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 Table of Contents  
ORIGINAL ARTICLE
Year : 2020  |  Volume : 113  |  Issue : 2  |  Page : 69-76

Internal limiting membrane peeling effect on visual outcomes after diabetic vitrectomy


1 Department of Ophthalmology, Faculty of Medicine, Alexandria University, Alexandria, Egypt
2 Department of Ophthalmology, Faculty of Medicine, Port-Said University, Port-Said, Egypt
3 Department of Ophthalmology, Alexandria, Egypt

Date of Submission29-Dec-2019
Date of Acceptance07-Jan-2020
Date of Web Publication10-Jul-2020

Correspondence Address:
MBCCH, PhD, FRCSed Mohamed A Elmassry
29 Fawzy Moaz Street, Semouha, Alexandria, 21500
Egypt
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ejos.ejos_75_19

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  Abstract 

Aim and Objectives To determine whether Internal Limiting Membrane (ILM) peeling has an effect on visual outcomes after vitrectomy for diabetic tractional retinal detachment.
Settings and Design A prospective randomized interventional case series.
Patients and Methods Pars Plana Vitrectomy (23-Gauge) was performed on 34 cases with diabetic epi-macular traction affecting the vision due to advanced proliferative diabetic retinopathy. The usual steps of vitrectomy were performed. The ILM was randomly chosen to be peeled in 16 cases (group I), or left not peeled in 18 cases (group II). Eventually, either air, Sulphur hexafluoride (SF6) gas or silicone oil tamponade was used. Final visual acuity results were tabulated six months after surgery, and compared between the two groups.
Results The mean pre-operative visual acuity (VA) was 0.06 (decimals) and 0.03 in groups I and II respectively. The mean post-operative VA was significantly better: 0.26 and 0.27 in groups 1 and 2 respectively (P=0.001). There were no statistically significant differences between VA gains in both groups (P=0.721). Air tamponade was used in 18.8% and 33.3%, SF6 in 37.5% and 33.3%, and silicone oil in 43.8% and 33.3% in groups I and II respectively.
Conclusions ILM peeling had no effect on the final visual outcome after vitrectomy for diabetic tractional retinal detachments.

Keywords: ILM peeling, proliferative diabetic retinopathy, tractional retinal detachment, vitrectomy


How to cite this article:
Shaarawy AS, Elbaha SM, Ghoneim EM, Elmassry MA. Internal limiting membrane peeling effect on visual outcomes after diabetic vitrectomy. J Egypt Ophthalmol Soc 2020;113:69-76

How to cite this URL:
Shaarawy AS, Elbaha SM, Ghoneim EM, Elmassry MA. Internal limiting membrane peeling effect on visual outcomes after diabetic vitrectomy. J Egypt Ophthalmol Soc [serial online] 2020 [cited 2020 Aug 14];113:69-76. Available from: http://www.jeos.eg.net/text.asp?2020/113/2/69/289488


  Introduction Top


Diabetic retinopathy significantly affects vision nationally and globally [1],[2]. The annual death rate related to diabetic complications in Egypt is 86 478 [3]. Proliferative diabetic retinopathy (PDR) is characterized by the growth of new vessels on the retina or the optic disk [4],[5],[6],[7], leading to vitreous hemorrhage, tractional detachment, rubeosis iridis, and eventually blindness [8]. Panretinal photocoagulation has been the treatment for PDR since the 1970s. However, chronic vitreous hemorrhage, tractional, or combined tractional–rhegmatogenous retinal detachments [9] are indications for early vitrectomy [4]. Some surgeons peel the internal limiting membrane (ILM) after staining to prevent epimacular reproliferation (although not mandatory) aiming for better postoperative visual results [10],[11],[12].


  Patients and methods Top


This study was performed after obtaining an informed consent from the participants and approval of the study by the Institutional Review Board and the Institution’s Ethical Committee, after explaining the patients’ current condition, the surgery needed, benefits, and possible complications of the surgical intervention. All authors declare that there are no financial interests in any of the materials used or the work done in this study. The work done was in concordance with the Declaration of Helsinki.

This was a prospective, randomized interventional case series carried out between June 2017 and June 2019. Patients included in this study suffered from type I or type II diabetes mellitus, indicated for pars-plana vitrectomy for the first time for epiretinal gliosis exerting traction on the macula and threatening the fovea, or causing tractional macular detachment due to advanced PDR with absence of a coexisting rhegmatogenous retinal detachment or a coexisting macular hole. Cases with combined tractional–rhegmatogenous retinal detachments, a coexisting macular hole, cases with previous arterial or venous occlusions, cases with coexisting hereditary macular dystrophies, coexisting age-related macular degeneration or extensive macular scarring, or coexisting posterior segment inflammation, were all excluded from the study.

