| Patient Education |
|
Click here for patient education.
|
|
You are in: eMedicine Specialties >
Ophthalmology > CONJUNCTIVA
Filtering Bleb Complications
Article Last Updated: Jul 18, 2007
AUTHOR AND EDITOR INFORMATION
Section 1 of 11  
Author: Carlo E Traverso, MD, Associate Professor, University Eye Clinic, Genova; Consulting Staff and Head of Glaucoma and Cornea Clinical Unit, University of Genova Medical School, Italy
Carlo E Traverso is a member of the following medical societies: American Academy of Ophthalmology, Association for Research in Vision and Ophthalmology, and European Glaucoma Society
Editors: Neil T Choplin, MD, Adjunct Clinical Professor, Department of Surgery, Section of Ophthalmology, Uniformed Services University of Health Sciences; Simon K Law, MD, PharmD, Assistant Professor of Ophthalmology, Jules Stein Eye Institute; Chief of Section of Ophthalmology Surgical Services, Department of Veterans Affairs Healthcare Center, West Los Angeles; J James Rowsey, MD, Former Director of Corneal Services, St Luke's Cataract and Laser Institute, Florida; Lance L Brown, OD, MD, Ophthalmologist, Affiliated With Freeman Hospital and St John's Hospital, Regional Eye Center, Joplin, Missouri; Hampton Roy Sr, MD, Associate Clinical Professor, Department of Ophthalmology, University of Arkansas for Medical Sciences
Author and Editor Disclosure
Synonyms and related keywords:
buttonhole, tear, dehiscence, retraction, infection, blebitis, endophthalmitis, leakage, dysesthesia, encapsulated bleb, failing bleb, glaucoma
Background
The consequences of bleb-associated complications include the following, listed in order of potential morbidity: predisposition to or cause of infection, unsatisfactory bleb function (ie, intraocular pressure [IOP] too low, IOP too high), dysesthesia, decreased visual acuity, and/or loss of the globe, which can be the final outcome.
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.
Frequency
United States
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. Also, bleb failure with consequent rise in IOP is a possible consequence. 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
- Buttonholes and tears, dehiscence, or retraction
- Conjunctival buttonholes and tears, dehiscence, or 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 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.
Endophthalmitis, Postoperative
Other Problems to be Considered
Tearing or epiphora
Photophobia
Hypotony
Lab Studies
Imaging Studies
- Optical coherence tomography (OCT) is used to assess macular edema in cases of decreased visual acuity 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).
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 bleb 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.
- The following can be attempted:
- Compression suture
- Autologous blood injection
- Continuous wave Nd:YAG laser application over fluorescein stained conjunctiva
- Cryotherapy
- Trichloroacetic acid coagulation
- Excision of redundant bleb
- Conjunctival grafting either free or sliding/pedunculated
- Amniotic membrane, pericardium, dura, or scleral patch graft
- Surgical revision and repair is the most 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. 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
- Diffuse bulbar hyperemia
- Congestion around the bleb
- Variable anterior chamber (AC) reaction
- Discharge
- Possible purulent material within the bleb
- No vitreous involvement
- Conjunctival swabs over the bleb for identification and culture
- Topical fortified antibiotics every hour with subconjunctival antibiotics daily
- AC tap depending on the presentation and on the clinical course
- Endophthalmitis
- Diffuse bulbar hyperemia
- Congestion around the bleb
- Variable AC reaction with hypopyon
- Discharge
- Possible purulent material within the bleb
- Vitreous involvement
- Conjunctival swabs over the bleb and AC tap for identification and culture
- Vitreous tap for identification and culture and for intravitreal antibiotic injection (see Endophthalmitis, Postoperative)
- Topical fortified antibiotics every hour with subconjunctival antibiotics daily
- Early vitrectomy depending on the presentation and on the clinical course
- Hypotony
- Hypotony is caused by the following:
- Large overfiltering blebs
- Leakage of aqueous through conjunctival tears and holes
- Leakage of aqueous through the retracted (fornix-based flap) or dehisced (limbus-based flap) edges of the conjunctival flap
- 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:
- Firm patching, placing a small roll of cotton over the lid corresponding to the filtration area
- Placement of a large bandage soft contact lens
- Revision with further suturing of the scleral flap
- Overfiltration, late in the postoperative period - The following can be attempted:
- Compression suture
- Autologous blood injection
- Continuous wave Nd:YAG laser application over a fluorescein stained conjunctiva
- Cryotherapy
- Trichloroacetic acid coagulation
- Excision of redundant bleb
- Conjunctival grafting either free or sliding/pedunculated
- Amniotic membrane, pericardium, dura, or patch graft
- 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 removal 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.
