Wearing soft contact lenses may lead to physiological changes in the cornea. In fact, although the cornea remains transparent in soft contact lens wearers, corneal densitometry may increase in the 0- to 6-mm annular zone of the anterior region, according to research published in Optometry and Vision Science.

While contact lenses have evolved greatly in the last 50 years, the current highly oxygen-permeable silicone hydrogel soft lenses may cause more lens-related corneal infiltrative events than hydrogel lenses. These infiltrates, which can be seen on the cornea in biomicroscopic examination, can change corneal clarity, corneal thickness, and contrast sensitivity, according to researchers. 

Corneal densitometry software may detect these physiological changes by monitoring their effects on corneal transparency. To assess corneal densitometry values and corneal endothelium, investigators examined 36 eyes of 36 participants with soft contact lens use (group 1) and 36 eyes of 36 additional participants in a healthy control group (group 2). In group 1, the mean duration of contact lens wear was 4.45±2.15 years. 


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A total corneal area of 12 mm was divided into four annular zones (0 to 2, 2 to 6, 6 to 10, and 10 to 12 mm) and three regions as anterior, central, and posterior for densitometry examination. Cell density, cell distribution, and cell morphology (quadrangular, pentagonal, hexagonal, and other cell percentages) of the endothelial layer were examined in both groups using specular microscopy. The anterior segment parameters were not significantly different between the groups (P >.05). The anterior 0- to 2- and 2- to 6-mm corneal densitometry values were significantly higher in group 1 compared with group 2 (23.2±4.7 for group 1 and 17.3±5.6 for group 2 [P =.03]; 22.4±6.4 for group 1 and 17.8±1.4 for group 2 [P =.03], respectively). There were no significant differences between the groups for corneal densitometry values between 6 and 12 mm or cell density, cell distribution, and cell morphology (P >.05).

“Higher densitometry values determined in contact lens wearers may stabilize over time, and this effect should be followed by routine examination,” investigators advised.

This study had some limitations, including its retrospective design, small sample size, and lack of information about corneal densitometry before contact lens wearing. 

Reference

Ozek D, Karaca EE, Kazanci B, et al. Evaluation of corneal densitometry and endothelial layer in soft contact lens users. Optom Vis Sci. 2021;98(6):592-596. doi:10.1097/OPX.0000000000001707.