Abstract
Background
Late subluxation of an intraocular lens (IOL) within the capsular bag is a rare complication of cataract surgery, primarily associated with progressive zonular weakening in conditions such as pseudoexfoliation syndrome, high myopia, prior vitreoretinal surgery, connective tissue disorders, or ocular trauma. While IOL-capsular bag subluxation is well-documented, its impact on glaucoma drainage devices remains poorly understood. We present a rare case of Valsalva-induced IOL subluxation obstructing an Ahmed glaucoma valve, resulting in acute intraocular pressure (IOP) elevation in a patient with pseudoexfoliative glaucoma.
Case presentation
A 66-year-old man with pseudoexfoliative glaucoma underwent uneventful phacoemulsification with IOL implantation in his left eye in 2013. He subsequently required trabeculectomy in 2015 and later an Ahmed glaucoma valve implantation due to uncontrolled IOP (38 mmHg). Postoperatively, his IOP remained stable (8–10 mmHg) without medication. Six months postoperatively, the patient developed persistent visual deterioration and ocular pain, which began three days after a severe coughing episode. Examination revealed a best-corrected visual acuity of 20/100 and IOP of 32 mmHg. Slit-lamp biomicroscopy demonstrated superior IOL subluxation, with the displaced IOL pushing the iris forward and resulting in obstruction of the Ahmed tube tip by the iris. Intraoperatively, the IOL was repositioned without posterior vitrectomy, restoring tube patency and IOL centration. Postoperatively, IOP normalized to 9 mmHg, and best-corrected visual acuity remained 20/100. Two months post-repositioning, IOP remained stable at 12 mmHg, with no further IOL displacement or tube obstruction.
Conclusions
This case highlights an uncommon mechanism of glaucoma tube obstruction caused by Valsalva-induced IOL subluxation. While common causes of glaucoma drainage devices obstruction include vitreous prolapse, inflammatory debris, and tube malposition, clinicians should recognize IOL subluxation as a potential cause of mechanical blockage. Given the progressive nature of zonular instability in pseudoexfoliation, close monitoring of IOL position, IOP, and tube function is crucial.
Keywords: Ahmed glaucoma valve, Glaucoma drainage device, Intraocular lens subluxation, Pseudoexfoliative glaucoma
Background
Late subluxation of an intraocular lens (IOL) within the capsular bag is an uncommon complication following uneventful cataract surgery [1]. It is primarily associated with progressive zonular weakening in patients with conditions such as pseudoexfoliation syndrome, uveitis, high myopia, prior vitreoretinal surgery, retinitis pigmentosa, connective tissue disorders, or a history of zonular trauma [2–4]. However, the impact of IOL-capsular bag subluxation on eyes with implanted glaucoma drainage devices remains poorly understood. Here, we report a case in which an IOL-capsular bag subluxation led to obstruction of an Ahmed glaucoma valve in an elderly patient with pseudoexfoliative glaucoma following a Valsalva maneuver.
Case presentation
A 66-year-old man with no underlying conditions other than hypertension underwent uneventful phacoemulsification with implantation of a one-piece hydrophobic acrylic IOL in his left eye in 2013. He was later diagnosed with pseudoexfoliative glaucoma in the same eye and underwent trabeculectomy with mitomycin C application in 2015. There was no prior history of pars plana vitrectomy. Despite maximal medical treatment, his intraocular pressure (IOP) remained elevated at 38 mmHg, necessitating implantation of an Ahmed glaucoma valve (model FP7; New World Medical, Inc., Rancho Cucamonga, CA) with the plate positioned superotemporally and the tube tip inserted into the anterior chamber. Following Ahmed glaucoma valve implementation, the best-corrected visual acuity (BCVA) was 20/25, and IOP was maintained between 8 and 10 mmHg without the use of ocular hypotensive medication (Fig. 1).
Fig. 1.
Postoperative day 1: Slit-lamp photograph of the left eye showing the Ahmed glaucoma valve implanted in the superotemporal quadrant
At six months postoperatively, the patient presented with persistent visual deterioration and ocular pain in the left eye, which began three days after a severe coughing episode. The BCVA of the left eye was 20/100, and the IOP was 32 mmHg. Slit-lamp biomicroscopy revealed superior IOL subluxation, with the displaced IOL pushing the iris forward, resulting in the iris obstructing the tip of the Ahmed glaucoma valve tube (Fig. 2). Intraoperative examination revealed superior subluxation of the IOL–capsular bag complex. No vitreous prolapse or vitreous strands were observed in the anterior chamber. Therefore, the IOL was repositioned by gently pushing it back into place, without requiring a posterior vitrectomy.
Fig. 2.
