Diagnosing dry eye with dynamic-area high-speed videokeratoscopy

In Vitro Evaluation of Soft Contact Lens Wettability With a Nonmodified Commercial Videokeratoscope

PURPOSE

To evaluate a new in vitro technique for measuring soft contact lens wettability using a nonmodified commercial videokeratoscope, the Medmont E300. To this end, the capability of different artificial tears containing hyaluronic acid (HA) to improve soft contact lens wettability in vitro was investigated.

METHODS

An experimental in vitro study was conducted to assess the wetting properties of three artificial tears containing different concentrations of HA (0.1%, 0.2%, and 0.3%) on soft contact lenses. A saline solution was used as the control. For each solution, 15 hydrogel (Ocufilcon D) contact lenses and 15 silicone-hydrogel (Somofilcon A) contact lenses were evaluated. The in vitro wettability of the lenses was measured using the Medmont E300 with a self-developed technique, which involved measuring the tear film surface quality (TFSQ) mean, TFSQ area, TFSQ central, and TFSQ inferior.

RESULTS

Compared with the saline solution, all the concentration of HA (0.1%, 0.2%, and 0.3%) improved the in vitro wettability of both soft contact lenses by decreasing their TFSQ mean and TFSQ area ( P <0.05). Regression models revealed an exponential relationship between contact lens wettability and the concentration of HA for both soft contact lenses ( R >0.5, P <0.05). Furthermore, the hydrogel contact lens presented a wetter surface than the silicone-hydrogel contact lens ( P <0.05).

CONCLUSIONS

The measurement of in vitro wettability of soft contact lenses with a nonmodified Medmont E300 seems to be a useful technique to evaluate the wetting properties of contact lens products.

Medmont Meridia™: Much More Than a Corneal Topographer

In recent years, advanced diagnostic instruments have become widely available in optometric practices, offering various functions that optimize clinical information gathering. This article focuses on the Medmont Meridia™, a state-of-the-art multipurpose diagnostic device with corneal topography and cutting-edge features. Corneal topography is pivotal in the early diagnosis of corneal disorders, determining baseline ocular surface assessment, helping in contact lens fitting, and monitoring ocular health over time. The Medmont Meridia boasts Placido-disc-based imaging with extensive corneal coverage. Furthermore, the Meridia accurately measures the horizontal visible iris diameter, pupil diameter, and palpebral fissure width, which assists in making contact lens parameter decisions. Additionally, it offers sagittal height data for scleral lens design and first lens selection, streamlining the fitting process. Beyond its topography capabilities, the Meridia excels as a comprehensive dry eye assessment tool. With features like tear meniscus height, tear film surface quality, and meibography capabilities, it aids in diagnosing dry eye and monitoring its progression. The device also provides customizable dry eye reports with integrated grading scales and questionnaires, making dry eye management, patient education, and compliance more accessible. In conclusion, the Medmont Meridia consolidates a multitude of examination tools in a single instrument, enhancing practice efficiency and elevating patient care and communication. Its versatility and accuracy make it an invaluable asset in optometric practices worldwide.

Improvement of Soft Contact Lens Wettability After the Instillation of Hyaluronic Acid Eye Drops

PURPOSE

To evaluate the effect of the topical instillation of hyaluronic acid eye drops with different viscosity on soft contact lens wettability and comfort.

METHODS

A randomized and participant-masked study was performed, involving 20 participants (25.4±2.6 years). One eye wore hydrogel (ocufilcon D) contact lenses, and another eye wore silicone-hydrogel (somofilcon A) contact lenses. The in vivo wettability tear film surface quality (TFSQ) index and comfort were measured before and after the instillation of different eye drops: saline solution (control) and 0.1%, 0.2%, and 0.3% hyaluronic acid.

