Anterior chamber washout is a procedure in which pathologically accumulated substances in the anterior chamber are flushed out with irrigation fluid. Pathological substances targeted for washout include blood, pus, inflammatory mediators, chemicals, and ophthalmic viscosurgical devices (OVDs). Anterior chamber washout is not an independent disease but is positioned as a therapeutic procedure performed for various anterior segment diseases and postoperative complications.
The anterior chamber is a closed space of approximately 0.2 mL, with the only substantial outflow route being the aqueous humor drainage pathway through the trabecular meshwork. In conditions such as endophthalmitis, hyphema, and chemical burns where pathological substances accumulate rapidly, natural drainage is limited, and early mechanical removal directly protects intraocular tissues such as the corneal endothelium, iris, and lens.
The main indications and purposes of anterior chamber washout are shown below.
| Indication | Purpose of washout |
|---|---|
| Endophthalmitis | Removal of causative bacteria/inflammatory substances; protection of corneal endothelium and intraocular tissues |
| Hemorrhagic glaucoma (hyphema) | Removal of hyphema, intraocular pressure control, prevention of rebleeding |
| Hyphema in infants | Prevention of visual deprivation amblyopia |
| Recurrent hemorrhagic glaucoma (corneal blood staining) | Prevention of corneal blood staining, intraocular pressure reduction |
| Chemical (alkali) burns | Removal of intraocular chemical substances and reduction of inflammation |
In addition to the above five diseases, anterior chamber irrigation is also performed in the following conditions.
Meta-analyses have shown that intraoperative intracameral antibiotic administration reduces the risk of postoperative endophthalmitis1), and the importance of intraoperative antibiotic administration is recognized from a prophylactic perspective of anterior chamber irrigation.
The main indications are conditions where pathological substances accumulate in the anterior chamber, such as endophthalmitis, hyphema, and chemical burns. It is also indicated for elevated intraocular pressure due to retained viscoelastic material after cataract surgery, and for non-infectious anterior segment inflammation called TASS. Surgical irrigation is chosen when conservative treatment fails to improve the condition, or when prevention of irreversible complications such as corneal blood staining is necessary.
The main subjective symptoms that occur depending on the condition requiring anterior chamber irrigation are shown below.
Slit-lamp examination of the anterior chamber determines the need for and urgency of irrigation.
Moderate
Hypopyon: White to yellow fluid level in the inferior anterior chamber. Seen in endophthalmitis and TASS.
Hyphema with fluid level: Formation of a blood level in the anterior chamber. Corresponds to Grade I–II.
Fibrin deposition: Reticular to membranous deposits appear in the anterior chamber.
Severe
Total hypopyon/total hyphema: The entire anterior chamber is filled with inflammatory material or blood. Corresponds to Grade III–IV.
Mutton-fat keratic precipitates: Large inflammatory cell deposits on the corneal endothelium. Suggests severe endophthalmitis.
Corneal edema/opacity: Reflects sustained high intraocular pressure or corneal endothelial damage.
Inability to visualize the fundus: Ultrasound examination is necessary to determine the need for vitrectomy.
Acute postoperative vision loss is an important sign of endophthalmitis. Onset within 1–2 days after surgery suggests TASS (non-infectious), while onset from several days to one week postoperatively strongly suggests infectious endophthalmitis 1). TASS primarily presents with hyperemia and vision loss, often with mild eye pain, whereas infectious endophthalmitis is accompanied by eye pain, discharge, and hypopyon. Prompt ophthalmologic evaluation is essential in either case.
The risk factors for each condition requiring anterior chamber irrigation are described below.
The main risk factors for postoperative endophthalmitis after cataract surgery are as follows 2)7).
Non-infectious anterior segment inflammation, with the main causes as follows8).
The following examinations are performed in combination to determine the indication for anterior chamber irrigation.
The main indications for hyphema and endophthalmitis are shown below.
| Condition | Surgical Indication Criteria |
|---|---|
| Hyphema (healthy individuals) | ≥50 mmHg for 5 days, or ≥35 mmHg for 7 days |
| Hyphema (sickle cell disease) | ≥25 mmHg persisting for ≥24 hours |
| Hyphema (corneal blood staining) | Emergency surgery upon signs of corneal blood staining |
| Hyphema (infants and children) | When total hyphema causes visual deprivation with risk of amblyopia |
| Endophthalmitis (anterior chamber localized type) | Hypopyon present, mild vitreous opacity → anterior chamber washout + intracameral antibiotic injection |
| Endophthalmitis (vitreous opacity type) | If vitreous opacity is severe → prioritize emergency vitrectomy |
In healthy individuals, anterior chamber washout is indicated when intraocular pressure is 50 mmHg or higher for 5 days or more, or 35 mmHg or higher for 7 days or more11). If signs of corneal blood staining are present, early surgery should be considered regardless of intraocular pressure level. In patients with sickle cell disease, the criteria are stricter: intervention should be considered if pressure is 25 mmHg or higher for more than 24 hours. In children, more aggressive decision-making is required due to the risk of amblyopia from visual deprivation.
