Enhancing glaucoma care with smart contact lenses: An overview of recent developments

Abstract

Glaucoma is a leading cause of irreversible blindness worldwide, affecting millions of individuals due to its progressive damage to the optic nerve, often caused by elevated intraocular pressure (IOP). Conventional methods of IOP monitoring, such as tonometry, provide sporadic and often inaccurate readings due to fluctuations throughout the day, leaving significant gaps in diagnosis and treatment. This review explores the transformative potential of smart contact lenses equipped with continuous IOP monitoring and therapeutic capabilities. These lenses integrate advanced materials such as graphene, nanogels, and magnetic oxide nanosheets alongside sophisticated biosensing and wireless communication systems. By offering continuous, real-time data, these lenses can detect subtle IOP fluctuations and provide immediate feedback to patients and clinicians. Moreover, drug-eluting capabilities embedded in these lenses present a groundbreaking approach to glaucoma therapy by improving medication adherence and providing controlled drug release directly to the eye. Beyond IOP management, these innovations also pave the way for monitoring biochemical markers and other ocular diseases. Challenges such as biocompatibility, long-term wearability, and affordability remain, but the integration of cutting-edge technologies in smart contact lenses signifies a paradigm shift in glaucoma care. These developments hold immense promise for advancing personalized medicine, improving patient outcomes, and mitigating the global burden of blindness.

Keywords: Biocompatible materials; Biosensors; Continuous monitoring; Drug delivery systems; Glaucoma; Intraocular pressure (IOP) monitoring; Ocular health; Smart contact lenses.

Fig. 1

(a) Illustration of the GAT method. In this method, a cone-shaped prism exerts a force F onto the cornea. This applied force results in the deformation of the corneal surface, causing it to flatten to a surface area A. Consequently, the intraocular pressure (IOP) is determined by the relationship P=F/A. (b) digital Goldmann tonometer. (c) Goldmann applanation tonometer positioned on the slit lamp. (d) Cone prism on the top and two applanation rings being calibrated to become an ’S’ shape on the bottom (Brusini et al. 2021)

Fig. 2

(a) The principle of the noncontact tonometry operation. An air pump puffs the air straight to the cornea surface, and the reflection of this air is captured to measure the IOP. (b) The schematic of the rebound tonometer includes a probe going toward the cornea surface, and the deceleration of the probe on its way toward the cornea after touching the surface measures the IOP (Kim et al. 2017)

Fig. 3

Diagram illustrating the primary components of the MCL, including a microfluidic channel, Pt electrode, spiral MNS coil, and Ecoflex. And the data acquisition unit (Xie et al. 2022)

Fig. 4

(a) (Top left) CAD design of a lens without a hole. (b) (Top right) CAD design of a lens featuring a 4.7 mm hole. (c) (Bottom left) Physical lens without a hole. (d) (Bottom right) Physical lens with a 4.7 mm hole. The blue plastic serves as a convex base for lens positioning and is not part of the sensor (Helgason and Lai 2022)

Fig. 5

(a) A contact lens with an imprinted manufactured moiré pattern. (b) Intraocular pressure (IOP) monitoring using moiré pattern-based techniques in rabbits with glaucoma induced through continuous BSS (Balanced Salt Solution) injection. In the first row, contact lenses embedded with moiré patterns show IOP changes. In the second row, overlaid moiré patterns alongside virtual reference images implicitly reflect IOP variations (Lee et al. 2020). Se-Hee Lee, Kyung-Sik Shin, Jae-Woo Kim, Ji-Yoon Kang, and Jong-Ki Kim, Translational Vision Science & Technology, Vol. 9, Article 1, 2020; licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License

Fig. 6

(a) Schematic representation of ERG recordings in response to light stimuli from a human eye using a corneal sensor. (b) Schematic representations of the corneal sensor, with inset images detailing the embedded encapsulation and anchoring layers (top panel) and its seamless integration with the connection wire (bottom panel) (Kim et al. 2021)

Fig. 7

(a) Diagram of the dual-functional contact lens sensor, featuring an antiopal structure designed for intraocular pressure (IOP) monitoring and a peptide-functionalized gold nanobowl (AuNB) SERS substrate tailored for MMP-9 biomarker detection. (b) Schematic representation of the IOP monitoring mechanism using structural color contact lenses. (c) Schematic representation of the Tamra-pep cleavage by MMP-9 on the AuNBs SERS substrate attached to contact lenses. Ye et al. (2022)

Fig. 8

Schematic of the theranostic smart contact lens, which integrates an AuHNW-based IOP sensor, drug delivery system (DDS), and wireless circuitry for glaucoma treatment with real-time IOP sensing and timolol release (Kim et al. 2022)

Fig. 9

(a) The schematic of the different layers of the proposed SSCL. (b) the SEM image of the SSCL (Zhang et al. 2022)

Fig. 10

(a) Schematic illustrating the wireless operation for IOP monitoring and on-demand drug delivery in a minimally invasive manner. The soft device, designed as a double-layer contact lens, incorporates an LCR circuit and a wireless power transfer (WPT) receiver. These components are wirelessly linked to an external integrated antenna, enabling IOP signal recording and activation of iontophoresis for drug release when required. The inset figures highlight key components of the IOP sensing and drug delivery units. (b) Exploded view of the WTCL structure (Yang et al. 2022)

Fig. 11

Schematic representation of the soft, smart contact lens featuring a hybrid substrate, integrated functional devices (rectifier, LED, glucose sensor), and a transparent, stretchable conductor for the antenna and interconnects (Park et al. 2018)