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anindya anuradha, Stephanie A.W. Low, Yvonne M Buys, Graham Eric Trope; Temporal positional changes in Ahmed tubes . Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):929.
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© ARVO (1962-2015); The Authors (2016-present)
The movement of glaucoma drainage tubes can cause corneal endothelium damage, iris atrophy, pupil distortion, iritis and tube extrusion. In the present study we prospectively evaluated the change in position of Ahmed tubes from baseline to 2 years post-surgery using anterior segment OCT.
Prospective observational series. Patients ≥18 years old and 6 weeks - 3 months post-glaucoma drainage device (GDD) implantation were included in the study. Exclusion criteria included surgical revision of a GDD or subsequent intraocular surgery. GDD position was evaluated using anterior segment-OCT imaging. The following measurements were recorded: intracameral tube-length (ICL), distance between the tip of the tube and the posterior corneal endothelial surface (TC), distance between the tip of the tube and the anterior surface of the iris (TI), angle between the posterior surface of the cornea and the tube (CTA), and axis of the scanning beam which is parallel to the longitudinal cross section of tube (TA). Paired t-tests were used to compare GDD tube position measurements at baseline and 2 years post-surgery.
Thirty eyes of 26 patients are enrolled. Eight eyes were excluded due to poor quality scans and/or subsequent ipsilateral intraocular surgery. Of the remaining 22 eyes 11 have completed two years follow-up. Mean ICL decreased from 2.21±0.97 mm at baseline to 1.99±0.95 mm at 2 years (p=0.012). Mean TC decreased from 1.59 ±0.53 mm to 1.35 ± 0.47 mm (p=0.014). Mean TI increased from 0.67±0.32 mm to 0.90±0.24 mm (p=0.02). Mean CTA decreased from 36.1±5.9˚ to 33.5±6.2˚ (p=0.076). Though the mean decrease in CTA was not statistically significant 2 of 11 tubes showed >20% reduction. There was no statistically significant change in tube axis, however 1 tube shifted >20˚ in axis at 2 yrs post-op.
Tube length shortened >0.2mm in 5/11 eyes and moved anteriorly >0.2 mm in 4/11 eyes after 2 years of follow up. One of the 11 tubes moved horizontally by 2 years post surgery.
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