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thus , the purpose of this study was to compare the effectiveness of stta injection to that of ppv in eyes with dme .
the medical records of 52 eyes of 50 patients with dme who were examined in chiba university hospital between january 1 , 2010 and december 31 , 2010 were reviewed .
twenty - six eyes of 26 patients had 20 mg of triamcinolone acetonide ( ta ) injected into the sub - tenon space alone .
the outcomes of these 26 eyes that underwent stta were compared to 26 nave eyes of 24 patients who underwent 20-gauge or 23-gauge vitrectomy combined with cataract surgery between january 1 , 2009 and december 31 , 2010 .
any remaining vitreous and posterior vitreous membrane was meticulously removed by using ta to visualize the vitreous .
in addition , the peeling of the internal limiting membrane was performed in accordance with the operator s decision .
the specific indication of vitrectomy for dme was not determined in our hospital but the patients without posterior vitreous detachment were usually recommended .
although the specific indication of stta for dme was not determined , if the patients did not agree to vitrectomy , stta was considered .
however , vitrectomy and stta were usually recommended for the patients with slightly thicker fovea than the patients treated with micropulse diode laser photocoagulation in our previous study.5 after a complete explanation of the procedures to be performed , a signed informed consent was obtained from all patients .
all of the procedures conformed to the tenets of the world medical association declaration of helsinki .
approval for this study was obtained from the institutional review board of chiba university hospital , japan . the central macular thickness ( cmt )
was measured by spectral domain - optical coherence tomography ( sd - oct ) before and 1 , 3 , and 6 months after the procedures . the best - corrected visual acuity ( bcva )
the significance of differences was determined by student s t - tests , paired t - tests , chi - square tests , and repeated measured analysis of variance ( anova ) .
no significant differences were detected in age , sex , glycated hemoglobin ( hba1c ) , numbers of pseudophakic eyes , preoperative bcva , and preoperative oct between the ppv and stta groups . in the ppv group , however , 21 eyes underwent pan retinal photocoagulation ( prp ) which was significantly different from the 12 eyes that underwent prp in the stta group .
dr stages of the remaining eyes in both groups were of non - proliferative dr .
the significance of differences in age , hba1c , bcva , and cmt were determined by student s t - tests .
the preoperative bcva was 0.650.4 logarithm of the minimum angle of resolution ( logmar ) units in the stta group and 0.770.3 logmar units in the ppv group ( p=0.237 ; student s t - test ; figures 1 and 2 ) .
at 1 , 3 , and 6 months , the bcvas in logmar units were 0.600.4 , 0.590.5 , and 0.640.5 respectively , in the stta group and 0.680.4 , 0.590.4 , and 0.590.4 respectively in the ppv group ( figures 1 and 2 ) .
the differences in the bcva between the two groups were not significant before and at any time after treatment ( p=0.441 , p=0.960 , p=0.717 ; student s t - tests and p=0.5477 by repeated measured anova ) . in the stta group
, there were no significant differences between the pre - treatment bcva and that at any time after the stta ( p=0.226 , p=0.340 , p=0.775 ; paired t - tests ) . in the ppv group
, there was no significant difference between the pre - treatment bcva and that at 1 month after ppv , but there were significant differences between the pre - treatment bcva and that at 3 and 6 months after ppv ( p=0.389 , p=0.0066 , p=0.0169 respectively ; paired t - tests ) .
the preoperative cmt was 569.2167 m in the stta group and 534.4157 m in the ppv group ( figure 3 ) .
at 1 , 3 , and 6 months , the cmt was 356.1116 m , 326.7111.7 m , and 377.4137.6 m , respectively in the stta group , and 386.8175 m , 354.2101.7 m and 354.2156.4 m , respectively in the ppv group ( figure 3 ) .
the differences in the cmt between the two groups were not significant before and at any time after the ppv ( p=0.444 , p=0.460 , p=0.469 , p=0.273 respectively by student s t - tests and p=0.2053 by repeated measured anova ) . in both the stta and ppv groups ,
there were significant differences between the pre - treatment cmt and that at 1 , 3 , and 6 months after treatment ( stta ; p<0.0001 , p<0.0001 , p=0.0001 respectively by paired t - tests , ppv ; p=0.0013 , p<0.0001 , p<0.0001 respectively by paired t - tests ) .
three eyes in the stta group had a temporary increase in the intraocular pressure ( iop ) , and topical anti - glaucoma drugs controlled the iop during this period .
one eye in the ppv group had a temporary increase in iop , another eye developed wound infection but not endophthalmitis .
doi et al reported that ivta in eyes with dme significantly reduced the cmt , and the cmt was not significantly different from that in the ppv group at 3 months after the treatment.10 the results of their study are in accordance with our results .
however , the dme recurred 6 months after ivta in their study while it remained resolved after ppv.10 in this study , three eyes were retreated with stta 36 months after the first treatment .
