Morphological Changes Of Schlemm’S Canal In Post Penetrating Keratoplasty Glaucoma: A Comparative As-Oct Study

To quantitatively compare Schlemm’s canal (SC) structural parameters between eyes with medically controlled post-penetrating keratoplasty glaucoma (PPKG) and healthy controls using anterior segment optical coherence tomography (AS-OCT).

Cross-sectional, comparative study.

This study included 24 eyes with medically controlled PPKG and 27 age-matched healthy controls. BCVA (logMAR), IOP (Tono-Pen AVIA®), RNFL thickness, and central corneal thickness (CCT) were evaluated. Eyes with ocular trauma, previous glaucoma surgery, active inflammation, poor AS-OCT image quality, or <6 months post-PK follow-up were excluded. Swept-source OCT (Triton DRI-OCT, Topcon, Japan) images of the nasal and temporal limbus were obtained. Images were exported in JPEG format and analyzed using ImageJ (1.54d, NIH) to measure SC length (SCL) and area (SCA). Demographic, clinical, and SC parameters were compared between groups. Correlations between SC parameters, IOP, number of antiglaucomatous medications (NAGM), and CCT were analyzed.

The PPKG and control groups were comparable in terms of age,gender distribution,laterality and CCT(p>0.05 for all).Main PK indications were pseudophakic bullous keratopathy(33.3%) and corneal dystrophy(25%).BCVA was worse in PPKG(1.30[0.30–3.00] vs 0.00[0.00–0.20] logMAR) and RNFL was thinner(72.75±26.58µm vs 107.52±7.88µm)(p<0.001).Mean IOP was 14.04±6.22 vs 15.07±2.46mmHg(p=0.43).Mean NAGM was 2.33±1.2.SC measurements were lower in PPKG.Nasal SCL and SCA were 113.21±42.74µm and 1649(1025–3272)µm² vs 275.7±72.15µm and 5917(1632–9005)µm².Temporal SCL and SCA were 128.75±44.99µm and 2420.38±974.84µm² vs 269.33±62.55µm and 4898.59±2165.86µm²(p<0.001).No correlations existed between SC parameters and post-PK duration,IOP,NAGM,or CCT.

Eyes with PPKG demonstrate significant reductions in SC dimensions compared with healthy controls. These structural changes may reflect postoperative anterior segment remodeling and may contribute to altered aqueous outflow dynamics following PK. Further longitudinal studies are needed to clarify the relationship between SC morphology and the risk of glaucoma after keratoplasty.