Comparison Between 20- Gauge And 23-Gauge Vitrectomy In Diabetic Patients

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1 Asok Nataraj MS Abstract Aim: - Comparison Between 20- Gauge And 23-Gauge Vitrectomy In Diabetic Patients The purpose of this study was to directly compare the outcome, safety and efficacy of the 20G and 23G vitrectomy systems in diabetic patients. Methods: - 24 eyes of diabetic patients who underwent 23G and 30 eyes of patients who underwent 20G pars plana vitrectomy with or without intraocular silicone oil tamponade for complications of proliferative diabetic retinopathy were included retrospectively. Visual acuity using snellen s chart, ocular examination including slit lamp exam and indirect ophthalmoscophy was performed. Post operative comfort was assessed using an ocular discomfort scale ranging from 1 to 4. Post operative complications including raised intraocular pressure cataract, persistent or recurrent vitreous hemorrhage and retinal detachment was assessed at every follow up over a period of 3 months. Results: - In both the groups majority were males (63%).The most common indication for vitrectomy was vitreous hemorrhage (75%) and rest macular tractional retinal detachment(trd).visual acuity pre and post op were comparable in both the groups except those who developed complications. Day 1 intraocular pressure(iop), duration of surgery and ocular discomfort post op was less in 23G group in comparison to 20G patients, the difference being statistically significant. Conclusion: - 20G and 23G vitrectomy are comparable with respect to anatomical and functional outcome in diabetic patients.23g appears to be far superior to 20G as far as post op ocular comfort and IOP rise is concerned. Introduction Pars plana vitrectomy (PPV) was first introduced in 1971 [1]. One of the most recent development in vitreoretinal surgery has been transconjunctival suture less vitrectomy (TSV). Fujii et al [2] introduced the 25-gauge TSV in 2002 and 3 years later, based on the same surgical principle, Eckardt [3] developed the 23-gaugeTSV. Compared to traditional 20-gauge (20G) vitrectomy system, the 23-gauge (23G) system allows for sutureless self sealing sclerotomies with minimal ocular discomfort. This offers a number of potential advantages including less post operative inflammation and faster post operative recovery [4]. Avoiding sutures may also shorten total operating time [5]. Aim Original Article The purpose of this study was to directly compare the outcome, safety and efficacy of the 20G and 23G vitrectomy systems in diabetic patients. Materials and methods Data was collected from 30 consecutive PPV cases performed using the 20G system between October 2008 and June 2009 and 24 consecutive cases of 23G TSV between October 2009 and March 2010 for complications of proliferative diabetic retinopathy. All surgeries were carried out by one surgeon (AN) at a single centre. Statistical analysis was carried out using unpaired Student s t-test for a comparison of means of the overall operating times and day 1 IOPs. The postoperative ocular discomfort between the groups was compared using the Mann-Whitney U-test. This study was designed as an interventional case series. Patients with combined retinal detachment were excluded from this study. and gender, lens status, indications for surgery, complications including iatrogenic retinal tears, time taken for surgery, day I intraocular pressure (IOP) and day 1 post operative ocular discomfort. All surgeries were carried out using Alcon Accurus vitrectomy system.post operative day 1 ocular discomfort was assessed using the ocular discomfort scale as shown below. Ocular discomfort scale Mild (1) :- patient not complaining of discomfort and eye is relatively white. Moderate (2) :- patient says mild irritation and eye shows circumcorneal congestion. Severe (3) :-patient complaining of irritation with gross congestion and chemosis. Very severe (4):- Results All of the above, with severe lid edema The proportion of male versus female patients was 63% versus 62.5% in 20G and 23G respectively.in the 20G group average age of patients was 59 years with a range of years and in the 23G group the average age was 56 years with a range of years. Visual acuity both before and after the procedure was comparable in both the groups as shown in the table below (Table A) Address for correspondence: Tony s superspeciality eye hospital, Aluva 293

