13. Tearing in the morning, especially in winter (cold air)? This complaint is one of the hallmarks of hyperevaporative dry eye. In a way, it is contrary to
the very name of this condition- dry eye, and only shows that it is in many ways inappropriate. Lipids, which are secreted by the meibomian glands, prevent hyperevaporation of tears, as
well as their passage over the eyelids (tearing). The secretion of the meibomian glands is blink- dependent. Eyes do not blink during the night, therefore, no secretions are produced, and upon waking the tear film is relatively lipid-deficient. In case of decreased lipid secretion (hypereva- porative dry eye), an increased need for secretion of lipids in the morning may cause decom- pensation of the meibomian glands’ capacity to secrete lipids, therefore inducing symptoms of tearing. A positive answer to this question strongly suggests hyperevaporative dry eye.
If the answer to most or all of the above is yes, a diagnosis of dry eye should be considered!
MEDICAL HISTORY The following systemic conditions or procedures may exacerbate dry eye symptoms:
autoimmune diseases rheumatoid arthritis systemic lupus erythematosus scleroderma etc.
dermatological disease (e.g. ocular pemphigoid)
nerve trauma or disease (e.g. Parkinson’s disease)
refractive surgery (LASIK)
History of medicine use The use of certain systemic medications is frequently accompanied by dry eye symptoms. Should the patient exhibit symptoms of dry eye, discontinuation of the medication should be taken into consideration if that does not adversely influence the patient’s overall medical con- dition. Examples are:
Antihyperetensives (beta-blockers, reserpine, thiazide, diuretics etc.)
Psychopharmaceuticals (benzodiazepines), antidepressants, neuroleptics
Anti acne treatment in conjunction with doxycycline therapy
Physical examination A general practitioner generally does not have the opportunity to diagnose external eye disea- ses using a slit lamp, an ophthalmologist’s tool. However, physical examination using only the naked eye may in many cases be adequate, and may add valuable information to that alrea- dy gathered by asking the previously listed case history questions. Observe conjunctival hyperaemia and discharge; if minimal to moderate: consider a diagnosis of DRY EYE.
Interpretation of tests used in dry eye diagnostics by the ophthalmologist As previously mentioned, ophthalmologists diagnose dry eye using a slit lamp to observe the
eye surface under magnification. They use various tests to diagnose this condition and to differentiate between several subtypes of dry eye, especially the hyperevaporative and hypo- secretory types. This is important, since therapy options vary for each dry eye subtype.
Below are listed diagnostic tests that are used by the ophthalmologist. General practitioners are not supposed to use them by themselves, since they lack the necessary equipment and
experience. However, they should be able to interpret findings that they receive from oph- thalmologists, when they have referred patients to them for more thorough testing.
It must be noted, however, that cut-off values for most of the tests listed are not universally accepted, and that the ophthalmologist’s final opinion (diagnosis) should be his/her opinion regarding the observed patient's condition.
1. Fluorescein staining By using 1 % sodium fluorescein solution, epithelial de- fects of the eye surface are stained, and may be observed using a slit lamp. Distribution of fluorescein staining may be highly pathognomonic of dry eye.
Bilateral corneal staining, predominantly on the inferior cornea:
Bilateral conjunctival staining, predominantly in the aperture:
Figure 2 – Fluorescein staining (courtesy of Alcon) Visible are epithelial defects in the lower portion of the cornea, typical of dry eye
2. TBUT (Tear Break-Up Time Test) Tear film stability, together with osmolarity, are two parameters that are changed in every type of dry eye. Therefore, the Tear Break-Up Time test (TBUT) is one of the pivotal tests in diagnosing dry eye. TBUT measures stability of the tear film, by instilling sodium fluorescein
solution in the eye and observing the appearance of dark spots in the stained tear film, using a slit lamp. The value is expressed in seconds after opening the eye. Although it is extremely important in diagnosing dry eye, TBUT is notorious for the variability of its results, making it, in many ways, unreliable. The reason for this lies in the fact that measurement is not standardized, as it is performed
Figure 3 – TBUT Test (courtesy of Alcon) Visible are multiple breaks in fluoresceine- stained tear film
in many different ways, thus making results non-comparable between practitioners. The values mentioned below are those most universally accepted, but again the ophthalmologist’s interpretation should be honoured as the most reliable.
TBUT lower than TBUT lower than
10 sec: 3– 5 sec:
consider diagnosis of dry eye dry eye is the most probable cause of symptoms