Surgeries were performed by two highly experienced vitreoretinal surgeons. Pars-plana vitrectomy (23 G) was performed on 34 cases with macular traction affecting the vision due to advanced PDR. The usual steps of vitrectomy were performed, including cataract surgery if needed, core vitrectomy, removal of the posterior hyaloid membrane, segmentation and delamination of epiretinal gliosis, either unimanually using high-speed cutting rates (5000 cuts/min) by the vitreous cutter, or using bimanual techniques for dissection of epiretinal gliotic elements using an end-gripping forceps and curved scissors. After that, removal of residual posterior hyaloid tissue and shaving of the vitreous base was done, then endolaser photocoagulation was performed. IILM peeling from the macular area was randomly chosen to be done in 16 cases (group I) or left not peeled in 18 cases (group II). Two cases in group I was lost to follow-up before completion of the 6-month period; hence group I had two patients less than group II. ILM peeling was performed in group I after removal of the posterior hyaloid face and removal of epimacular traction. It can be aided by the use of Brilliant Blue G stain (ILM-BLUE; DORC, Zuidland, The Netherlands). Eventually, either air, sulfur hexafluoride (SF6) gas, or silicone oil tamponade was used. Some of the surgical steps are demonstrated in [Figure 1],[Figure 2],[Figure 3],[Figure 4],[Figure 5].
Figure 1 Intraoperative view showing core vitrectomy and underlying tractional retinal detachment with an area of subhyaloid hemorrhage.

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Figure 2 Intraoperative view showing segmentation of the epiretinal gliosis by the vitreous cutter.

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Figure 3 Bimanual dissection of adherent membranes using the end-gripping forceps and curved scissors.

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Figure 4 ILM peeling using the ILM peeling forceps. ILM, internal limiting membrane.

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Figure 5 Completed ILM peel. ILM, internal limiting membrane.

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All patients received postoperative treatment in the form of topical antibiotics (moxifloxacin drops) and topical steroids (prednisolone acetate eye drops). Patient follow-up was carried out at 1-day, 1-week, 1-month, 3-month, and 6-month intervals. Final visual acuity (VA) results were tabulated 6 months after surgery, and compared between the two groups.

All data were tabulated, and were subjected to statistical analysis using the Statistical Package for the Social Sciences 22.0 (IBM SPSS; IBM, Armonk, New York, USA). Data were analyzed to assess the visual outcomes.


  Results Top


The mean age of the patients is 55.6 (ranging from 24 to 75) years in group I and 55.9 (ranging from 25 to 68) years in group II. Women (n=23) included in the current study were significantly more than men (n=11). Concerning the type and duration of diabetes mellitus (DM), group I contained three patients with type I (T1D), and 13 with type II diabetes (T2D); on the other hand, group II included five and 13 patients with T1D and T2D, respectively. The mean duration of DM in the current study was 14 years in group I and 12 years in group II. Statistical analysis of these data is illustrated in [Table 1], showing no statistically significant difference between both groups concerning the duration of type and duration of DM.
Table 1 Comparison between the two studied groups according to the type and duration of diabetes mellitus

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Regarding the other (nonoperated upon) eye, 15/34 eyes had PDR, 6/34 had persistent active PDR, 3/34 eyes had quiescent NPDR, 6/34 eyes had tractional retinal detachment, and 4/34 eyes were vitrectomized.

On the other hand, regarding the kind of tamponade used, gas tamponade (SF6) was used more in group II, while air or silicone were used more in group I. The statistical analysis of the kind of tamponade used is demonstrated in [Table 2] and [Figure 6].
Table 2 Comparison between the two studied groups according to the type of tamponade used

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Figure 6 Bar chart comparing usage of air, gas, or silicone oil as a tamponade in both groups.

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As regards VA, the preoperative and postoperative VA outcomes in group I were more or less similar to group II. In both groups, there was a statistically significant improvement in VA after surgeries, the mean preoperative VA in group I was 0.06 (decimals) and 0.03 in group II, while the mean final visual outcome 6 months after surgery was 0.26 in group I and 0.27 in group II. There were no statistically significant differences between initial visual acuities and final visual outcomes in both groups. Statistical analysis of VA is demonstrated in [Table 3] and [Figure 7].
Table 3 Comparison between the two studied groups according to visual acuity

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Figure 7 Bar chart plotting the mean visual acuity before and after surgeries in both groups.

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In addition, when observing the change in VA in both groups, or in other words, the patients’ VA gains comparing preoperative and postoperative visual acuities, it was noticed that 62.5% of patients in group I and 61.1% of patients in group II had VA gains of up to two decimal lines compared with the initial VA. On the other hand, about a quarter of patients in each group gained more lines (≥five) after surgery; meanwhile, a minority of patients (one in group I and three in group II) gained more than five lines after surgery. On the other hand, a single patient in group I had worse vision 6 months after surgery due to ischemic optic atrophy. All changes of visual acuities were statistically similar when compared between both groups as shown in [Table 4] and [Figure 8]. [Figure 9],[Figure 10],[Figure 11] demonstrate the optical coherence tomography comparison between the preoperative and postoperative status in one of the cases.
Table 4 Comparison between the two studied groups according to the change of visual acuity

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Figure 8 Comparison between both groups according to VA change 6 months after surgery. One patient in group I suffered worse vision after surgery, while the majority of patients gained up to two lines (VA measured in decimals, two lines=0.2). VA, visual acuity.

