Filtering Bleb Complications

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Background

The consequences of bleb-associated complications include the following, listed in order of potential morbidity:

Pathophysiology

The goal of glaucoma filtering surgery is to reduce IOP with surgery. The pressure can be too high or too low following the surgery.

Epidemiology

Frequency

United States

This condition is uncommon.

Mortality/Morbidity

Bleb complications can be classified according to their vision-threatening potential and impact on quality of life.

All bleb-related complications have infection/endophthalmitis as a possible consequence, with high morbidity.[1] Also, bleb failure with consequent rise in IOP or excessively low IOP are possible consequences.

The cost for the individual and the community in terms of discomfort, unplanned care, loss of work time, direct medical expenses, and decrease in visual function cannot be estimated and may be high.

Race

No racial predisposition exists.

Sex

No sexual influence exists.

Age

No influence of age exists.

History

History includes previous filtration surgery for the management of glaucoma. Presentation varies remarkably depending on the complication being observed.

Physical

Clinical picture varies considerably depending on the complication. These eyes show evidence of filtration surgery in common, with a range of associated glaucomatous damage.

Causes

Causes may include buttonholes and tears, dehiscence, or retraction.

Conjunctival buttonholes and tears, dehiscence of the conjunctival incision, or retraction of the conjunctival edge are usually a result of suboptimal surgical techniques. Examples of these are shown in the images below.



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Suboptimal suturing techniques can cause gaping of the conjunctival incision.



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Retraction of a fornix-based conjunctival flap. It can progress to uncover the scleral flap.

Care must be taken in handling the tissues, and meticulous suturing techniques need to be used. Attention to detail is key in the prevention of these problems.

Dehiscence and retraction are almost unavoidable when using absorbable sutures in conjunction with antimetabolites.

Each of the above events can cause an entire spectrum of bleb-associated complications (see Complications).

The most evident risk factor for late bleb leaks, bleb ruptures, and infections is the intraoperative or postoperative use of antimetabolites. After antimetabolites, blebs tend to be more ischemic and thinner, with progressive thinning and possible spontaneous rupture.

Laboratory Studies

For infections, full microbiological workup is necessary.

See Endophthalmitis, Postoperative.

Imaging Studies

Optical coherence tomography (OCT) is used to assess macular edema in cases of decreased visual acuity associated with hypotony.

Depending on the clinical picture, ultrasound B-scan can be useful to assess the vitreous cavity if endophthalmitis is suspected or present and to establish the retinochoroidal relationships in cases of hypotony.

Other Tests

Perform aqueous and vitreous taps in cases of infection.

Perform a Seidel test to look for leakage (see Surgical Care). Example results are shown below.



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Seidel test. While holding the upper lid to avoid blinking during this evaluation, a dry fluorescein strip is moved over the conjunctival bleb, so as to smear it with dry fluorescein, which will appear very dark under blue light. As soon as the aqueous leaks, the color will turn to very bright yellow.



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Fluorescein staining of the conjunctiva shows an obvious leakage of aqueous.



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After fluorescein staining, aqueous is percolating slowly, forming tiny droplets on the surface that mimic a sweating bleb.

Surgical Care

Late leaking bleb and/or late bleb rupture

Thin blebs, especially after antimetabolites, are at risk for late leaks. They often are linked to, but not necessarily associated with, hypotony.

Thin blebs can show an obvious leak or a more subtle percolation (ooze) when tested with fluorescein.

Fluid can also pass transconjunctivally very slowly, thus being missed unless the observation of the fluorescein stained bleb is prolonged enough, while holding the upper lid to prevent blinking; pearls of aqueous can be observed to form on the conjunctiva in such cases, which can be described as "sweating" bleb.

In case of an excessively functioning filtering bleb causing side effects the following can be attempted, depending on the clinical features:

Surgical revision and repair is a reliable and definitive treatment. However, leaks can recur and/or the filtration effect can be lost with a subsequent rise in IOP.

