Consensual eye intraocular pressure rise following unilateral glaucoma surgery

Dear Editor, I read with interest the recent prospective study by Rajsrinivas et al.[1] describing intraocular pressure (IOP) increase in the fellow eye (FE) following ipsilateral glaucoma surgery. The authors reported a significant increase from the baseline IOP in FE at 1 week and 1 month postoperatively, and a maximum increase in FE IOP of nearly 3.5 mmHg when the index eye (IE) IOP was persistently <5 mmHg at 1 month postoperatively. Although the findings appear promising to evaluate IOP changes in FEs following ipsilateral glaucoma surgery, I noticed some critical points in the paper that I would like the authors to clarify. In this series, 187 consecutive IEs that underwent surgery for primary or secondary glaucoma were included, whereas patients on systemic or topical steroids because of ocular or systemic conditions were excluded. I wonder whether the potential inclusion of IEs with uveitic glaucoma (UG) not on topical or systemic steroids may significantly bias the results, as intraocular inflammation and IOP may have not been adequately controlled at the time of surgery. In UG, active inflammation contributes to elevated IOP, and IOP may revert to normal once inflammation subsides.[2] Also, surgery was performed for primary open-angle glaucoma in 45.5% and primary angle closure glaucoma (PACG) in 41% of IEs. However, preoperative IE lens status (phakic/pseudophakic) and possible mutations in the BEST1 gene were not specified for PACG patients. PACG eyes with bestrophinopathies have a higher risk of aqueous misdirection (especially if phakic),[3] and the potential inclusion of these eyes may alter IOP results in IEs and FEs. Pars plana vitrectomy is an established treatment for aqueous misdirection in these cases,[3] for RRD (including cases complicated by proliferative vitreoretinopathy) and with vitreoretinal interface syndrome.[4-12] I commend the authors' frank acknowledgment in the discussion of the limitations of the present study but seek clarification of the raised points. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.