"Culture-positive exogenous endophthalmitis related to XEN45 gel stent implantation"

Abstract

Purpose: The XEN45 gel stent implant (Allergen, CA, USA) is one of many micro-invasive surgical options available to glaucomatologists. Our case series describes the presentation, treatment, and possible risk factors of XEN45 gel stent related endophthalmitis.

Observations: A 71 year old Chinese man and a 88 year old Caucasian woman underwent XEN45 gel stent implantation for primary open angle glaucoma. They presented with endophthalmitis at 7 and 4 months post-surgery respectively. The first patient had stent exposure with blebitis while the second patient did not show any signs of conjunctival defect, stent exposure, bleb leak nor blebitis. Both patients were treated immediately with intravitreal, topical and systemic antibiotics, followed by early vitrectomy. The implant was removed in the first, but not in the second patient. Vitreous cultures grew Streptococcus Viridans in the first patient and Haemophilus influenzae in the other. Unfortunately, the first patient eventually sustained a total retinal detachment requiring surgery and did not recover his vision. The second patient however, recovered with a good Snellen's visual acuity of 6/9 and maintenance of good intraocular pressure and bleb formation.

Conclusions: Exogenous endophthalmitis related to XEN45 gel stent implantation is a rare but devastating complication. The risks factors identified were multiple post-operative procedures, bleb exposure, conjunctival defect, use of antifibrotics, blepharitis and prolonged post-operative antibiotics. XEN45 gel stent implant provides a different challenge to ophthalmologists compared to trabeculectomy as more post-operative procedures are required to prevent subconjunctival scarring. Great care should be taken to individualize the use of antifibrotics in each patient to balance the risk of subconjunctival fibrosis with the risk of infection. In patients with stent exposure we propose early closure of the conjunctiva to close off the portal of entry for pathogens and reduce the need for prophylactic topical antibiotics.

Keywords: Blebitis; Endophthalmitis; Glaucoma; Infection; Minimally-invasive.

Fig. 1

Patient 1: 10–2 automated perimetry showing initial visual field loss before XEN45 implantation.

Fig. 2

Patient 1: XEN stent exposure taken before the infection. Unfortunately we were unable to document photos of stent erosion during the presentation of endophthalmitis.

Fig. 3

Patient 1: The patient presented with typical features of endophthalmitis: Severe conjunctival injection, corneal oedema and a hypoyon.

Fig. 4

Patient 1: B scan ultrasound scan showing dense vitreous opacities.

Fig. 5

Patient 2: Optical coherence tomography and 24–2 perimetry showing initial field loss before XEN45 implantation.

Fig. 6

Patient 2: No blebitis, leak, or stent exposure was noted during presentation of endophthalmitis.

Fig. 7

Patient 2: Similar to the 1st patient, the second patient presented with typical features of endophthalmitis including severe anterior chamber cells and flare.

Fig. 8

Patient 2: B scan ultrasound scan showing moderate - dense vitreous opacities.

Fig. 9

Patient 2: 24–2 automated perimetry showing worsening of visual field defect after resolution of infection.