Pupillary Capture of Intraocular Lens (IOL Capture)

Key Points at a Glance

Pupillary capture of the intraocular lens (IOL capture) is a postoperative complication of cataract surgery in which part of the IOL optic prolapses in front of the iris.
It occurs more frequently after extracapsular fixation, sutured IOL, or intrascleral fixation IOL, and the risk increases with concurrent vitrectomy and gas injection.
The incidence with scleral-sutured IOL is reported to be approximately 3.6% (18 out of 495 eyes). ⁶⁾
Glare and photophobia from the IOL edge are characteristic, and the impact on corrected visual acuity is usually minimal.
Spontaneous reduction with mydriasis and supine positioning is the first-line treatment; for recurrent cases, surgical reduction or laser iridotomy is performed.
Because reverse pupillary block can be a cause of recurrence, appropriate evaluation and management are important.
If the IOL haptic contacts the corneal endothelium, prompt repositioning is required.

1. What is pupillary capture of the intraocular lens?

Pupillary capture refers to a condition in which part of the optic of an intraocular lens (IOL) that is not completely fixed within the capsular bag prolapses in front of the iris. It is more likely to occur after extracapsular fixation or suturing, but even with in-the-bag fixation, the portion not covered by the anterior capsule may protrude in front of the iris. It is known to occur more frequently when gas is injected during combined vitrectomy surgery. In addition, it tends to recur after IOL suturing, and is thought to be sometimes caused by reverse pupillary block.

In modern practice, since in-the-bag fixation has become standard, the overall frequency has been decreasing, but it remains a problem in cases with posterior capsule rupture or in aphakic eyes after sutured or scleral-fixated IOLs. The incidence of pupillary capture with scleral-sutured IOLs has been reported as 18 out of 495 eyes (3.6%), ⁶⁾ and it has also been documented as a late complication in long-term follow-up studies of sutured IOLs inserted during vitrectomy. ¹⁾

Note that intentional insertion of the IOL optic through a posterior continuous curvilinear capsulorhexis (posterior CCC) into the posterior capsule opening, known as “posterior optic capture,” is a deliberate technique to prevent posterior capsule opacification and is distinct from the accidental pupillary capture discussed in this article.

Association with UGH syndrome

When the IOL haptic directly contacts the iris or surrounding tissues due to extracapsular or asymmetric fixation, the haptic mechanically chafes the iris, releasing iris pigment. This pigment deposits in the trabecular meshwork, causing pigmentary glaucoma, and if iris damage is significant, it may be accompanied by iridocyclitis and hyphema. This series of conditions is called uveitis-glaucoma-hyphema (UGH) syndrome. Fixation of a one-piece acrylic IOL in the ciliary sulcus can cause transillumination defects, pigment dispersion, elevated intraocular pressure, recurrent hyphema, and inflammation; therefore, insertion into the ciliary sulcus is contraindicated. ⁷⁾

Q How soon after cataract surgery can pupillary capture occur?

When combined with vitrectomy or after gas injection, it tends to occur early postoperatively (within days to weeks). After sutured or scleral-fixated IOLs, it may develop months to years after surgery and has a tendency to recur. In a study by Vote et al., it was reported as a late complication in long-term follow-up after vitrectomy with sutured IOL. ¹⁾

2. Main symptoms and clinical findings

Slit-lamp photograph showing the IOL optic completely prolapsed in front of the iris, occupying the pupillary area

Ahuja R. Pupillary capture of IOL optic in eye. Wikimedia Commons. 2006. License: CC BY-SA 2.5. https://commons.wikimedia.org/wiki/File:Optic_Capture_of_IOL.jpg

Slit-lamp photograph showing the IOL optic completely dislocated anterior to the iris, with iris tissue pushed behind the optic. This corresponds to the slit-lamp finding of IOL optic anterior dislocation (pupillary capture) discussed in the section “Main Symptoms and Clinical Findings”.

