Table 1 Summary of the ophthalmological work-up.

Tear osmolarity

Tear collection procedure was performed according to the user manual²⁸. A nanoliter tear sample is obtained with a standard single-use micropipette, which is attached to the device and then transferred to a chip surface. A reading is obtained a few seconds after placing the test pen in the machine. Recommended threshold values in the literature indicating dry eye disease are ≥308 mOsm/L, intereye difference >8 mOsm/L and ≥316 mOsm/L

≥308 mOsm/L^a,

≥316 mOsm/L,

inter-eye difference>8 mOsm/L

TFBUT

The interval in seconds between the last complete blink and the first appearance of a dry spot, or disruption in the tear film following instillation of fluorescein

≤5 seconds

Inter-blink interval

Time between complete blinks in seconds

OPI

The OPI is equal to the TFBUT divided by the IBI. The principle of the test is that when TFBUT < IBI, the ocular surface is at risk of focal dryness and consequent damage. If the OPI score is <1, then a patient’s cornea is at risk of exposure

<1

OSS

Following fluorescein instillation, the staining scores of the exposed cornea and interpalpebral conjunctiva are summarized using the Oxford grading scheme (range: 0–15)

>0

Schirmer I test

Paper test strips are placed in the lower lateral third of the conjunctival sac and the eyes are closed for 5 minutes, and wetting of the paper is measured in millimeters

≤10 mm/5 min

Meibum expressibility

Assessed in central five glands according to the number of expressible glands: 0 = all glands expressible; 1 = 3–4 glands expressible; 2 = 1–2 glands expressible; 3 = no glands expressible

>0

Meibum quality

Assessed in central eight glands scored on a scale of 0–3 for each gland: 0 = clear; 1 = cloudy; 2 = cloudy with debris (granular); 3 = thick, toothpaste-like, and the sum of the central eight glands is calculated (total score range, 0–24)

>0