Journal List > J Korean Ophthalmol Soc > v.54(3) > 1009623

Won, Tae, Ki, and Dong: Location of the Tube Tip in the Anterior Chamber and Change in Corneal Endothelium after Ahmed Valve Implantation

Abstract

Purpose

To evaluate the impact of location of a silicone tube tip in the anterior chamber on corneal endothelium after Ahmed glaucoma valve implantation.

Methods

We measured the distance from the tip of a silicone tube in the anterior chamber to the posterior surface of the cornea by anterior segment optical coherence tomography (OCT) in 24 eyes of 21 patients who underwent Ahmed glaucoma valve implantation. All surgeries were performed by a single surgeon. The corneal endothelial cells of central, superior, superotemporal, and superonasal area of the cornea were examined by specular microscope before and after surgery. Results: The distance from the tip of the silicone tube in the anterior chamber to the posterior surface of the cornea and the corneal endothelium were measured at 19.2 ± 11.8 months (2.8-41.2 months) after surgery. At the central corneal area, a statistically significant decrease in the number of corneal endothelial cells (2278 ± 565/mm2 vs. 2177 ± 529/mm2, p = 0.043) after surgery was observed, but no relationship was found between the amount of decrease and distance from the tip to the posterior surface of the cornea. At the superotemporal corneal area where the tip of the silicone tube was located in the anterior chamber, there was more significant loss of corneal endothelial cells than in the other areas after surgery (p = 0.006). Moreover, the amount of endothelial cell loss at the superotemporal area was negatively correlated to the distance from the tip to the posterior surface of the cornea (partial correlation coefficient by time -0.558, p = 0.031).

Conclusions

To minimize the loss of corneal endothelial cells after Ahmed glaucoma valve implantation, ensuring a sufficient distance from the tip of the silicone tube to the posterior surface of the cornea is important.

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Figure 1.
Visante OCT single scan along long axis of the silicone tube of Ahmed glaucoma valve showed the position and patency of the silicone tube in the anterior chamber. The distance from the tip of silicone tube to the posterior surface of cornea was measured to be 1.27 mm.
jkos-54-469f1.tif
Figure 2.
Topographical corneal endothelial cell density and coefficient of variation of cell area (CV) after Ahmed glaucoma valve implantation. The cell density and CV at superotemporal corneal area where the tip of the silicone tube was located in the anterior chamber got worse, compared to those at central corneal area.Values are presented as mean ± SD, Cell density (cells/mm2), Coefficient of variation of cell area (CV). *p = 0.006, W ilcoxon signed ranks test; p = 0.013, W ilcoxon signed ranks test.
jkos-54-469f2.tif
Figure 3.
The difference of corneal endothelial cell density between central and superotemporal corneal area (ΔCD C-ST) was negatively correlated to the distance from the tip of the silicone tube in the anterior chamber to the posterior surface of the cornea (partial correlation coefficient adjusted by time -0.558, p = 0.031).
jkos-54-469f3.tif
Table 1.
Demographics
Characteristics
Age (mean± SD, years) 58.9 ± 9.4 (37-71)
Gender (M:F) (eyes) 16:8
Previous trabeculectomy (eyes) 5
Preoperative diagnosis (eyes)
Neovascular glaucoma 10
Aphakic/Pseudophakic glaucoma 6
Uveitic glaucoma 5
Glaucoma after retinal procedures 2
Primary angle closure glaucoma 1
F/U period (mean± SD, months) 19.2 ± 11.8 (2.8-41.2)
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