Subjective Symptoms

Glare and photophobia from IOL edge: Characteristically occurs when the optic edge is exposed in the pupillary area. Direct impact on corrected visual acuity is usually minimal.
Refractive error: Astigmatism or changes in spherical power due to IOL decentration are common.
Elevated intraocular pressure: Pupillary block caused by the dislocated optic can increase intraocular pressure, presenting symptoms similar to acute angle-closure attack.
Decreased visual acuity: Usually mild, but may occur with UGH syndrome or cystoid macular edema (CME). ⁶⁾
Pupil deviation or irregular pupil: Pupil shape may change due to interaction between the IOL and iris.

Clinical Findings

Anterior dislocation of IOL optic: Easily observed under dilated pupil with slit-lamp microscopy. Part or all of the optic is seen anterior to the iris.
Changes in anterior chamber depth: In cases of reverse pupillary block, the anterior chamber deepens and the iris bows posteriorly, a characteristic finding.
Iris transillumination defects: Findings of iris chafing by IOL haptics. Confirmed as a sign of UGH syndrome.
Pigment dispersion and anterior chamber pigmentation: Pigment deposition on the trabecular meshwork suggests UGH syndrome.
Hyphema: May occur recurrently.
Corneal edema: Occurs when IOL haptics contact the corneal endothelium.

Q Is treatment necessary even if visual acuity is not decreased?

Even if visual acuity is not significantly affected, treatment should be considered when photophobia due to the IOL edge is severe or when intraocular pressure elevation due to pupillary block is present. If the IOL haptic is in contact with the corneal endothelium, prompt repositioning is necessary; if left untreated, corneal endothelial damage may progress and eventually lead to bullous keratopathy.

3. Causes and Risk Factors

The fundamental cause of pupillary capture is that the IOL is not completely fixed within the capsular bag. The following risk factors have been reported.

Risk Factor	Mechanism
Extracapsular fixation / asymmetric fixation	IOL is not completely covered by the capsule
IOL ciliary sulcus suture	No capsular support, prone to recurrence
Intrascleral fixation (including Yamane technique) ⁸⁾	No capsular support, residual IOL movement
Simultaneous vitrectomy with gas tamponade	Expansile gas pushes the IOL forward
Post-vitrectomy ⁶⁾	Loss of vitreous support for IOL + flaccid iris
Young patients	High iris extensibility
Ciliary sulcus implantation of one-piece acrylic IOL ⁷⁾	Iris chafing due to sharp anterior edge (contraindicated)
Scleral suture placement less than 2 mm from the limbus ⁶⁾	IOL too close to the iris

In a study by Kokame et al., recurrence was significantly lower in the group where the scleral suture position was standardized to 2 mm posterior to the limbus (p=0.025). ⁶⁾

Q What is reverse pupillary block?

Contrary to normal pupillary block, this is a condition where anterior chamber pressure exceeds posterior chamber pressure, and the pupillary margin adheres to the anterior surface of the IOL, acting as a valve. It presents characteristic findings of a deep anterior chamber and posterior bowing of the iris. When the IOL moves anterior to the iris, the flow of aqueous humor from the anterior chamber to the posterior chamber is blocked, further increasing posterior chamber pressure, creating a vicious cycle. Laser iridotomy (LI) is effective in resolving the pressure gradient between the anterior and posterior chambers. ²⁾

4. Diagnosis and Examination Methods

Examination method	Evaluation content	Key points
Slit-lamp microscopy	Positional relationship between IOL optic and iris	Evaluate optic coverage under mydriasis. Also check for haptic prolapse into the anterior chamber.
Tonometry	Intraocular pressure elevation due to pupillary block	Emergency management for acute elevation
Anterior segment OCT	Objective assessment of anterior chamber depth, IOL position, and iris curvature	Useful for evaluating reverse pupillary block
Ultrasound biomicroscopy (UBM)	Positional relationship between IOL and ciliary body/sulcus	Confirmation of IOL position in sutured or intrascleral fixation
Corneal endothelial specular microscopy	Corneal endothelial cell density	Assessment of endothelial damage due to IOL haptic contact
Gonioscopy	Evaluation of pigment deposition and peripheral anterior synechiae	Used for evaluation of UGH syndrome

