Journal List > J Korean Ophthalmol Soc > v.59(7) > 1098733

Park, Yeom, and Park: Choroidal Thickness Changes Following Vitrectomy in Epiretinal Membrane Based on the Optical Coherence Tomography Pattern

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.

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Figure 1.
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.
jkos-59-637f1.tif
Figure 2.
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.
jkos-59-637f2.tif
Figure 3.
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.
jkos-59-637f3.tif
Figure 4.
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.
jkos-59-637f4.tif
Table 1.
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.

Table 2.
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.

Table 3.
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).

Table 4.
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).

Table 5.
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.

Table 6.
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.

Table 7.
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.

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