Infection

Early infection develops within the first week following surgery. Early infection is caused by the introduction of the infective agent at the time of the procedure and is not specifically related to bleb complications.

Late infection occurs weeks to months after surgery.[4] Late infections probably are due to transconjunctival migration of microorganisms through leaks, holes, breaks, or weakened thin tissue. Thin blebs after the use of antimetabolites are a definite risk factor for late infections.

Blebitis

Endophthalmitis

Hypotony

Hypotony is caused by the following:

It can be accompanied by shallow/flat AC and choroidal detachment.

Management is to repair the cause.

Overfiltration, early in the postoperative period - The following can be attempted:

Overfiltration, late in the postoperative period - The following can be attempted:

Circumferential blebs

Blebs, which are functioning well, can extend inferiorly even to 360°

Once the bleb starts to extend downward from the superior quadrants, its downward expansion is favored by the relative thinness of the Tenon layer laterally.

When bulging, these blebs can cause symptoms as they interfere with blinking and tear flow.

Management can include lubricants and tear supplements, as well as staged excision of the sectors of the conjunctiva, away from the functioning upper quadrant.

Corneal dissecting blebs

The anterior edge of the bleb extends over the cornea within the epithelium, forming a white, nonvascularized, multiloculated, and spongy tissue, which can protrude for several millimeters. An example is shown in the image below.



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Corneal dissecting bleb, extending forward within the corneal epithelium.

The Bowman layer and the stroma remain intact.

This condition can cause symptoms when it interferes with blinking or tear flow, causes bubble formation, or irritates corneal nerves.

Management can include lubricants and tear supplements. If not effective, the part of the bleb lying over the peripheral cornea can be excised under topical anesthesia at the slit lamp or under a surgical microscope in the minor operating room. Simple excision without suturing or grafting is usually sufficient.

Dellen

Corneal dellen develop in front of steep-walled blebs usually when placed either nasally or temporally.

The bulk of the bleb impedes the contact of the inner surface of the upper lid with the peripheral cornea.

Lubricants and tear supplements are indicated for management, and they need to be used intensively. Ointments and patching are the next levels of intervention. When symptoms persist, a Palmberg compression mattress suture usually is effective. Surgical revision is to be considered when all else fails.

Decreased visual acuity

Severe complications, such as infections or prolonged hypotony, carry the most risk for a permanent decrease in visual acuity.

Visual function can be adversely affected by the following:

Consultations

In cases of endophthalmitis, a vitreoretinal surgeon may be consulted.

Activity

Limitations on physical activity and/or any activity that will cause Valsalva-like effects are to be considered in cases of hypotony.

Medication Summary

Prophylactic antibiotics are not effective to prevent late endophthalmitis.

Vancomycin hydrochloride (Vancocin, Vancoled, Lyphocin)

Clinical Context:  Indicated for treatment of serious or severe infections caused by gram-positive organisms.

Ceftazidime (Ceptaz, Fortaz, Tazicef, Tazidime)

Clinical Context:  Third-generation cephalosporin with broad-spectrum, gram-negative activity; lower efficacy against gram-positive organisms; higher efficacy against resistant organisms. Arrests bacterial growth by binding to one or more penicillin-binding proteins.

Class Summary

Therapy must be comprehensive and cover all likely pathogens in the context of this clinical setting.

Dexamethasone intravitreal implant (Decadron, AK-Dex, Alba-Dex)

Clinical Context:  Decreases inflammation by suppressing migration of polymorphonuclear leukocytes and reducing capillary permeability.

Prednisolone ophthalmic (AK-Pred, Delta-Cortef, Econopred)

Clinical Context:  Synthetic analog of naturally occurring glucocorticoid used to suppress the inflammatory response.

Class Summary

Have anti-inflammatory properties and cause profound and varied metabolic effects. Corticosteroids modify the body's immune response to diverse stimuli.

Further Outpatient Care

Specialist and subspecialist care is recommended, tailored to both the type and the severity of the complication.

