this was a prospective , randomized , pilot study conducted at l v prasad eye institute between may 2007 and december 2008 . the institutional review board approved the study , and all the study procedures adhered to the tenets of the declaration of helsinki . all the subjects were explained the benefits and risks of the procedure , the composition , and the source of the collagen implant before obtaining an informed consent . the study subjects included individuals  18 years of age with medically uncontrolled primary open angle glaucoma ( poag ) or primary angle closure glaucoma ( pacg ) with no previous intraocular surgery . poag was defined in the presence of an iop > 21 mmhg , open anterior chamber angle on gonioscopy , glaucomatous optic disc damage on clinical examination , and corresponding glaucomatous visual field defects . pacg was defined in the presence of an occludable angle on gonioscopy ( posterior trabecular meshwork not seen in at least 180 of the total circumference of the angle in primary position ) , glaucomatous optic disc damage , and corresponding glaucomatous visual field defects . the iop was measured using goldmann applanation tonometer , and gonioscopy was performed using a sussmann 's 4 mirror gonioscope under appropriate testing conditions . optic disc changes that were considered to be glaucomatous were focal or diffuse neuroretinal rim thinning , localized notching or nerve fiber layer defects . visual field defects were considered glaucomatous if at least 2 of the 3 anderson 's criteria ( 3 or more non - edged points in a cluster depressed to p < 5% and 1 of which is depressed to p < 1% , glaucoma hemifield test outside normal limits and pattern standard deviation depressed to p < 5% ) were fulfilled . age , gender , type of glaucoma , presence of systemic diseases ( diabetes mellitus and systemic hypertension in particular ) , presenting iop , highest recorded iop , number of anti - glaucoma medications and visual field parameters were noted . after enrollment , patients were randomized into 1 of the 2 groups ; trabeculectomy with ologen implant was group 1 ( ologen group ) , and trabeculectomy with mmc was group 2 ( mmc group ) . block size of 4 was determined , and 2 eyes of group 1 and 2 eyes of group 2 were randomly allocated into each block . all the surgeries were performed by 1 of the 4 experienced surgeons . under peribulbar anesthesia ( bupivacaine 0.5% + xylocaine 2% ) , a superior rectus bridle suture was applied with 40 silk and fornix - based conjunctival flap at the superior limbus was dissected . a 4  4 mm triangular , partial thickness scleral flap was reflected , a trabeculectomy of 2  2 mm was performed using a vanna 's scissors , and a peripheral iridectomy was completed . the scleral flap was closed with single 10 - 0 nylon suture at the apex , and conjunctiva was secured with two 8 - 0 vicryl wing sutures . the procedure was the same for both the groups , except that the eyes randomized to ologen group had scleral flap closure with a single apical loose suture ( as per the manufacturers recommendation ) , and a 6 mm  2 mm ologen implant was placed on top of the sclera and the conjunctiva was then closed [ fig the mmc group had 4 mmc ( 0.4 mg / ml ) soaked sponges placed sub - conjunctivally over a wide area for 2 minutes ( after making the superficial scleral flap ) . the sponges were removed , and the area was copiously irrigated with 20 cc of ringer lactate . postoperatively , all patients were treated with prednisolone acetate 1% eye drops in tapering doses over 5 weeks , antibiotic eye drops 4 times - a - day for a week and cyclopentolate 1% eye drops 3 times - a - day for 2 to 3 weeks . biodegradable collagen matrix implant positioned directly above the scleral flap . note the laser peripheral iridotomy at 110 clock and a surgical pi at 120 clock post - operative visits were scheduled at day 1 , day 7 , 1 month , 3 months , 6 months , and 6-monthly thereafter . at each visit , bcva , iop , primary outcome measure was success , which was defined as complete success if an iop was > 5 and  21 mm hg without any glaucoma medications or re - surgery . qualified success was defined as iop  21 mm hg with or without anti - glaucoma medications . secondary outcome measures were number of eyes achieving iop  18 mm hg and  15 mm hg in both the groups without anti - glaucoma medications and complications in the 2 groups . failure was defined as iop  22 mm hg despite medications or  5 mm hg ( on 2 or more