Intraoperative Complications of Cataract Surgery

Overview

Phacoemulsification is a closed, high-pressure system that depends on two structures staying intact through the whole case: the posterior capsule, which holds the vitreous back from the anterior segment, and the zonular fibers, which keep the capsular bag centered and stable while instruments move through it. Nearly every serious intraoperative complication traces to a breach of one of these structures, or to a secondary consequence of that breach: vitreous prolapsing forward once the capsule is gone, a nucleus fragment dropping posteriorly with nothing left to catch it, or a bag that destabilizes because its zonular support has failed.

A second category of complications has nothing to do with capsule or zonular integrity. These reflect iris behavior, thermal energy at the wound, or a sudden pressure event inside the eye instead. What matters clinically is recognizing each complication's intraoperative sign rather than only its downstream consequence, since that is what lets a surgeon intervene before a manageable problem becomes a vision-threatening one.

Posterior Capsule Rupture & Vitreous Loss

Posterior Capsule Rupture (PCR)

Posterior capsule rupture (PCR) is the most common serious intraoperative complication of phacoemulsification, occurring in roughly 1–5% of cases. Its classic warning signs are a sudden, unexplained deepening of the anterior chamber, a momentary pupil dilation, and lens fragments that suddenly resist engagement or rotation after moving freely moments before. Any one of these findings should stop the case: reduce irrigation flow and inspect the capsule before proceeding. Continuing to emulsify against a torn capsule is how a small, manageable rent turns into vitreous loss or a dropped nucleus.

Vitreous Loss Management

Once vitreous has prolapsed into the anterior chamber, the standard of care is a mechanized anterior (or bimanual) vitrectomy with a vitreous cutter, not manual sweeping with a spatula or simply continuing the case under more viscoelastic. A cutter clears vitreous from the anterior segment and wound while transmitting minimal traction to the retina. That traction is the real hazard: strands still attached posteriorly drive the two feared downstream consequences of vitreous loss, retinal detachment and cystoid macular edema. Triamcinolone acetonide is often injected first to stain the vitreous; its particles adhere to vitreous strands and render otherwise invisible vitreous visible against the red reflex, turning the vitrectomy into a complete procedure rather than a guess.

That retinal detachment risk doesn't end when the case does. A large national cataract-surgery audit linked posterior capsule rupture with vitreous loss to a sharply higher rate of retinal detachment surgery within the following months, and separate population-based follow-up shows the elevated risk persists for several years rather than settling back toward baseline once the eye has quieted down. The practical consequence is a lower threshold to dilate and examine the periphery at these patients' follow-up visits, not only in the first postoperative week.

Dropped Nucleus / Retained Lens Fragments

If a posterior capsule rupture is large enough, a lens nucleus fragment can drop posteriorly into the vitreous cavity instead of staying accessible in the anterior segment. Chasing it with anterior segment instruments risks catastrophic traction on the retina. The correct move is to stop, stabilize the anterior segment, and refer for pars plana vitrectomy by a retina specialist. Retained lens material is not inert: the longer it sits in the vitreous, the more inflammation, elevated intraocular pressure, and cystoid macular edema it provokes, which is why vitrectomy to remove it is pursued rather than observation alone.

Intraoperative Floppy Iris Syndrome & Iris Prolapse

Intraoperative Floppy Iris Syndrome (IFIS)

IFIS is most strongly associated with alpha-1 adrenergic antagonists, tamsulosin being the prototype (used for benign prostatic hyperplasia), which cause atrophy of the iris dilator muscle. The classic intraoperative triad: a billowing, floppy iris that undulates with ordinary irrigation flow, progressive intraoperative miosis despite adequate preoperative dilation, and iris tissue that tends to prolapse toward the phaco and side-port incisions. The effect is on the dilator muscle itself, not on pupil size, so a good preoperative dilation does not rule IFIS out. A documented history of tamsulosin or another alpha-blocker is the more reliable predictor, and it is worth asking about even when the pupil looks fine at the slit lamp.

Iris Prolapse

Iris tissue prolapsing through a corneal incision, whether from IFIS, a tight wound, or simple positive vitreous pressure, is first managed by gently repositioning it with viscoelastic to reform the anterior chamber and reduce the pressure differential pushing it out. Excising the prolapsed tissue or suturing the wound closed over it are overly aggressive first responses. Both risk permanent iris damage and a resulting cosmetic or photic disturbance; repositioning addresses the pressure imbalance directly instead.

Suprachoroidal Hemorrhage, Wound Burn & Descemet's Detachment

Suprachoroidal (Expulsive) Hemorrhage

Acute suprachoroidal hemorrhage is rare but among the most feared intraoperative events, caused by rupture of a choroidal vessel. Its hallmark presentation is sudden severe ocular pain, loss of the red reflex, and a rock-hard eye: a triad that demands immediate wound closure to prevent expulsion of intraocular contents through the incision. The strongest recognized risk factor is poorly controlled systemic hypertension. Advanced age, arteriosclerosis, and a sudden intraoperative drop in intraocular pressure (hypotony) add further stress to choroidal vessels already made fragile by chronic vascular disease.

Phaco Wound Burn

Excessive phacoemulsification energy or inadequate irrigation cooling near the incision can thermally injure the corneal wound: a phaco wound burn. The resulting stromal coagulation causes visible wound gape and contributes to postoperative astigmatism, because a burned wound no longer seals or heals like an unburned incision. Irrigation flow around the phaco tip dissipates the ultrasonic energy as heat before it reaches the stroma, so sudden occlusion of irrigation, a plugged phaco tip, for instance, is a common precipitant.

Descemet's Membrane Detachment

An extensive Descemet's membrane detachment noted during surgery is managed by injecting air or gas into the anterior chamber to tamponade the detached membrane back against the posterior stroma, a technique known as descemetopexy. Simple observation risks a persistently detached membrane and chronic stromal edema, while immediate endothelial keratoplasty is a far bigger procedure than most detachments actually warrant as a first-line response.

Capsulorhexis Tears & Zonular Dehiscence

Capsulorhexis Complications

An anterior capsulorhexis tear that extends radially to the lens equator, a radial tear-out, compromises the entire continuous curvilinear capsulorhexis and can propagate posteriorly, raising the risk of posterior capsule rupture and vitreous loss later in the case. Intumescent (swollen) white cataracts carry a particular risk: high intralenticular pressure inside the swollen lens can tear the capsulorhexis radially the moment it is initiated. When the case starts with trypan blue capsule staining, this failure pattern produces a recognizable finding: alternating blue-white-blue bands radiating from the tear, the Argentinian flag sign, named for its resemblance to the country's flag.

Zonular Dehiscence

Zonular dehiscence during surgery is most significantly increased by pseudoexfoliation syndrome, which deposits abnormal fibrillar material along the zonular fibers and weakens their attachment to both the lens capsule and the ciliary body. A weakened zonular apparatus predisposes to zonular dialysis, lens subluxation, and capsular instability intraoperatively. That connection, and how it is anticipated and managed preoperatively rather than discovered mid-case, is covered in more depth on the pseudoexfoliation and zonular instability page.

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