It’s a Material World

PhD, MSc, MBA - University of Zaragoza - Spain

Introduction

Lens material properties play a huge role in lens acceptance on the eye. But how exactly? Not much research in our field goes into understanding this. Our research team at the University of Zaragoza in Spain delved into the impact of different soft contact lens material properties on corneal tissue alterations to give eye care practitioners a better understanding of this effect.

Are silicone hydrogel lenses superior to hydrogel lenses?

Soft contact lens prescribing has steadily increased over the years, paralleled by significant advancements and research in the field. Initially, hydrogel lenses emerged in the late 1960s, marking a pivotal shift in contact lens vision correction by offering superior comfort compared to rigid lenses. Subsequently, silicone hydrogel lenses were introduced in the 2000s their enhanced oxygen permeability represented a technological leap, enabling extended wear with increased breathability [1]. According to these historical definitions, one might argue that silicone hydrogel lenses are a superior choice compared to hydrogel lenses. However, recent research underscores the critical aspect of contact lens biocompatibility. In essence, there isn't a definitive superior material the suitability depends entirely on the wearer. Advances in technology have empowered researchers to pioneer novel, intricately detailed factors that, although currently confined to research settings, hold immense promise for clinical applications. Rooted in routine examinations, these factors provide in-depth, objective insights into corneal tissue and corneoscleral profiles. Our research team delved into the impact of soft contact lens wear on corneal tissue alterations, [2] focusing specifically on corneal tissue transparency and homogeneity as indicators of low-level hypoxia or 'corneal stress'. Over half of the participants exhibited alterations to the eye due to lens wear. Intriguingly, no specific material was consistently found to be more responsible for these corneal changes it varied among individuals.

"Intriguingly, no specific material was consistently found to be more responsible for these corneal changes: it varied among individuals."

Effect of lens material on topographical limbus and corneoscleral junction angle

A similar outcome emerged when examining corneoscleral parameters, such as the topographical limbus and corneoscleral junction angle. In one study comparing wear of one silicone hydrogel lens with wear of one hydrogel lens, while individual differences were noticeable, there was no conclusive evidence indicating that one material caused more significant corneoscleral alterations than the other [3]. Moreover, it's crucial to note that corneal tissue changes remain independent of corneoscleral alterations, offering complementary insights into how contact lenses affect our eyes [4].

Closing Remarks

These findings challenge conventional assumptions and offer two key conclusions. First, the growing research interest and technological advancements, such as corneoscleral topographers, provide access to new, sensitive parameters related to contact lens fit. Second, concerning hydrogel and silicone hydrogel soft lens materials, no single material type outshines the other—it's a matter of individual variability. In essence, our evolving understanding emphasizes the necessity of personalized approaches in prescribing soft contact lenses. As we delve deeper into the intricacies of ocular interactions with contact lens materials, tailored solutions will continue to redefine the landscape of contact lens vision correction.

References

1. Ţălu Ş, Ţălu M, Giovanzana S, Shah RD. A brief history of contact lenses. Human and Veterinary Medicine. 2011 Jun 13(1):33-7.

2. Consejo A, Trillo‐Moreno I, Remon L. Corneal tissue changes following short‐term soft contact lens wear of different materials. Ophthalmic and Physiological Optics. 2023 Jan43(1):35-45.

3. Consejo A, Roll V, Roman DM, Remon L. The influence of soft contact lens material on the corneoscleral profile. Ophthalmic and Physiological Optics. 2023 Jun 27.

4. Consejo A, Roman DM, Roll V, Remon L. Relationship between corneal tissue and shape in short‐term soft contact lens wear. Ophthalmic and Physiological Optics. 2023 Aug 8.

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