About Dry Eye: From the Journal of the Japanese Ophthalmological Society

Definition of dry eye:
“A disease in which the stability of the tear film a) is decreased by various factors, producing eye discomfort b) and visual dysfunction c), and which may be accompanied by damage to the ocular surface d)” (2016)

About dry eye: from the Journal of the Japanese Ophthalmological Society

This introduces the “Dry Eye Clinical Practice Guidelines” in the Journal of the Japanese Ophthalmological Society (May 2019).

“The way we think about the pathophysiology of dry eye has changed over time and is still evolving.”

Changes in the definition and diagnostic criteria of dry eye in Japan
↓
1995: “Keratoconjunctival epithelial damage caused by qualitative or quantitative abnormalities of the tear (film)”
2006: “A chronic disease of the tears and keratoconjunctival epithelium caused by various factors, accompanied by eye discomfort and visual dysfunction”
Over the next 10 years, more research results accumulated, and the definition was revised in 2016 as above.

Main mechanisms of dry eye (core mechanisms):

• Tear film instability(the tears that spread over the eye’s surface with each blink are unstable)
• Increased friction during blinking(blinking rubs the surface of the black of the eye)

In Japan, “inflammation” is regarded as the result of these two vicious circles,
while in other countries (especially the United States), “inflammation” is regarded as the main mechanism of dry eye.


Because I was involved in research on ocular immunology and ocular surface disease when I first studied abroad, I have always thought of “dry eye as an inflammatory disease.”
: Inflammation caused by CD4-positive T cells among lymphocytes (in the West, treated with immunosuppressants; not covered by insurance in Japan)

Since returning to Japan, I have continued to put the idea of “suppressing inflammation” at the center of dry eye care.
There are differences between Japanese and Western people, but I believe treatment effects are being obtained.

Dry Eye Care

a) Tear film stability
We stain the surface of the eye with a fluorescein strip and evaluate the stability of the three-layer structure of the tears (oil / water / mucin layers) by measuring the tear film breakup time (BUT).

b) Eye discomfort
Judged by interview. Please feel free to tell us.
We can also use a questionnaire (Dry Eye related Quality of life Score, DEQS).

c) Visual dysfunction
When needed, we can perform visual acuity tests, corneal topography, wavefront analysis, and so on.

d) Ocular surface damage
Evaluated at the same time as item 1.
Corneal epithelial damage associated with Sjögren’s syndrome, etc.

Prevalence of dry eye

How common is dry eye?
In a large epidemiological survey of residents aged 40 and over in Japan (the Koumi Study), it was 12.5% in men and 21.6% in women.
What external factors (region, race, age, season, sex) affect the onset of dry eye?
Regional differences: no clear evidence
Racial differences: prevalence is higher in Hispanic and Asian women than in white women
Season: prevalence is higher from winter to spring
Sex: prevalence is higher in women
Age: aging is a risk factor

The influence of lifestyle on dry eye (smoking, VDT work, contact lens wear)

What is the influence of lifestyle on the onset of dry eye (smoking, VDT work, contact lens wear)?
Smoking: a risk factor for the onset of dry eye
Long hours of VDT work / eating more omega-6 fatty acids than omega-3 fatty acids
　　　　　　: risk factors for the onset of dry eye
Contact lens wear
　　　　　　: unclear whether it is a risk factor

Diseases related to dry eye

Drug-induced corneal epithelial damage

　Preservatives in various eye drops can have an effect. Other causes include the effect of anti-glaucoma drugs.
　We may reduce or stop eye drops, or use preservative-free eye drops.

Meibomian gland dysfunction

　There may be an infection-related allergy to acne bacteria at the edge of the eyelid.

Superior limbic keratoconjunctivitis

　Associated with thyroid eye disease, etc.

Neuroparalytic keratopathy

　Trigeminal nerve damage, for example after neurosurgery or after herpetic keratitis.

Filamentary keratitis

Conjunctivochalasis

　A loose state of the conjunctiva: we see it often in daily practice.

lid-wiper epitheliopathy

　Damage to the conjunctiva on the inner surface of the eyelid. It occurs often in people who use soft contact lenses.
　* When needed, we also consider treatments such as punctal plugs and diquafosol sodium eye drops.