Wipe-out or snuff-out phenomenon is a rare but serious complication that occurs after glaucoma surgery. It is characterized by idiopathic and irreversible vision loss that occurs early postoperatively.
It has been mainly reported in association with trabeculectomy, but there are also case reports after cataract surgery. The incidence varies from 0.75% to 13.6% in past studies, and recent evidence suggests it is even less frequent.
A prospective study evaluating the outcomes of end-stage glaucoma has provided important insights into visual prognosis after surgery. Most earlier reports were limited to retrospective analyses, and the variability in incidence is largely due to differences in study design.
Of note, the very existence of this phenomenon has long been a subject of debate, and no clear consensus has been reached.
Past reports have shown a wide range of 0.75% to 13.6%, but recent prospective studies suggest it is even less frequent. The variability in incidence reflects differences in study design and severity of the target patients.
The exact etiology of the wipe-out phenomenon is currently unknown. Several potential mechanisms have been proposed.
Identified causative factors include the following:
Having a severely constricted visual field (end-stage glaucoma) before surgery is considered the greatest predisposing factor.
The main risk factors are listed below.
| Classification | Risk Factors | Details |
|---|---|---|
| General | Advanced age, systemic diseases | Cardiovascular disease, diabetes |
| Preoperative | End-stage glaucoma | MD < −20 dB, fixation split |
| Postoperative | Severe hypotony | IOP ≤ 2 mmHg, choroidal detachment |
Risk factors for suprachoroidal hemorrhage include myopia, glaucoma, diabetes, arteriosclerotic vascular disease, hypertension, and prolonged intraoperative hypotonia1).
Risk factors for expulsive hemorrhage include advanced age, glaucoma, high myopia, aphakia, and arteriosclerotic cardiovascular disease, with an incidence of approximately 0.04–0.1% during cataract surgery.
A careful comparison of the benefits and risks of surgery is necessary, and it cannot be said that surgery should always be avoided. It is possible to choose surgical techniques that reduce the risk of wipeout, such as non-penetrating deep sclerectomy (NPDS) or trabeculectomy with mitomycin C (MMC). For details, see the section on standard treatments.
Wipeout phenomenon is a clinical diagnosis. It is diagnosed as vision loss occurring immediately after glaucoma surgery in patients with risk factors for end-stage glaucoma.
It is important to rule out the following diseases.
| Differential diagnosis | Key differentiating points |
|---|---|
| Ocular hypotony maculopathy | Intraocular pressure ≤4 mmHg |
| Choroidal detachment/hemorrhage | Dome-shaped elevation on ultrasound |
| Macular edema | Macular thickening on OCT |
| Retinal detachment | Fundus/Ultrasound |
| Optic neuropathy | Visual field/OCT |
The main examination methods are shown below.
Prevention is the most important measure against the wipe-out phenomenon. The following strategies are recommended.
The focus is on postoperative intraocular pressure stabilization and improvement of ocular perfusion.
NPDS
Non-penetrating deep sclerectomy (NPDS): This surgical technique avoids a sudden drop in intraocular pressure by not penetrating the eye, minimizing the wipe-out risk while achieving intraocular pressure reduction.
Indications: Particularly useful in cases with high risk for penetrating surgery, such as advanced glaucoma.
Trabeculectomy with Mitomycin C
Trabeculectomy with mitomycin C: Trabeculectomy with adjunctive use of mitomycin C (MMC).
Evidence: A prospective analysis reported no evidence of the wipe-out phenomenon. Proper suture management and postoperative intraocular pressure control are important.
Antifibrotic agents are associated with increased risks of hypotony, hypotony maculopathy, late bleb leak, and late infection 2). Laser suture lysis or removal of releasable sutures can be used to adjust aqueous outflow in the early postoperative period 2). Transconjunctival needling (with 5-FU/mitomycin C) is considered effective for reactivating a failing bleb 2).
If expulsive hemorrhage occurs during surgery, first close all wounds. Intraoperative blood pressure management and sedation are effective for prevention.
Vision loss is generally irreversible, and no established treatment currently exists to restore it. Therefore, preventive management is most important. The risk of onset can be reduced through stepwise intraocular pressure reduction, careful patient selection, and appropriate postoperative management.
In end-stage glaucoma, long-term elevated intraocular pressure increases the structural vulnerability of the optic nerve. Additionally, impaired blood flow autoregulation heightens sensitivity to intraocular pressure fluctuations, and a rapid postoperative drop in intraocular pressure is thought to easily induce ischemia of the optic disc and retina. For details on the pathogenesis, see the “Pathophysiology” section.
In end-stage glaucoma, the optic nerve is severely damaged due to long-term elevated intraocular pressure and progressive loss of retinal ganglion cells. Such an optic nerve is considered particularly vulnerable to changes in ocular perfusion and pressure dynamics. Accumulation of histopathological studies is insufficient, and the pathological basis has not yet been fully defined.
Mechanical Factors
Deformation of the lamina cribrosa: A sudden decrease in intraocular pressure causes mechanical deformation of the lamina cribrosa, leading to axonal damage.
Structural vulnerability of the optic nerve: In end-stage glaucoma, the structure of the lamina cribrosa is already weakened and reacts excessively to even slight pressure changes.
Vascular factors
Decreased perfusion pressure: Low intraocular pressure reduces ocular perfusion pressure, leading to ischemia of the optic disc and retina.
Impaired autoregulation of blood flow: Excessive response to intraocular pressure fluctuations leads to microcirculatory collapse. Sudden intraoperative low intraocular pressure may cause optic nerve hemorrhage or microembolic episodes.
Inflammatory and Hemorrhagic Factors
Postoperative inflammation: Inflammatory cytokines exacerbate vascular damage and enhance direct injury to the optic nerve.
Suprachoroidal hemorrhage: Caused by rupture of deep choroidal vessels. The main cause is intraoperative and postoperative hypotony, with expulsive hemorrhage due to rupture of the posterior ciliary artery being the most severe form.
Markedly low intraocular pressure (IOP ≤4 mmHg) causes the posterior segment of the eye to bow forward, leading to the formation of macular folds. Prolonged hypotony can cause these folds to become fixed, resulting in permanent visual impairment. IOP ≤4 mmHg often leads to severe vision loss (≤0.2).
A meta-analysis of trabeculectomy outcomes reported frequencies of shallow anterior chamber 13.6%, hypotony 11.7%, choroidal effusion 8.3%, and endophthalmitis 1.7%3). These complications can serve as a basis for the wipe-out phenomenon.
NPDS has been reported to significantly lower intraocular pressure while minimizing the risk of wipe-out. Since it does not involve perforation, sudden intraocular pressure fluctuations can be avoided, raising expectations for safety in patients with end-stage glaucoma.
In a prospective analysis of trabeculectomy combined with mitomycin C, no evidence of wipeout phenomenon occurring after surgery was observed. Recent evidence suggests that the incidence of wipeout may be much lower than the figures reported in early retrospective studies.
Sakamoto et al. (2018) reported that in hypotony maculopathy after trabeculectomy, excessive scleral contraction, rather than choroidal thickening, is the main cause 4). This finding provided a new perspective on the understanding of the pathology and treatment strategy for hypotony maculopathy.
Shirato et al. (2004) reported a transconjunctival scleral flap resuturing technique for hypotony due to overfiltration 5). This procedure, which resutures the scleral flap without incising the conjunctiva, is noted as a minimally invasive and effective treatment.
Eha et al. (2013) reported long-term outcomes of transconjunctival scleral flap resuturing 6). This technique may be a useful option for managing postoperative hypotony.
