Success was defined with some criteria: (1) complete success when IOP of 21mmHg or less with out antiglaucoma mediations & (2) qualified success when IOP of 21 mmHg with the use of antiglaucoma medication. Hyptony was defined as an IOP <6mmHg. Flat anterior chamber can be defined as peripheral iridocorneal touch with central at least I corneal thickness depth.

Surgical Technique
Surgeries were done by single surgeon (SMN). After peribulbar anesthesia & proper drapping, fornix based incision was given around 12’O Clock. Triangula, superficial scleral flap (4x4mm) was produced facing apex towards 12 O’ clock position. 2x1 mm deep sclerectomy & a peripheral iridectomy was performed thereafter. Scleral flap was closed with a single suture (10/O nylon). Ologen was placed over the apex of the triangular flap beneath the conjunctiva after making the operation area dry. Conjunctiva was closed like a wing with 2 sutures by 10/O nylon. Post operatively all patients were treated with Atropin 1%, 3 times daily for 2 weeks, Moxifloxacin 4 times daily for 1 week & Prednisoln acetate eye drop 6 times daily for 3 weeks then tapered gradually.

Statistical analysis was done with windows SPSS. Pre operative & demographic data & IOP comparison were analyzed with students T test. Surgical failure success & complications were analyzed with the χ² test. With long rank test, Kaplan-Meier survival analysis for surgical success were calculated.

P values < 0.05 were taken as statistically significant.

60 eyes were enrolled in the study & randomly divided into two groups of Trabeculectomy wth or without ologen implant.

Table 1 describes demographic & diagnostic data before operation. There were no significant differences between the groups in terms of age, gender, eye laterality, diagnosis, pre operative IOP and number of topical & systemic anti glaucoma medications. 8 patients from the study group and 9 patients from control group needed systemic carbonic anhydrase inhibitors.

Mean IOPs for both groups are listed in Table-2 No difference is observed in IOP measurement 6 month after operation between two groups. Post operative IOP levels in both groups is significantly lower than preoperative one. (P<0.05) None of the eyes in the study group developed high IOP>21mmHg post operatively where 2 eyes of control group developed so at the six month visit.

Post operatively in control group mean number of antiglaucoma medications was dropped from (3.5 ± 0.7) to (0.4 ± 0.1) (P < 0.001). Where in the study group from (3.5 ± 0.5) to (0.2 ± 0.5) (P < 0.001). There is no significant difference in their reduction between & groups.

Figure 3 shows Kaplan-Meier survival analysis for both groups using complete success definition. No statistical differences observed between survival curves.

At the 6 month 27 (90%) eyes in both groups showed complete success. All eyes in the study grops 100% & 29 (97%) of 30 eyes in the control group showed qualified success. (P > 0.66)

No statistical significance difference was observed in post operative patients in terms of post operative complication (Table-3).

In the first post operative day 2 eyes in the control group & 2 eyes in the study group developed hypotony those were improved within one month.

Two eyes in the control group & two eyes in the study group developed flat anterior chamber with out positive Seidel test those were resolved spontaneously after giving patching for two days. 1 Patient from the control group & 1 patient from the study group developed encapsulated bleb. No patient developed cataract in the study group where as 1 patient developed cataract in the control group at the end of the 5th month. No patient develop endophthalmitis in either groups.

Penitrating glaucoma surgical procedures allow a powerful reduction of IOP. The pressure reducing effect of penetrating surgery is probably still higher than that of non peneterating strategies, particularly in the long run. [5, 6, 7].

Trabeculectomy is the most standard procedure in penetrating anti glaucoma surgery was introduced by Cairns in 1968 [8].

The method was developed further over subsequent decades to address various problems. In 1990, MMC was applied as an anti metabolite during trabeculectomy [9]. Various studies demonstrated significant enhancement of success rates and post operative IOP through intra operative use of MMC [10] this is associated with an increase in adverse effect such as cataract formation, avascular blebs, thinning of the conjunctiva, subsequent blebitis and end ophthalmoties. [11-13]

The current focus is on the development of less toxic agents & implants to inhibit cicatrisation with out adverse effects.

One approach in the development of biodegradable implants to serve as a place holder and prevent conjunctiva and scleral adhesion.

