The influence of a mineral oil cationic nanoemulsion or perfluorohexyloctane on the tear film lipid layer and higher order aberrations

Abstract

Purpose: To prospectively assess the effect of a single and regular application of either a cationic nanoemulsion of mineral oil (CN) or perfluorohexyloctane (F6H8) on the lipid layer of the tear film and higher order aberrations (HOA) in patients with Dry Eye Disease (DED).

Methods: Fifty-seven patients with a lipid layer thickness (LLT) ≤ 75 interferometric colour units (ICU) were included in the study. In group A (20 patients) the effect of a single drop of F6H8 or CN on HOA and LLT was assessed immediately after application and up to two hours later. For long term effects (Group B) 37 patients applied CN or F6H8 five times a day for 12 weeks. Measurement of LLT, HOA, non-invasive-tear-break-up-time (NIBUT) and meibography were assessed prior to as well as at 4 weeks and 12 weeks after initiation of treatment. Our study is registered in the "German Clinical Trials Register" under the trial number: DRKS00028696.

Results: CN led to an increase of the LLT from 46.8 ± 16.9 ICU to 76.3 ± 23.5 ICU (p = 0.021) and to an increase of HOA from 0.43 ± 0.06 μm to 0.48 ± 0.08 μm immediately after application (p = 0.027). There was no correlation between the increase of LLT and HOA (r = -0.04; p = 0.90). In group B an increase of LLT was observed in the F6H8 group from 45.8 ± 8.8 ICU at baseline to 66.7 ± 19.5 ICU at 12 weeks (p = 0.002). No changes of HOA were measured throughout the observation period in group B. After 12 weeks CN increased NIBUT from 9.9 ± 5.3 seconds to 15.5 ± 5.6 seconds (p = 0.04). F6H8 increased NIBUT from 12.4 ± 5.9 seconds to 16.9 ± 4.7 seconds (p = 0.02) after 12 weeks.

Conclusion: CN leads to a short-term increase in LLT and HOA, but only immediately after application. In contrast F6H8 does lead to an increase of LLT after regular long-term use but has no effect on HOA. The regular application of lipid-based products does not seem to decrease the quality of vision as measured in HOA. Instead, CN and F6H8, both are able to stabilize the tear film after regular application.

Fig 1

a—CONSORT Flow Diagram for short-term effect group. b—CONSORT Flow Diagram for long-term effect group.

Fig 2. Lipid layer thickness (in ICU) at baseline and consecutive measurements.

The measurement values up to 120 min after application were compared with the baseline using the Wilcoxon test. All p-values were adjusted for 3 comparisons according to the Bonferroni method. An asterisk with the corresponding p-value indicates a significant change compared to baseline measurement. ICU = Interferometric Colour Units; CN = cationic nanoemulsion; F6H8 = perfluorohexyloctane.

Fig 3. RMS values (in μm) at baseline and consecutive measurements.

The measurement values up to 120 min after application were compared with the baseline using the Wilcoxon test. All p-values were adjusted for 3 comparisons according to the Bonferroni method. An asterisk with the corresponding p-value indicates a significant change compared to the baseline. RMS = Root Mean Square; μm = micrometer; CN = cationic nanoemulsion; F6H8 = perfluorohexyloctane.

Fig 4. Lipid layer thickness (in ICU) at consecutive measurements.

The LLT at 4 and 12 weeks were compared to the LLTat baseline using the Wilcoxon test. All p-values were adjusted for 2 comparisons according to the Bonferroni method. An asterisk with the corresponding p-value indicates a significant change compared to the baseline. ICU = Interferometric Colour Units; CN = cationic nanoemulsion; F6H8 = perfluorohexyloctane.

Fig 5. RMS values (in μm) at baseline and consecutive measurements.

The RMS values at 4 and 12 weeks were compared with the values of the baseline using the Wilcoxon test. All p-values were adjusted for 2 comparisons according to the Bonferroni method. An asterisk with the corresponding p-value indicates a significant change compared to the baseline. RMS = Root Mean Square; μm = micrometer; CN = cationic nanoemulsion; F6H8 = perfluorohexyloctane.

Fig 6. NIBUT at baseline and consecutive measurements.

The NIBUT at 4 and 12 weeks were compared with the NIBUT of the baseline using the Wilcoxon test. All p-values were adjusted for 2 comparisons according to the Bonferroni method. An asterisk with the corresponding p-value indicates a significant change compared to the baseline. NIBUT = non-invasive tear break-up time; CN = cationic nanoemulsion; F6H8 = perfluorohexyloctane.

Fig 7. Meibomian gland scores of the upper and lower eyelid.

Grade 0: No loss of Meibomian glands; Grade 1: Loss of Meibomian glands less than one third of the total density on the eyelid; Grade 2: Loss between one and two thirds of the total density of the glands on the eyelid; Grade 3: Loss of glands is greater than two-thirds of the total density of glands on the eyelid; MGD = Meibomian gland dysfunction; CN = cationic nanoemulsion; F6H8 = perfluorohexyloctane.