- 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:
- Intermittent astigmatism induced by the upper lid in case of hypotony
- Induced astigmatism caused by the pressure of the upper lid on a large cystic bleb extending over the limbus
- Induced astigmatism caused by a scleral flap that is too tight or too loose
- Ocular surface disturbances
- Macular edema, chorioretinal folds
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.
Prophylactic antibiotics are not effective to prevent late endophthalmitis.
Drug Category: Antibiotics
Therapy must be comprehensive and cover all likely pathogens in the context of this clinical setting.
| Drug Name | Vancomycin hydrochloride (Vancocin, Vancoled, Lyphocin) |
|---|
| Description | Indicated for treatment of serious or severe infections caused by gram-positive organisms. |
|---|
| Adult Dose | Intravitreal: 1 mg in 0.1 mL
Subconjunctival injection: 25 mg
Topical: 50 mg/mL gtt |
|---|
| Pediatric Dose | Not established |
|---|
| Contraindications | Documented hypersensitivity |
|---|
| Interactions | None reported for subconjunctival and intravitreal applications |
|---|
| Pregnancy | C - Safety for use during pregnancy has not been established.
|
|---|
| Precautions | Prolonged use may result in overgrowth of nonsusceptible organisms |
|---|
| Drug Name | Ceftazidime (Ceptaz, Fortaz, Tazicef, Tazidime) |
|---|
| Description | 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. |
|---|
| Adult Dose | Intravitreal: 2.25 mg in 0.1 mL
Subconjunctival: 100 mg
Topical: 50 mg/mL gtt |
|---|
| Pediatric Dose | Not established |
|---|
| Contraindications | Documented hypersensitivity |
|---|
| Interactions | None reported for subconjunctival and intravitreal applications |
|---|
| Pregnancy | B - Usually safe but benefits must outweigh the risks.
|
|---|
| Precautions | Adjust dose in severe renal insufficiency (high doses may cause CNS toxicity); superinfections and promotion of nonsusceptible organisms may occur with prolonged use or repeated therapy |
|---|
Drug Category: Corticosteroids
Have anti-inflammatory properties and cause profound and varied metabolic effects. Corticosteroids modify the body's immune response to diverse stimuli.
| Drug Name | Dexamethasone (Decadron, AK-Dex, Alba-Dex) |
|---|
| Description | Decreases inflammation by suppressing migration of polymorphonuclear leukocytes and reducing capillary permeability. |
|---|
| Adult Dose | Intravitreal: 0.4 mg in 0.1 mL
Subconjunctival injection: 12 mg |
|---|
| Pediatric Dose | Not established |
|---|
| Contraindications | Documented hypersensitivity; active bacterial or fungal infection |
|---|
| Interactions | None reported for subconjunctival and intravitreal applications |
|---|
| Pregnancy | C - Safety for use during pregnancy has not been established.
|
|---|
| Precautions | Enhanced effect of corticosteroid in patients with hypothyroidism and in those with cirrhosis; caution in patients with ocular herpes simplex |
|---|
| Drug Name | Prednisolone acetate 1% (AK-Pred, Delta-Cortef, Econopred) |
|---|
| Description | Synthetic analog of naturally occurring glucocorticoid used to suppress the inflammatory response. |
|---|
| Adult Dose | 1 or 2 gtt bid/qid |
|---|
| Pediatric Dose | Administer as in adults |
|---|
| Contraindications | Documented hypersensitivity; epithelial herpes simplex keratitis; mycobacterial infection; fungal diseases of ocular structures |
|---|
| Interactions | None reported for subconjunctival and intravitreal applications |
|---|
| Pregnancy | C - Safety for use during pregnancy has not been established.
|
|---|
| Precautions | Possibility of persistent fungal infection of the cornea |
|---|
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, or 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
- Loss of vision
- Loss of bleb function
- Loss of anatomical integrity of the globe
- Phthisis
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.