examinations ) with hypotony maculopathy or if an additional procedure like needling or repeat trabeculectomy was required to control the iop or if there was loss of light perception . both the study groups were compared using student 's t test for continuous variables and fisher 's exact test for discrete variables . under peribulbar anesthesia ( bupivacaine 0.5% + xylocaine 2% ) , a superior rectus bridle suture was applied with 40 silk and fornix - based conjunctival flap at the superior limbus was dissected . a 4  4 mm triangular , partial thickness scleral flap was reflected , a trabeculectomy of 2  2 mm was performed using a vanna 's scissors , and a peripheral iridectomy was completed . the scleral flap was closed with single 10 - 0 nylon suture at the apex , and conjunctiva was secured with two 8 - 0 vicryl wing sutures . the procedure was the same for both the groups , except that the eyes randomized to ologen group had scleral flap closure with a single apical loose suture ( as per the manufacturers recommendation ) , and a 6 mm  2 mm ologen implant was placed on top of the sclera and the conjunctiva was then closed [ fig . 1 ] . the mmc group had 4 mmc ( 0.4 mg / ml ) soaked sponges placed sub - conjunctivally over a wide area for 2 minutes ( after making the superficial scleral flap ) . the sponges were removed , and the area was copiously irrigated with 20 cc of ringer lactate . postoperatively , all patients were treated with prednisolone acetate 1% eye drops in tapering doses over 5 weeks , antibiotic eye drops 4 times - a - day for a week and cyclopentolate 1% eye drops 3 times - a - day for 2 to 3 weeks . biodegradable collagen matrix implant positioned directly above the scleral flap . note the laser peripheral iridotomy at 110 clock and a surgical pi at 120 clock post - operative visits were scheduled at day 1 , day 7 , 1 month , 3 months , 6 months , and 6-monthly thereafter . at each visit , bcva , iop , primary outcome measure was success , which was defined as complete success if an iop was > 5 and  21 mm hg without any glaucoma medications or re - surgery . qualified success was defined as iop  21 mm hg with or without anti - glaucoma medications . secondary outcome measures were number of eyes achieving iop  18 mm hg and  15 mm hg in both the groups without anti - glaucoma medications and complications in the 2 groups . failure was defined as iop  22 mm hg despite medications or  5 mm hg ( on 2 or more examinations ) with hypotony maculopathy or if an additional procedure like needling or repeat trabeculectomy was required to control the iop or if there was loss of light perception . both the study groups were compared using student 's t test for continuous variables and fisher 's exact test for discrete variables . we enrolled 39 eyes of 33 subjects into 2 groups : 19 eyes to trabeculectomy with ologen group and 20 eyes to mmc group . of these , 7 eyes of 5 patients , who had less than 6 months of follow - up , were excluded from the outcome analysis , but were included in the analysis of complications . for the outcome analysis , there were 16 eyes of 14 patients in trabeculectomy with ologen group and 16 eyes of 14 patients in trabeculectomy with mmc group . all the pre - operative parameters were similar between the 2 groups , except severity of disease at presentation , which was significantly worse in ologen group , ( p = 0.05 , mean md in ologen group was 22.87  9.04 as compared to 16.43  9.75 in mmc group ) . comparison of demographic and clinical features between the 2 groups compared to the pre - operative iop , the mean iop after surgery was significantly less at all time points in both the groups ( p < 0.05 ) . the post - operative iop was similar in the 2 groups at all post - operative visits , except at 1 month and at 6 months where the iop in the mmc group was significantly lower ( p = 0.01 ) than that in ologen group . 2 shows 2 weeks post - operative bleb appearance following trabeculectomy with mmc , and fig . the iop reduction ( both absolute and percentage ) as well as the number of anti - glaucoma medications post - surgery was similar between the 2 groups . post - operative features in the ologen and mmc groups 2-week postoperative slitlamp photograph following trabeculectomy with mitomycin c , showing a diffuse well formed bleb 2-week post - operative slitlamp photograph following trabeculectomy with collagen implant , showing an elevated bleb and sub - conjunctival implant probability of success was looked at using kaplan - meier graphs [ fig . 