Sarbari Ray, B.Optom.

Fellow Optometrist at Dr. Shroff’s Charity Eye Hospital, Delhi, India

Background

Refracting telescopes is a type of afocal compound telescope that has two lenses, which works by magnifying the image of the object which we focus on. Those telescopes can be of many types like spectacle mounted, monocular telescope, handheld telescope, bioptic telescope, contact lens telescopes, etc, which we provide to the low vision patients according to their needs. ⁽¹⁾

Bioptic telescope provides a telescopic system to the patient while maintaining mobility. It is mounted on a carrier lens, the telescope is “out of the way” when the patient is moving or doing normal work but is used for distance viewing. Handheld telescopes are somewhat burdensome to carry, and the spectacle mounted are not cosmetically good and provide a small field of view. ⁽²⁾

Contact lens (CL) effectively improves the quality of life. Contact lenses being lightweight, having a wider field of view (FOV), greater stability, unaffected by fogging up or rain, lesser minification or magnification, better depth perception, fewer distortion, and fewer reflections are much more beneficial than spectacles, and as well as some are beneficial than telescope too. ⁽³⁾

Figure 1: Telescopic Contact Lenses
(Picture Courtesy: https://images.app.goo.gl/REj1XzUAQ77DrgtM6)

As early as in the 1960s the pioneer in the field of low vision an American Optometrist named William Feinbloom started to develop an eye-integrated magnification device named as mini-scope. ⁽⁴⁾ In 1930, an airspace refractive 2x Galilean telescope was encapsulated within a 4.4mm thick contact lens which too thick for long-term use. The material used in early rigid contact lenses called polymethyl methacrylate (PMMA), is impermeable to gas. So those CLs can only be worn for short periods of time because they don’t deliver much-needed oxygen to the cornea. ⁽⁵⁾

Figure 2: Telescopic Contact Lenses Design
(Picture courtesy: https://images.app.goo.gl/aW9rJF67R9TQb1ibA)

In 2013, a contact lens designed magnifying telescope was invented which is switchable in nature and relatively smaller than the previous one. This contact lens is 8 mm in diameter, centre thickness is 1 mm, maximum thickness is 1.17 mm, and radius of curvature is 1.53mm.⁽⁶⁾ The wearer of the telescopic contact lens can switch between normal and magnified vision and its focus is controlled by the wink of an eye and the magnification is up to 2.8X.⁽⁷⁾ The design of the lens has also been changed to allow oxygen to reach the eyes.  Since the lenses are large and thick in the middle, they limit airflow to the surface of the eye and can only be worn for a limited time.  To fix this, the contact lens team who gave the new structure of this CL, added a small channel about 0.1 mm wide for air travel to the bottom of the lens.⁽⁸⁾ In another study have been shown, that these telescopic contact lenses are more adjuvant in patients who have central vision loss such as macular degeneration.⁽⁹⁾

Figure 3: Zoom in & zoom out
(Picture Courtesyhttps://images.app.goo.gl/JBWVErLRjwGr4Shs5)

The new generation believes in lighter and smarter, more useful, and attractive things. Research is ongoing about telescopic contact lenses and a human trial is not done till now. It is a smart goal that will benefit people with visual impairments in the future. 

References: 

1. Vincent SJ. The use of contact lens telescopic systems in low vision rehabilitation. Contact Lens and Anterior Eye. 2017 Jun 1;40(3):131-42.
2. https://images.app.goo.gl/JBWVErLRjwGr4Shs5Designs for vision telescopic optical aids. Available at: https://www.designsforvision.com/LVhtml/LVte l.htm 
3. Isen A. Feinbloom miniscope contact lens. Encyclopedia of contact lens practice. 1963;13:53
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. Wearable telescopic contact lens. Available at :https://www.osapublishing.org/ao/ 
6. Telescopic contact lenses let you zoom in on demand. Available at : 
7. https://www.newscientist.com/article/dn26968-telescopic-contact-lenses-let-you-zoom-in-ondemand/ 
8. Telescopic contact lens shows promise for AMD. Available at https://www.medicalnewstoday.com/articles/289504 
9. Vincent SJ. The use of contact lens telescopic systems in low vision rehabilitation. Contact Lens and Anterior Eye. 2017 Jun 1;40(3):131-42. 
10. Telescopic contact lenses could improve eyesight for the visually impaired. Available at : https://jacobsschool.ucsd.edu/news/release/13 86