Factors related to filtration-bleb morphology after Ex-PRESS® surgery

Factors Correlated With Mid-Term Morphology of Functional Blebs Following Implantation of Preserflo MicroShunt Using AS-OCT

Purpose

Evaluating bleb morphology is crucial after glaucoma filtering surgery. Advances in anterior segment optical coherence tomography (AS-OCT) allow for objective assessment. While various parameters differentiate functional from failed blebs, limited information exists regarding variations within functional blebs. This study aimed to identify factors influencing morphology of functional blebs following implantation of Preserflo MicroShunt.

Methods

Eyes with functional blebs after Preserflo were retrospectively included. Age, gender, lens status, preoperative intraocular pressure (pre-IOP) and number of glaucoma medications were documented along with biometric measurements as axial length (AL), white-to-white distance, and anterior chamber depth. Postoperative data included time elapsed since surgery (TaS) and postoperative IOP (post-IOP). Bleb dimensions were measured using AS-OCT including maximal bleb height (MBH), width, length (MBL), bleb wall thickness (BWT), and bleb distance to limbus (DtL) along with dimensions of episcleral lake (maximal height, width [MLW], and length). Linear regression models were applied to correlate these parameters with bleb dimensions.

Results

Included were 50 eyes from 50 patients. Mean IOP decreased from 25.3 ± 10.0 to 11.9 ± 3.0 mm Hg after 278.5 ± 221.9 days after surgery. MBH correlated negatively with age (unstandardized coefficients [uSC] = -0.012) and TaS (uSC = -0.001, P = 0.008 for both). BWT correlated negatively with age (uSC = -0.013, P = 0.02), MBL with AL (uSC = -0.566, P = 0.01) and MLW with pre-IOP (uSC = -0.073, P = 0.02). DtL exhibited a positive correlation with post-IOP (uCS = 0.136, P = 0.02).

Conclusions

Morphology of functional blebs might be influenced by multiple factors such as age, TaS, AL, and pre- and post-IOP.

Translational Relevance

Age, time after surgery, axial length, and preoperative and postoperative IOP could affect the morphology of a functional bleb; hence, these factors should be taken into consideration when making treatment decisions.

Updates on the utility of anterior segment optical coherence tomography in the assessment of filtration blebs after glaucoma surgery

The formation of filtration blebs is the main drainage mechanism for reducing intraocular pressure after traditional incisional glaucoma surgery such as trabeculectomy and non-penetrating deep sclerotomy. Early and short-lasting blebs may also occur after canaloplasty. Bleb formation also plays an important role after the implantation of glaucoma drainage devices, including Minimally Invasive Glaucoma Surgery devices. Anterior segment optical coherence tomography (AS-OCT) is a rapid and non-invasive high-resolution imaging technique that has evolved in recent years to become a routine examination. Anterior segment optical coherence tomography (AS-OCT) provides key information in the assessment and follow-up of glaucoma surgery, especially in the assessment of filtration blebs. Thus, bleb morphology can be qualitatively classified into diffuse, cystic, encapsulated and flattened, and AS-OCT imaging can also provide several quantitative parameters of the bleb, such as total bleb height, bleb fluid-filled cavity height, bleb wall thickness, number of microcysts and trabeculectomy opening size. These parameters could have an impact on clinical management during follow-up because they may predict the success or failure of the surgery in the early and late postoperative periods. Additionally, they may also guide the procedures used to increase filtration and reduce intraocular pressure, such as bleb needling and laser suture lysis.

Ex-Press® versus Baerveldt implant surgery for primary open-angle glaucoma and pseudo-exfoliation glaucoma

PURPOSE

To compare surgical outcomes between Ex-Press^® (EXP) and Baerveldt glaucoma implant (BGI) surgeries for primary open-angle glaucoma (POAG) and pseudo-exfoliation glaucoma (PEXG) patients.

PATIENTS AND METHODS

This was a retrospective single-facility study. The inclusion criteria were that the patient's preoperative intraocular pressure (IOP) was > 21 mmHg and the post-surgery follow-up was > 1 year. We recruited 161 patients who had undergone a trabeculectomy with EXP (89 eyes) or BGI surgery (72 eyes). We compared these groups' postoperative IOP values and postoperative glaucoma medications, the reduction rate of corneal endothelial cell density (ECD), surgical outcomes, complications, the hospital stay duration, and the number of visits within 3 months post-surgery.

RESULTS

Both the EXP and BGI surgeries could significantly decrease the IOP. When the surgical success was defined postoperative IOP ≤ 21 mmHg, the surgical outcome of BGI was significantly better than EXP (p = 0.0148). When the surgical success was defined postoperative IOP ≤ 18, 15 , and 12 mmHg, the surgical outcomes between BGI and EXP surgeries were not significantly different (p = 0.0815, p = 0.331, and p = 0.910). The mean ECD reduction rate was significantly faster in the EXP group. The BGI patients had significantly shorter stays in the hospital and fewer visits within 3 months post-surgery (p < 0.0001).

CONCLUSIONS

BGI surgery could provide comparable surgical outcomes as EXP surgery for POAG or PEXG patients with high preoperative IOP. BGI surgery has some advantages: fewer post-surgery visits, less postoperative interventions, and a lower ECD reduction rate.