The Seidel sign is a medical finding observed during an ophthalmic examination, indicating the leakage of aqueous humor from the anterior chamber of the eye through a full-thickness defect in the cornea or sclera. It is named after German ophthalmologist Erich Seidel (1882–1962), who first described it.
Method of Detection: The Seidel sign is typically detected using fluorescein dye. A concentrated strip of fluorescein is applied to the ocular surface, usually near the suspected site of leakage. The eye is then examined under a cobalt blue filter, often with a slit lamp. If a full-thickness defect is present, the clear aqueous humor leaking from the eye will dilute the yellow-orange fluorescein. This dilution appears as a dark, negative stream or "waterfall" against the surrounding green-stained tear film. The flow of aqueous humor can sometimes be seen pushing the fluorescein away from the defect.
Clinical Significance: The presence of a Seidel sign is a critical finding as it confirms a full-thickness breach in the integrity of the globe. This can occur due to various reasons, including:
- Traumatic corneal laceration or globe rupture: Following injury, a penetrating wound allows aqueous humor to escape.
- Corneal ulceration with perforation: Severe infections or sterile ulcers can lead to tissue breakdown and perforation.
- Post-surgical complications: After ophthalmic surgeries such as cataract extraction, glaucoma filtering surgery (trabeculectomy), or corneal transplantation, the surgical wound may not be watertight, leading to wound dehiscence and leakage.
Detection of a Seidel sign necessitates urgent medical attention and often surgical intervention to seal the leak, prevent complications such as hypotony (low intraocular pressure), intraocular infection (endophthalmitis), and potential vision loss.