A few different biodegradable implants are due to be tested in animal models. With a poly (L-lactide-co-epsilon-caprolactone) film, designed to work as an adhesion barrier in filtration surgery, a significantly lower postoperative IOP was found in relation to control eyes and no signficant difference to outcome in MMC-treated eyes was detected. [14] A solid hyaluronic acid-carboxymethyl cellulose film significantly inhibited sub conjunctival scar formation and prevented adhesions of conjunctiva and sclera.[15] The use of seprafilm (sodium hyaluronate and carboxymethylcellulose) reduced postoperative conjunctiva-sclera adhesion. A porous collagen-glycosaminoglycan matrix (ologen implant) was tested in animal models. This implant was designed to prevent collapse of the subconjunctival space, for example, the conjunctive-sclera adhesion. It led to a randomsed collagen deposition and microcyst formation after penetrating anti-glaucomatous surgery in contrast to the negative control and decreased early postoperative scarring [16, 17]. Moreover, the ologen implant will also be adjuvant in repairing postoperative bleb leaks [17]. In human subjects, the ologen implant was tested non augmentation in deep sclerectomy. This study revealed that deep sclerectomy with ologen implantation is an effective and well-tolerated method for reduction of IOP. [18] A further pilot study revealed non-significant differences in postoperative IOP after trabeculectomy with ologen and sole trabeculectomy. [19] In summary of the previous studies, the use of the ologen implant promises comparable IOP reduction after trabeculectomy and a lower risk profile in comparison with the use of anti-metabolites, for example, MMC and 5-fluorouracil, although the use of ologen implant does not seem to offer a significant advantage compared with trabeculectomy alone in a pilot study. [19]

Recent studies in animal models reported that, the use of a bio-engineered biodegradable, porous collagen implant offers the potential for a new method of providing controlled resistance seteveen the anterior chamber and the subconjunctional space in the early post operative period, as well as maintaining long term IOP control by avoiding loosely structured filtering bleb [4]. According to the manufacturer, the Ologen implant used in our study may normalize sub conjunctival wound healing and maintain good filtration & biodegrade within 30-90days.

Our study reveals that trabeculectomy with implanation of an ologen implant is a safe method for penetrating anti-glaucomatous surgery. We did not detect any ologen-specific side effects, such as translocation of the implant or erosion of the conjunctive. No allergy was detected and corkscrew vessel scores were comparable in the two interventional groups.

In the early post operative period, excessive aqueous filtration could cause low IOP. Severe hypotony could result in severe complications such as choroidal detachment, gradual bleb failure, cataract & corneal edema & can be associated with maculopathy and loss of visual acuity. [19]

In our study, there was no vision threatening complications were observed except temporary hypotony & shallow anterior chamber (same number of patients in both groups) those were improved with conservative management gradually.

Post operative IOP levels were significantly lower than pre operative levels with both groups at 6 months after operation.

The mean number of antiglaucoma medications used in both groups was significantly reduced after surgery, there was no significant difference between the two groups in terms of either the mean post operative IOP with the mean number of antiglaucoma medications used. This result is very much similar with the study of Papaconstantinou et al. [19] There were non statistically significant differences between the two groups in terms of post operative complications. That is very similar with other study [19].

Papconstantenour et al [19] experienced one case of endopthalkmitis with 2 cases of positive Seidel test in the study group. In our study we did not face such complications in either groups.

One patient from the control group developed cataract at the end of 5th month after filtration surgery. He underwent cataract surgery with implantation. Still bleb Morophology & IOP are normal limit in that patient.

4 eyes from the control groups & 2 eyes from the study groups developed hyphema at immediate post operative period (1st to 3rd).

This is probably due to leaking of blood from the scleral flap angle to the anterior chamber. In the study group probably it is less due to relative tight sealing due to pressure of the ologen.

Even though there were no statistically significant differences between the two groups in terms of post operative complications, there may be clinical significance in the fact that 4 eyes from the control group developed hyphaema & one eye developed cataract which needed cataract surgery.

Ologen did not show any allergy to anybody in our study. But biodegradation is slower than the mentioned period of 60-90 days. Even in all eyes of the ologen group the implant degraded partially even at the end of 6 month after filtration surgery.

In conclusion of their study we can say that, trabeculectmy with ologen implantation have not significant advantage over trabeculactomy only. Additionally there were no statistically significant differences between the two groups in terms of complications.

Large sample sizes, prolong follow up are needed to confirm those outcomes with safely as well as efficacy of ologen in filtration surgery.