Keratography Is Not Yet Reliable for Dry Eye Diagnosis

Noninvasive, objective keratography is not yet able to independently diagnose dry eye disease (DED) and no clinical or noninvasive test yet reliably distinguishes meibomian gland dysfunction from Sjögren syndrome, according to a study published in Cornea.

Noninvasive keratography break-up time (NIKBUT), tear meniscus height (TMH), and bulbar redness (BR) measured with the Keratograph^® 5M (OCULUS) were weakly correlated with the clinical testing measures of tear break-up time (TBUT), Schirmer test, and bulbar erythema.

“We were unable to confirm that noninvasive testing using the Keratograph is an equal substitute to the more invasive clinical methods,” according to the researchers. “Therefore, there remains an unmet need for objective measures of dry eye that correlate with patient symptoms.”

The study included 288 patients (576 eyes) who participated in the Dry Eye Assessment and Management (DREAM) study of the use of omega-3 fatty acid supplementation for DED. The patients had moderate-to-severe DED symptoms based on the Ocular Surface Disease Index (OSDI).

The researchers evaluated bulbar erythema with slit-lamp examination as none (normal), mild (a flush reddish color), moderate (more prominent red color), or severe (definite redness). They measured TBUT using fluorescein dye. They performed the Schirmer test using test strips and classified results as clear, opaque, or thick. Patients with Sjögren syndrome were identified based on blood tests. They used the Keratograph to measure TMH, BR, and NIKBUT (using infrared illumination).

NIKBUT was compared with TBUT to assess tear stability. TMH was compared with the Schirmer test regarding the quantity of tears. BR was compared with bulbar erythema. The measures were compared at baseline, 6 months, and 12 months.

Sjögren syndrome was significantly associated with lower TBUT (P =.01), NIKBUT (P =.04), Schirmer test (P =.005), and TMH (P <.001). Meibomian gland dysfunction was only significantly associated with lower TBUT (P =.002) (all others P ≥.53).

TBUT and NIKBUT (95% CI, 0.09–0.28) had weak correlation at baseline, as did Schirmer test and TMH (95% CI, 0.05–0.25). All had similar levels of correlation weakness at 6 months and 12 months. Correlations between the measures and OSDI were all very weak.

“As we continue to search for the best metrics to define DED and its severity, we continue to depend on clinical tests that are themselves variable and often not reproducible; the search for objective minimally invasive metrics that best “capture” DED diagnosis and severity and correlate with symptoms continues,” report the investigators.

Disclosure: Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.  

Reference

Sutphin JE, Ying G, Bunya VY, et al. Correlation of measures from the OCULUS keratograph and clinical assessments of dry eye disease in the dry eye assessment and management study. Cornea. Published online July 22, 2021. doi:10.1097/ICO.0000000000002804