2 Kerala Journal of Ophthalmology Vol. XXIII, No.3, Sept Table A Vit Hg =Vitreous hemorrhage, TRD= Tractional retinal detachment. Indications for surgery: The most common indication for surgery was vitreous hemorrhage followed by macular tractional retinal detachment (TRD). These two sub groups were subject to a more detailed analysis. Table 1 Lens status: - In the 20G group, 18 patients were phakic and 12 pseudophakic with PCIOL. 12 patients had immature cataract, out of which 3 patients underwent combined phaco vitrectomy.in the 23G group 15 patients were phakic and remaining pseudophakic with PCIOL.7 patients had immature cataract out of which 1 patient underwent combined phaco vitrectomy. Tamponade:- Silicone oil was used as tamponade when recquired.in the 20G group 8 patients with macular TRD and 4 out of 22 patients with vitreous hemorrhage needed tamponade.in the 23G group tamponade was used in 6 patients with macular TRD and 1 out of 18 patients with vitreous hemorrhage. Iatrogenic Retinal tear rate:-the number of non-entry site iatrogenic retinal tears occurring during vitrectomy was similar in both the groups 10 versus 8 (20Gvs23G). However, there were 2 entry site tears in the 20G group as compared to none in 23g group.at 3 months follow up 2 patients in the 20G group operated for macular TRD showed recurrent RD. Enlargement of superotemporal port was done in all patients who underwent 23G vitrectomy where tamponade was required to facilitate silicone oil injection (29%). This only required a single suture for closure. None of the other patients in this group required sutures. The 20G patients had all the three ports sutured. Day 1 IOP s and glaucoma:-the mean first Day IOP was 17.5 mm Hg and 25.75mm Hg in the 20G group for vitrectomy for vitreous hemorrhage and macular TRD respectively. In the 23G group the mean first day IOP was mm Hg and 14.33mm Hg for vitreous hemorrhage and macular TRD groups respectively. The difference in IOP S between 20G and 23G surgeries for either of these indications was statistically significant (p< 0.01, 23G group being much lower). The distribution of day I IOP S between the two groups is as shown below(table 2,3). Four patients in the 23G group had IOP< 10mm which was found to be normal at 2 weeks follow up. In the 20G group 4 patients required long term antiglaucoma medications. One patient in 23g group subsequently developed neovascular glaucoma. Operating times:-the mean operating times for vitrectomy for vitreous hemorrhage and macular TRD in 20G group was 74 minutes(mts) and 101 minutes(mts) and 23G group was 58.4 minutes(mts) and minutes(mts), the difference being statistically significant (P<0.01,23G group taking much less time).the mean operating times for each of these indications and statistical analysis is as illustrated below. (table2,3) Table 2 Vitreous hemorrhage patients without silicone oil 294

3 Asok Nataraj - 20G Vs 23G Vitrectomy Table 3 Macular TRD Table 4 Vitreous hemorrhage patients, viitrectomy with silicone oil T = time taken for surgery in minutes Ocular discomfort:-ocular discomfort was much higher in the 20G group than in the 23G group for either of the indications and the difference was statistically significant(p<0.01). The relationship between time taken for surgery and ocular discomfort, IOP and ocular discomfort is as shown in tables Table 5 Vitreous hemorrhage patients without silicone oil Table 6 Vitreous hemorrhage patients without silicone oil Table 7 Vitreous hemorrhage patients without silicone oil Table 8 Macular TRD 295

4 Kerala Journal of Ophthalmology Vol. XXIII, No.3, Sept Table 9 Macular TRD Table 10 Macular TRD T = time taken for surgery in minutes Discussion Sutureless self sealing vitrectomy was first described by Chen [6] in 1996.Complications of this procedure include retinal tears,wound leakage, and hypotony and often required suturing.fuji et al [2] developed the 25-gauge vitrectomy system and the 23-gauge system introduced by Eckardt [3] mirrors the 20-gauge systems in terms of instrument stiffness and functionality. This study compares 20G and 23G vitrectomies in a number of aspects including indications, postoperative intraocular pressure, time taken for surgery, ocular discomfort and intraoperative retinal tear rates. Similar studies have been done in the past, [8] but there are no such studies using Accurus vitrectomy system in the literature till date. Vitreous hemorrhage remains the most common indication for vitrectomy in diabetic patients in our series. Anatomical and visual results were similar in both the groups irrespective of the technique used. Silicone oil was used as tamponade as it was the surgeons [AN] preference in such cases.entry-site tears was uncommon in both the groups(none in the 23G group compared to two in the 20G group) which compares well with other studies [8,7]. Non-entry site tears which occurred either during induction of posterior vitreous detachment or membrane peeling were similar in 20G and 23G groups:10 and 8 respectively. Misra et al [8] reported seven and six, other site tears for 20-and 23G vitrectomies. No patient without a prior retinal detachment developed subsequent retinal detachment. Traditional 20G sclerotomies have 1.15mm width when compared to 0.72mm sclerotomies with 23G system [8]. This combined with tangential self-sealing tunnel incisions negates the need for sutures. In our series sutures where required only for those in whom superotemporal port was intentionally enlarged to facilitate easy oil injection. Only one patient[misra et al (8) in his series of 50 patients undergoing 23G vitrectomy needed suturing. Postoperative hypotony following 23G vitrectomy is widely reported [4,7]. Four patients in the 23G group had IOP< 10mm on the first post operative day, compared to no patients in the 20G group. All the 4 patients belonged to vitrectomy group without intraocular tamponade and the IOP reverted back to normal spontaneously over a period of 2 weeks without any complications..in this group of patients the 23G sclerotomy blade was found to be already used multiple times (>5) which would have lead to improper tunnel construction and subclinical incision site leaks causing hypotony. In our series silicone oil as tamponade prevented post operative hypotony. Sutureless sclerotomies may present a theoretical risk of endophthalmitis [8]. Meticulous aseptic technique is mandatory. We had no cases of endophthalmitis in our series. The mean day 1 IOP was significantly higher(p<0.01) in the 20G group when compared to the 23G group irrespective of whether tamponade was used or not. Mean intraocular pressure was also found to be higher in those cases where silicone oil was used as tamponade(25.75mmhg versus 17.5 mm hg for 20G and mm hg versus mm hg for 296

