.003
Precorneal coma (µm)^#	0.20 ± 0.09	0.20 ± 0.07	0.36
Postcorneal coma (µm)	0.41 ± 0.16	0.36 ± 0.20	0.32
Pre-higher-order aberration (µm)	0.35 ± 0.08	0.36 ± 0.08	0.65
Post-higher-order aberration (µm)	0.64 ± 0.14	0.62 ± 0.15	0.47
Preendothelia cell density (/mm²)	2343 ± 472	2369 ± 501	0.28
Postendothelia cell density (/mm²)	2321 ± 487	2336 ± 455	0.35

We classified intraoperative OBL into 3 levels, which are mild, moderate, and severe; low frequency, ^&3 cpd; high frequency, ^@18 cpd; BCDVA, best-corrected distance visual acuity; UCDVA, uncorrected distance visual acuity; SR, Strehl ratio; OSI, objective scatter index; MTF cutoff, modulate transfer function cutoff value; coma^# = [(C₇) [2] + (C₈) [2]]^1/2. ^aFisher’s exact test.