RESULTS

Compared with saline solution, the instillation of 0.1%, 0.2%, and 0.3% hyaluronic acid improved the in vivo wettability of the hydrogel contact lenses by decreasing their TFSQ mean for 5, 10, and 30 min, respectively ( P <0.05). During silicone-hydrogel contact lens wear, the hyaluronic acid did not affect wettability because there were no changes in TFSQ mean ( P ≥0.05), but the 0.3% hyaluronic acid produced a decrease in comfort for the first 3 min ( P <0.05).

CONCLUSIONS

The instillation of hyaluronic acid eye drops increased the in vivo wettability of the hydrogel contact lens, and the duration of this effect was directly related to its concentration and viscosity.

Effect of overnight orthokeratology lenses on tear film stability in children

PURPOSE

To assess the tear film surface quality after orthokeratology using an automated Medmont E300 corneal topographer.

METHODS

Children who wore orthokeratology lenses for more than one year were selected in this retrospective study. Tear film disruption (TFD) and central tear film disruption (cTFD) were measured with Medmont E300 corneal topographer at initial and each follow-up visit after fitting with orthokeratology lenses, providing a nominal value from 0 (perfect) to 1 (poor). Tear film surface quality before and after ortho-k treatment was compared.

RESULTS

145 children using orthokeratology lenses were observed. TFD and cTFD significantly increased at 1-day follow up (TFD, t = -17.3, P < 0.001; cTFD, t = -10.4, P < 0.001). This change remained consistent through to 12-months visit (TFD, F = 51.1, P < 0.001; cTFD, F = 28.0, P < 0.001). A sub-group of n = 11 children were discontinued for 1-month before being refit with OrthoK lenses of a different design. Similarly, there was a significant increase in TFD compared to pre-orthoK scans (0.172 ± 0.161), but this returned to baseline levels after ceasing lens wear (0.084 ± 0.059). A sub-group of monocular OrthoK wearers (n = 23) found that TFD and cTFD values increased in eyes with monocular lens-wearing but remained stable in the lateral eyes.

CONCLUSIONS

Objective measurements of tear-film quality are reduced in children after fitting with orthokeratology lenses, but return to baseline after 1-month of lens cessation. It is of importance to ensure tear film surface quality is continuously monitored throughout use of orthoK lenses.

Automation of dry eye disease quantitative assessment: A review

Dry eye disease (DED) is a common eye condition worldwide and a primary reason for visits to the ophthalmologist. DED diagnosis is performed through a combination of tests, some of which are unfortunately invasive, non‐reproducible and lack accuracy. The following review describes methods that diagnose and measure the extent of eye dryness, enabling clinicians to quantify its severity. Our aim with this paper is to review classical methods as well as those that incorporate automation. For only four ways of quantifying DED, we take a deeper look into what main elements can benefit from automation and the different ways studies have incorporated it. Like numerous medical fields, Artificial Intelligence (AI) appears to be the path towards quality DED diagnosis. This review categorises diagnostic methods into the following: classical, semi‐automated and promising AI‐based automated methods.

Stabilization of comfort and visual quality after the insertion of soft contact lenses

PURPOSE

To evaluate comfort, visual function, and in vivo wettability after the insertion of hydrogel and silicone hydrogel contact lenses for a better understanding of how long practitioners should wait for the initial evaluation of soft contact lenses.

METHODS

A short-term prospective, contralateral, randomized, and participant-masked study was carried out. Twenty healthy participants (25.4 ± 2.6 years) were evaluated after the insertion of two different soft contact lenses at different times (1, 5, 10, 20, 30 min). Ocufilcon D (hydrogel) and Somofilcon A (silicone hydrogel) contact lenses were randomly assigned to both eyes of the same participant. Comfort, visual function under photopic conditions in terms of high-contrast visual acuity, low-contrast visual acuity, contrast sensitivity, and in vivo wettability were measured.