5 Asok Nataraj - 20G Vs 23G Vitrectomy 23G). A crucial observation in our study was that no patient in the 23G group had IOP > 30 mm hg when compared to 2 patients in the 20G group. These 2 patients were operated for macular TRD and had silicone oil filled as tamponade. The 23G system appears to reduce the risk of extremely high pressure as ports allow for small leaks if the IOP rises beyond a certain level without compromising the wound integrity [8]. Thus using 23G system can potentially reduce inconvenience to the patient by reducing hospital visits for frequent IOP monitoring. Sutureless surgery is less time consuming when compared to conventional 20G vitrectomy [4,5].Misra et al [8] in their study of 50 patients reported a statistically significant difference in time taken for surgery,23g vitrectomy taking much less time than 20G vitrectomy. Binder et al [9] in a randomized control trial of 60 patients reported no difference in time taken for surgery between 23G and 20G vitrectomy. In his study shorter time for wound closure was found to be neutralized by a longer vitrectomy time in the 23G group. In our series 23G vitrectomy took less time in comparison to 20G vitrectomy for similar indications,the difference being statistically significant(p<0.01). This trend was found to be uniform through all subgroups irrespective of whether tamponade was used or not.reduced operating time is beneficial for the patient as it can reduce patient discomfort and allow for more cases to be done on the same operating day. Post operative day 1 ocular discomfort assessed using the ocular discomfort scale showed significant reduction in ocular discomfort in the 23G group when compared to conventional vitrectomy [tables 5,8].Binder et al [9] has also reported a significant reduction in post operative conjunctival injection and pain in 23G group in comparison to 20G group in their series of 60 patients.sclerotomy and conjunctival sutures are known to cause irritation and pain. An interesting observation in our series was that even the 23G cases,where a single suture was applied after silicone oil injection, showed a significant reduction in post operative ocular discomfort when compared to 20G cases of the same group. This shows that there are factors other than sutures that contribute to post operative ocular discomfort and pain. A single suture when compared to three sutures in the 20G group could also be a contributing factor. Sub group analysis revealed that cases with higher post operative IOP and in those who had longer duration of surgery had more postoperative discomfort than those with less IOP and shorter operating times [Tables 7,9,10]. Tissue trauma and suture related a local inflammatory response which is significant in 20G vitrectomy can lead to more post operative inflammation and discomfort [8]. Conclusion The 20G and 23G vitrectomy are comparable with respect to anatomical and visual outcome in diabetic patients. The 23G system for pars plana vitrectomy appears to be far superior to 20G in certain aspects like less total operating time, less postoperative discomfort and less post operative intraocular pressure rise. Thus 23G vitrectomy offers additional advantages over the conventional 20G system in diabetic patients. References 1.Machemer R,Beuttner, Norton EW,Parel JM.Vitrectomy:a pars plana approach.trans Am Acad Ophthalmol Otolaryngol 1971;75: Fujii GY, de Juan Jr E, Humayun MS, Pieramici DJ, Chang T S, Awh C et al.a new 25-gauge instrument system for transconjunctival sutureless vitrectomy surgery. Ophthalmology 2002;109: Eckardt C. Transconjunctival sutureless 23-gauge vitrectomy. Retina 2005;25: Soni M, McHugh D.23-gauge transconjunctival sutureless vitrectomy: a way forward.eye News 2007;14: Lakhanpal RR,Humayun MS,de Juan Jr E, Chang TS et al. Outcomes of 140 consecutive cases of 25-gauge transconjunctival surgeryfor posterior segment disease. Ophthalmology 2005;112: Chen JC. Sutureless pars plana vitrectomy through self sealing sclerotomies.arch Ophthalmol 1996; 114: Fine HF, Iranmanesh R, Iturralde D, Spaide RF.Outcomes of 77 consecutive cases of 23-gauge transconjunctival vitrectomy surgery for posterior segment disease.ophthalmology 2007;114: A Misra; G Ho-Yen; R L Burton. 23-gauge Sutureless Vitrectomy and 20-gauge Vitrectomy: A Case Series Comparison. Eye.2009;23(5): Dr S Binder et al. 23-gauge versus 20-gauge system for pars plana vitrectomy: a prospective randomised clinical trial. Br J Ophthalmol 2008;92: