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  • Cornea/External Disease, Glaucoma

    Review of: Different patterns in the corneal endothelial cell loss after pars plana and pars limbal insertion of the Baerveldt glaucoma implant

    Chihara E, Tanito M, Kono M, et al. American Journal of Ophthalmology, September 2023

    Despite similar initial outcomes, pars plana (PP) insertion of a Baerveldt glaucoma implant into the vitreous cavity may offer better long-term preservation of corneal endothelial (CE) cells than pars limbal (PL) insertion into the anterior chamber (AC).

    Study design

    This was a retrospective, interventional study that included 192 patients (192 eyes) with glaucoma from five institutions in Japan who underwent insertion of a Baerveldt glaucoma implant either via PP insertion into the vitreous cavity (104 patients) or via PL placement into the anterior chamber (limbal/AC; 88 patients). All patients had a follow-up period of greater than 3 years. Corneal endothelial cell measurements were obtained preoperatively as well as 6 months and 1–5 years after surgery to assess CE loss.


    The average follow-up time was 67.6 months. After 5 years, the prevalence of bullous keratopathy (BK) was 5.2% in the PP group vs 20.7% in the PL group (p = 0.003); low preoperative CE density and tube placement into the anterior chamber were identified as significant risk factors for BK. While the annual percentage CE losses in the PP and PL groups were not significantly different from each other early on, the differences grew over time, with the PP cohort showing 1.2% loss after 4–5 years vs 7.2% in the PL cohort (p = 0.006). Similarly, the annual CE loss in cells/mm2/year grew more dissimilar over time, with loss of 18.7 in the PP group and 126.8 in the PL group at 4–5 years (p = 0.005).


    Limitations of this study include that different specular microscopy devices were used at different institutions. Furthermore, because this was a retrospective trial, the types of glaucoma may not have been equivalent between the PP and PL groups.

    Clinical significance

    These results suggest that the PP approach to placing a Baerveldt glaucoma implant may better preserve CE in the long term compared to the PL technique. Hence, PP implantation of glaucoma tubes into the vitreous cavity may be preferable to PL insertion into the anterior chamber to minimize CE loss, especially in cases where preoperative CE density is low and the cornea is particularly vulnerable.

    Financial Disclosures: Dr. Zeba A. Syed discloses financial relationships with Bio-Tissue, Recordati (Lecture Fees/Speakers Bureau); Dompé, Glaukos (Grant Support).