Intraocular lens subluxation obstructing glaucoma drainage device: After a coughing episode, superior intraocular lens subluxation was observed, with the displaced intraocular lens pushing the iris forward and resulting in obstruction of the Ahmed tube tip by the iris
After IOL repositioning, the IOL was well-centered, and the Ahmed tube tip remained patent. Postoperatively, the BCVA was 20/100, and the IOP was 9 mmHg. Two months after IOL repositioning, the IOP was 12 mmHg, and the BCVA remained 20/100. No further IOL displacement or tube obstruction was observed (Fig. 3).
Fig. 3.
Two months after IOL repositioning: No further IOL displacement or tube obstruction was observed
Discussion
We report an unusual case of Valsalva-induced IOL subluxation obstructing a glaucoma valve shunt, leading to acute IOP elevation. In the context of glaucoma drainage device surgery, tube obstruction in the anterior chamber is a recognized complication, resulting in sudden IOP spike, ocular pain, inflammation, and vision deterioration [5]. Common causes of tube obstruction include iris incarceration, blood clots, vitreous incarceration, inflammatory debris, silicone oil, and tube malposition [6]. However, this case presents a rare instance of mechanical blockage in which the iris, displaced by a subluxated IOL, occluded the glaucoma drainage tube—highlighting the need for clinicians to consider IOL subluxation as a potential cause of glaucoma drainage device malfunction.
Pseudoexfoliation syndrome is a well-established risk factor for late IOL subluxation [7, 8]. In eyes with pseudoexfoliation syndrome, the accumulation of fibrillar material on ocular structures leads to progressive zonular weakening [9]. This degradation of the zonules compromises the stability of the IOL-capsular bag complex over time, increasing the risk of subluxation or dislocation. In the present case, the patient’s history of pseudoexfoliation syndrome likely contributed to zonular instability, predisposing the IOL to displacement following a Valsalva maneuver.
The Valsalva maneuver, which involves forceful exhalation against a closed glottis, is known to increase intrathoracic and intra-abdominal pressures [10]. This action can lead to elevated IOP and increased vitreous pressure within the eye [11]. The mechanism involves increased venous pressure, which impedes aqueous humor outflow and elevates IOP [11]. In susceptible individuals, such as those with zonular weakness, this pressure elevation can further destabilize the IOL-capsular bag complex, leading to subluxation or dislocation. A previously reported case in the literature described this mechanism in action: following a Valsalva maneuver induced by coughing, the increased vitreous pressure pushed the IOL–capsular bag complex anteriorly [12]. As a result, the Ahmed glaucoma valve tube tip, which had been positioned anterior to the IOL optic, was displaced posteriorly behind the IOL–capsular bag complex. This case highlights how transient yet substantial shifts in intraocular dynamics during Valsalva maneuvers can lead to significant anatomical displacement, particularly in eyes with predisposing factors such as zonular instability.
In our case, IOL repositioning alone successfully restored IOL centration and relieved the tube obstruction, leading to normalization of IOP. Although this patient exhibited significant zonular weakness and IOL dislocation, and the iris blocking the tube tip was notably thick—prompting consideration of surgical intervention—laser iridotomy may still represent a potential treatment option for lowering IOP. Given the progressive nature of zonular weakness, which predisposes the eye to recurrent IOL subluxation, further deterioration may necessitate additional interventions, such as pars plana vitrectomy and/or IOL scleral fixation, to stabilize the IOL. Therefore, close follow-up is essential to monitor IOL position, IOP, and tube patency over time.
Conclusions
We described a rare complication of Valsalva-induced IOL subluxation obstructing a glaucoma valve shunt in a patient with pseudoexfoliative glaucoma. This case highlights the importance of monitoring IOL stability in patients with pseudoexfoliation syndrome and educating them about activities that may trigger IOL displacement. Clinicians should remain vigilant for uncommon causes of glaucoma drainage device obstruction, such as IOL subluxation, to facilitate timely and appropriate management.
Acknowledgements
Not applicable.
Abbreviations
- BCVA
Best-corrected visual acuity
- IOL
Intraocular lens
- IOP
Intraocular pressure
Authors’ contributions
JJ designed the work. AH worte the main manuscript. KTN collected the patient’s data. SK and JWC interpreted the clinical data. All authors read and approved the final manuscript.
Funding
This work was supported by the 2025 education, research and student guidance grant (C3197) funded by Jeju National University.
Data availability
No datasets were generated or analysed during the current study.
Declarations
Ethics approval and consent to participate
The participant provided written informed consent.
Consent for publication
Written informed consent to publish the case report was obtained from the patient.
Competing interests
The authors declare no competing interests.
Footnotes
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Data Availability Statement
No datasets were generated or analysed during the current study.