JKOS Journal of the Korean Ophthalmological Society J Korean Ophthalmol Soc 0378-6471 2092-9374 Korean Ophthalmological Society 10.3341/jkos.2018.59.7.637 jkos-59-637 Original Article Choroidal Thickness Changes Following Vitrectomy in Epiretinal Membrane Based on the Optical Coherence Tomography Pattern ParkJun Min MD YeomMyeong In MD ParkJung Min MD, PhD Department of Ophthalmology, Maryknoll Medical Center, Busan, Korea Address reprint requests to Jung Min Park, MD, PhD Department of Ophthalmology, Maryknoll Medical Center, #121 Junggu-ro, Jung-gu, Busan 48972, Korea Tel: 82-51-461-2549, Fax: 82-51-465-7470 E-mail: pjm1438@hanmail.net 09 2018 25 09 2018 597 637 649 22032018 09052018 22062018 Copyright © 2018 Korean Ophthalmological Society 2018 This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Abstract Purpose

To analyze the influence of morphological classification in epiretinal membrane (ERM) based on surgical outcomes and optical coherence tomography (OCT) of the postoperative choroidal thickness.

 Methods

This observational study included 122 eyes with ERM who underwent vitrectomy. Using OCT, the preoperative ERM was classified into six types: cystoid macular edema (CME), convex, flat, normal foveal contour (Normal), pseudolamellar hole (PLH), and vitreomacular traction (VMT). The preoperative multifocal electroretinogram (mfERG), postoperative change in subfoveal choroidal thickness (SCT), central macular thickness (CMT), and best-corrected visual acuity (BCVA) were compared.

 Results

Preoperative subfoveal choroidal thickness increased in the VMT type compared to the fellow eye (207 µm vs. 234 µm, p = 0.028). Choroidal thickness decreased in all types at 12 months after vitrectomy (all, p < 0.05). There was a positive linear correlation between the mfERG and the preoperative BCVA (p = 0.001). The initial visual acuity was best in the Normal type followed by the flat, PLH, convex, CME, and VMT types (p = 0.001). The final visual acuity was the best in the Normal type, followed by the PLH, Flat, VMT, Convex, and CME types (p = 0.030). Gas tamponade during the surgery did not affect the surgical outcomes of the CMT (p = 0.458), BCVA (p = 0.550), and SCT (p = 0.127).

 Conclusions

Preoperative SCT increased only in the VMT type, but choroidal thickness decreased in all types after vitrectomy, regardless of the preoperative morphology.