Deterrence/Prevention

Conjunctival buttonholes and tears, dehiscence, and retraction of the conjunctival incision are usually a result of suboptimal surgical techniques.

Care must be taken in handling the tissues, and meticulous suturing techniques need to be used. Attention to detail is paramount in the prevention of these problems.

Dehiscence and retraction are almost unavoidable when using absorbable sutures in conjunction with antimetabolites.

The use of a larger area for the application of antimetabolites reduces the occurrence of small ischemic blebs, which are more prone to complications.

Complications

Potential complications include the following:

Prognosis

Prognosis is favorable with prompt treatment.

Patient Education

Instruct patients undergoing filtration surgery to report immediately to an ophthalmologist at any time after surgery if persisting redness, discharge, decreased vision, or pain occurs.

Author

Carlo E Traverso, MD, Professor and Chairman, Clinica Oculistica of Department of Neurosciences, Ophthalmology, Maternal and Pediatrics and Genetics, University of Genova Medical School/IRCCS Azienda Ospedaliera Universitaria San Martino-IST, Italy

Disclosure: Nothing to disclose.

Specialty Editors

Simon K Law, MD, PharmD, Clinical Professor of Health Sciences, Department of Ophthalmology, Jules Stein Eye Institute, University of California, Los Angeles, David Geffen School of Medicine

Disclosure: Nothing to disclose.

J James Rowsey, MD, Former Director of Corneal Services, St Luke's Cataract and Laser Institute

Disclosure: Nothing to disclose.

Chief Editor

Hampton Roy, Sr, MD, Associate Clinical Professor, Department of Ophthalmology, University of Arkansas for Medical Sciences

Disclosure: Nothing to disclose.

Additional Contributors

Neil T Choplin, MD, Adjunct Clinical Professor, Department of Surgery, Section of Ophthalmology, Uniformed Services University of Health Sciences

Disclosure: Nothing to disclose.

