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Year : 2021  |  Volume : 9  |  Issue : 3  |  Page : 128-130

Ologen collagen matrix for bleb repair in long standing sweating bleb- A case report with histopathological correlation

Glaucoma Services, LV Prasad Eye Institute, MTC Campus, Bhubaneswar, Odisha, India

Date of Submission20-Aug-2020
Date of Decision28-Jan-2021
Date of Acceptance08-Feb-2021
Date of Web Publication27-Sep-2021

Correspondence Address:
Rakhi P Dcruz
L V Prasad Eye Institute, MTC Campus, Patia, Bhubaneswar - 751 024, Odisha
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/jcor.jcor_169_20

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A 68-year-old man, presented with reduced vision and hypotony 6 years after combined cataract + glaucoma (phacoemulsification + trabeculectomy + intraocular lens) surgery with Mitomycin-C, clinical evaluation depicted a sweating bleb. Surgical repair was done with the use of donor scleral patch graft and collagen matrix implant along with conjunctival advancement. Histopathology of the excised thinned-out bleb wall showed a single layer of metaplastic conjunctival epithelium with the complete absence of goblet cells. The use of adjuvant mitomycin-C in trabeculectomy is known to cause bleb leak and associated complications in the long run. However, the histopathological features of sweating blebs and their surgical management is not well defined in the literature.

Keywords: Collagen matrix, metaplasia, Mitomycin C, sweating blebs

How to cite this article:
Rao A, Dcruz RP, Sahoo N. Ologen collagen matrix for bleb repair in long standing sweating bleb- A case report with histopathological correlation. J Clin Ophthalmol Res 2021;9:128-30

How to cite this URL:
Rao A, Dcruz RP, Sahoo N. Ologen collagen matrix for bleb repair in long standing sweating bleb- A case report with histopathological correlation. J Clin Ophthalmol Res [serial online] 2021 [cited 2023 Mar 25];9:128-30. Available from: https://www.jcor.in/text.asp?2021/9/3/128/326788

Bleb leaks are known to occur after many years of use of Mitomycin-C and are known to cause hypotony and visually threatening complications.[1],[2] While leaking blebs are well characterized clinically with surgical options being well defined, the histopathological features of a sweating bleb without a frank leak and their surgical management has not been well described. We herein present a case of long-standing sweating bleb which was managed successfully with the use of the collagen matrix (Ologen).

  Case Report Top

A 68-year-old male presented with redness, watering, and foreign body sensation in the left eye of 2 months. He had undergone uneventful combined cataract and glaucoma surgery outside (phacoemulsification + intraocular lens (IOL), +trabeculectomy with Mitomycin-C) for uncontrolled glaucoma and cataract in both eyes, 6 years back. He also gave a history of consulting multiple surgeons locally for his ocular symptoms. Examination revealed a best-corrected visual acuity (BCVA) of 20/100, intraocular pressure (IOP) of 0 mm Hg, open angles by very careful 4 mirror gonioscopy (taking utmost care not to compress), and shallow anterior chamber (AC), with no IOL touch. The bleb was large diffuse thin-walled, well-covered cystic and avascular, allowing clear visibility of the ostium with the naked eye. Posterior segment evaluation showed an epiretinal membrane explaining the sub-optimal vision. Seidel's test showed no frank leak, although the fluorescein was seen to be penetrating through the thin bleb wall into the subconjunctival space of the bleb base in 10–15 s, with subsequent pooling of dye seen inferiorly. This suggested a sweating bleb, wherein aqueous was leaking through the outer thinned out bleb wall, with no frank leak or conjunctival defect. The absence of a frank leak was further confirmed intraoperatively with the use of trypan blue, which was seen to ooze out slowly through the bleb wall without a frank leak [Figure 1]a, [Figure 1]b, [Figure 1]c.
Figure 1: Intra-operative pictures showing sweating bleb (a-c) Intraoperative picture showing slow leakage of trypan blue which is slowly seen to ooze out of the bleb wall without a frank leak. Intra-operative pictures of surgical repair (d-h) Intraoperative pictures showing the surgical steps of bleb wall excision followed by scleral patch graft, collagen matrix implant over the graft and conjunctival advancement for tight closure

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The patient underwent bleb repair, with the removal of the unhealthy thin-walled conjunctiva over the bleb (sent for histopathology), debridement of the thin scleral roof, and conjunctival advancement from the adjacent healthy area. A donor-scleral patch graft was sutured in place with Ologen® Collagen Matrix sponge (Aeon Astron USA Inc., Model 830601, 6 mm × 2 mm) placement over the patch. The collagen matrix sponge was cut into the desired size to cover the patch graft making sure it was not too thick to compress the ostium [Figure 1]d, [Figure 1]e, [Figure 1]f, [Figure 1]g, [Figure 1]h.