 Choroidal thickness Idiopathic epiretinal membrane Multifocal electroretinogram Optical coherence tomography Visual acuity References Pearlstone AD The incidence of idiopathic preretinal macular gliosis Ann Ophthalmol 1985 1737880 Fraser-Bell S Guzowski M Rochtchina E Five-year abdominal incidence and progression of epiretinal membranes: the Blue Mountains Eye Study Ophthalmology 2003 1103440 Meyer CH Rodrigues EB Mennel S Spontaneous separation of epiretinal membrane in young subjects: personal observations and review of the literature Graefes Arch Clin Exp Ophthalmol 2004 24297785 Johnson TM Johnson MW Epiretinal membrane Ophthalmology 2nd ed. St Louis Mosby 2004 94750 Wilkins JR Puliafito CA Hee MR Characterization of abdominal membranes using optical coherence tomography Ophthalmology 1996 103214251 Sezer T Altı nışı k M Koytak İ A Özdemir MH The choroid and optical coherence tomography Turk J Ophthalmol 2016 46307 Stanga PE Lim JI Hamilton P Indocyanine green angiography in chorioretinal diseases: indications and interpretation: an abdominal-based update Ophthalmology 2003 1101521 quiz 22–3. Michalewska Z Michalewski J Adelman RA Choroidal abdominal measured with swept source optical coherence tomography abdominal and after vitrectomy with internal limiting membrane peeling for idiopathic epiretinal membranes Retina 2015 3548791 Ahn SJ Woo SJ Park KH Choroidal thickness change following vitrectomy in idiopathic epiretinal membrane and macular hole Graefes Arch Clin Exp Ophthalmol 2016 254105967 Casini G Loiudice P Lazzeri S Analysis of choroidal abdominal change after 25-gauge vitrectomy for idiopathic epiretinal membrane with or without phacoemulsification and intraocular lens implantation Ophthalmologica 2017 2377884 Kang EC Lee KH Koh HJ Changes in choroidal thickness after vitrectomy for epiretinal membrane combined with vitreomacular traction Acta Ophthalmol 2017 95e3938 Kim CH Kim JI Cho HY Kang SW Correlation between pre-operative OCT pattern and visual improvement in macular abdominal membrane J Korean Ophthalmol Soc 2007 487582 Kinoshita T Kovacs KD Wagley S Arroyo JG Morphologic abdominals in epiretinal membranes on ocular coherence tomography as a predictive factor for surgical outcome Retina 2011 3116928 Seo SJ Lee SJ Park JM Surgical outcome according to abdominal in epiretinal membrane based on optical coherence abdominal (OCT) J Korean Ophthalmol Soc 2013 5473644 Smiddy WE Maguire AM Green WR Idiopathic epiretinal membranes. Ultrastructural characteristics and clinicopathologic correlation Ophthalmology 1989 9681120 discussion 821. Wei WB Xu L Jonas JB Subfoveal choroidal thickness: the Beijing Eye Study Ophthalmology 2013 12017580 Chung SE Kang SW Lee JH Kim YT Choroidal thickness in abdominal choroidal vasculopathy and exudative age-related macular degeneration Ophthalmology 2011 1188405 Koizumi H Kano M Yamamoto A Subfoveal choroidal thickness during aflibercept therapy for neovascular age-related macular degeneration: twelve-month results Ophthalmology 2016 12361724 Cho GE Cho HY Kim YT Change in subfoveal choroidal abdominal after argon laser panretinal photocoagulation Int J Ophthalmol 2013 65059 Kofod M la Cour M Quantification of retinal tangential abdominal in epiretinal membranes Ophthalmology 2012 119188691 Kozak I Barteselli G Sepah YJ Correlation of vitreomacular traction with foveal thickness, subfoveal choroidal thickness, and vitreomacular/foveal angle Curr Eye Res 2017 42297301 Kadonosono K Itoh N Nomura E Ohno S Perifoveal abdominal in eyes with epiretinal membranes Br J Ophthalmol 1999 83132931 Kinoshita H Suzuma K Maki T Cyclic stretch and abdominal increase retinal succinate: potential mechanisms for ex-acerbation of ocular neovascularization by mechanical stress Invest Ophthalmol Vis Sci 2014 5543206 Campa C Effect of VEGF and anti-VEGF compounds on retinal pigment epithelium permeability: an in vitro study Eur J Ophthalmol 2013 236906 Holekamp NM Shui YB Beebe DC Vitrectomy surgery increases oxygen exposure to the lens: a possible mechanism for nuclear abdominal formation Am J Ophthalmol 2005 13930210 Lim LS Tan L Perera S Retinal vessel oxygen saturation increases after vitrectomy Invest Ophthalmol Vis Sci 2014 5538516 Friberg TR Lace JW A comparison of the elastic properties of abdominal choroid and sclera Exp Eye Res 1988 4742936 Kondo M Miyake Y Horiguchi M Clinical evaluation of multifocal electroretinogram Invest Ophthalmol Vis Sci 1995 36214650 Arroyo JG Irvine AR Retinal distortion and cotton-wool spots abdominal with epiretinal membrane contraction Ophthalmology 1995 1026628 Yamamoto T Hitani K Tsukahara I Early postoperative abdominall thickness changes and complications after vitrectomy for abdominal macular edema Am J Ophthalmol 2003 135149 Tan CS Ouyang Y Ruiz H Sadda SR Diurnal variation of abdominal thickness in normal, healthy subjects measured by spectral abdominal optical coherence tomography Invest Ophthalmol Vis Sci 2012 532616 Yilmaz T Karci AA Yilmaz İ abdominal changes in abdominal choroidal thickness after cataract surgery Med Sci Monit 2016 22156670 Shahzad R Siddiqui MAR Zafar S Choroidal thickness changes following cataract surgery using swept source optical abdominal tomography Can J Ophthalmol 2018 53604 Cobos E Arias L Ruiz-Moreno J Preoperative study of the inner segment/outer segment junction of photoreceptors by spectral-abdominal optical coherence tomography as a prognostic factor in patients with epiretinal membranes Clin Ophthalmol 2013 7146770 Kim MH Jeon CY Baek SK The Thickness of each retinal layer and visual acuity after vitrectomy in idiopathic epiretinal membrane J Korean Ophthalmol Soc 2017 584209 Figures and Tables