thus , repeated treatment of ivta or stta may be considered 36 months after steroid - based treatment for refractory dme .
qi et al reported that within 3 months , ivta is more effective than stta in improving va and reducing cmt in patients with refractory dme .
however , the benefits of either regimen were no longer evident at 6 months.11 taken together , our results indicate that although repeated injections may be required , the effect of stta is not inferior to that of ivta or ppv in the short term .
hoerauf et al studied 50 patients who had undergone ppv for dme and reported that iatrogenic tears developed intraoperatively in ten patients , cataracts developed within 6 months in 42/44 ( 95.45% ) phakic eyes , a dense postoperative vitreous hemorrhage requiring a second vitrectomy with silicone oil tamponade developed in one patient , and a retinal detachment developed in three eyes which required a second vitrectomy.12 because a cataract is highly complicated after ppv , we routinely combined cataract surgery with ppv for dme patients with phakic eyes . in the ppv group , 21 eyes had mild to moderate cataract and underwent cataract removal simultaneously during ppv .
thus , the results of the comparison of bcva between stta and ppv groups should be interpreted with caution . on the other hand , no significant progression of cataract stages
thus , the cataract formation may not be related to no significant improvement of visual acuity at 3 months or 6 months after stta injection and the reduction of macular thickness seemed not to be paralleled to the improvement of bcva in the stta group .
further outcomes including retinal sensitivity may be required to assess visual function before and after dme treatment .
vegf is one of the main factors involved in the development and the progression of dme.13 vegf is upregulated in retinal cells because of inflammation , ischemia , and hyperglycemia in diabetic patients , and the upregulation causes an increase in vascular permeability in the retina.11,14 in addition , there is increasing evidence that inflammation induced by diabetic stress is involved in the pathogenesis of increased vascular permeability that may cause dme.15 in addition , an earlier study showed that steroids can upregulate the tight junction proteins , zo-1 , which occlude the endothelial cells under diabetic conditions and tighten the retinal blood barrier.16 thus , ivta3,17 and stta4,18 can be used to treat dme by suppressing inflammation and reducing vegf expression in the retina.1921 the major complications of ivta are cataracts , iop elevation and endophthalmitis .
hirano et al reported that ivta led to higher elevations of iop than stta.22 according to the japanese survey of ta for ocular diseases , endophthalmitis occurred in seven ( 0.12% ) of 5,665 eyes administered with ivta , and seven ( 0.026% ) of 26,819 eyes with ppv that used ta as an adjunct to separate posterior hyaloids from the retina.23 after stta , however , the incidence of endophthalmitis was only 0.008% ( one eye ) of 12,344 eyes.23 a recent study indicates that the incident risk of endophthalmitis after intravitreal injection of anti - vegf drugs was 0.025% in the united kingdom.24 usually , however , repeated injection of anti - vegf drugs is required for the treatment of dme.69 thus , the risk of post - intravitreal anti - vegf endophthalmitis is significantly increased .
in fact , the pooled analysis of the resolve and restore studies showed that an incidence rate of endophthalmitis was 1.4% at 1 year.6 in the study of the diabetic retinopathy clinical research network , endophthalmitis occurred in one eye ( 0.5% ) of 187 participants in the ranibizumab prompt laser treatment group and two eyes ( 1% ) of 188 participants in the ranibizumab plus deferred laser treatment groups.7 taken together , stta has a significantly lower risk of endophthalmitis than ivta and intravitreal injection of anti - vegf drugs .
our study has a limitation because it was a retrospective study and the number of patients is small . in addition , the follow - up period of this study is not long .
thus , further randomized control studies with longer follow - up periods are needed to confirm the effectiveness of stta compared to other treatments including ppv .
stta and ppv significantly reduced cmt in patients with dme , and the differences in the bcva and cmt between the two groups were not significant .
although the results of recent studies recommend combined therapies for the treatment of dme , stta may be an alternative treatment for dme , especially when patients do not agree to undergo surgical treatments .
purposeto compare the effect of posterior sub - tenon s capsule triamcinolone acetonide ( stta ) injection to that of pars plana vitrectomy ( ppv ) for diabetic macular edema ( dme).patients and methodsthe medical records of 50 patients ( 52 eyes ) with dme were reviewed . 
 twenty - six eyes underwent stta ( 20 mg ) and the other 26 eyes underwent vitrectomy combined with cataract surgery . the central macular thickness ( cmt ) , measured by optical coherence tomography , and best - corrected visual acuity ( bcva ) were determined before and 1 , 3 , and 6 months after treatment.resultsthe differences in the bcva and the cmt between the stta group and the ppv group were not significant before or at any time after the treatment . in both the stta and ppv groups , there were significant differences between the pre - treatment cmt and bcva at any time after treatment.conclusionwe recommend stta injection for the treatment of dme .