The Hubble Telescope of the Eye
The quest for truly non-invasive ocular biomechanical measurements
John Marshall, Julian Stevens, Penh Shao, Amira Eltony and Andy Yun |
When it comes to rheology – the branch of physics that deals with the deformation and flow of matter, especially the non-Newtonian flow of liquids and the plastic flow of solids – the eye is one hell of a playground. Some structures are somewhat rigid (like the sclera) and others barely at all (the aqueous humor). It’s a pressurized system, drainage issues can cause huge problems, there’s a multitude of muscles that can change not only the direction of the eye at any given moment but also the shape of the tissues inside it. Aging progressively stiffens the principal component of the eye’s focusing system: the lens, and this is all before we get to refractive surgery like astigmatic keratotomy, PRK, LASIK, and SMILE weakening the cornea, let alone any disease states.
The cornea is an exquisite example of a close structure-function relationship. It is mechanically strong – strong enough to cope with a wide range of intraocular pressures that can be present in the eye (not just ocular hypertension or glaucoma, but intraocular surgical procedures like cataract surgery, too) and still maintain its geometry. In all of these situations (unless a pathology is present), it is also able to remain transparent throughout life, which is important as the cornea provides about two-thirds of the refractive power of the eye. So the cornea has two main functions: protect the eye and refract light. But even a small change to the structure of cornea can make a big difference to one – or both. The classic example is keratoconus: cone development and progression can rapidly lead to huge dioptric changes in patients’ refraction (and if untreated, ultimately rupture). Further, small arcuate incisions or the laser ablation of relatively small amounts of tissue can both lead to big changes in how the cornea refracts incoming light.
Read the full article now
Log in or register to read this article in full and gain access to The Ophthalmologist’s entire content archive. It’s FREE and always will be!
Or register now - it’s free and always will be!
You will benefit from:
- Unlimited access to ALL articles
- News, interviews & opinions from leading industry experts
- Receive print (and PDF) copies of The Ophthalmologist magazine
Or Login via Social Media
By clicking on any of the above social media links, you are agreeing to our Privacy Notice.