Diagnosis and Screening
Tests and procedures that may be used to determine the cause of dry eyes include:
Patient History and Symptom Evaluation
A detailed medical and ocular history is essential, as subjective symptoms do not always correlate with objective findings.
a.Symptom Questionnaires:
Ocular Surface Disease Index (OSDI)
may be used to quantify severity. The questionnaire uses three subscales to assess dry eye symptoms: ocular symptoms, visual-related function, and environmental triggers [30]. It is accessible through
Dry Eye Questionnaire (DEQ-5)
consists of five questions that assess the following: frequency of watery eye, discomfort, and dryness (scored on a 0–4 scale), and late-day discomfort and dryness intensity (scored on a 0–5 scale). The overall DEQ-5 was calculated by summing the scores on the individual questions. The maximum score on the DEQ-5 questionnaire is 22. [30, 31] It can be accessed through
Contact Lens Dry Eye Questionnaire (the CLDEQ-8)
score consists of frequency plus late-day intensity of dryness, discomfort, and "blurry vision"; frequency of "closing eyes to rest them" and "removing CLs to relieve discomfort". [32] It can be accessed through
b.History Includes: [33]
- Onset and pattern of symptoms (burning, grittiness, blurred vision)
- Systemic diseases (e.g., autoimmune, hormonal disorders)
- Medications (antihistamines, antidepressants, isotretinoin)
- Environmental and occupational factors (digital screen use, air conditioning)
Clinical examination
Impairment of tear film quality or changes in its composition can result in dry eye disease, which is categorized as either aqueous-deficient dry eye (ADDE) or evaporative dry eye (EDE). The TFOS DEWS II Diagnostic Guidelines and major ophthalmological societies recommend the following assessments. [34]
a.Assessment of tear stability
1.Tear film breakup time (TBUT)
- The Tear Breakup Time (TBUT) is the duration between a complete blink and the onset of the first break in the tear film. [34, 35]
- This measurement is most commonly conducted in a clinic using a slit lamp microscope, typically after applying sodium fluorescein dye to enhance the visibility of the tear film.
- A TBUT of fewer than 10 seconds is generally considered indicative of Dry Eye Disease (DED). [35]
2.Non-Invasive Tear Breakup Time (NIBUT)
- It can be measured without fluorescein. This method, which is more commonly used in clinical practice, employs instruments that analyze reflections of patterns or rings in the tear film or that use interferometry to detect discontinuities in the lipid layer after a blink. Studies have indicated that eyes with a shorter TBUT may exhibit corneal hyperalgesia. [34, 35]
b. Assessment of tear volume
1.Schirmer test
- The Schirmer test is performed by folding the Schirmer paper strip (5 × 35 mm) at the notch and hooking the folded end over the temporal one-third of the lower lid margin. The score is the measured length of wetting from the notch after 5 min. The Schirmer test without anesthesia is well standardized and provides an estimate of stimulated reflex tear flow. Although some authors have reported that the Schirmer test with topical anesthesia or nasal stimulation might be more objective and reliable in DED detection [34].
- The Schirmer test without anaesthetic remains a diagnostic test recommended for confirming severe aqueous deficiency (such as in Sjögren syndrome) [36].
2.Phenol Red Test
- Like Schirmer testing, a cotton thread dyed with phenol red is hooked over the temporal eyelid into the sulcus for 15 seconds while the patient rests with closed eyes. When wet, the thread turns red (pH-sensitive dye), with cutoff values ranging from <10 to 20 mm used clinically. [35]
c.Ocular Surface Assessment
1.Fluorescein Staining
- Fluorescein staining allows the assessment of corneal damage. A minimal volume of fluorescein is instilled into the tear film, with optimal viewing 1 to 3 minutes later. Greater than five spots of staining are considered positive results, with various grading scales [35, 37].
2.Lissamine Green Staining
- Lissamine allows the assessment of conjunctival and lid margin damage and, to a lesser extent, corneal damage. A count of more than 9 spots is a positive result. Lid wiper epitheliopathy, or staining of the lid margin, can be performed with a positive result as 2 mm or more staining in length or greater than 25% in sagittal width. [35]
- The ocular surface well tolerates lissamine green as fluorescein; it stains epithelial cells only if the cell membrane is damaged (a vital dye), irrespective of the presence of mucin. [34, 38]
3.Conjunctival Redness
- Conjunctival redness, or hyperemia, is not specific to DED, as this may result from any stimulus that results in conjunctivitis, including infective, allergic, chemical, or mechanical etiologies. Grading is generally determined subjectively by slit lamp examination, although some devices with automated grading or digital photography can also be used. [39]
d.Tear Film Assays
1.Tear Film Osmolarity
- Elevated osmolarity and increased variability of osmolarity of tears are characteristics of DED.
- Osmolarity values typically increase with disease severity. Various cutoff values have been reported, with 308 mOsm/L used as a threshold for mild-to-moderate disease, and 316 mOsm/L used as a cutoff for more severe disease.
- High osmolarity levels can lead to proinflammatory effects on the ocular surface, with the secretion of inflammatory cytokines and metalloproteinases that can cause chronic epithelium dysfunction [35, 40].
2.Tear markers
- Elevated matrix metalloproteinase-9 (MMP-9) and inflammatory mediators in tears are rapid and sensitive for identifying inflammatory dry eye and ocular surface disease [41].
- Reduced lactoferrin in tears is associated with altered immune regulation and dry eye [42].
e.Assessment of the lipid layer integrity and meibomian gland dysfunction (MGD) obstruction.
- The meibomian glands, found in the upper and lower eyelids, excrete lipids onto the ocular surface that form the outermost layer of the tear film, lubricating the ocular surface during blinking and protecting against tear evaporation. Dysfunction of the meibomian glands reduces lipid secretion, contributing to tear film instability and entry into the vicious circle of dry eye disease (DED).[43]
- LipiScan is a diagnostic imaging device that provides high-resolution digital images of the lower and upper meibomian glands. [44]