Differential Diagnosis

IOL dislocation/subluxation: When the IOL is completely displaced and falls into the vitreous cavity, it is managed as a separate condition.
UGH syndrome: This is a related complication of pupillary capture, but can occur without pupillary capture due to IOL contact alone.
IOL decentration/tilt: The IOL is displaced within the capsular bag but does not prolapse in front of the iris.
Acute angle-closure attack: Presents with elevated intraocular pressure, shallow anterior chamber, and fixed dilated pupil; after IOL surgery, differentiation from pupillary capture is important.

Q Is anterior segment OCT necessary for diagnosing pupillary capture?

It is not essential if the diagnosis is clear on slit-lamp examination, but it is useful for evaluating reverse pupillary block (increased anterior chamber depth, posterior bowing of the iris) and for objective documentation of IOL position. Especially in recurrent cases, quantitative assessment of IOL position using anterior segment OCT or UBM helps determine treatment strategy.

5. Standard Treatment

Treatment is selected stepwise according to the onset situation, presence of adhesions, and recurrence frequency.

Step 1: Conservative Repositioning (Acute onset, no adhesions)

After administration of mydriatics (1% tropicamide + 2.5% phenylephrine), place the patient in supine position → attempt spontaneous repositioning.
Effective when the iris and IOL are not adherent.
If pupillary block occurs due to anterior chamber IOL dislocation, use mydriatics (miotics are contraindicated).

Step 2: Surgical Repositioning (If spontaneous repositioning fails)

Reposition the IOL optic behind the iris using a hook or spatula through a side port.
The procedure is easy if the iris and capsule are not significantly adherent.
Outpatient 30G needle paracentesis technique: under topical anesthesia, anterior chamber paracentesis is performed and viscoelastic material is injected to push the IOL posteriorly. Kokame et al. managed all 54 outpatient procedures for pupillary capture in 18 of 495 eyes (3.6%) without transfer to the operating room. ⁶⁾

Step 3: Prevention of recurrence (recurrent cases after sutured IOL)

After IOL suturing or intrascleral fixation, the optic is not covered by the capsule, so pupillary capture tends to recur.

Laser iridotomy (LI / iridectomy): Resolves the pressure difference between the anterior and posterior chambers when reverse pupillary block is involved. Although difficult to decide, it can be effective in some cases. ²⁾
Suture technique (retention suture): If recurrence occurs even after LI, consider passing a suture to prevent the IOL from prolapsing anterior to the iris. Lin et al. reported a rectangular loop suture, and Kim et al. reported a tram-track suture technique. ^3,4)
Iris constriction or additional suturing: For repeated recurrences, reduce the pupil size or the passageway in front of the IOL to prevent optic prolapse. Suppression of recurrence using flanged polypropylene sutures has also been reported. ⁵⁾

Step 4: IOL exchange (irreducible or severe cases)

Performed only when visual function is significantly impaired (highly invasive).
If the iris and capsule are strongly adherent or if the IOL repeatedly dislocates into the anterior chamber, reduction alone is difficult and IOL exchange is necessary.
If the haptic is in the anterior chamber and contacting the corneal endothelium, reposition as soon as possible.
Fixation method during exchange: Ciliary sulcus fixation of a three-piece IOL and optic capture preserving the anterior capsulorhexis provide excellent stability. ⁷⁾

