Why does better wettability improve visual acuity?

Why does better wettability improve visual acuity?

• A. Lower oxygen permeability
• B. Increased deposits
• C. More stable tear film
• D. Thicker lens

Answer: (C)

Better wettability means the lens surface allows tears to spread quickly and form a smooth, stable tear film over the optical area. When the tear film is uniform and persistent, light passes through a consistent refractive interface, reducing surface irregularities and light scatter. This stable, even tear film minimizes fluctuations in vision that come from tear break-up or irregularities on the eye-lens surface, yielding crisper, more reliable visual acuity. If the tear film is unstable, areas of thinning or breakup create refractive variations, causing haziness or fluctuating vision. Good wettability supports a continuous, low-frriction tear layer, which helps maintain optical quality throughout wear. Lower oxygen permeability doesn’t directly affect wettability or the immediate optical surface, and increased deposits or a thicker lens tend to disrupt the tear film or add thickness without improving the smooth, even tear layer needed for sharp vision.

Better wettability means the lens surface allows tears to spread quickly and form a smooth, stable tear film over the optical area. When the tear film is uniform and persistent, light passes through a consistent refractive interface, reducing surface irregularities and light scatter. This stable, even tear film minimizes fluctuations in vision that come from tear break-up or irregularities on the eye-lens surface, yielding crisper, more reliable visual acuity.

If the tear film is unstable, areas of thinning or breakup create refractive variations, causing haziness or fluctuating vision. Good wettability supports a continuous, low-frriction tear layer, which helps maintain optical quality throughout wear.

Lower oxygen permeability doesn’t directly affect wettability or the immediate optical surface, and increased deposits or a thicker lens tend to disrupt the tear film or add thickness without improving the smooth, even tear layer needed for sharp vision.