Anterior segment inflammation and its association with dry eye parameters following myopic SMILE and FS-LASIK

Figures & data

Table 1. Demographic characteristics between groups.

Variable	SMILE	FS-LASIK	Statistics	P
Gender (male/female)	14/10	12/12	0.336	0.562^a
Age (years)	23.38 ± 6.21	25.33 ± 5.85	–1.345	0.179^c
MRSE (D)	–5.16 ± 1.45	–5.38 ± 1.69	–0.290	0.772^c
Cylinder (D)	–0.90 ± 0.53	–0.96 ± 0.90	–0.917	0.359^c
HADS	5.13 ± 3.42	6.42 ± 4.48	–1.123	0.267^b

MRSE: manifest refraction spherical equivalent; HADS: hospital anxiety and depression scale.

^aRepresents chi-square test.

^bRepresents independent-samples t test.

^cRepresents Mann–Whitney U test.

Figure 1. Time-dependent change of inflammatory markers and dry eye metrics. BR: bulbar redness, LR: limbal redness, OSDI: ocular surface disease index, TMH: tear meniscus height, NIBUT-1: noninvasive tear film break-up time first, NIBUT-a: noninvasive tear film break-up time average, FBUT: fluorescein tear film break-up time, CFS: corneal fluorescein staining score using the Oxford scheme; *statistically significant difference from preoperative value, ^#statistically significant difference between groups.

Table 2. Factors correlated with flare during all follow-up time points.

GEE1	β	P	GEE2	β	P
Intercept	2.423	<0.001	Intercept	2.437	<0.001
Time 0	Reference	–	Time 0	Reference	–
Time 1	1.493	<0.001	Time 1	1.512	<0.001
Time 2	0.731	<0.001	Time 2	0.735	<0.001
Time 3	0.396	0.028	Time 3	0.402	0.026
Time 4	0.161	0.353	Time 4	0.165	0.349
MRSE (D)	−0.302	<0.001	MRSE (D)	−0.299	<0.001
NIBUT-1 (s)	–0.013	0.357	NIBUT-a (s)	–0.010	0.558

NIBUT-1 and NIBUT-a showed collinearity, thus we took GEE respectively in Table 2: 2-1 (Dependent Variable: Flare. Model: (Intercept), Time, MRSE, NIBUT-1) and 2-2 (Dependent Variable: Flare. Model: (Intercept), Time, MRSE, NIBUT-a). Time 0: baseline; Time 1: day 1; Time 2: week 1; Time 3: month 1; Time 4: month 3; MRSE: Manifest refraction spherical equivalent; NIBUT-1: noninvasive tear film break-up time first; NIBUT-a: noninvasive tear film break-up time average.

Table 3. Brief summary of flare after laser vision correction.

Author	Laser flare meter	Group	Number of eyes	Follow-up time	Main findings
Tomas-Barberan et al. [19]	Kowa FM 500	PRK (1-week)	10	1 week	Aqueous flare increased significantly in both groups. Topical corticosteroids did not prevent breakdown of the blood-aqueous barrier after operation.
		PRK (1-month)	15	1 month
Vita et al. [20]	Kowa FM 500	PRK	15	15 days	Neither PRK or LASIK induced statistically significant increased flare. PTK resulted in significant elevations in flare.
		LASIK	11	15 days
		PTK	10	15 days
Pérez-Santonja et al. [21]	Kowa FC 1000	LASIK	20	3 months	LASIK did not induce inflammation in the anterior chamber.
Tomas-Barberan et al. [22]	Kowa FM 500	PRK (diclofenac)	20	3 days	Although not statistically significant, there is a tendency toward less flare elevation in the anterior chamber in eyes treated with topical diclofenac and dexamethasone compared to placebo.
		PRK (dexamethasone)	20	3 days
		PRK (placebo)	20	3 days
Nguyen et al. [23]	Kowa FC 1000	PRK	31	3 months	No significant increase of aqueous flare was found.
Pisella et al. [24]	Kowa FM 500	PRK	N/A	21 days	Aqueous flare increased significantly in both groups. The increase probably correlated with the depth of photoablation.
		LASIK	N/A	21 days
El-Harazi et al. [18]	Kowa FM 500	LASIK	43	7 days	Despite the topical corticosteroids used, a significant increase in anterior chamber flare occurred.
Sen et al. [25]	Kowa FM 500	LASIK	10	2 weeks	LASIK induced a short-term postoperative increase in aqueous flare.
Özbilen et al. [26]	Kowa FM 700	FS-LASIK	30	3 months	FS-LASIK caused minimal inflammation in the anterior chamber.

PRK: photorefractive keratectomy; LASIK: laser in situ keratomileusis; PTK: phototherapeutic keratectomy.

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Data availability statement

The data that support the findings of this study are available from the corresponding authors (LH & QWG) upon reasonable request.