The type of epiretinal membrane in optical coherence tomography images. (A) The cystoid macular edema type shows globally adherent membrane and formation of intraretinal cystoid space. (B) The convex type shows globally adherent membrane and dome shaped retina due to diffuse thickening of neurosensory retina. (C) The flat type shows globally adherent membrane and flat foveal contour. (D) The normal type shows normal foveal contour. (E) The pseudolamellar hole type shows steepened foveal fit. (F) The vitreomacular traction type shows focal adherent membrane bridging between vitreous and retina.

Longitudinal changes of the best corrected visual acuity (BCVA) before and after epiretinal membrane surgery. BCVA significantly increased in all types after surgery. CME = cystoid macular edema type; Convex = convex type; Flat = flat type; Normal = normal foveal contour type; PLH = pseudolamellar hole type; VMT = vitreomacular traction type.

Scattergram demonstraing the relation between preoperative multifocal electroretinogram (Ring1 amplitude) and best corrected visual acuity (BCVA). (A) Ring1 amplitude is significantly related to the preoperative BCVA (rho = −0.316, R2 = 0.126, p = 0.001*). (B) Ring1 amplitude is not significantly related to the postoperative BCVA (rho = −0.113, R2 = 0.022, p = 0.308*). Regression lines are shown on the scattergram as the red lines. M = months; mfERG = multifocal electroretinogram. * Spearman correlation analysis.

Scattergram demonstraing the relation between the preoperative central macular thickness (CMT) and best corrected visual acuity (BCVA). (A) Preoperative CMT is significantly related to the preoperative BCVA (rho = 0.587, R2 = 0.398, p < 0.001*). (B) Preoperative CMT is significantly related to the BCVA change (at 12 months) (rho = 0.244, R2 = 0.061, p = 0.009*). (C) Preoperative CMT is significantly related to the CMT change (at 12 months) (rho = 0.860, R2 = 0.758, p < 0.001*). M = months. Regression lines are shown on the scattergram as the red lines. * Spearman correlation analysis.

Demographic and clinical characteristics of patients

  Total CME Convex Flat Normal PLH VMT p-value
Number of eyes 122 14 30 37 11 21 9  
Gender (female:male) 85:37 12:5 25:9 27:10 8:3 16:5 4:5 0.613†
Age (years) 67.5 ± 7.3 65.6 ± 9.8 69.9 ± 6.5 65.9 ± 7.1 67.8 ± 5.8 66.4 ± 6.9 71.4±7.2 0.153*
Phakic:Pseudophakic 89:33 10:4 21:9 24:13 10:1 19:2 5:4 0.252†
Recurrent of ERM 12 2 3 4 0 1 2 0.590†
ERM in fellow eye 18 3 4 4 1 4 2  
EZ disruption 10 3 2 2 0 1 2 0.620†

Values are presented as number or mean ± SD unless otherwise indicated.

CME = cystoid macular edema type; Convex = convex type; Flat = flat type; Normal = normal foveal contour type; PLH = pseudolamellar hole type; VMT = vitreomacular traction type; ERM = epiretinal membrane; EZ = ellipsoid zone (photoreceptor inner segment/outer segment).

Kruskal-Wallis test

Pearson's chi-square test.

