A protocol for reliable dry eye diagnosis

Dry eye disease significantly impacts patient wellbeing worldwide^1,2.Tear meniscus height (TMH) is a critical aetiological indicator of aqueous-deficient dry eye, with TFOS DEWS II guidelines defining <0.20mm as the deficiency threshold^3,4. Clinical TMH measurement reliability could vary according to the location of image capture along the lower lid margin, or to the timing of assessment relative to a blink, or to the illumination used⁵.To address these potential inconsistencies, we, together with OSL's Professor Jennifer Craig during her research visit to Aston University, aimed to optimise a standardised protocol using digital video imaging and image analysis⁶.

Methods

A total of 38 healthy adults (mean age 33 ± 10.6 years; 45% male) were evaluated with the Oculus Keratograph 5M⁶. After two non-forced blinks, the lower tear meniscus was video recorded for five seconds, under infrared light, then white light. This was repeated twice. Participants also completed the Ocular Surface Disease Index (OSDI), and tear film stability was assessed via three averaged non-invasive keratograph breakup time (NIKBUT) measurements^5,6.

Fig 1. TMH measurements using infrared (A) and white light (B) imaging. Yellow markings show measurement points along the temporal, centre and nasal regions of the lower eyelid

For the meniscus height assessments, still frames were extracted at 0.5 second intervals following two successive blinks, for the five seconds of each recording. TMH was measured at seven predefined locations along the lower eyelid margin using the ImageJ software analysis tool, centrally beneath the pupil, then 1, 3 and 6mm nasally and temporally, as shown in (Fig 1). A single trained observer performed all measurements.

Results

TMH measured slightly greater in magnitude under infrared light (0.29 ± 0.08 mm) than with white light (0.27 ± 0.08 mm). This difference is clinically insignificant and aligns with prior reports⁵.TMH was consistent during the 1.0–2.5 second period after each blink, defining the optimal measurement window⁶. Taking the measurement directly below the pupil centre and within 1mm nasally or temporally (pupil centre ± 1mm) yielded similarly reliable values, while measurements at peripheral locations showed greater variability⁶.

No significant relationship emerged between TMH and age, sex, OSDI scores or NIKBUT⁶. Notably, 34% of healthy participants met the TFOS DEWS II dry eye criteria for aqueous deficiency³. TMH distribution was <0.1mm (0.7%), 0.1–0.2mm (16.9%), 0.21–0.3mm (50.1%), 0.31–0.4mm (24.2%), >0.4mm (8.0%)⁶. A small but statistically significant TMH increase occurred with repeated measurements⁶.

Conclusion

The protocol we optimised as a proxy for tear volume provides a dependable means of evaluating tear meniscus height⁶. Imaging centrally on the lid margin, within 1.0–2.5 seconds after the blink and under consistent illumination reduces variability^3,5,6.Only a single measurement from a single tear meniscus image is required. The manual protocol establishes a clinical benchmark for subjective or objective analysis of TMH⁵.

Clinical implications

Implementing this protocol has the potential to deliver:

Improved diagnostic reliability for aqueous deficiency^3,6
Objective treatment monitoring (eg. following punctal plug insertion)
Enhanced inter-clinician consistency^5,6.

Key points

Either white or infrared light can be used for imaging or observation, as long as it is consistent
The measurement should be taken 1.0–2.5s after two consecutive blinks
The height of the tear meniscus should be assessed within ± 1mm of pupil centre, perpendicular to the eyelid margin and with only a single measurement required^5,6
Staff training can help to identify and exclude artefacts⁶ .

Automated analysis tools reduce subjectivity and enable large-scale screening^2,8. Adopting these protocols helps bridge the research-clinical gap to improve dry eye management^1,7.

References

Dash N, Choudhury D. Dry Eye Disease: An Update on Changing Perspectives on Causes, Diagnosis, and Management. Cureus. 2024;16(5):e59985. Published 2024 May 9. doi:10.7759/cureus.59985
Stapleton F, Alves M, Bunya VY, et al. TFOS DEWS II Epidemiology Report. Ocul Surf. 2017;15(3):334-365
Wolffsohn JS, Arita R, Chalmers R, et al. TFOS DEWS II Diagnostic Methodology report. Ocul Surf. 2017;15(3):539-574
Pena-Verdeal H, Garcia-Queiruga J, Sabucedo-Villamarin B, Garcia-Resua C, Giraldez MJ, Yebra-Pimentel E. A Comprehensive Study on Tear Meniscus Height Inter-Eye Differences in Aqueous Deficient Dry Eye Diagnosis. J Clin Med. 2024;13(3):659. Published 2024 Jan 23.
Soares I, Ramalho E, Brardo FM, Nunes AF. Tear meniscus height agreement and reproducibility between two corneal topographers and spectral-domain optical coherence tomography. Clin Exp Optom. 2025;108(4):430-436
Wolffsohn JS, Ayaz M, Bandlitz S, von der Höh F, Ebner A, Craig JP. Optimising the methodology for assessing tear meniscus height using digital imaging. Cont Lens Anterior Eye. 2025;48(4):102419.

Professor James Wolffsohnis head of the School of Optometry at Aston University, UK, and an honorary professor in the University of Auckland’s department of ophthalmology. His main research areas are the development and evaluation of ophthalmic instrumentation, contact lenses, intraocular lenses and the tear film.