An analytical study of the surgical outcomes of trabeculectomy with and without collagen implants

Glaucoma is a leading cause of irreversible blindness throughout the world. The modern understanding of the disease dates back to the mid- 19th century. However, this disease was recognised by the Greeks and Hippocrates refers to the entity as “glaucosis”. World Health Organisation statistics indicate that glaucoma accounts for 13.5% of global blindness (5.1 million persons). Glaucoma is not a single disease process but a large group of disorders with a common denominator of a characteristic optic neuropathy. Although elevated intraocular pressure (IOP) is the most frequent risk factor for glaucomatous optic atrophy, it is not the only factor and attempts to classify glaucoma on the basis of ocular tension are no longer valid. Nevertheless, the IOP remains a crucial parameter to the clinician as along with the aqueous dynamics, it is the only factor that can be controlled to prevent progressive optic neuropathy. OBJECTIVES OF THE STUDY An analytical study of the surgical outcomes of trabeculectomy with and without ologen implant was done. The aims of the study were • To evaluate the success rate of trabeculectomy with OloGen implant and to compare the outcomes with plain trabeculectomy. • To look for any local effects due to the implant & bleb related complications MATERIALS & METHODS: Subject Selection: Patients presenting to the Glaucoma services of RIO-GOH over a period of 2 years (July 2010 to June 2012). Screening & Procedure: 39 Glaucomatous eyes of 35 patients meeting the eligibility criteria were enrolled in this prospective study. After obtaining the informed consent from the patient detailed history taking followed by thorough glaucoma evaluation- Visual acuity recording by the Snellen’s chart, IOP by both non-contact tonometry and by Goldmann applanation tonometry (after correction for the central corneal thickness by pachymetry), slit lamp examination & gonioscopy by Goldmann single mirror, fundus examination by 78D lens, fields by Octopus automated perimetry (AP) & ONH topography with retinal nerve fiber thickness (RNFL thickness) by Optical Coherence Tomography (OCT) was done. The patients are randomly allotted into 2 groups. Those in group A underwent trabeculectomy alone while those in group B underwent trabeculectomy with an Ologen implant. 20 eyes were allotted to group A and 19 eyes were allotted to group B. In the trabeculectomy group, there were 9 eyes with POAG, 9 eyes with PACG and 2 eyes with developmental glaucoma. Similarly the trabeculectomy with OloGen group had 8 eyes with POAG, 8 eyes with PACG and 3 eyes with developmental glaucoma. CONCLUSION: Trabeculectomy has traditionally been considered the gold standard surgery for glaucoma. Any new modality is always compared to trabeculectomy in terms of efficacy and complications. In spite of the coveted status it enjoys, trabeculectomy has its own limitations. Most surgeons find that trabeculectomy tends to fail over a course of time. This is primarily because of scarring of the bleb and the adjacent conjunctiva. The novel bio-integrable collagen implant regulates the process of bleb formation. It provides a framework for orderly deposition of collagen and hence ensures minimal scarring and bleb disorganization. In our study, we have described and compared the results of trabeculectomy surgery performed on 20 patients and trabeculectomy surgery with Ologen implant performed on 19 patients. At the end of a two year follow-up, though the drop in IOP in both groups was significant, sustained low levels were achieved more often in patients who had the collagen implant. Moreover, other ocular parameters suggestive of glaucoma progression like increase in the loss variance on automated perimetry or thinning of the retinal nerve fiber layer were not encountered. Bleb morphology tends to be favourably altered with the use of the implant as can be seen with use of the Moorefields bleb grading system. At the end of a two year follow up period, more number of eyes in the implant group maintained the complete success of surgery. Some patients showed adverse reactions to the implant. Nevertheless, serious complications like bleb leak and blebitis were not seen. The collagen implant can hence be use as a safe additive to the trabeculectomy surgery since it enhances the results of the procedure without any serious ocular effects directly attributable to the implant. As all steps of surgery are essentially the same as trabeculectomy, surgeons can carry out the procedure confidently to better the outcomes of their surgery in the long run