logMAR visual acuity and mean BCVA change according to the ERM type

BCVA CME Convex Flat Normal PLH VMT p-value†
Preoperative 0.54 ± 0.31 0.53 ± 0.22 0.34 ± 0.18 0.31 ± 0.28 0.41 ± 0.19 0.56 ± 0.27 0.002*
1 month 0.41 ± 0.29 0.27 ± 0.26 0.16 ± 0.13 0.12 ± 0.14 0.22 ± 0.21 0.26 ± 0.17 0.010*
2 months 0.30 ± 0.27 0.24 ± 0.22 0.13 ± 0.13 0.06 ± 0.11 0.13 ± 0.12 0.22 ± 0.16 0.009*
3 months 0.24 ± 0.22 0.21 ± 0.20 0.10 ± 0.10 0.05 ± 0.10 0.11 ± 0.11 0.18 ± 0.17 0.017*
6 months 0.25 ± 0.23 0.21 ± 0.22 0.11 ± 0.13 0.06 ± 0.10 0.11 ± 0.13 0.16 ± 0.18 0.031*
12 months 0.19 ± 0.21 0.16 ± 0.19 0.09 ± 0.13 0.02 ± 0.04 0.10 ± 0.08 0.13 ± 0.14 0.030*
BCVA change (1) 0.13 ± 0.18 0.24 ± 0.26 0.19 ± 0.15 0.19 ± 0.28 0.19 ± 0.21 0.30 ± 0.30  
p-value‡ 0.017* 0.010* <0.001* 0.240 0.003* 0.020*  
BCVA change (2) 0.24 ± 0.15 0.27 ± 0.23 0.23 ± 0.18 0.25 ± 0.31 0.28 ± 0.15 0.33 ± 0.22  
p-value‡ 0.010* 0.010* <0.001* 0.011* <0.001* 0.010*  
BCVA change (3) 0.31 ± 0.19 0.30 ± 0.24 0.24 ± 0.17 0.25 ± 0.31 0.30 ± 0.18 0.38 ± 0.24  
p-value‡ 0.010* 0.010* <0.001* 0.011* <0.001* 0.011*  
BCVA change (6) 0.31 ± 0.18 0.30 ± 0.24 0.23 ± 0.20 0.25 ± 0.3 0.30 ± 0.19 0.40 ± 0.24  
p-value‡ 0.010* 0.010* <0.001* 0.011* <0.001* 0.012*  
BCVA change (12) 0.36 ± 0.21 0.34 ± 0.24 0.24 ± 0.20 0.29 ± 0.27 0.32 ± 0.18 0.42 ± 0.23  
p-value‡ 0.010* 0.010* <0.001* 0.005* <0.001* 0.012*  
Overall p-value§ <0.001* <0.001* <0.001* <0.001* <0.001* <0.001*  

Values are presented as mean ± SD unless otherwise indicated.

BCVA = best corrected visual acuity (logMAR); ERM = epiretinal membrane; CME = cystoid macular edema type; Convex = convex type; Flat = flat type; Normal = normal foveal contour type; PLH = pseudolamellar hole type; VMT = vitreomacular traction type.

Indicates statistical significance

Kruskal-Wallis test (comparing among the groups)

Wilcoxon signed rank test (compairing the BCVA before and after surgery)

Friedman test.

Relation among preoperative multifocal ERG results, BCVA and preoperative CMT

Type ERM eye mfERG Fellow eye mfERG p-value† Preoperative BCVA Postoperative BCVA (6 months) Postoperative BCVA (12 months) ) Preoperative CMT (μm)
CME 85.66 ± 29.63 117.50 ± 30.6 0.012 0.54 ± 0.31 0.25 ± 0.23 0.19 ± 0.21 490.0 ± 92.9
Convex 89.08 ± 42.56 142.60 ± 39.75 <0.001 0.53 ± 0.22 0.21 ± 0.22 0.16 ± 0.19 476.0 ± 62.6
Flat 90.98 ± 34.26 107.10 ± 36.08 0.007 0.34 ± 0.18 0.11 ± 0.13 0.09 ± 0.13 374.0 ± 38.9
Normal 111.50 ± 35.55 126.00 ± 41.00 0.028 0.31 ± 0.28 0.06 ± 0.10 0.02 ± 0.04 301.0 ± 37.8
PLH 90.57 ± 35.01 116.20 ± 46.33 0.011 0.41 ± 0.19 0.11 ± 0.13 0.07 ± 0.08 376.0 ± 72.3
VMT 79.34 ± 27.51 109.40 ± 67.25 0.021 0.56 ± 0.27 0.16 ± 0.18 0.13 ± 0.14 444.0 ± 101
p-value 0.038*,§0.076§   0.001*,§ 0.733‡ 0.308‡ 0.054‡

Values are presented as mean ± SD unless otherwise indicated.

ERG = electroretinogram; BCVA = best corrected visual acuity (logMAR); CMT = central macular thickness; ERM = epiretinal membrane; mfERG = multifocal electroretinogram of Ring1 amplitude (nV/deg2); CME = cystoid macular edema type; Convex = convex type; Flat = flat type; Normal = normal foveal contour type; PLH = pseudolamellar hole type; VMT = vitreomacular traction type.

