Comparison of lacrimal gland dimensions and volume in unilateral Ahmed glaucoma valve versus trabeculectomy

Abstract

Purpose To evaluate radiographic lacrimal gland (LG) volume and dimensions in Ahmed glaucoma valve (AGV)- versus trabeculectomy-treated eyes and contralateral non-treated eyes. Methods In this retrospective cohort study, 1616 medical records acquired between 2010 and 2020 were examined. In AGV-treated (group 1) eyes, there were 19 patients with records sufficient for radiological LG evaluation, and in trabeculectomy-treated (group 2) eyes, there were 18. The hospital workstation software was used to assess high-resolution computed tomography (HRCT) scans conducted under standard protocol using a 128 SL Optima CT 660 scanner. The software (Vitrea (TM)) was used to perform semi-quantitative volumetric measurements. LG dimensions were obtained in the axial and reformatted coronal planes on each side, and four measures were generated using the widest LG tip-to-tip diameters in two planes: coronal length, coronal width (CW), axial length (AL), and axial width. Results The time interval between surgery and HRCT imaging was 50.97 +/- 26.25 months. Group 1 had significantly lower LG volume than group 2 (594.11 +/- 259.45 vs. 933.67 +/- 294.09 mm3, P = 0.001). When compared to non-treated eyes, AGV-treated eyes had lower LG volume (P = 0.065) while trabeculectomy-treated eyes had higher LG volume (P = 0.031). Further, group 1 had decreased length and width in both the axial and coronal planes as compared to group 2, with AL and CW being significantly different (P < 0.05). Conclusions AGV and trabeculectomy had varied impacts on LG volume and dimensions despite being conducted in the same quadrant. HRCT appears to be effective in analysing AGV position, which may be related to LG volumetric and dimensional issues.