Corneal striae are fine lines or folds that can appear within the transparent tissue of the eye’s front surface, the cornea. Their presence often indicates underlying changes or stress within the corneal structure. Understanding what corneal striae are and what they signify is important for maintaining eye health and recognizing when professional medical attention may be needed.
What Are Corneal Striae?
Corneal striae appear as fine, parallel lines within the corneal tissue. These lines can be oriented vertically or obliquely and are translucent, making them difficult to detect without specialized equipment. They are primarily located in the deeper layers of the cornea, specifically within Descemet’s membrane or the posterior stroma.
An eye care professional observes corneal striae using a slit lamp microscope, which provides a magnified, illuminated view of the eye’s structures. They are best visualized with retroillumination, where light reflects off deeper structures, or direct illumination. Their appearance results from mechanical stress or swelling within the cornea, representing undulations in the corneal collagen lamellae rather than ruptures.
Common Causes of Corneal Striae
Corneal striae arise from conditions that cause the cornea to swell, stretch, or change shape. One such condition is corneal hydrops, an acute event often seen in advanced keratoconus. In hydrops, a sudden rupture occurs in Descemet’s membrane, allowing fluid from inside the eye to leak into the corneal stroma. This causes significant swelling and the formation of striae, as the influx of fluid creates mechanical stress leading to visible folds.
Keratoconus, a progressive thinning and outward bulging of the cornea into a cone shape, is a common cause of striae, particularly in advanced stages. As the cornea thins and stretches, stress lines known as Vogt’s striae, which are typically vertical, appear in the posterior stroma. These striae reflect the biomechanical changes as the cornea loses structural integrity.
Another significant cause is Fuchs’ endothelial dystrophy, a condition where endothelial cells, responsible for pumping fluid out of the cornea, gradually deteriorate. This cellular dysfunction leads to chronic corneal edema, which can result in striae as the posterior corneal lamellae become edematous and wrinkle Descemet’s membrane. The fluid accumulation causes the corneal layers to fold under pressure.
Elevated intraocular pressure, such as in glaucoma, can also induce corneal striae. When eye pressure becomes too high, it can lead to corneal edema by forcing fluid into the corneal layers or damaging endothelial cells. This increased pressure and swelling create mechanical forces that manifest as striae. Physical trauma or changes following certain eye surgeries, like LASIK, can also cause corneal stress and swelling, leading to striae.
Symptoms and Significance
Corneal striae generally do not cause direct symptoms like pain or discomfort. They are primarily a clinical sign observed by an eye care professional during an examination. Any symptoms experienced, such as blurred vision, glare, light sensitivity, or eye pain, are due to the underlying condition that caused the striae to form. For instance, significant corneal edema or distortion associated with conditions like Fuchs’ dystrophy or keratoconus directly impacts vision and causes discomfort.
The presence of corneal striae holds diagnostic importance for ophthalmologists. Observing these lines indicates an underlying issue affecting the cornea’s structure and fluid balance. They serve as a clinical indicator, prompting further investigation to identify and manage the root cause of corneal stress or swelling. This diagnostic clue allows for timely intervention, which can help prevent further progression of the underlying condition and preserve vision.
Diagnosis and Treatment Approaches
Diagnosing corneal striae involves a thorough eye examination, primarily using a slit lamp microscope. Once striae are identified, the focus shifts to determining their underlying cause through additional diagnostic tests, such as corneal topography or pachymetry, which measure corneal shape and thickness.
Treatment for corneal striae is not aimed at the striae themselves, as they are a manifestation of a deeper problem. Instead, management focuses on addressing the specific underlying condition responsible for their formation. For conditions like corneal hydrops or keratoconus, treatment options may include specialized contact lenses to improve vision, corneal collagen cross-linking to strengthen the cornea and halt disease progression, or in severe cases, a corneal transplant to replace damaged tissue.
In cases of Fuchs’ endothelial dystrophy, early stages might be managed with hypertonic saline eye drops to reduce corneal swelling. If the disease progresses and vision is significantly affected, surgical interventions such as Descemet’s Stripping Endothelial Keratoplasty (DSEK) or Descemet’s Membrane Endothelial Keratoplasty (DMEK) may be performed to replace diseased inner layers of the cornea with healthy donor tissue. For striae caused by high intraocular pressure, as seen in glaucoma, treatment involves lowering eye pressure through prescription eye drops, laser procedures, or surgery to improve fluid drainage or or reduce fluid production within the eye. Managing the primary condition is the most effective way to improve corneal health and address the presence of corneal striae.