The technique of anterior chamber washout is selected based on the severity of the condition and the facility’s situation.
This method is performed as an outpatient procedure for mild cases or when rapid intervention is needed.
For thorough washout, an irrigation/aspiration (I/A) device used in cataract surgery is employed in the operating room.
This is indicated when inflammation is confined to the anterior chamber and vitreous opacity is mild. Along with anterior chamber irrigation, the following antibiotics are injected into the anterior chamber and vitreous cavity.
If vitreous opacity is extensive, emergency vitrectomy is performed. According to the Endophthalmitis Vitrectomy Study (EVS), in acute postoperative endophthalmitis with initial visual acuity of hand motion (HM) or better, tap and inject and immediate vitrectomy showed equivalent visual outcomes. However, for eyes with initial visual acuity of light perception (LP) or worse, immediate vitrectomy was significantly superior3).
TASS is a non-infectious anterior segment inflammation that develops within 1–2 days after surgery, and differentiation from infectious endophthalmitis is important. The timing of onset, degree of eye pain, and culture results of the anterior chamber fluid should be comprehensively evaluated 8). In many cases, anterior chamber irrigation and aggressive steroid eye drops rapidly reduce inflammation.
| Item | Outpatient two-site puncture method | Operating room I/A device method |
|---|---|---|
| Anesthesia | Topical anesthesia | Topical to local anesthesia |
| Washing efficiency | Low to moderate | High |
| Intracapsular irrigation | Difficult | Possible |
| Indicated conditions | Mild/emergency | Moderate to severe |
If performed as an outpatient procedure (two-site puncture method), it may be possible as a day procedure. Irrigation using an I/A device in the operating room can also be done as a day procedure for mild cases, but for endophthalmitis or severe hyphema, hospitalization is desirable for postoperative infection control and systemic management.
The anterior chamber has the trabecular meshwork and Schlemm’s canal as its only substantial outflow pathway for aqueous humor. When blood, pus, viscoelastic substances, or chemicals accumulate in this space, the outflow mechanism becomes physically and chemically obstructed, leading to a cascade of elevated intraocular pressure and tissue damage.
Rapid proliferation of bacteria in the anterior chamber triggers the following cascade.
Intraocular pressure elevation associated with hyphema occurs through multiple mechanisms11).
When high intraocular pressure persists and hyphema is prolonged, the pump function of the corneal endothelium is impaired. Hemoglobin breakdown products (hemin, bilirubin, etc.) gradually deposit in the corneal stroma, causing the cornea to become yellowish-brown to brown and cloudy. Once corneal blood staining develops, there is no effective treatment, and only waiting for absorption is possible. Therefore, from a preventive perspective, early anterior chamber washout is important to prevent the development of corneal blood staining in cases of prolonged hyphema with elevated intraocular pressure.
Viscoelastic substances (such as sodium hyaluronate) are used in the anterior chamber and capsular bag during surgery. If not sufficiently removed postoperatively, their viscosity can physically obstruct the trabecular meshwork, causing transient postoperative ocular hypertension 12). High molecular weight, high viscosity OVDs carry a higher risk of intraocular pressure elevation.
Alkali is fat-soluble and therefore penetrates the full thickness of the cornea, raising the pH in the anterior chamber. pH changes damage the corneal endothelium, iris stroma, and lens epithelium. Alkali dissolves intraocular lipid membranes and causes tissue necrosis, so rapid dilution and removal of alkali from the anterior chamber is important to reduce tissue damage.
When an intraocular lens is fixated outside the capsular bag or becomes asymmetrically fixated, the haptic directly contacts and rubs against the iris. Iris pigment clogs the trabecular meshwork, leading to pigmentary glaucoma. If iris damage is severe, it may be accompanied by iridocyclitis and hyphema (uveitis-glaucoma-hyphema syndrome). If conservative treatment does not improve the condition, IOL exchange or removal is necessary.
Large multicenter studies have shown the efficacy of intracameral cefuroxime (1 mg/0.1 mL) administration during surgery for preventing postoperative endophthalmitis. The risk of endophthalmitis was significantly reduced in the intracameral cefuroxime group, with an odds ratio of 0.26 (95% CI: 0.15–0.45)1). Anterior chamber irrigation is a treatment procedure for postoperative endophthalmitis, but prophylactic intracameral antibiotic administration during surgery is becoming more widespread.
The Shimada method, which involves repeated intraoperative irrigation of the ocular surface with 0.25% povidone-iodine solution, has been reported to reduce the rate of anterior chamber bacterial contamination at the end of surgery (p = 0.0017)6). Intraoperative irrigation in addition to conventional preoperative disinfection may contribute to the prevention of postoperative endophthalmitis.
Recent systematic reviews have pointed out that systemic antibiotics have limited intravitreal penetration in postoperative endophthalmitis5), leading to a reassessment of the role of systemic administration. Local administration into the anterior chamber and vitreous cavity is considered the mainstay of treatment, while systemic administration is thought to play only an adjunctive role.