The gross examination of the bleb wall revealed a very thin paper-like consistency of the outer bleb wall. Histopathology demonstrated a single layer of thinned out squamous metaplastic epithelium with sub-epithelial and intraepithelial bullae [Figure 2]. There was stromal hyalinization, with no evidence of goblet cells, collagen, or identifiable features of normal conjunctival epithelium in any part of the bleb wall [Figure 2]a.
Figure 2: Title-histopathologocal pictures of excised bleb wall. Histopathological features of the excised bleb wall (a, c) showing single layer of metaplastic epithelium, stromal hyalinization, and complete absence of goblet cells. postoperative slit lamp picture. (b) The postoperative slit lamp photograph showing well-formed anterior chamber, covered raised diffuse healthy bleb at 3.5 months follow up

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The postoperative course of the patient was uneventful with a BCVA of 20/80, fully formed AC, IOP of 12 mmHg, healthy functioning bleb, and no sweating seen through the bleb wall at 3.5 months after surgery [Figure 2]b.

  Discussion Top

Late bleb leaks are very common after the use of ant-fibrotic agents like Mitomycin C.[1]

However owing to the adoption of safer techniques and concentrations, the incidence of such complications after trabeculectomy has decreased.[2],[3],[4],[5]

Histologically, walls of failed blebs have a dense collagenous connective tissue that differs from functioning blebs which have loose connective tissue separated by clear spaces.[2],[3],[4],[5] Histopathological studies on leaking blebs postanti-fibrotic use in trabeculectomy report attenuation of the epithelial lining, damage to the substantia propria, fragmented basement membrane, reduced goblet cells, and evidence of areas of acellular stroma, all of which contribute to bleb leakage. These changes are caused by a delayed response to anti-fibrotic which damage deoxyribonucleic acid of adjacent cells years after surgery.[2],[3],[4],[5] Leaking blebs may also have epithelial tracts, which form the routes of persistent leakage after anti-fibrotic use.[4] The consistent features of leaking blebs after the use of Mitomycin-C or other anti-fibrotics have been observed to include reduced epithelial thickness, reduced goblet cell density, with added areas of prominent avascularity.[2],[4] Our patient had histopathological features of a leaking bleb with the complete absence of goblet cells. The epithelium was a single layer of thinned out metaplastic cells, with no evidence of disruption in the epithelial layer. The metaplasia and stromal hyalinization suggest a dysfunctioning bleb. This phenomenon may be possibly caused by abnormal gap junctions between the epithelial cells, which act like a “fistulous tract” from the aqueous to sweat through the intact albeit thinned-out bleb wall. This may be easily overlooked until high suspicion of the same entity is considered. This may be the reason why definitive treatment was not offered by other clinicians to our patient owing to absence of a frank leak.

The Ologen® Collagen matrix implant is a safe alternative to prevent scarring with proven efficacy in conditions like pterygium surgery, conjunctival tumour resections, or conjunctival leaks.[6] The collagen matrix has dual functions of preventing scarring/exuberant fibroblastic response while providing a mechanical support over thin areas. A significant concern in our case, with the use of scleral patch alone, was the functionality of the bleb owing to re-surgery on a long-standing chronically sweating bleb area which is known to enhance fibroblastic response, a major deterrent to a functioning bleb. While a donor scleral patch graft over leaking blebs is reported, use of the collagen matrix in a sweating bleb helped achieve a functioning bleb and optimal outcome in our case even years after surgery.

  Conclusion Top

Sweating blebs can be easily be missed on routine examination, causing devastating vision-threatening complications with features like that of a frankly leaking bleb. Metaplastic changes and abnormality of the gap junctions may explain the underlying mechanism of the dysfunctioning bleb, despite a continuous epithelial lining or intact bleb wall, and a diffuse clinical appearance of the bleb.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initial s will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.


Dalmia Ocular Pathology services at LV Prasad Eye Institute, MTC campus, Patia, Bhubaneswar.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

Sinnreich Z, Barishak R, Stein R. Leaking filtering blebs. Am J Ophthalmol 1978;86:345-9.  Back to cited text no. 1
Nuyts RM, Felten PC, Pels E, Langerhorst CT, Geijssen HC, Grossniklaus HE, et al. Histopathologic effects of mitomycin C after trabeculectomy in human glaucomatous eyes with persistent hypotony. Am J Ophthalmol 1994;118:225-37.  Back to cited text no. 2
Addicks EM, Quigley HA, Green WR, Robin AL. Histologic characteristics of filtering blebs in glaucomatous eyes. Arch Ophthalmol 1983;101:795-8.  Back to cited text no. 3
Shields MB, Scroggs MW, Sloop CM, Simmons RB. Clinical and histopathologic observations concerning hypotony after trabeculectomy with adjunctive mitomycin C. Am J Ophthalmol 1993;116673-83.  Back to cited text no. 4
Mietz H, Brunner R, Addicks K, Krieglstein GK. Histopathology of an avascular filtering bleb after trabeculectomy with mitomycin-C. J Glaucoma 1993;2:266-70.  Back to cited text no. 5
Cillino S, Casuccio A, Di Pace F, Cagini C, Ferraro LL, Cillino G. Biodegradable collagen matrix implant versus mitomycin-C in trabeculectomy: Five-year follow-up. BMC Ophthalmol 2016;16:24.  Back to cited text no. 6


  [Figure 1], [Figure 2]


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