4 ] . considering complete success criteria , survival probability in ologen group was 100% at 6 months , 92.9% ( 95% ci : 59.1 - 99.0 ) at 12 months , and 82.5% ( 45.1 - 95.1 ) at 24 months . the corresponding survival probability in mmc group was 93.8% ( 63.2 - 99.1 ) at 6 months and 12 months and 56.3% ( 13.1 - 85.0 ) at 24 months . considering qualified success criteria , survival probability in ologen group was 100% at 6 months , 92.9% ( 59.1 - 99.0 ) at 12 months , and 92.9% ( 59.1 - 99.0 ) at 24 months . the corresponding survival probability in mmc group was 100.0% at 6 and 12 months and 83.3% ( 27.3 - 97.5 ) at 24 months . the difference in the success rates ( complete as well as qualified ) was not statistically significantly different ( p > 0.5 ) between the groups . number of eyes achieving an iop of less than or equal to 18 mm hg at 6 months follow - up were similar between the groups ( 15/16 in ologen vs. 15/16 in trab mmc group , p = 1.0 , chi - square test ) . number of eyes achieving an iop of less than or equal to 15 mm hg at 6 months follow - up were also similar between the groups ( 10/16 in ologen vs. 14/16 in trab mmc group , p = 0.1 ) . associations between failure and age , sex , highest iop , severity of visual field damage ( md ) , number of pre - operative anti - glaucoma medications , presence of systemic hypertension and diabetes mellitus , type of glaucoma , and type of surgery ( trabeculectomy with ologen or mmc ) were investigated using cox proportional hazard regression models . none of the associations were statistically significant ( p > 0.05 for all associations ) . kaplan - meier survival analysis showing the survival probability of the 2 groups considering complete ( a ) and qualified ( b ) success criteria separately . the number of eyes at risk in both the groups at each time point is given below the graph there were no intra - operative complications in any of the eyes in both the groups . the early post - operative complications in the 2 groups are shown in table 3 . the incidences of early post - operative complications were similar in the 2 groups , except hyphema , which was significantly more in ologen group . the number of eyes , which experienced one or more of the complications , was 12/19 in the ologen group and 7/20 in the mmc group ( p = 0.08 ) . the number needed to experience a complication ( number needed to harm , nnh ) was 3.5 ( 95% confidence interval : 1.5 , infinity ) , which means that for every 3.5 eyes treated with ologen , 1 eye experienced a complication beyond that occurred when mmc was used . however , most of the complications were minor and subsided within 3 - 4 weeks after surgery ( with conservative management ) in both the groups , except hypotony in 1 eye in mmc group , which resolved by 8 weeks . none of the eyes in either group required any intervention for the management of early post - operative complication , and none of the eyes lost any lines of visual acuity . early post - operative complications between the 2 groups 8-week postoperative slit lamp photograph of an eye with partially absorbed sub - conjunctival collagen implant the higher success rate of trabeculectomy with mmc as compared to simple trabeculectomy has made this procedure a preferred surgical choice for primary glaucoma . however , mmc application is associated with higher long - term bleb - related complications . aimed to improve the long - term surgical success of trabeculectomy but with less attendant complications of mmc , ologen , a bioengineered porcine collagen , has been developed . in this prospective , pilot study , we found the success rate of trabeculectomy at 6 months was similar in eyes with adjunctive mmc use compared to ologen ( 100% in the ologen group and 93.8% in the mmc group , p > 0.5 ) . although the iop at 6 months was significantly less in mmc group ( p = 0.01 ) , the same trend was not seen during subsequent follow - up visits at 12 and 24 months . the complete and qualified success probabilities were similar between the 2 groups over all these time points . hence , the results have to be interpreted with caution . further studies with larger sample size and longer duration of follow - up would be required to come to a meaningful conclusion . collagen implants have been used as an adjunct during trabeculectomy to modulate post - operative wound healing in various animal studies with an improved success . they have been used along with deep