internal limiting membrane ( ilm ) peeling is a crucial part of macular hole ( mh ) surgery , and using ilm peeling to remove and treat epiretinal membrane ( erm ) improves anatomical outcomes . the importance of the ilm in the pathogenesis of mh was also reported by yoon et al . . pars plana vitrectomy ( ppv ) and ilm peeling are used to treat not only mh , but also erm , diabetic macular edema , and retinal vein occlusion - related macular edema . optical coherence tomography ( oct ) is the gold standard for diagnosing mh and assessing anatomic outcomes after surgery . oct also provides prognostic information , such as basal mh diameter , mh height , mh minimum diameter , and other indexes of mh formation [ 6 , 7 ] . spectral domain optical coherence tomography ( sd - oct ) can also assess structural changes in the macular layers , such as the inner and outer segment ( is / os ) and external limiting membrane [ 8 , 9 ] . age , basal mh diameter , mh index ( mhi ) , stage , symptom duration , ilm peeling , and preoperative visual acuity affect the anatomic outcomes of mh surgery [ 10 , 11 ] . however , no studies assess the relationship between peeled ilm area and anatomic outcomes following mh surgery . this study quantitatively evaluates the effects of peeled ilm area on open and surgically closed mhs . forty - one eyes in 37 consecutive patients with idiopathic , gass stage 3 - 4  mh were enrolled in this retrospective comparative study . all mh cases underwent standard , sutureless , 3-port , 23-gauge vitrectomy surgery between march 2012 and march 2014 . all surgeries were performed by the same surgeon ( ahmet taylan yazici ) at beyoglu eye research and training hospital . all patients received a complete ophthalmic examination , including measurement of best corrected visual acuity ( bcva ) using an etdrs chart , biomicroscopy of the anterior segment , and dilated fundus examination ; all examinations were performed preoperatively on day 1 and week 1 and 1 , 3 , and 6 months after surgery . spectral domain optical coherence tomography ( sd - oct ) ( spectralis heidelberg engineering , heidelberg , germany ) was used preoperatively to assess each patient and postoperatively at 1 , 3 , and 6 months . exclusion criteria included refractive error > 6.00  d , traumatic mh , and history of ocular surgery ( except phacoemulsification ) . symptom duration was defined as the number of weeks from diagnosis to surgery . all patients provided informed consent prior to surgery , and this study adheres to the declaration of helsinki . all patients underwent standard , sutureless , 3-port , 23-gauge ( g ) pars plana vitrectomy ( ppv ) with triamcinolone acetonide- ( ta- ) assisted posterior vitreous detachment ( pvd ) ( if not already present ) . the ilm was grasped using ilm forceps and peeled off the retina using 0.2  ml of brilliant blue g dye ( brilliant peel ; geuder , heidelberg , germany ) . the area of the removed ilm was intended to reach the vascular arcades of the macula . fluid - air exchange was performed through an extrusion cannula to flatten the hole , which was followed by the injection of 15% perfluoropropane ( c3f8 ) or 20% sulfur hexafluoride ( sf6 ) . anatomic success was defined as complete mh closure and the absence of subretinal fluid on sd - oct . a second observer  who was blind to the results of the first observer  performed the same measurements in order to assess interobserver reproducibility . the first observer then scanned the same patient again to measure the same parameters and thereby assess intraobserver reliability . to reduce the likelihood of intraobserver bias , > 10 minutes was allowed to elapse before the first observer repeated the measurements . the observers were not present in the oct room during each other 's examinations and were unaware of each other 's final measurements . only the lowest section of the retinal macula was scanned to evaluate peeled ilm area . the borders of the peeled and nonpeeled ilm were seen and marked on the oct scan . the software of the device calculates the area of the peeled ilm in square millimeters ( figure 1 ) . basal mh diameter was defined as the diameter at the widest mh cross - section at the retinal pigment epithelium ( rpe ) [ 6 , 7 ] . mhi ( hole height / basal hole diameter ) was