Medical/Legal Pitfalls
- Special care must be taken because the management of complications has intrinsic legal risks. Whenever possible, refer the patient to the surgeon who performed the original procedure, and document such an attempt. Accurate history with the sequence of events must be recorded. Before attempting any treatment, visual acuity must be recorded. An informed consent is obviously mandatory. It is advisable not to generate negative feelings toward the surgeon who performed the original procedure.
Special Concerns
| Media file 1:
Retraction of a fornix-based conjunctival flap. It can progress to uncover the scleral flap. |
 |  View Full Size Image | |
Media type: Photo
|
| Media file 2:
Suboptimal suturing techniques can cause gaping of the conjunctival incision. |
 | View Full Size Image | |
Media type: Photo
|
| Media file 3:
Fluorescein staining of the conjunctiva shows an obvious leakage of aqueous. |
 | View Full Size Image | |
Media type: Photo
|
| Media file 4:
After fluorescein staining, aqueous is percolating slowly, forming tiny droplets on the surface that mimic a sweating bleb. |
 | View Full Size Image | |
Media type: Photo
|
| Media file 5:
Cystic, thick-walled bleb, defined most commonly as a Tenon cyst. |
 | View Full Size Image | |
Media type: Photo
|
| Media file 6:
Large, extended, overfiltering bleb causes symptoms because of tear flow disturbances and ocular surface wetting. |
 | View Full Size Image | |
Media type: Photo
|
| Media file 7:
Corneal dissecting bleb, extending forward within the corneal epithelium. |
 | View Full Size Image | |
Media type: Photo
|
- Azuara-Blanco A, Katz LJ. Dysfunctional filtering blebs. Surv Ophthalmol. Sep-Oct 1998;43(2):93-126. [Medline].
- Busbee BG, Recchia FM, Kaiser R, Nagra P, Rosenblatt B, Pearlman RB. Bleb-associated endophthalmitis: clinical characteristics and visual outcomes. Ophthalmology. Aug 2004;111(8):1495-503; discussion 1503. [Medline].
- Fluorouracil Filtering Surgery Study Group. Five-year follow-up of the Fluorouracil Filtering Surgery Study. Am J Ophthalmol. Apr 1996;121(4):349-66. [Medline].
- 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. [Medline].
- Higginbotham EJ, Stevens RK, Musch DC, Karp KO, Lichter PR, Bergstrom TJ, et al. Bleb-related endophthalmitis after trabeculectomy with mitomycin C. Ophthalmology. Apr 1996;103(4):650-6. [Medline].
- 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. Feb 2003;110(2):345-52. [Medline].
- Jonas JB, Dugrillon A, Kluter H, Kamppeter B. Subconjunctival injection of autologous platelet concentrate in the treatment of overfiltrating bleb. J Glaucoma. Feb 2003;12(1):57-8. [Medline].
- Kangas TA, Greenfield DS, Flynn HW, Parrish RK, Palmberg P. Delayed-onset endophthalmitis associated with conjunctival filtering blebs. Ophthalmology. May 1997;104(5):746-52. [Medline].
- Mochizuki K, Jikihara S, Ando Y, Hori N, Yamamoto T, Kitazawa Y. Incidence of delayed onset infection after trabeculectomy with adjunctive mitomycin C or 5-fluorouracil treatment. Br J Ophthalmol. Oct 1997;81(10):877-83. [Medline].
- Parrish R, Minckler D. "Late endophthalmitis"--filtering surgery time bomb?. Ophthalmology. Aug 1996;103(8):1167-8. [Medline].
- Sony P, Kumar H, Pushker N. Treatment of overhanging blebs with frequency-doubled Nd:YAG laser. Ophthalmic Surg Lasers Imaging. Sep-Oct 2004;35(5):429-32. [Medline].
- 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. Jan 2004;88(1):99-103. [Medline].
- Wolner B, Liebmann JM, Sassani JW, Ritch R, Speaker M, Marmor M. Late bleb-related endophthalmitis after trabeculectomy with adjunctive 5-fluorouracil. Ophthalmology. Jul 1991;98(7):1053-60. [Medline].
- Yarangumeli A, Koz OG, Kural G. Encapsulated blebs following primary standard trabeculectomy: course and treatment. J Glaucoma. Jun 2004;13(3):251-5. [Medline].
Filtering Bleb Complications excerpt Article Last Updated: Jul 18, 2007
|
