Posterior corneal curvature changes following Refractive Small Incision Lenticule Extraction

Figures & data

Table 1 Number of patients, Intraocular pressure & Residual bed thickness

Group	Patients (n)	Pre-op IOP (mmHg)	Post-op IOP (mmHg)	Residual bed thickness (µm)
Low myopia	3	13±1.73	8.33±0.57	368±32.51
Moderate myopia	29	14.1±3.29	12.65±2.91	351.62±41.15
High myopia	20	14.69±2.22	11.85±2.75	318±32.04

Note: Data are presented as Mean ± SD.

Abbreviations: IOP, intraocular pressure; post-op, post-operative; pre-op, pre-operative.

Table 2 Refractive error (Diopters) and Visual acuity (in LogMAR scale)

	Pre-op			Post-op
	DS (D)	DCYL (D)	BCVA	DS (D)	DCYL (D)	UCVA	BCVA
Low myopia	−2.17±0.14	−0.67±0.38	0.00±0.00	−0.12±0.04	−0.09±0.04	0.00±0.00	0.00±0.00
Moderate myopia	−3.68±0.75	−0.81±0.48	0.03±0.06	−0.22±0.19	−0.16±0.08	−0.01±0.05	−0.04±0.05
High myopia	−6.36±1.37	−1.34±0.67	0.006±0.02	−0.35±0.28	−0.24±0.17	0.006±0.04	−0.04±0.05

Note: Data are presented as Mean ± SD.

Abbreviations: DCYL, diopter cylinder; DS, diopter sphere; D, diopters; post-op, post-operative; pre-op, pre-operative; UCVA, uncorrected distant visual acuity; BCVA, best corrected distant visual acuity.

Table 3 Pre-operative (pre-op) and post-operative (post-op) pachymetry

Central corneal thickness	Low myopia	Moderate myopia	High myopia
Pre-op (µm)	547.67±24.01	550.48±35.54	532.15±33.81
Post-op (µm)	468.33±43.13	454.10±43.70	400.90±38.15
P-value	0.042	<0.001	<0.001

Note: Data are presented as Mean ± SD.

Table 4 Comparison of corneal keratometric power of anterior surface at 3, 5, and 7 mm zones before and 3 months after ReLEx SMILE

Corneal power:anterior surface	Low myopia	Moderate myopia	High myopia
3 mm
Pre-op (D)	42.49±1.98	43.86±1.47	43.64±0.43
Post-op (D)	39.33±1.58	39.95±1.88	38.99±1.26
P-value	0.035	<0.001	<0.001
5 mm
Pre-op (D)	42.34±1.96	43.78±1.49	43.57±0.44
Post-op (D)	39.20±1.58	39.96±1.83	39.07±1.14
P-value	0.114	<0.001	0.047
7 mm
Pre-op (D)	42.10±1.88	43.60±1.49	43.42±0.44
Post-op (D)	39.07±1.47	39.99±1.78	39.27±0.95
P-value	0.029	<0.001	<0.001

Note: Data are presented as Mean ± SD.

Abbreviations: D, diopter; post-op, post-operative; pre-op, pre-operative; ReLEx SMILE, Refractive Small Incision Lenticule Extraction.

Table 5 Comparison of corneal asphericity of anterior surface at 3, 5, and 7 mm zones before and 3 months after ReLEx SMILE

Corneal asphericity (Q-value): anterior surface	Low myopia	Moderate myopia	High myopia
3 mmQ
Pre-op	−0.20±0.14	−0.21±0.21	−0.24±0.23
Post-op	0.25±0.16	0.45±0.68	0.04±0.49
P-value	0.653	0.015	<0.001
5 mmQ
Pre-op	−0.37±0.13	−0.27±0.15	−0.28±0.18
Post-op	−0.47±0.22	−0.03±0.43	0.57±0.45
P-value	0.026	<0.001	<0.001
7 mmQ
Pre-op	−0.35±0.07	−0.30±0.13	−0.32±0.14
Post-op	−0.33±0.16	0.05±0.36	0.63±0.44
P-value	0.833	<0.001	<0.001

Note: Data are presented as Mean ± SD.

Abbreviations: post-op, post-operative; pre-op, pre-operative; ReLEx SMILE, Refractive Small Incision Lenticule Extraction.

Table 6 Comparison of corneal keratometric power of posterior surface at 3, 5, and 7 mm zones before and 3 months after ReLEx SMILE

Corneal power: posterior surface	Low myopia	Moderate myopia	High myopia
3 mm
Pre-op (D)	−5.87±0.17	−6.14±0.23	−6.19±0.16
Post-op (D)	−6.06±0.29	−6.29±0.22	−6.4±0.18
P-value	0.143	<0.001	<0.001
5 mm
Pre-op (D)	−5.87±0.19	−6.14±0.23	−6.21±0.15
Post-op (D)	−6.02±0.27	−6.26±0.23	−6.37±0.17
P-value	0.347	0.014	<0.001
7 mm
Pre-op (D)	−5.88±0.19	−6.14±0.23	−7.01±2.40
Post-op (D)	−5.99±0.27	−6.23±0.24	−6.34±0.17
P-value	0.135	<0.001	<0.001

Note: Data are presented as Mean ± SD.

Abbreviations: D, diopter; post-op, post-operative; pre-op, pre-operative; ReLEx SMILE, Refractive Small Incision Lenticule Extraction.

Table 7 Comparison of corneal asphericity of posterior surface at 3, 5, and 7 mm zones before and 3 months after ReLEx SMILE

Corneal asphericity (Q-value): posterior surface	Low myopia	Moderate myopia	High myopia
3 mmQ
Pre-op	0.23±0.43	0.00±0.28	0.18±0.41
Post-op	−0.40±0.71	−0.28±0.56	−0.34±0.39
P-value	0.170	<0.001	<0.001
5 mmQ
Pre-op	−0.10±0.16	−0.10±0.17	−0.04±0.20
Post-op	−0.51±0.27	−0.37±0.32	−0.45±0.22
P-value	0.151	<0.001	0.228
7 mmQ
Pre-op	−0.14±0.11	−0.15±0.13	−0.08±0.16
Post-op	−0.40±0.13	−0.35±0.23	−0.34±0.16
P-value	0.145	<0.001	<0.001

Abbreviations: post-op, post-operative; pre-op, pre-operative; ReLEx SMILE, Refractive Small Incision Lenticule Extraction.

Table 8 Change in corneal keratometric power and asphericity in relation to optical zone

	Change in keratometric power (D)			Change in asphericity
	Optical zone 6.00–6.50 mm	Optical zone 6.51–7.00 mm	P-value	Optical zone 6.00–6.50 mm	Optical zone 6.51–7.00 mm	P-value
Change in 3 mm zone	0.17±0.12	0.22±0.09	0.328	0.36±0.53	0.57±0.63	0.325
Change in 5 mm zone	0.13±0.10	0.17±0.07	0.306	0.31±0.32	0.41±0.27	0.412
Change in 7 mm zone	0.26±1.63	0.13±0.05	0.506	0.21±0.18	0.32±0.20	0.113

Note: Data are presented as Mean ± SD.

Abbreviation: D, diopter.