Smart Scleral Lenses for Visual Augmentation

Vipin G., B.Optom

M.Optom Student, The Sankara Nethralaya Academy, Chennai, India

 

Introduction

Scleral lenses are large diameter rigid contact lenses that cover the entire cornea and rests upon the sclera.⁽¹⁾ Between the back surface of the contact lens and front surface of the cornea, a lens vault filled with tear is present which helps in correcting vision due to corneal irregularities.⁽¹⁾ The different types of scleral lenses are:

• Corneal
• Corneo-Scleral
• Full Scleral
• Mini Scleral
• Large Scleral

Scleral lenses are widely used for ⁽¹⁾

• Vision correction in irregular corneas like keratoconus, keratoglobus, Pellucid Marginal Degeneration.
• Ocular surface protection in patients with dry eye, Steven Johnson’s syndrome, Sjogren’s syndrome, etc.
• Cosmetics and sporting activities.
• Ocular drug delivery.

Smart Scleral Lenses (SSL)

Scleral lenses are rotationally stable and have minimal movement with blink, because of which they have several optical applications. SSL is a reflecting telescopic system embedded within a sclera lens. It can alternate between unmagnified and 3X magnification in response to controlled blink. It can be useful for the military and for rehabilitation of low vision. ⁽²⁾

Design of Smart Scleral Lens

The SSL has a combination of Cassegrain reflector and polarizers, a 480µm display, almost the size of a sand-grain, having 70,000 pixels. ⁽²⁾ These are supported by micro components like microprocessor and an image sensor (Figure 2). The display has a pixel pitch of more than 14,100ppi and pixel density of over 200Mppi. It is the smallest and densest display for moving objects. The power source is a tiny solid-state battery. It can be recharged in the lens case itself at the end of the day. To send and receive data, it must be paired with another device. ⁽³⁾

Figure 2: Telescopic Scleral Lens. 
 Image courtesy: https://www.science.org/content/article/telescopic-contact-lenses-could-magnify-human-eyesight

Advantages of Smart Scleral Lenses

These lenses improve the magnification for distance and stabilise the magnified view. The miniature telescopes project rays into the healthy part of the retina, in turn improving vision. ⁽⁴⁾ The patient can switch between normal view for central and peripheral vision and magnified view for central vision. ^(4,5)

Applications of Smart Scleral Lenses

SSL can be used in patients with age related macular degenerations, ⁽⁶⁾ low vision rehabilitation and visual augmentation. ⁽⁷⁾ It can also be useful to reduce glare by its inbuilt collecting light properties, ⁽⁴⁾  and can be helpful in the field of military.

Conclusion:

Technological advancements have brought about massive changes in the field of medical sciences and these smart lenses are not anything different. Thus, these innovations will play a big role in improving the quality of life of patients going through irreversible loss of sight and who rely solely on low vision aids and rehabilitation for carrying out the activities of daily living.

 

References

1. Van der Worp E. A guide to scleral lens fitting. College of Optometry, Pacific University; 2010.
2. Johns, B. M. B. O. Advanced and additional uses of sclerals. 2022 [https://www.reviewofcontactlenses.com/article/advanced-and-additional-uses-of-sclerals; Last accessed:18Jan2024;06:00amAEDT]
3. Arianpour A, Schuster GM, Tremblay EJ, Stamenov I, Groisman A, Legerton J, Meyers W, Amigo GA, Ford JE. Wearable telescopic contact lens. Applied optics. 2015 Aug 20;54(24):7195-204.
4. Tremblay EJ, Stamenov I, Beer RD, Arianpour A, Ford JE. Switchable telescopic contact lens. Optics express. 2013 Jul 1;21(13):15980-6.
5. Tirado, E., Kinkade, R.,Low Vision Services throughout the state of Connecticut US :: Telescopic Contact Lens. 2023 [https://lowvisioneyeglasses.com/new-treatments/telescopic-contact-lens.html; Last accessed- 18Jan2024;07:00amAEDT]
6. Ford JE, Tremblay E, inventors. Telescopic contact lens. United States patent US 9,063,352. 2015 Jun 23.
7. Smart contact lenses for the blind – living well with low vision. Living Well with Low Vision. 2014 [https://lowvision.preventblindness.org/smart-contact-lenses-for-the-blind/; Last accessed – 18Jan2024; 05:00pmAEDT]