References

  1. Busbee BG, Recchia FM, Kaiser R, Nagra P, Rosenblatt B, Pearlman RB. Bleb-associated endophthalmitis: clinical characteristics and visual outcomes. Ophthalmology. 2004 Aug. 111(8):1495-503; discussion 1503. [View Abstract]
  2. Halkiadakis I, Lim P, Moroi SE. Surgical results of bleb revision with scleral patch graft for late-onset bleb complications. Ophthalmic Surg Lasers Imaging. Jan-Feb 2005. 36(1):14-23. [View Abstract]
  3. Maruyama K, Shirato S. Efficacy and safety of transconjunctival scleral flap resuturing for hypotony after glaucoma filtering surgery. Graefes Arch Clin Exp Ophthalmol. 2008 Dec. 246(12):1751-6. [View Abstract]
  4. Yamamoto T, Kuwayama Y, Nomura E, Tanihara H, Mori K. Changes in visual acuity and intra-ocular pressure following bleb-related infection: the Japan Glaucoma Society Survey of Bleb-related Infection Report 2. Acta Ophthalmol. 2013 Sep. 91(6):e420-6. [View Abstract]
  5. Bochmann F, Kaufmann C, Kipfer A, Thiel MA. Corneal patch graft for the repair of late-onset hypotony or filtering bleb leak after trabeculectomy: a new surgical technique. J Glaucoma. 2014 Jan. 23(1):e76-80. [View Abstract]
  6. Quaranta L, Riva I, Floriani IC. Outcomes of conjunctival compression sutures for hypotony after glaucoma filtering surgery. Eur J Ophthalmol. 2013 Jul-Aug. 23(4):593-6. [View Abstract]
  7. Azuara-Blanco A, Katz LJ. Dysfunctional filtering blebs. Surv Ophthalmol. 1998 Sep-Oct. 43(2):93-126. [View Abstract]
  8. Fluorouracil Filtering Surgery Study Group. Five-year follow-up of the Fluorouracil Filtering Surgery Study. Am J Ophthalmol. 1996 Apr. 121(4):349-66. [View Abstract]
  9. Higginbotham EJ, Stevens RK, Musch DC, Karp KO, Lichter PR, Bergstrom TJ, et al. Bleb-related endophthalmitis after trabeculectomy with mitomycin C. Ophthalmology. 1996 Apr. 103(4):650-6. [View Abstract]
  10. Hu CY, Matsuo H, Tomita G, Suzuki Y, Araie M, Shirato S, et al. Clinical characteristics and leakage of functioning blebs after trabeculectomy with mitomycin-C in primary glaucoma patients. Ophthalmology. 2003 Feb. 110(2):345-52. [View Abstract]
  11. Jonas JB, Dugrillon A, Kluter H, Kamppeter B. Subconjunctival injection of autologous platelet concentrate in the treatment of overfiltrating bleb. J Glaucoma. 2003 Feb. 12(1):57-8. [View Abstract]
  12. Kangas TA, Greenfield DS, Flynn HW, Parrish RK, Palmberg P. Delayed-onset endophthalmitis associated with conjunctival filtering blebs. Ophthalmology. 1997 May. 104(5):746-52. [View Abstract]
  13. Yamamoto T1, Kuwayama Y, Kano K, Sawada A, Shoji N. Clinical features of bleb-related infection: a 5-year survey in Japan. Acta Ophthalmol. 2013 Nov. 91(7):619-24.
  14. Parrish R, Minckler D. "Late endophthalmitis"--filtering surgery time bomb?. Ophthalmology. 1996 Aug. 103(8):1167-8. [View Abstract]
  15. Sony P, Kumar H, Pushker N. Treatment of overhanging blebs with frequency-doubled Nd:YAG laser. Ophthalmic Surg Lasers Imaging. 2004 Sep-Oct. 35(5):429-32. [View Abstract]
  16. Tannenbaum DP, Hoffman D, Greaney MJ, Caprioli J. Outcomes of bleb excision and conjunctival advancement for leaking or hypotonous eyes after glaucoma filtering surgery. Br J Ophthalmol. 2004 Jan. 88(1):99-103. [View Abstract]
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  18. Yarangumeli A, Koz OG, Kural G. Encapsulated blebs following primary standard trabeculectomy: course and treatment. J Glaucoma. 2004 Jun. 13(3):251-5. [View Abstract]

Suboptimal suturing techniques can cause gaping of the conjunctival incision.

Retraction of a fornix-based conjunctival flap. It can progress to uncover the scleral flap.

Seidel test. While holding the upper lid to avoid blinking during this evaluation, a dry fluorescein strip is moved over the conjunctival bleb, so as to smear it with dry fluorescein, which will appear very dark under blue light. As soon as the aqueous leaks, the color will turn to very bright yellow.

Fluorescein staining of the conjunctiva shows an obvious leakage of aqueous.

After fluorescein staining, aqueous is percolating slowly, forming tiny droplets on the surface that mimic a sweating bleb.

Large, extended, overfiltering bleb causes symptoms because of tear flow disturbances and ocular surface wetting.

Corneal dissecting bleb, extending forward within the corneal epithelium.

Cystic, thick-walled bleb, defined most commonly as a Tenon cyst.

Retraction of a fornix-based conjunctival flap. It can progress to uncover the scleral flap.

Suboptimal suturing techniques can cause gaping of the conjunctival incision.

Fluorescein staining of the conjunctiva shows an obvious leakage of aqueous.

After fluorescein staining, aqueous is percolating slowly, forming tiny droplets on the surface that mimic a sweating bleb.

Cystic, thick-walled bleb, defined most commonly as a Tenon cyst.

Large, extended, overfiltering bleb causes symptoms because of tear flow disturbances and ocular surface wetting.

Corneal dissecting bleb, extending forward within the corneal epithelium.

Seidel test. While holding the upper lid to avoid blinking during this evaluation, a dry fluorescein strip is moved over the conjunctival bleb, so as to smear it with dry fluorescein, which will appear very dark under blue light. As soon as the aqueous leaks, the color will turn to very bright yellow.