Treatment	Indication	Notes
Mydriasis + supine position	Acute onset, no adhesions	First choice. Miotics are contraindicated
Hook/spatula repositioning	Cases where spontaneous repositioning is not possible	Performed via side port
30G needle paracentesis⁶⁾	Outpatient repositioning	Under topical anesthesia, no operating room required
Laser iridotomy²⁾	Suspected reverse pupillary block	Resolve anterior-posterior chamber pressure difference
Suture fixation method^{3, 4)}	Cases that recur after LI	Scleral fixation suture
Iris suturing and additional suturing⁵⁾	Recurrent repositioning failure	Adjust pupil size and passage
IOL exchange⁷⁾	Irreducible or severe cases	Only when visual function is significantly impaired

Prevention

Fixation position of scleral-sutured IOL: Fixation 2 mm posterior to the limbus significantly reduces recurrence (p=0.025).⁶⁾
Optic capture during ciliary sulcus fixation: If the anterior capsulorhexis is preserved, engaging the optic into the CCC opening improves IOL stability.⁷⁾
Do not insert single-piece acrylic IOL into the ciliary sulcus (risk of iris chafing and UGH syndrome).⁷⁾

Q What should be done if recurrence is repeated?

Recurrence is common after sutured IOL or intrascleral fixation IOL. First, try laser iridotomy to relieve reverse pupillary block²⁾. If recurrence persists, manage with suture tensioning method^3,4) or additional suturing⁵⁾ to prevent the IOL from moving anterior to the iris. In some cases, repositioning can be performed in the outpatient setting using a 30G needle paracentesis technique without transferring to the operating room.⁶⁾

6. Pathophysiology and detailed mechanism

1. Physical instability due to poor IOL fixation

When the IOL is not completely fixated within the capsular bag, eye movements, blinking, and postural changes cause the IOL to oscillate anteriorly and posteriorly. In extracapsular fixation, the haptics are in the ciliary sulcus and the optic is just behind the iris, resulting in insufficient coverage by the anterior capsule. A slight anterior displacement can cause the optic to prolapse beyond the iris.

2. Forward displacement by vitreous gas

When gas is injected during concurrent vitrectomy, the expanding gas pushes the IOL forward, causing the optic to dislocate anterior to the iris beyond the pupillary plane. Although the IOL may reposition after gas absorption, recurrence is common in cases with insufficient capsular support.

3. Iris flaccidity after vitrectomy

Removal of the vitreous eliminates vitreous support for the IOL, making it unstable. In the absence of the lens capsule, iris flaccidity (iridodonesis/flaccid iris) occurs, increasing the anteroposterior mobility of the iris. As a result, the optic is more likely to dislocate anterior to the iris during pupil dilation. ⁶⁾

4. Reverse pupillary block

When anterior chamber pressure exceeds posterior chamber pressure, the pupillary margin adheres to the anterior surface of the IOL, acting as a valve (reverse pupillary block). The anterior dislocation of the IOL obstructs the flow of aqueous humor from the anterior chamber to the posterior chamber, creating a vicious cycle that further increases posterior chamber pressure. Characteristic findings include a deep anterior chamber and posterior bowing of the iris. ²⁾

5. Mechanism of UGH syndrome

Mechanical chafing of the iris by the IOL support releases iris pigment. Pigment deposition in the trabecular meshwork leads to pigmentary glaucoma, and persistent chafing progresses to UGH syndrome, which combines iridocyclitis and hyphema.

6. Influence of IOL material and design

Ciliary sulcus fixation of one-piece acrylic IOLs tends to cause iris transillumination defects and pigment dispersion due to the sharp anterior optic/haptic edge. ⁷⁾ Three-piece IOLs have a posterior haptic angle and lower risk of iris chafing during ciliary sulcus fixation. Adequate optic diameter (≥6.0 mm) and haptic length contribute to stability in ciliary sulcus fixation.