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Figure 9 Preoperative OCT and OCT angiography of diabetic partial posterior vitreous detachment with a broad vitreomacular adhesion and vitreomacular traction. OCTA showed inaccurate results due to false segmentation due to the presence of cystic spaces and macular distortion. OCT, optical coherence tomography.

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Figure 10 OCT and OCTA of the same patient 6 months after vitrectomy, ILM peeling with sparing a central narrow ILM flap at the fovea to prevent the formation of an iatrogenic lamellar macular hole. ILM, internal limiting membrane; OCT, optical coherence tomography.

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Figure 11 OCT of the same patient above showing the narrow central ILM flap attached to a point in the center of the fovea, with marked reduction of central thickness and restoration of near-normal anatomy. ILM, internal limiting membrane; OCT, optical coherence tomography.

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  Discussion Top


Surgical complications of PDR are challenging to address. In addition, obtaining a satisfactory visual outcome is not always achievable. Among the surgical steps that can be done during diabetic vitrectomy is ILM peeling, as published by Chang et al. [13], where it was proven that ILM peeling minimizes the incidence of epimacular membrane formation. This is due to the fact that ILM acts as a scaffold for glial cells to proliferate on the macular area. This study showed that ILM peeling did not improve the final visual outcomes, which is comparable to the results published by Chang et al. [13] However, visual results in the current study have reached far better outcomes, as the mean postoperative VA reported by Chang et al. [13] was 0.1 compared with 0.28 (decimals) in this study.

Our current study results showed a statistically significant visual improvement in most of the cases 6 months after surgery with a successful surgical reattachment. Gas tamponade (SF6) was used in ∼25% of the cases, while air was utilized in 35% and silicone oil was used in 38% of cases. These results are comparable to those of Rahimy et al. [14] in 2015, who reported a mean preoperative VA of 0.01 and a postoperative VA of 0.04, which is less of a final visual outcome than our study. Rahimy and colleagues reported comparable results with our study concerning the kind of tamponade used (36% air, 39% gas, and silicone oil in 25% approximately). On the other hand, Wang et al. [15] in 2016 included cases operated upon using the bimanual technique as we used in a subset of patients. They reported improvement of the mean VA from 0.007 to 0.06. Wang et al. [15] had a much lower mean initial preoperative VA values, may be that is why the mean final postoperative VA was not that comparable to our current study. Another reason for that which have definitely contributed to lower final VA is that Wang et al. [15] included cases with combined tractional–rhegmatogenous retinal detachment, which are far more advanced pathologically than tractional retinal detachment cases without combined rhegmatogenous elements, and these cases (combined tractional–rhegmatogenous retinal detachment) were excluded from our study.

In addition, Sokol et al. [16] in 2019 reported a mean preoperative VA of 0.01, which improved to a mean VA of 0.16 after surgery. They needed C3F8 in more than 90% of cases, while silicone oil was needed as a long-term tamponade in less than 10% of cases.On the other hand, Milkhail et al. [17] in 2017 used the 25 G vitrectomy for diabetic tractional retinal detachment. They reported a mean preoperative VA of 0.07, which significantly improved to a mean postoperative VA of 0.16, with air used as a tamponade in 40% of cases, gas in more than 50% of cases, and silicone oil in less than 10% of cases.

Choovuthayakorn et al. [18] reported in 2019 a significant improvement in VA after surgery, more than 44% of cases in their study have gained two Snellen lines, with silicone oil needed as a tamponade in more than 40% of cases. However, Shroff et al. [19] in 2018 used the bimanual technique in all cases, and reported improvement of the mean VA from 0.03 to 0.16 which is comparable to our results, using gas in 50% of cases, and silicone in 25%.

As described previously, the mean VA showed a significant improvement after surgeries for diabetic epiretinal traction in our current study as well as a big subset of studies that have been mentioned in the current discussion. Needless to say, the VA values reported previously showed some variation when compared with our current study and when compared with each other. This may be due to multiple reasons. One of the factors that definitely contribute to this is the variation in disease severity. In addition, there is no doubt that the extent of epiretinal gliosis, the surgical status of the macula whether it is attached or detached, duration of the disease, degree of macular ischemia, condition of the optic nerve, patients’ age, patients’ ethnicity and background, and the surgeon’s skills and experience, all these factors, definitely have a huge impact on the final visual outcome. However, there is a general agreement that early intervention and meticulous surgical techniques give better final visual outcomes.

Concerning the surgical techniques, a variety of techniques have been used, as regards using unimanual versus bimanual surgery, or using 23 vs 25 G. As it was previously mentioned, we used a 23 G vitrectomy, either the unimanual or the bimanual technique. The previous publications also used unimanual and bimanual techniques depending on each case and its severity. Relative limitations of this study may be the need for a larger sample size, and longer follow-up durations. It is concluded from this study, which investigated the effects of ILM peeling on the final visual outcome in diabetic vitrectomy, that ILM peeling did not contribute to the final visual outcome, even if it was proven that it decreases the incidence of epimacular proliferation. These data are much valuable to be taken into consideration when a vitreoretinal surgeon considers ILM peeling during surgery.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

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    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10], [Figure 11]
 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4]



 

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