Ectropion uveae is an eye condition where the iris has its inner pigmented layer turn outward. This condition can be present from birth or develop later in life. It can sometimes be a sign of other underlying conditions or lead to complications if left unaddressed.
What is Ectropion Uveae?
Ectropion uveae describes the eversion of the iris’s posterior pigmented epithelial layer. The iris is a thin, circular structure in the eye responsible for controlling the size of the pupil and, consequently, the amount of light reaching the retina. Normally, the pigmented cells of the iris are on its posterior surface, facing the back of the eye. With ectropion uveae, these dark pigment cells become visible on the anterior, or front, surface of the iris, often around the pupil’s edge. This can appear as a dark, sometimes irregular, rim around the pupil.
Causes of Ectropion Uveae
Congenital ectropion uveae (CEU) is a rare developmental anomaly where the iris pigment epithelium proliferates onto the anterior surface of the iris. This is thought to result from developmental issues during eye formation. While CEU itself is often non-progressive, it can be associated with systemic conditions such as neurofibromatosis type 1 (NF1), Rieger’s anomaly, and Prader-Willi syndrome.
Acquired ectropion uveae (AEU) is more common and progresses unless its underlying cause is treated. AEU often develops due to the formation of a fibrovascular membrane on the anterior surface of the iris. This membrane contracts, pulling the posterior pigmented epithelium, iris sphincter muscle, and iris stroma forward around the pupillary margin.
Common causes of this membrane formation include neovascularization of the iris (rubeosis iridis), which is the growth of abnormal new blood vessels. Neovascularization is frequently associated with conditions causing ischemia or lack of blood flow in the eye, such as proliferative diabetic retinopathy, central retinal vein occlusion, and ocular ischemic syndromes. Other acquired causes include inflammation within the eye (uveitis), trauma, surgical procedures, and certain tumors or cysts of the iris. Chronic elevated intraocular pressure, as seen in some types of glaucoma, can also deform the iris structure and contribute to AEU.
Symptoms and Diagnosis
Symptoms can be subtle or absent, especially in early or mild cases. When present, symptoms may include blurred vision, discomfort, or sensitivity to light. The most apparent sign is the visible presence of the dark, everted iris pigment on the front surface of the iris, often as a pigmented ring or patch around the pupil. The pupil may appear distorted in shape or size, or be displaced from the center of the iris. Mild drooping of the eyelid (ptosis) may also be observed.
An eye care professional diagnoses ectropion uveae through a thorough eye examination. A slit-lamp biomicroscopy is a primary diagnostic tool, allowing the doctor to examine the iris and pupil under high magnification and bright illumination. This examination helps identify the characteristic outward curling of the pigmented iris epithelium. The eye doctor will also assess the overall structure of the iris, looking for associated findings like iris neovascularization or adhesions within the eye.
Gonioscopy, a specialized examination of the drainage angle of the eye, may also be performed to check for new blood vessels or other abnormalities. The diagnostic process often involves identifying the underlying cause, as this directs subsequent management.
Treatment and Management
Managing ectropion uveae involves addressing its underlying cause rather than directly treating the eversion itself. For instance, if the condition is linked to glaucoma, treatment focuses on controlling intraocular pressure. This might involve eye drops to lower pressure, laser procedures, or surgical interventions like trabeculectomy or the placement of glaucoma drainage devices. The prognosis for eyes with congenital ectropion uveae and associated glaucoma is often poor, making early diagnosis and treatment important for preserving vision.
If an inflammatory process is the cause, anti-inflammatory medications may be prescribed. In cases where abnormal blood vessel growth (neovascularization) is present, intravitreal injections of anti-vascular endothelial growth factor (anti-VEGF) agents may be used to help regress these vessels. Laser therapy, such as pan-retinal photocoagulation (PRP), can also be employed to manage retinal ischemia that drives neovascularization. For ectropion uveae caused by tumors or cysts, their removal would be considered. Regular follow-up appointments are advised to monitor the eye and ensure the stability of any underlying conditions.