Corneal biomechanical properties after SMILE versus FLEX, LASIK, LASEK, or PRK: a systematic review and meta-analysis

Table 1 Example of how to combine effect size and variance of change score of CH and CRF within studies

Study	Outcome (mmHg)	SMILE			LASIK			Effect size (Hedges’ g)	Variance of Hedges’ g	Combined effect size	Correlation between CH and CRF	Combined variance
Study	Outcome (mmHg)	Mean	SD	N (eye) at last follow-up	Mean	SD	N (eye) at last follow-up	Effect size (Hedges’ g)	Variance of Hedges’ g	Combined effect size	Correlation between CH and CRF	Combined variance
Alper Agca [38]	CH	−1.94	1.52	30	−1.98	1.5	30	0.03	0.06	−0.07	0.71	0.06
Alper Agca [38]	CRF	−2.96	1.69	30	−2.69	1.44	30	−0.17	0.07
Di Wu [39]	CH	−1.94	0.82	37	−2.34	1.08	34	0.42	0.06	0.48	0.71	0.05
Di Wu [39]	CRF	−3.59	0.91	37	−4.29	1.6	34	0.54	0.06
Wenjing Wu [40]	CH	−1.86	1.13	75	−2.23	1.33	75	0.3	0.03	0.4	0.71	0.02
Wenjing Wu [40]	CRF	−3.14	1.06	75	− 3.8	1.53	75	0.5	0.03
Bingjie Wang [41]	CH	−2.55	1.44	50	− 2.53	1.38	56	−0.01	0.04	0.4	0.71	0.03
Bingjie Wang [41]	CRF	−2.24	1.29	50	−3.33	1.34	56	0.82	0.04

Abbreviation: CH corneal hysteresis, CRF corneal resistance factor, LASIK laser-assisted in situ keratomileusis, SD standard deviation, SMILE small incision lenticule extraction

ISSN: 1471-2415