Amsler Sign

Issues of Concern

Pathophysiology

Gonioscopy in Fuchs heterochromic uveitis reveals the following findings: [5][6]

• Small twig-like vessels in the angle that likely give rise to the Amsler-Verrey sign
• The visibility of large vessels at the peripheral iris is likely due to the atrophy of the iris
• Loss of the details in the anterior chamber angle, appearing dull or covered with a felt-like texture
• Small, irregular areas of non-confluent goniosynechiae

The fine vessels in the anterior chamber angle are fragile and prone to rupture after trivial trauma. The exact nature of these vessels is unknown; they may represent abnormal vasculature or new vessels. There is no clear correlation between the hyphema and abnormal angle vessels.[7] The hemorrhage in the anterior chamber originates from the angle in a filiform appearance and then may settle inferiorly when the patient is upright. There are claims that the Amsler-Verrey sign is a diagnostic sign in FHI, especially in Europe.[7]

In FHI, the angular vessels can be injured during diagnostic procedures using a 30-gauge needle inserted through the limbus or during paracentesis with a blade in cataract surgery. This damage can result in a micro-hyphema known as the Amsler sign. The hyphema may occur from the anterior chamber angle, away from the entry site. This occurrence is due to sudden decompression of the anterior chamber and hypotony, leading to hemorrhage from the anterior chamber angle vessels.

However, similar anterior chamber hemorrhage after paracentesis may also present in other conditions, including:

• Neovascular glaucoma
• Neovascularization of the anterior chamber angle
• Sudden hypotony or shallowing of the anterior chamber during anterior segment surgery
• Patients on anticoagulant therapy or with bleeding disorders

Despite these possibilities, the presence of this sign should raise a strong suspicion of Fuchs heterochromic uveitis.  

Causes of Anterior Chamber Hemorrhage

Amsler and Verrey noted hyphema after paracentesis in FHI.[1][7] Other causes of the Amsler-Verrey sign include the following: [8][9]

• Spontaneous or possibly from trivial trauma such as rubbing the eyes
• Gonioscopy
• Applanation tonometry
• Pharmacological dilatation of the pupil
• Posterior capsulotomy
• Honan balloon before cataract surgery
• During cataract surgery
• Peribulbar anesthesia

Clinical Significance

The hyphema due to the Amsler sign is typically mild. Active bleeding from the anterior chamber angle may stop spontaneously. In cases with continuing intraoperative hemorrhage, forming the anterior chamber with a viscosurgical device or raising the intraocular pressure typically stops the bleeding. The hyphema typically does not worsen the visual outcomes, and most cases of Fuchs heterochromic uveitis have mild perioperative hemorrhage after cataract surgery. Hyphema may not be present on the first postoperative day. For postoperative mild hyphema, a medication regimen of antibiotics and steroid drops is typically sufficient to manage inflammation. In severe hyphema or postoperative inflammation, topical cycloplegics are necessary to prevent posterior synechia. Although posterior synechia is otherwise uncommon in Fuchs heterochromic uveitis, postoperative inflammation can lead to posterior synechia, necessitating treatment with both steroids and cycloplegics. Typically, the outcome of cataract surgery is good in Fuchs heterochromic uveitis with cataracts. However, some cases may have anterior chamber reaction, deposits on the intraocular lens, decentration of intraocular lens, glaucoma, vitreous inflammation/haze, posterior capsular opacification, cystoid macular edema, corneal edema, and macular hole.[10][11] 

Nursing, Allied Health, and Interprofessional Team Interventions

Amsler's sign is a vital clinical indicator that is typically innocuous. However, in all cases of intraoperative hyphema, the medical history should be reviewed specifically to rule out uncontrolled systemic diseases, including hypertension, clotting disorders, or anticoagulant therapy. Effective collaboration among the nursing team, physicians, and pharmacists is necessary to enhance patient care and achieve optimal ocular and systemic outcomes.