Impact of modulus of elasticity of silicone hydrogel contact lenses on meibomian glands morphology and function

Background: To evaluate and compare the effect of modulus of elasticity of silicone hydrogel contact lenses on morphological and functional parameters of the meibomian glands. Methods: A prospective study was conducted on soft silicone hydrogel contact lens wearers of different modulus of elasticity and age and gender-matched controls. Morphological and functional parameters were assessed along with standard patient evaluation of the eye dryness questionnaire. Results: A statistically significant difference was noted in meibomian gland loss in the upper lid (percent) between the low modulus (18.23 +/- 6.63) and high modulus group (27.40 +/- 10.21) (p < 0.001) and between high modulus (27.40 +/- 10.21) and non-contact lens wearers (19.57 +/- 7.65) (p = 0.001). The current study reported significantly higher total meiboscore grading in the high modulus group 3 (2-3) compared to the low modulus 2(2-3) (p = 0.007) and non-contact lens wearing groups 2 (2-3) (p = 0.012). Meibum quality was significantly compromised in the high modulus group 1 (0-1) compared to the low modulus 0 (0-0.75) group (p = 0.01). Standard patient evaluation of the eye dryness questionnaire was found to be significantly higher (p = 0.01) in high modulus 4 (2-8) compared to low modulus wearers 2 (2-4). A significant difference was noted (p < 0.001) in corneal staining grading only between high modulus 0 (0-1) and non-contact lens wearers 0 (0-0) group. A positive correlation was noted in the low modulus group between total meiboscore and meibomian gland expressibility (Rs = +0.69, p < 0.001) and also noted between standard patient evaluation of the eye dryness questionnaire scoring and meibomian gland expressibility (Rs = +0.45, p = 0.012) in the high modulus group. Conclusion: Higher modulus of elasticity of silicone hydrogel contact lens may influence meibomian gland morphology and function over a period of contact lens wear.