sclerectomy with better long term success , and have been used as a spacer following capsule excision after failed gdd surgery . papaconstantinou et al . , in their pilot study , have compared trabeculectomy with and without ologen implant . with a 6 month follow - up , and a sample size of 20 eyes in each group , they reported similar success rate of 90% in both the groups , similar to what we have shown in our study . rosentreter et al . , compared 10 eyes each in trabeculectomy with mmc and ologen groups and reported significantly higher complete success rate ( iop  18 mm hg and at least 20% reduction of pre - operative iop ) at the end of 12 months in trabeculectomy with mmc group ( 100% with mmc vs. 50% with ologen , p = 0.01 ) . boey et al . , in their prospective case - control study comparing phacotrabeculectomy with mmc and ologen implants , have reported significantly greater ( p < 0.001 ) iop control in mmc group at 3 months follow - up . we found the post - operative complications to be similar in the 2 groups , except for transient hyphema , which was more in ologen group . the possible explanation is a loose apical scleral suture , recommended with ologen implant , would have allowed the ooze from the cut - ends of the sclera to enter into the ac . we did not notice any serious post - operative complications , and none of the eyes needed any 5 fu injection , needling , or re - surgery in our study . were bleb leaks ( 2 eyes in ologen group , which resolved on re - suturing ) , encapsulated blebs ( 2 eyes in ologen group and 5 eyes in trabeculectomy group needing 2 to 7 5fu injections ) , and endophthalmitis ( 1 eye in the ologen group ) . in the study by rosentreter et al . , 2 cases in ologen group developed tenons cyst that required needling and 1 case in mmc group needed re - suturing for bleb leak . there is a theoretical risk of increased inflammation in eyes with ologen implant as the implant is non - human ( porcine ) in origin . reports in reconstructive surgery have shown an increased inflammation with signs of foreign body reaction related to the porcine cross - linked collagen implants when used in the repair of incisional hernia . there are no such reports when used in ocular procedures , and we did not notice any increase in inflammation in our study , either in the form of increased anterior chamber reaction or hyperemic blebs . the number of eyes lost to follow - up at 2 years was close to 50% , and this was a limitation of our study . since our sample size was small , the statistical differences should be interpreted with caution . a study with higher sample size and a longer follow - up would be required to conclusively evaluate the equivalence or superiority of the collagen implant over mmc augmentation during trabeculectomy . in summary , from our pilot study , we found that success of trabeculectomy in eyes with mmc was similar to the eyes with ologen implant .
purpose : to compare the safety and efficacy of trabeculectomy with ologen implant vs. trabeculectomy with mitomycin c ( mmc).materials and methods : in a prospective , randomized , pilot study , 39 eyes of 33 subjects with medically uncontrolled primary glaucoma , aged 18 years or above underwent trabeculectomy either with mmc ( 20 eyes ) or with ologen implant ( 19 eyes ) . 
 the primary outcome measure was cumulative success probability , defined as complete if the intraocular pressure ( iop ) was > 5 and  21 mm hg without anti - glaucoma medications or additional surgery and qualified if an iop was > 5 and  21 mm hg with or without anti - glaucoma medications.results:mean (  standard deviation ) follow - up in ologen group was 19.1  8.1 months , and in mmc group was 18.0  8.4 months . 
 mean iop reduction at 6 months was significantly lower ( p = 0.01 ) in the mmc group ( 11.9  2.9 mm hg ) as compared to ologen group ( 14.6  2.7 mm hg ) . 
 however , at 12 months ( p = 0.81 ) and 24 months ( p = 0.32 ) , the mean iop was similar between the 2 groups . 
 complete success probability at the end of 6 months in ologen group was 100% ( 95% confidence interval : 59.1 - 99.0 ) was similar ( p = 0.53 ) to that in mmc group ( 93.8% , 95% ci : 63.2 - 99.1 ) . 
 the incidences of early post - operative complications were similar in the 2 groups , except hyphema , which was significantly more in ologen group ( p = 0.02).conclusion : in this pilot study , the success of trabeculectomy and complications were similar in both ologen and mmc groups at the end of 6 months .