What might cause a myopic shift in vision related to cataracts?

The thickening of the lens is indeed a contributing factor to a myopic shift in vision in the context of cataracts. As cataracts develop, the lens becomes cloudy and can also become thicker and more rigid. This change in the lens's structure increases its refractive power, which can lead to a shift toward myopia, or nearsightedness. In simpler terms, as the lens thickens, it bends light rays more sharply than the eye is accustomed to, causing distant objects to appear blurrier while closer objects may still be seen clearly.

The other options present factors that do not directly cause a myopic shift related to cataracts. A thin cornea can affect overall eye health and vision, particularly in conditions like keratoconus or during refractive surgeries, but it is not specifically linked to cataract-induced changes in lens thickness. Macular degeneration primarily affects the retina and does not cause refractive changes associated with cataracts. Increased intraocular pressure is associated with glaucoma rather than the refractive changes that cataracts cause. Thus, the thickening of the lens directly correlates with the development of myopia in the presence of cataracts.