Which magnification allows you to visualize the corneal layers—epithelium, stroma, and endothelium—during slit lamp examination?

• A. 4x
• B. 10x
• C. 16x
• D. 20x

Answer: (C)

The ability to see the corneal layers depends on having enough resolving power from the slit lamp combined with proper illumination. The cornea has three distinct layers—the epithelium on the outside, the thick stroma in the middle, and the endothelial layer on the inner surface—and each layer alters light differently. At very low magnifications, the cornea looks like a single, continuous structure, so the boundaries between layers aren’t clearly discernible. A moderate-high magnification is needed to differentiate the subtle differences in reflex and thickness that define each layer. Among common slit-lamp settings, this level of detail is attainable at about 16x, which balances enough zoom to visualize the epithelium, the stroma, and the endothelium as distinct zones while still providing a workable field of view. Going higher, such as 20x, can offer more detail, but the essential visualization of the layered architecture is already achievable at 16x. For observing finer endothelial cell morphology or microfeatures, even greater magnification with specific illumination would be used, but the question of identifying the three layers in a routine exam is best satisfied at 16x.