7. Recent research and future perspectives

Advances in outpatient repositioning techniques

Kokame et al. (2022) reported a 30G needle paracentesis technique that managed pupillary capture in 18 of 495 eyes (3.6%) over 54 outpatient procedures. All procedures were performed painlessly under topical anesthesia and may serve as an effective alternative when operating room access is limited. Setting the scleral suture position 2 mm posterior to the limbus significantly reduced recurrence (p=0.025), indicating that optimizing intraoperative fixation position is important as a preventive strategy. ⁶⁾

Advances in intrascleral fixation

The Yamane method (flanged intrascleral fixation, 2017) uses a double-needle technique to fixate the IOL haptic within the sclera. Its advantage over conventional suturing is the avoidance of suture erosion or breakage, but since it lacks capsular support like suturing, the risk of pupillary capture remains. ⁸⁾ The concept of sutureless intrascleral fixation was first reported by Gabor & Pavlidis (2007) ⁹⁾, and Agarwal (2008) ¹⁰⁾ described a sutureless fixation method using fibrin glue. The incidence of pupillary capture and comparison with suturing methods are topics for future investigation.

Optimization of scleral suture position

Fixation at 2 mm posterior to the limbus has been shown to significantly reduce recurrence of pupillary capture (p=0.025), and accumulation of data toward standardization of optimal fixation position is desired. ⁶⁾

Q Is pupillary capture less likely with intrascleral fixation (Yamane method)?

Intrascleral fixation avoids suture-related complications (erosion, breakage) compared to suturing methods, but since it also lacks capsular support, the risk of pupillary capture remains. Direct comparative data on the incidence of both are limited and require future investigation. ⁸⁾

8. References

Vote BJ, Tranos P, Bunce C, et al. Long-term outcome of combined pars plana vitrectomy and scleral fixated sutured posterior chamber intraocular lens implantation. Am J Ophthalmol. 2006;141(2):308-312. PMID: 16458685
東出朋巳. 眼内レンズ毛様溝縫着後の逆瞳孔ブロックによる虹彩捕獲とその治療. IOL & RS. 2009;23(3):410-412. URL: https://cir.nii.ac.jp/crid/1573950399792764160
Lin K, Hu Z, Lin Z, Chen T, Tang Y, Wu R. Rectangular loop suture to correct iris capture of the posterior chamber intraocular lens. BMC Ophthalmol. 2020;20:383. doi:10.1186/s12886-020-01650-3.
Kim SI, Kim K. Tram-Track Suture Technique for Pupillary Capture of a Scleral Fixated Intraocular Lens. Case Rep Ophthalmol. 2016;7(2):290-295. PMID: 27462257. PMCID: PMC4943309. doi:10.1159/000446208.
Kim DH, Moon DRC, Kang YK, et al. Case report: Management of recurrent pupillary optic capture with sutureless surgical technique using 7-0 polypropylene flange. Front Med (Lausanne). 2024;11:1367905. doi:10.3389/fmed.2024.1367905.
Kokame GT, Card K, Pisig AU, Shantha JG. In office management of optic capture of scleral fixated posterior chamber intraocular lenses. Am J Ophthalmol Case Rep. 2022;25:101356. doi:10.1016/j.ajoc.2022.101356.
American Academy of Ophthalmology. Cataract in the Adult Eye Preferred Practice Pattern. Ophthalmology. 2022;129(4):P52-P142.
Yamane S, Sato S, Maruyama-Inoue M, Kadonosono K. Flanged intrascleral intraocular lens fixation with double-needle technique. Ophthalmology. 2017;124(8):1136-1142. PMID: 28457613
Gabor SGB, Pavlidis MM. Sutureless intrascleral posterior chamber intraocular lens fixation. J Cataract Refract Surg. 2007;33(11):1851-1854. PMID: 17964387
Agarwal A, Kumar DA, Jacob S, et al. Fibrin glue-assisted sutureless posterior chamber intraocular lens implantation in eyes with deficient posterior capsules. J Cataract Refract Surg. 2008;34(9):1433-1438. PMID: 18721701

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