Indicates statistical significance

Wilcoxon signed rank test (compairing between the eyes affected by ERM and the normal fellow eyes)

Spearman correlation analysis (linear correlation between mfERG and BCVA or mfERG and CMT)

Kruskal-Wallis test (comparing among the groups).

Preoperative OCT results of SCT

Preoperative SCT CME (μ m) Convex (μ m) Flat (μ m) Normal (μ m) PLH (μ m) VMT (μ m) Total (μ m)
ERM eye 213.4 ± 73.0 179.2 ± 73.4 186.9 ± 61.6 186.1 ± 68.2 185.6 ± 65.1 234.0 ± 39.8 189.7 ± 63.9
Fellow eye 199.2 ± 47.9 184.3 ± 76.6 193.0 ± 51.1 183.0 ± 70.6 183.4 ± 69.8 207.1 ± 48.4 192.6 ± 68.4
p-value† 0.162 0.513 0.319 0.504 0.601 0.028* 0.162
p-value‡ 0.475 1.000 0.718 0.759 0.875 0.043* 0.249

Values are presented as mean ± SD unless otherwise indicated.

OCT = optical coherence tomography; SCT = subfoveal choroidal thickness; CME = cystoid macular edema type; Convex = convex type; Flat = flat type; Normal = normal foveal contour type; PLH = pseudolamellar hole type; VMT = vitreomacular traction type; ERM = epiretinal membrane.

Indicates statistical significance

Wilcoxon signed rank test (comparing between the ERM eye and the fellow eye)

Wilcoxon signed rank test (excluding the cases of ERM patients in the fellow eye).

Subfoveal choroidal thickness (SCT) before and after surgery

SCT CME (μ m) Convex (μ m) Flat (μ m) Normal (μ m) PLH (μ m) VMT (μ m) Total (μ m) p-value‡
Preoperative 213.4 ± 73.0 179.2 ± 73.4 186.9 ± 61.6 186.1 ± 68.2 185.6 ± 65.1 234.0 ± 39.8 191.3 ± 66.6 0.085
1 wk 210.7 ± 69.5 185.1 ± 76.4 189.3 ± 60.9 188.5 ± 67.7 190.7 ± 63.8 224.6 ± 57.0 192.7 ± 67.2 0.149
 p-value† 0.432(+) 0.063(+) 0.037*(+) 0.032*(+) 0.079(+) 0.108(+) 0.125(+)  
1 month 208.29 ± 70.6 179.6 ± 74.9 186.8 ± 63.9 182.2 ± 57.9 185.7 ± 64.5 219.5 ± 58.2 191.8 ± 67.2 0.434
 p-value† 0.078 0.572 0.011* 0.285 0.986 0.050* 0.001*  
3 months 201.1 ± 70.0 170.4 ± 73.2 186.8 ± 60.0 177.4 ± 56.2 182.1 ± 65.3 203.4 ± 63.5 184.1 ± 65.7 0.712
 p-value† 0.008* 0.024* 0.001* 0.012* 0.053 0.018* <0.001*  
6 months 199.0 ± 69.3 170.8 ± 68.3 186.7 ± 59.5 174.3 ± 58.5 182.7 ± 65.1 196.4 ± 58.4 182.7 ± 63.7 0.701
 p-value† 0.002* 0.013* 0.015* 0.007* 0.067 0.012* <0.001*  
12 months 197.2 ± 68.3 170.5 ± 66.4 182.1 ± 62.7 169.5 ± 57.6 179.5 ± 62.5 193.1 ± 53.5 180.1 ± 62.6 0.470
 p-value† 0.002* 0.024* 0.004* 0.022* 0.048* 0.008* <0.001*  
Overall p-value§ <0.001* <0.001* <0.001* <0.001* <0.001* <0.001* <0.001*  

Values are presented as mean ± SD unless otherwise indicated. (+) means increased SCT, otherwise means decreased SCT.

CME = cystoid macular edema type; Convex = convex type; Flat = flat type; Normal = normal foveal contour type; PLH = pseudolamellar hole type; VMT = vitreomacular traction type; wk = week.

Indicates statistical significance

Wilcoxon signed rank test (compairing the SCT before and after surgery)

Kruskal-Wallis test (comparing among the groups)

Friedman test.

