Definition/Introduction

Amsler sign (aka Amsler-Verrey sign) is present in Fuchs heterochromic uveitis (FHU). It is characterized by hemorrhage in the anterior chamber (hyphema) after anterior chamber paracentesis or entry with the microvitreoretinal blade during anterior segment surgeries, including cataract surgery or minor trauma. This hemorrhage is due to the presence of fine, fragile vessels in the angle of the anterior chamber. The sign got its name from Dr. Marc Amsler and Dr. Florian Verrey, who described it in 1946.[1]

Dr. Marc Amsler (1891-1968) was a Swiss ophthalmologist and a great teacher.  He was a student of Jules Gonin (1870-1935) at the University of Lausanne. He was a strong supporter of Gonin's ideas on the repair of rhegmatogenous retinal detachments. Dr. Amsler was known as "Le marcheur de l'operation de Gonin" (The seller of Gonin's surgical procedure).[2] Dr. Amsler became the chief of the Zurich Eye Clinic. His contribution to ophthalmology includes the Amsler grid and the Amsler- Dubois chart. Amsler grid is a 10 cm X 10 cm square-shaped chart that has seven different variants. The chart is a useful and inexpensive tool to monitor metamorphopsia and scotoma in various macular diseases, most commonly wet age-related macular degeneration. The Amsler-Dubois chart is an important chart to document posterior segment lesions, including retinal detachment. Dr. Amsler's research interests included the study of the macular function, the study of aqueous humor in uveitis, and keratoconus. He invented a mirror for retinal examination using a monocular indirect ophthalmoscope.[2]

Dr. Florian Verrey (1911-1976) was a Swiss ophthalmologist who worked with Dr. Amsler at the University of Lausanne and later at Zurich Eye Clinic. His research focused on uveitis and aqueous humor.

FHU gets its name from Ernst Fuchs (1851-1930), an Austrian ophthalmologist. He was the clinical director of the Second Vienna Eye Hospital.[3] The Textbook of Ophthalmology, written by Dr. Fuchs, was considered one of the best textbooks on the subject at that time. Fuchs endothelial corneal dystrophy and Fuchs spot in myopia have their name dedicated to him.

FHU is characterized by unilateral heterochromia, cataract, glaucoma, with no posterior synechia. Typically FHU has fine stellate keratic precipitates that are present over the endothelium in a diffuse manner involving both the superior and inferior cornea. The iris usually loses detail on the surface (featureless iris) due to atrophy compared to the other eye, and iris nodules at the pupillary margin (Koeppe nodules) may be noted. However, frank heterochromia may not be present, especially in patients with heavily pigmented iris. Typically, anterior chamber reaction, if present, is mild. Vitreous may show some debris, and retrolental cells may be noted on slit-lamp examination.

Issues of Concern

Pathophysiology

Gonioscopy in FHU reveals[4][5]

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

The fine vessels at the angle of the anterior chamber are fragile and prone to rupture after trivial trauma. The actual nature of these vessels is unknown and may be abnormal vasculature or new vessels. There is no clear correlation between the hyphema and abnormal angle vessels.[6] 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.[6]

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

• Neovascular glaucoma
• Neovascularization of the angle of the anterior chamber
• Sudden hypotony or shallowing of the anterior chamber during anterior segment surgery
• Patients on anticoagulant therapy or bleeding disorders
• However, the sign may lead the clinician to a strong suspicion of FHU.  

Causes of Anterior Chamber Hemorrhage

Amsler and Verrey noted hyphema after paracentesis in FHI.[1][6] Other causes of Amsler-Verrey sign include[7][8]:

• Spontaneous or possibly from trivial trauma like 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 usually mild. Active bleeding from the angle into the anterior chamber may stop spontaneously. In cases with continuing intraoperative hemorrhage, forming the anterior chamber with a viscosurgical device or raising the intraocular pressure usually stops the bleeding. The hyphema typically does not worsen the visual outcomes, and most cases of FHU will 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 antibiotic and steroid drops are usually enough to control inflammation. In severe hyphema or severe postoperative inflammation, topical cycloplegics are necessary to prevent posterior synechia. Though posterior synechia is otherwise uncommon in FHU, postoperative inflammation can cause posterior synechia and thus requires control with both steroid and cycloplegics. Typically, the outcome of cataract surgery is good in FHU with cataract though some cases may have anterior chamber reaction, deposit over the intraocular lens (IOL), decentration of IOL, glaucoma, vitreous inflammation/haze, posterior capsular opacification, cystoid macular edema, corneal edema, and macular hole.[9][10] 

Nursing, Allied Health, and Interprofessional Team Interventions

Amsler sign is an important clinical sign which is usually innocuous. However, in all cases of intraoperative hyphema, it is prudent to review the medical history specifically to rule out uncontrolled systemic diseases, including hypertension, clotting disorders, or anticoagulant therapy. The role of the nursing staff is very important in this regard. Interprofessional coordination with the physician and pharmacist is needed in such cases to improve patient care and to deliver excellent outcomes, both ocular and systemic.