CaseWise 25

Conjunctival erosion after Ahmed glaucoma valve 

Dr Jyotsna Jareda, Dr Sarang Lambat, Dr Vinay Nangia
Suraj Eye Institute, Nagpur, India

Introduction
Glaucoma drainage devices (GDD) have been used in the management of complicated glaucomas. However they are associated with various complications. Erosion of conjunctiva and exposure of the GDD remains a risk factor for the development of endophthalmitis.1 We present to you a case of AGV with conjunctival erosion.
Case Report
A male, 60 years of age, known case of open angle glaucoma and on medication, presented to us with chief complaint of blurring of vision in both eyes (BE) since 2 month. He was hypertensive and diabetic since 15 years. Best corrected visual acuity (BCVA) in right eye (RE) was 6/9 and in Left eye (LE) was 6/6. Patient was  pseudophakic. IOP on applanation tonometry in RE was 34 mmHg and in LE was 23 mmHg. Patient was using brimonidine 0.2%+ timolol 0.5% e/d and brinzolamide 1% e/d in both eyes. Fundus examination of RE showed vertical C:D ratio (VCDR) of 0.7 and LE showed VCDR of 0.6. In view of uncontrolled IOP in RE on 3 AGM , patient was advised RE Ahmed glaucoma valve implantation, which was done on 12/2/2020. 1 week post op IOP in RE was 12 mm hg on brimonidine 0.2%+timolol 0.5% eye drops. On slit lamp biomicroscopy RE conjunctival sutures were avulsed, conjunctiva was eroded and scleral graft was visible, which appeared unhealthy (fig 2a). Patient then underwent removal of scleral patch graft, and placement of corneal graft along with autologous conjunctival graft, which was sutured in 2 layers on 21/2/2020 (fig2b). 1 week post corneal graft placement IOP in RE was 30 mmHg. Slit lamp biomicroscopy showed conjunctival erosion again along with exposed corneal graft. Patient then underwent RE scleral autograft placement along with conjunctival autograft from inferior quadrant on 3/3/2020. Patient was started on topical steroid in tapering dose. 3 weeks post op IOP in RE was 15 mm hg on topical  brimonidine 0.2% and timolol  0.5% eye twice daily and conjunctival graft appeared to be healthy .                                          

Figure 1a: RE fundus photograph showing C:D ratio of 0.7. Figure 1b: LE fundus photograph showing C:D ratio of 0.6
Figure 2a : shows right eye conjunctival melt showing scleral graft post AGV. Figure 2b: shows right eye 1 day post corneal patch graft and conjunctival autograft.
Fig 3a: shows scleral melt and exposed corneal graft Figure 3b : shows right eye day 1 post 3rd surgery of scleral and conjunctival autograft
Figure 4 shows healthy conjunctiva at 3 weeks post 3rd surgery

Discussion
One of the surgical complications of AGV is conjunctival erosion which is a risk factor for endophthalmitis.1 The frequency of conjunctival erosion ranges from 2-8%.2 Our patient developed conjunctival erosion twice after AGV implantation. Immunological response to donor scleral or corneal allograft could be the probable cause. Allografts can induce an immunological reaction in the recipient, which can contribute to the graft melt, shrinkage, necrosis, and absorption.3Conditions such as diabetes have also been associated with erosion, as it may cause ischemia of the conjunctiva leading to delayed healing and erosion.4. In view of the above we performed scleral  autograft and conjunctival  autograft graft to reduce the possibility of an immunological response in the post operative period. The eye responded well with the conjunctival and scleral graft remaining healthy with good control of IOP. 

References

  1. Conjunctival erosion after glaucoma drainage device surgery: A feasible option. Suneeta Dubey, Baswati Prasanth, Manisha C Acharya, Ritesh Narula.IJO 2013: 7 355-357.http://www.ijo.in/text.asp?2013/61/7/355/99852
  2. Budenz DL, Feuer WJ, Barton K, Schiffman J, Costa VP, Godfrey DG, et al. Postoperative complications in the Ahmed Baerveldt comparison study during five years of follow-up. Am J Ophthalmol 2016;163:75-82. https://doi.org/10.1016/j.ajo.2015.11.023.
  3. Brandt JD (1993). Patch grafts of dehydrated cadaveric dura mater for               tube- shunt glaucoma surgery. Archives of Ophthalmology; 111(10):1436-1439. https://jamanetwork.com/journals/jamaophthalmology/article-abstract/640411 
  4. CG, Newsom RS, Rudnicka AR, Ellis TJ, Woodward EG. Vascular response of the bulbar conjunctiva to diabetes and elevated blood pressure. Ophthalmology 2005;112:1801-1808.https://doi.org/10.1016/j.ophtha.2005.04.030
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