OCT for Assessing Artificial Tears Effectiveness in Contact Lens Wearers

OCT applications in contact lens fitting

Optical Coherence Tomography (OCT) is a noninvasive, high-speed, high-resolution imaging technology based in the Michaelson interferometry. A near-infrared light beam is used to register the intensity variations for the light backscattered on each sample layer. Due to the high repeatability on corneal measurements, spectral domain OCT (SD-OCT) is the gold standard when talking about in vivo, non-invasive anterior segment imaging. Changes in the morphology of various ocular surfaces such as the cornea, conjunctiva, limbus or tear film with soft (SCL), rigid, corneal or scleral lens (SL) wear can be described by OCT measurements. For instance, evaluation of the corneoscleral region is essential on SL fitting. For orthokeratology lenses central epithelial thinning and peripheral thickening and their regression could be quantified with OCT after Ortho-K lens wear. Blood vessel compression on the landing zone as well as vault thickness and fluid reservoir (FR) turbidity could be imaged with OCT. Tear film evaluation on contact lens wearers is essential because its use could lead to variations on the biochemical components in tears. Changes in tear meniscus dynamics and several parameters such as volume (TMV), tear meniscus height (HMT) and turbidity could be determined with OCT and positively correlated with the instillation of different ophthalmic solutions with Non-Invasive Break Up Time (NIBUT) and Schirmer test values. This manuscript shows the increasing applicability of OCT technology for the in vivo characterization of contact lens fitting and interaction with the ocular surface in a faster, safer and non-invasive way. Future research will still allow exploring OCT imaging to its full potential in contact lens practice, as there is still a significant amount of information contained in the images that are not yet easy to extract, analyze and give clinical value.

Influence of Sodium Hyaluronate Concentration in Tear Meniscus Height: 10-min Dynamic Profile After Single Instillation

PURPOSE

To assess the height, area, and density of tear meniscus throughout 10 min after instillation of sodium hyaluronate (SH) of equal molecular weight at two different concentrations.

METHODS

Thirty-four eyes from 17 patients were enrolled in this longitudinal, nonrandomized, interventional and contralateral eye study. Tear meniscus height (TMH), corneal meniscus junction (CMJ), lower-lid meniscus junction (LLMJ), and tear meniscus area (TMA) images were obtained with the anterior segment module of the deep range imaging ocular coherence tomography ([DRI-OCT] Triton Swept-Source). Tear meniscus density (TMD) was calculated using the image processing and analysis software by Java (ImageJ program). Sodium hyaluronate artificial tears at 0.1% and 0.2% concentrations were instilled into all right and left eyes, respectively.

RESULTS

Patients' mean age was 61.05±11.43 years. Tear meniscus height, CMJ, LLMJ, and TMA measured at 1-, 5-, 7- and 10-min postinstillation of 0.1% SH proved significant differences among them (P<0.05). Sodium hyaluronate 0.2% instillation obtained similar findings, although no significant differences were found between 1- and 3-min postinstillation measurements (P>0.05). Fewer differences were found in TMD 0.2% SH group due to a lower baseline densitometry compared to the 0.1% group.

CONCLUSION

0.2% sodium hyaluronate achieved better TMH and TMA in 1 and 3 min after instillation than 0.1% concentration. However, there were no statistically significant differences between 0.1% and 0.2% sodium hyaluronate throughout a ten-minute longitudinal profile measurement using DRI-OCT.

Impact of contact lens material and design on the ocular surface

BACKGROUND

To evaluate the impact on the ocular surface of a daily disposable hydrogel contact lens with high water content compared with two silicone hydrogel daily disposable lenses of lower water content.

METHODS

The hydrogel lens assessed was made from nesofilcon A and the silicone hydrogel lenses were made of delefilcon A and stenfilcon A. Contact lens thickness was measured to assess material stability during daily wear, and ocular surface parameters such as tear film osmolarity, tear meniscus area and central corneal thickness were also assessed. Optical quality was analysed for all cases by means of wavefront aberrometry.

RESULTS

The nesofilcon A was shown to be the thinnest lens (p < 0.001), while no differences in lens thickness were found between the two silicone hydrogel lenses (p = 0.495). No significant differences were found in tear film osmolarity, tear meniscus area, central corneal thickness or corneal aberrations, either as a function of the lens measured or time of use (p > 0.05).

CONCLUSION

In spite of having the thinnest lens and the highest water content, the hydrogel does not significantly impact on tear film and corneal swelling after one day of use in first-time wearers.

Increased concentration of hyaluronan in tears after soaking contact lenses in Biotrue multipurpose solution

Purpose

This study was conducted to determine 1) the concentration of hyaluronan (HA) in the tear films of contact lens (CL) wearers versus non-CL wearers and 2) whether HA sorbed from Biotrue, an HA-containing multipurpose solution (MPS), onto senofilcon A lenses affects the concentration of HA in tears after 2 hours of wear.

Patients and methods

Tears of habitual CL wearers and non-CL wearers were collected on Schirmer strips at baseline and after 2 hours of wear of senofilcon A CLs that had first been either rinsed with Sensitive Eyes Saline or soaked in Biotrue MPS for 14 hours. HA concentrations were measured by enzyme-linked immunosorbent assay (ELISA) and adjusted for sample volumes.

Results

No difference in baseline concentrations of HA in tears was found between CL wearers and non-CL wearers (P=0.07), nor between males and females (P=0.06). However, age was significantly negatively associated with HA concentration (P<0.01), and mostly, CL wear contributed to a significant association (P<0.01). Among saline-rinsed CL wearers, no change in HA concentration in tears was observed after 2 hours of wear (P=0.38). By contrast, a significant increase in HA concentration was observed in the tears from eyes that had worn CLs soaked in Biotrue MPS when compared to baseline (P=0.01) or to saline-rinsed control (P=0.03).

Conclusion

1) In this study population, no difference in baseline concentration of HA was observed between CL wearers and non-CL wearers, and 2) after 2 hours of wear of senofilcon A lenses that were soaked in Biotrue MPS, HA concentrations in the tear films of CL wearers increased.