Management of implant plate exposure of silicone Ahmed glaucoma valve: a review of six cases

Comparison of Short and Long-Tunnel Needle Track for Ahmed Glaucoma Valve Implantation in a Private Eye Center in the Philippines: A Retrospective Study

Purpose

This study aimed to compare the success and complication rates among patients implanted with Ahmed Glaucoma Valve (AGV) using the short and long tunnel technique through retrospective chart review.

Patients and Methods

We reviewed 54 charts of adult patients who underwent AGV implantation using a Short-Needle Track (SNT) or Long-Needle Track (LNT) technique. Intraocular pressures (IOP), Best Corrected Visual Acuity (BCVA) and number of medications were recorded pre-operatively, and at Day 1, 3, 7, Month 1, 3, 6 post-operatively. Treatment success, occurrence of Hypertensive Phase (HP), complication and procedures done after AGV implantation were compared between the two groups using one-tailed Z-test of proportions.

Results

A total of 20 (LNT) and 21 (SNT) charts were included in the study. There was no significant difference between the median postoperative IOP, BCVA, and number of anti-glaucoma medications between the two groups at each time interval. The comparison between the occurrence of HP (P = 0.435) and success rates (P = 0.476) between the two groups yielded no significant difference. Flat/shallow anterior chamber (AC) was seen exclusively in three eyes (14%) in the SNT group (P = 0.039). There was one occurrence of plate exposure in the LNT group (P = 0.149).

Conclusion

The LNT technique of AGV Implantation may be used as an alternative to the traditional SNT (with autologous graft). The long needle track offers the advantage reducing the risk of complications arising from shallow anterior chamber post-operatively.

Tube Revision Outcomes for Exposure with Different Repair Techniques

Purpose

The aim of this study was to report our experience with eyes that presented with an initial GDD exposure and their subsequent outcome in terms of re-exposure.

Methods

A retrospective review of charts of 42 patients (43 eyes) who presented with a GDD exposure during the period 2008–2015 in a tertiary eye care center was performed. Demographic data, past ocular history, pre-operative and post-operative information including the surgical technique of GDD surgery and exposure repair were recorded. The patients were followed for further exposure to the date of the last follow-up clinic visit. For each type of repair technique, details were collected on risk and timing of GDD exposure. The baseline features of eyes that had further exposure after initial exposure were compared to eyes without further exposure.

Results

Forty-three eyes were identified which had repair after an initial exposure. The mean ± SD age was 54 ± 27 years. Of the GDDs, Ahmed FP7 was performed in 31 eyes, Ahmed FP8 in two eyes, Ahmed S2 in five eyes, Krupin valve in two eyes and Baerveldt 350 GDD in three eyes. The methods of repair and the relative risk [95% CI] of re-exposure were: conjunctival closure only (n=4; RR=2.10 [0.84–5.23]); repair with patch graft and conjunctival repair (n=18), RR=1.24 [0.51–3.01]; tube repositioning, use of patch graft and conjunctival repair (n=14), RR=1.0; tube removal with replacement in a different quadrant, patch graft and conjunctival repair (n=3), RR=1.87 [0.64–5.48]. After the first exposure, 18 eyes had a second re-exposure, four eyes had a third re-exposure, and 1 eye had a fourth exposure.

Conclusions

The GDD exposure rates at our institution are consistent with other reports. Lack of a patch graft for repair is associated with a two-fold risk of subsequent re-exposure.