to report the short - term efficacy and safety of the transfer of an ahmed glaucoma valve ( agv ) tube from the vitreous into the anterior chamber , in a patient with neovascular glaucoma who had undergone pars plana agv implantation and ultimately needed a silicone oil tamponade . a 41-year - old male with proliferative diabetic retinopathy in both eyes was referred to us for treatment in december 2009 . although the patient previously underwent several surgeries , he ultimately lost vision in his right eye . his left eye suffered from neovascular glaucoma after undergoing a pars plana vitrectomy for tractional retinal detachment . after several vitreous and glaucoma surgeries , the patient underwent implantation of a pars plana agv. postoperatively , although his intraocular pressure was stabilized at approximately 10 mmhg , he had repeated vitreous hemorrhage and hyphema without improvement . he ultimately underwent ppv with a silicone oil tamponade and at the same time , the agv tube was pulled out from the vitreous and inserted into the anterior chamber in order to avoid complications caused by the silicone oil . at 19 months postoperative , the patient s intraocular pressure had stabilized at 10 mmhg with no recurrence of vitreous hemorrhage and hyphema . the findings show that insertion of a pars plana agv tube into the anterior chamber in a patient undergoing a silicone oil tamponade is both effective and safe in the short - term . although tube - based surgeries for the treatment of glaucoma are prevalent in europe and america , they have only recently been approved for use in japan . the results of a questionnaire survey conducted by the american academy of ophthalmology revealed that the number of surgeons opting to perform trabeculectomy is apt to reduce , while the number of surgeons opting to perform tube implantation is apt to increase . the recent  tube versus trabeculectomy study ,  a comparative , randomized , multicenter study of tube implantation into the anterior chamber versus trabeculectomy conducted in the united states , showed that patients who underwent tube implantation obtained better intraocular pressure ( iop ) control and suffered overwhelmingly fewer complications . 1 thus , it is expected that the number of surgeons opting to perform the tube implantation procedure will greatly increase in the future . pars plana implantation , also referred to as the  fourth generation of implant tube  based surgery ,  was developed to prevent complications that can occur with implantation into the anterior chamber , such as a shallow anterior chamber , corneal decompensation , and adhesion of the iris , and is done for cases of secondary glaucoma , such as neovascular glaucoma ( nvg ) . in a pseudophakic eye treated with a silicone oil tamponade , insertion of the glaucoma valve tube into the anterior chamber seems to result in a better clinical course , due to the fact that the effect of silicone oil on the tube can probably be prevented . therefore , it would be advantageous if transfer of the tube from the vitreous into the anterior chamber is possible , especially in cases of pseudophakic eye . the purpose of this present case report was to report a case involving the transfer of an ahmed glaucoma valve ( agv ) ( new world medical , inc , rancho cucamonga , ca , usa ) from the vitreous cavity into the anterior chamber , in a patient with nvg who had undergone pars plana agv implantation and ultimately needed a silicone oil tamponade . this case report involved a 41-year - old male patient who first became aware of visual loss in both eyes in the summer in 2009 . he later visited an ophthalmologist in december 2009 , and was diagnosed with proliferative diabetic retinopathy ( pdr ) in both eyes . the patient was subsequently referred to us in the same month of that year , and he also visited a general physician and was diagnosed with diabetes mellitus on the same day ( blood sugar : 501 mg / dl , glycated hemoglobin [ hba1c ] : 14.0% ) . consultation with the patient revealed that his father had undergone dialysis treatment for kidney disease , yet the patient s own past medical history had nothing in particular to reveal . at the initial examination , the patient s visual acuity was 30 cm / hm in his right eye and 0.5 in his left eye . fundus examination of the patient revealed pdr with fibrovascular membrane , preretinal hemorrhage , and tractional retinal detachment in his right eye ; and pdr with fibrovascular membrane in his left eye ( figure 1 ) . in the right eye of the patient , vision was lost despite twice undergoing pars plana vitrectomy ( ppv ) , in february and july , 2010 . in october 2010 , we performed panretinal photocoagulation on his left eye ; however , the tractional retinal detachment in that eye progressed . examination of the patient in october 2010 revealed that visual acuity was 0.09 and iop was 12 mmhg in his left eye . in addition , iris neovascularization , ectropion uvea , and tractional retinal detachment were found , and peripheral anterior synechia ( pas ) index was approximately 60% in his left eye ( figure 2 ) . later in december 2010 , the patient underwent ppv combined with additional photocoagulation and cataract surgery . however , 1 month after surgery , iop rose to 50 mmhg and the pas index was 100% , in his left eye . the vitreous hemorrhage was removed and fibrovascular membrane of the peripheral retina was resected , followed by additional photocoagulation . at 1 month postoperative , the iop was again elevated for the filtering bleb dysfunction , due to repeated vitreous hemorrhage . the patient then underwent pars plana implantation of an agv ( model agv - pc7 ) in january 2011 . postoperatively , although his iop was stabilized at approximately 10 mmhg , the patient had repeated vitreous hemorrhage without improvement . he subsequently underwent ppv + silicone oil tamponade + insertion of a pars plana agv tube into the anterior chamber in may 2011 . during that operation , the tube was pulled out from the vitreous cavity and inserted into the anterior chamber , in order to avoid complications caused by the silicone oil ( figure 3 , supplementary material ) . four months after the last operation , the patient s visual acuity was 0.01 and iop stabilized at 10 mmhg . he suffered no recurrence of vitreous hemorrhage and no complications , such as disorder of eye movement ( figure 4 ) . the patient suffered from cerebral hemorrhage in october 2011 and lost vision in his left eye . in december 2012 , the patient s iop was still stabilized at 10 mmhg and there was no silicone oil migration into the anterior chamber , although fundus examination revealed tractional retinal detachment in the superior part of the fundus . it has been reported that 3%15% of diabetic retinopathy cases that needed vitrectomy were complicated by nvg.2 the findings of other studies have shown that 10%15% of pdr cases that underwent vitrectomy had repeated vitreous hemorrhage.35 moreover , 7.5% of cases that underwent vitrectomy for pdr reportedly required a silicone oil tamponade . 6 therefore , it can be considered that cases of severe diabetic retinopathy complicated by nvg have a high possibility of needing a silicone oil tamponade . reported results of pars plana tube implantation for the treatment of nvg showed a good success rate ( 72%94.4% ) at 6 months to 14.2 months , and if tube - based surgeries are performed widely in the future , many cases will require the insertion of a tube for an eye that has undergone silicone oil tamponade after vitrectomy , or require a silicone oil tamponade for an eye that has already undergone tube implantation.7 the agv and the baerveldt pars plana glaucoma implant ( model bg 102 - 350 ; abbot laboratories inc , abbott park , il , usa ) are the two main types of valves that are currently used . the agv model pc7 joins a pars plana clip to the usual agv model fp7 tube for the anterior chamber , and this pars plana clip is movable ( for positioning ) ; on the other hand , the baerveldt pars plana glaucoma implant uses a hoffman elbow at the tip of the tube for insertion into the pars plana and is fixed . thus , the agv tube can be transferred from the vitreous cavity into the anterior chamber . when tubes are implanted in eyes that have undergone a silicone oil tamponade , there is a high possibility of deterioration of the intraocular inflammation and subsequent blockage of the tube caused by the silicone oil . therefore , having undergone a silicone oil tamponade is a risk factor for implantation.8 our method of implanting a tube in the superior temporal location is used to avoid silicone oil leakage and blockage of the tube by silicone oil when we implant a tube for an eye that has undergone a silicone oil tamponade . several studies have reported that a massive amount of silicone oil moved into the subconjunctival space and orbit of the eyes through the tubes when implanted tubes were exposed to silicone oil , such as in cases of aphakic eyes or eyes with pars plana  implanted tubes.911 thus , we considered that it would be possible to put an implant tube in the superotemporal location in a pseudophakic eye , such as in the case presented in this study , because silicone oil only slightly migrates into the anterior chamber . in fact , the iop in this patient was stabilized , and there have been no complications to date . in conclusion , the findings of this case show that insertion of a pars plana agv tube into the anterior chamber in a patient undergoing silicone oil tamponade is both effective and safe in the short term . however , further investigation is needed to elucidate the long - term efficacy and safety of this treatment . the tube of the pars plana agv was pulled out from the vitreous cavity and inserted into the anterior chamber , before silicone oil tamponade .
purposeto report the short - term efficacy and safety of the transfer of an ahmed glaucoma valve ( agv ) tube from the vitreous into the anterior chamber , in a patient with neovascular glaucoma who had undergone pars plana agv implantation and ultimately needed a silicone oil tamponade.casea 41-year - old male with proliferative diabetic retinopathy in both eyes was referred to us for treatment in december 2009 . 
 although the patient previously underwent several surgeries , he ultimately lost vision in his right eye . 
 his left eye suffered from neovascular glaucoma after undergoing a pars plana vitrectomy for tractional retinal detachment . 
 after several vitreous and glaucoma surgeries , the patient underwent implantation of a pars plana agv. postoperatively , although his intraocular pressure was stabilized at approximately 10 mmhg , he had repeated vitreous hemorrhage and hyphema without improvement . 
 he ultimately underwent ppv with a silicone oil tamponade and at the same time , the agv tube was pulled out from the vitreous and inserted into the anterior chamber in order to avoid complications caused by the silicone oil.resultsat 19 months postoperative , the patient s intraocular pressure had stabilized at 10 mmhg with no recurrence of vitreous hemorrhage and hyphema . 
 eventually , he lost vision in his left eye because of cerebral hemorrhage.conclusionthe findings show that insertion of a pars plana agv tube into the anterior chamber in a patient undergoing a silicone oil tamponade is both effective and safe in the short - term .