calculated using previously described methods . anatomic success was defined by complete mh closure and the absence of subretinal fluid on sd - oct at month 1 postoperatively . the statistical analysis was performed using spss ( statistical package for the social sciences ) ( version 16 for windows ; spss inc . ) . the normality of the data was confirmed using the kolmogorov - smirnov test ( p > 0.05 ) . one - way anova was used to evaluate homogeneity between groups ( p > 0.05 ) . groups were analyzed using the parametric t - test or nonparametric mann - whitney test . multiple regression analysis was used to determine if there was a significant association between anatomic outcomes and several factors , including gass stage , basal mh diameter , peeled ilm area , mhi , symptom duration , and preoperative bcva . bcva was converted to logmar ( logarithm of the minimal angle of resolution ) equivalents for the statistical analysis . in this study , p the mean follow - up period was 17.4 months ( range = 630 months ) . thirty - two cases were included in the anatomic success group , and 9 cases were included in the anatomic failure group . the mean ages of the patients in each group were 67.1  7.3 and 66.3  5.7 years , respectively . three patients developed significant cataracts during follow - up and underwent phacoemulsification with intraocular lens implantation . no significant difference in lens status was found between groups ( p = 0.147 ) . therefore , combination surgery did not demonstrate a significant influence ( p = 0.332 ) . perfluoropropane ( c3f8 ) was used in 33 eyes as tamponade , and sulfur hexafluoride ( sf6 ) was used in 8 eyes . there was no significant difference between eyes treated with c3f8 or sf6 in terms of anatomic outcomes ( p = 0.616 ) . mean preoperative bcva was 0.85  0.33  logmar , which postoperatively improved to 0.66  0.37  logmar ( p = 0.001 ) ( 0.87  0.36 versus 0.80  0.25  logmar in patients classified as anatomic success or failure , resp . , however , there was no significant difference between groups ( p = 0.936 ) ) . symptom duration was 18.9  12.8 versus 17.22  14.65 weeks in patients classified as anatomic success or failure , respectively . therefore , symptom duration did not demonstrate a significant difference between groups ( p = 0.738 ) . mean peeled ilm area was 16.51  6.15  mm ( range = 3.9030.0  mm ) and 12.8  4.0  mm ( range = 6.8917.67  mm ) in patients classified as anatomic success or failure . there was a statistically significant difference between groups in terms of peeled ilm area ( p = 0.024 ) . mean basal mh diameter was 963.2  325.1  m ( range = 3021625  m ) and 1426.0  621.3  m ( range = 7602627  m ) in anatomic success and failure patients , respectively . furthermore , there was a significant association between anatomic outcomes and 2 factors  basal mh diameter and peeled ilm area ( p = 0.001 and 0.009 , resp.)according to the multiple regression analysis ( shown in table 3 ) . the primary and final anatomic success rates were 78% ( 32 of 41 cases ) and 92.7% ( 38 of 41 cases ) , respectively . overall , 9 cases remained open ( anatomic failure ) after the first surgery , and second surgery was recommended for 8 cases . one case that had not been recommended for second surgery developed wide rpe atrophy and would not have benefited from surgery . among the open mhs , 2 patients could not postoperatively over the past 20 years , ilm peeling has played a crucial role in the surgical treatment of a variety of retinal disorders , including epiretinal membrane , mh , diabetic macular edema , and retinal vein occlusions . the available evidence supports using ilm peeling as the treatment of choice for patients with idiopathic stages 24  mh . ilm removal relieves the forces around the fovea , including those that are tangential and axial ; however , there is no general consensus regarding the extent of the ilm area that should be peeled . in this retrospective study many factors affect anatomic outcomes , and age , gass stage , basal mh diameter , mhi , preoperative bcva , and symptom duration are some prognostic criteria for mh surgery [ 10 , 11 ] . these parameters  including basal mh diameter , mhi , peeled ilm area , gass stage , symptom duration , and preoperative bcva  were assessed by our multiple regression analysis , but only mh basal diameter and peeled ilm area were found to be statistically significant . reported early and late changes in retinal nerve fiber layer thickness ( rnflt ) after ilm peeling for idiopathic macular hole or epiretinal membrane . rnflt increased at 1 month after surgery , returned to preoperative levels by 3 months , and was lower than basal at 6 months after surgery . proposed that reduced rnflt at 6 months after surgery could indicate damage caused by ilm peeling . in addition , according to a retrospective study that used microperimetry , tadayoni et al . reported that decreased retinal sensitivity was associated with paracentral absolute and relative microscotomas in 8 of 16 eyes following ilm peeling and mh surgery due to large macular holes ( > 400  mm ) . some authors have proposed that ilm peeling causes the loss of mller cell footplates and affects retinal function . terasaki et al . reported delayed implicit time and reduced b - wave amplitude on focal electroretinography ( erg ) soon after ilm peeling . steven et al . reported that ilm peeling may result in retinal weakening via mller cell damage , which causes structural breakdowns and finally paracentral retinal hole formation . have all separately reported the increased risk of secondary paracentral retinal hole formation after ilm peeling [ 1719 ] . on the contrary , che et al . evaluated 134 eyes in 130 imh patients who received ppv in combination with ilm peeling ( 2 disk diameters ) . thirteen eyes underwent a second surgery that involved enlarging the peeled ilm area to the vascular arcades of the posterior fundus . the retina nerve fiber layers can hemorrhage and iatrogenic retinal holes may develop , and these hemorrhages may result in visual field defects and other retinal alterations . accordingly , many surgeons do not widen the peeled area , and a smaller peeled ilm results in less of mller cells loss , stronger retinal structure , lower risk of visual field defects , and paracentral retinal hole formation . on the other hand , small peeled ilm demonstrates worsened anatomic outcomes . there is tangential traction in the etiology of macular hole formation that is induced by vitreous shrinkage , as observed and reported by gaudric et al . . we propose that wider ilm peeling relieves this traction more efficiently , therefore resulting in better anatomic outcomes . here , the mean area of peeled ilm in anatomically successful patients was 16.51  mm , whereas patients with anatomic failure demonstrated a mean area of 12.8  mm . it is difficult to determine a good cut - off value for the peeled area that confirms the best anatomic outcomes . the surgeon should peel the ilm to as much close to the vascular arcades of the macula as possible . the limitations of the present study include the relatively small numbers of patients , its retrospective design , and the fact that the peeled ilm borders were only assessed using sd - oct . a strength of this study is the quantitative assessment of the peeled ilm using sd - oct . in conclusion , we propose that peeled ilm area is important in mh surgery and that it can affect anatomic outcomes .
purpose . to quantitatively evaluate the effects of peeled internal limiting membrane ( ilm ) area and anatomic outcomes following macular hole surgery using spectral domain optical coherence tomography ( sd - oct ) 
 . methods . 
 forty - one eyes in 37 consecutive patients with idiopathic , gass stage 3 - 4 macular hole ( mh ) were enrolled in this retrospective comparative study . 
 all patients were divided into 2 groups according to anatomic success or failure . 
 basal mh diameter , peeled ilm area , and mh height were calculated using sd - oct . 
 other prognostic parameters , including age , stage , preoperative bcva , and symptom duration were also assessed . 
 results . 
 thirty - two cases were classified as anatomic success , and 9 cases were classified as anatomic failure . 
 peeled ilm area was significantly wider and mh basal diameter was significantly less in the anatomic success group ( p = 0.024 and 0.032 , resp . ) . 
 other parameters did not demonstrate statistical significance . 
 conclusion . 
 the findings of the present study show that the peeled ilm area can affect the anatomic outcomes of mh surgery .