Metrological characterization of the refractive index (n_D)tear film in a Colombian population with dry eye using the Rx-5000α refractometer

Ingrid M. Martinez, Angie D. Piragua, Anny C. Lozano, Silvia J. Castellanos, Juan J. Barrios, Diana C. Palencia

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Base Information

Volume

V59 - N2 / 2026 Ordinario

Reference

52000

DOI

http://dx.doi.org/10.7149/OPA.59.2.52000

Language

Spanish

Keywords

Tear film, critical angle refractometry, refractive index, dry eye disease, metrological characterization

Abstract

Optical characterization of the tear film is fundamental to understanding visual quality, since variations in its refractive index nD can induce significant optical aberrations. Despite its importance, there is a gap in the literature regarding the metrological behavior of tear film in patients with Dry Eye Disease (DED). In this study, the influence of sociodemographic and clinical characteristics on tear nD was evaluated in a population from northeastern Colombia. An observational, descriptive, cross- sectional study was conducted on106 participants over 18 years of age diagnosed with dry eye disease (DED). The clinical evaluation included the Ocular Surface Disease Index (OSDI) questionnaire, Schirmer I tests, tear breakup time (BUT), and ocular surface staining with fluorescein and lissamine green. The nD measurement was performed by critical-angle refractometry using a high-precision RX 5000α refractometer (±0.00004 nD) under Peltier temperature control at 20°C. The results showed a sample with a median age of 48 years and a predominance of females (64.15%). A statistically significant correlation was identified between the increase in refractive index and the severity of dry eye disease as categorized by the OSDI questionnaire (p < 0.05). These findings suggest that the physicochemical alterations of the tear film in patients with dry eye impact its refractive behavior, providing critical data for the development of more accurate optical models of the ocular surface under pathological conditions.

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