Central subfield macular thickness before and after surgery

CMT CME (μ m) Convex (μ m) Flat (μ m) Normal (μ m) PLH (μ m) VMT (μ m) p-value‡
Preoperative 481.9 ± 94.0 475.9 ± 62.6 374.0 ± 38.9 301.7 ± 35.9 376.1 ± 72.3 419.2 ± 101.8 <0.001*
1 wk 449.7 ± 74.9 437.1 ± 52.1 365.4 ± 42.1 313.3 ± 47.3 372.2 ± 61.1 369.8 ± 69.6 <0.001*
 p-value† 0.002* <0.001* 0.031* 0.182(+) 0.498 0.066  
1 month 401.2 ± 65.2 411.3 ± 47.2 359.7 ± 39.4 329.6 ± 52.2 354.7 ± 54.8 341.9 ± 64.0 <0.001*
 p-value† 0.001* <0.001* 0.008* 0.050(+)* 0.130 0.021*  
3 months 371.2 ± 40.6 383.1 ± 39.1 343.3 ± 34.9 302.8 ± 42.3 346.1 ± 50.4 330.3 ± 49.9 <0.001*
 p-value† 0.001* <0.001* <0.001* 0.514(+) 0.018* 0.015*  
6 months 361.9 ± 39.3 371.3 ± 37.8 329.2 ± 37.2 300.2 ± 49.6 337.7 ± 44.5 325.7 ± 41.9 <0.001*
 p-value† 0.001* <0.001* <0.001* 0.213 0.005* 0.015*  
12 months 358.3 ± 38.1 356.5 ± 37.4 323.7 ± 36.3 291.5 ± 44.4 326.5 ± 45.0 318.0 ± 28.6 <0.001*
 p-value† 0.001* <0.001* <0.001* 0.130 0.001* 0.008*  
CMT reduction 123.6 ± 81.2 119.5 ± 49.9 50.3 ± 32.9 10.3 ± 35.6 49.1 ± 47.1 101.1 ± 108.4 <0.001*
Overall p-value§ <0.001* <0.001* <0.001* <0.001* <0.001* <0.001*  

Values are presented as mean ± SD unless otherwise indicated. (+) means increased central macular thickness (CMT), otherwise means decreased CMT.

CME = cystoid macular edema type; Convex = convex type; Flat = flat type; Normal = normal foveal contour type; PLH = pseudolamellar hole type; VMT = vitreomacular traction type; wk = week.

Indicates statistical significance

Wilcoxon signed rank test (compairing the CMT before and after surgery)

Kruskal-Wallis test (comparing among the groups)

Friedman test.

Effects of 10% SF6 gas tamponade in convex type

  Preoperative 1 week 1 month 3 months 6 months 1 year
BCVA            
 Group 1 0.48 ± 0.21 0.38 ± 0.23 0.26 ± 0.27 0.19 ± 0.13 0.20 ± 0.17 0.16 ± 0.13
 Group 2 0.58 ± 0.35 0.39 ± 0.08 0.29 ± 0.07 0.22 ± 0.07 0.21 ± 0.14 0.16 ± 0.07
 p-value* 0.919 0.556 0.622 0.639 0.898 0.550
CMT (μ m)            
 Group 1 468.5 ± 39.4 431.8 ± 41.9 398.6 ± 32.3 385.4 ± 33.8 374.1 ± 29.9 359.9 ± 30.1
 Group 2 480.9 ± 74.9 440.6 ± 58.9 419.8 ± 54.1 381.6 ± 43.2 369.5 ± 43.1 354.2 ± 42.4
 p-value* 0.657 0.204 0.398 0.719 0.641 0.458
SCT (μ m)            
 Group 1 184.1 ± 40.9 193.0 ± 29.4 189.0 ± 38.7 176.4 ± 45.0 175.7 ± 43.3 179.7 ± 43.7
 Group 2 192.1 ± 72.5 198.7 ± 81.2 189.9 ± 78.3 178.2 ± 75.9 179.0 ± 67.9 174.2 ± 64.1
 p-value* 0.116 0.792 0.676 0.769 0.461 0.127

Values are presented as number or mean ± SD unless otherwise indicated. ‘Group 1’ means ‘gas tamponade (n = 12)’ and ‘Group 2’ means

‘No gas tamponade (n = 18)’.

BCVA = best corrected visual acuity (logMAR); CMT = central macular thickness; SCT = subfoveal choroidal thickness.

Mann Whitney U-test.