Part 1 and Part 2 introduced Opt-Align and the Krall & Karpecki collaboration that is resurrecting awareness in our profession to the balance needed between disease and functional approaches to visual discomfort. In a previous blog post I wrote about the case of child who was diagnosed as having a dry eye so that the doctor could dismiss the child’s complaints, when there was no objective evidence of dry eye whatsoever. As Dr. Krall wrote in his article, most “dry eye complaints” are related to meibomian gland dysfunction or aqueous tear layer deficiencies. Yet the growing popularity of ocular surface disease as a wastebasket for chair-time complaints related to headaches, asthenoopia, and physical discomfort in or around the eyes tends to mask binocular vision problems that are increasingly overlooked.
It really shouldn’t be all that surprising that ocular motor/proprioceptive control issues show up at the masquerade ball in dry eye clinics. To review, here’s why. The eye is a specialized joint adapted for sight. It’s kinematics operate as a ball-in-socket joint. Its movements are constrained by the walls of the orbit or socket in which it is contained, as it pivots based on its intricate muscles, ligaments and pulley systems. Unlike other joint spaces in the body, the eyeball is the only one that is exposed directly to air. So its need for lubrication is at a premium.
Hyaluronic acid is a protein that is an essential component of the synovial fluid of articular joints for lubrication, the vitreous humor of the eye, and on the ocular surface. It acts as a shock absorber for the eye, and also serves to transport nutrients into the eye. Applied to the surface of the eye, hyaluronic acid reduces the symptoms and damage associated with dry eye. Think of the terms used when the ocular surface dries to the point of structural damage to the cornea/sclera interface, such as erosion and pannus. Those are commonly used terms on rheumatology, when joint spaces lose essential lubrication and shock absorption due to chronic inflammatory disease.
So it should come as no shock that many patients with arthritis have dry eyes — not because there is a gee whiz co-morbidity between the two conditions, but precisely because the eye is a specialized joint adapted for seeing, and chronic inflammation takes a toll on all joint spaces. Many dry eye patients will present with the corneal surface looking reasonably good, but be uncomfortable because the sclera is excessively dry. Touch it with a fluorescein strip and under UV light it looks like you dabbed it with a paint brush.
The approach to dry eye treatment has therefore become much more holistic. Treating the eye from the outside, or on its ocular surface, often offers only palliative relief. Steroid eye drops may provide temporary relief because they quell inflammation in the joint space where the kinematic structures have become even slightly edematous or engorged. What distinguishes dry eye practices now are not drugs and plugs. Nouveau dry eye clinics incorporate lifestyle changes, and they are the same as offered for rheumatoid conditions. Treat dry eye as a problem of inadequate joint nutrition – in other words, lubricate and adopt anti-inflammatory strategies for the eye’s joint spaces from within, such as drinking more fluid, exercise, flax oil, omega-3 fatty acids, anti-oxidants, etc.
In part 4 we’ll wrap up this concept of pain-in-the-asthenopia.
– Leonard J. Press, O.D., FCOVD, FAAO