RESULTS

There was an increase in comfort (p < 0.001), high-contrast visual acuity (p < 0.05), and contrast sensitivity (p < 0.001, only with silicone hydrogel) directly related to time after contact lens insertion. Besides, in vivo wettability suffered a statistically significant deterioration directly related to time with both contact lenses (p < 0.05). Except for comfort and contrast sensitivity, all the parameters stabilized their values 10 min after the insertion of both soft contact lenses. Additionally, in vivo wettability and visual acuity differences were found between hydrogel and silicone hydrogel contact lenses (p < 0.05).

CONCLUSIONS

It would be possible to properly evaluate high-contrast visual acuity, low-contrast visual acuity, and in vivo wettability 10 min after the insertion of both soft contact lenses.

Tear-film dynamics by combining double-pass images, pupil retro-illumination, and contrast sensitivity

Tear-film dynamics were analyzed by a synchronizing recording of double-pass (DP) and pupil retro-illumination (RI) images with contrast sensitivity (CS) measurements. Simultaneous DP and RI images were acquired in three subjects wearing contact lenses while keeping the eye open. Changes in contrast sensitivity for an 18 c/deg green grating were also estimated. From the DP retinal images, the effect of the tear film is described through the objective scattering index (OSI). This presented a negative correlation with the increase in CS during tear-film deterioration (as observed by RI imaging). These results show a relationship between visual outcome degradation due to tear-film breakup and the increase in intraocular scattering. This work shows a combined methodology for the evaluation of tear-film dynamics.

Supporting Dry Eye Diagnosis with a New Method for Noninvasive Tear Film Quality Assessment

SIGNIFICANCE

Noninvasive high-speed videokeratoscopy equipped with specific software has shown potential for assessing the homeostasis of tear film, providing clinicians with a fast and consistent tool for supporting dry eye diagnosis and management.

PURPOSE

The purpose of this study was to evaluate the efficacy of a recently proposed method for characterizing tear film dynamics using noninvasive high-speed videokeratoscopy in assessing the loss of homeostasis of tear film.

METHODS

Thirty subjects from a retrospective study, of which 11 were classified as dry eye and 19 as healthy, were included. High-speed videokeratoscopy measurements were performed using E300 videokeratoscope (Medmont Pty., Ltd., Melbourne, Australia). Raw data were analyzed using a recently proposed method to estimate the dynamics of the tear film based on a fractal dimension approach. This method provides three time-varying indicators related to the regularity of the reflected rings: tear film surface quality indicator, breaks feature indicator, and distortions feature indicator. From each indicator, five parameters were extracted and analyzed, including noninvasive breakup time, mean value of the indicator in the stability phase, mean value of the indicator in the whole interblink interval, mean value of the indicator in the leveling phase, and the general trend of the time series. Receiver operating characteristic curves were used to determine the sensitivity and specificity of each parameter in dry eye detection.

RESULTS

The best discrimination performance between dry eye and healthy subjects was achieved with the breaks feature indicator noninvasive breakup time parameter, with an area under the curve of 0.85. For a cutoff value of 10 seconds, the sensitivity was 100% and the specificity was 84%.

CONCLUSIONS

The analyzed method improves the assessment of tear film homeostasis in comparison with previous high-speed videokeratoscopy methods showing higher potential in assisting dry eye diagnosis.

Tear film inflammatory cytokine upregulation in contact lens discomfort

PURPOSE

To investigate the ocular inflammatory response, using clinical and immunological techniques, in people experiencing contact lens (CL) discomfort.

METHODS

This study involved 38 adults who were full-time, silicone-hydrogel CL wearers. Participants were categorized into groups based upon a validated CL dry-eye questionnaire (CLDEQ-8) (n = 17 'asymptomatic', CLDEQ-8 score <9; n = 21 'symptomatic', CLDEQ-8 score ≥13). Examinations were performed at two visits (one with, and one without, CL wear), separated by one-week. Testing included: tear osmolarity, ocular redness, tear stability, ocular surface staining, meibography, tear production and tear collection. Tear osmolarity was taken from the inferior-lateral and superior-lateral menisci. The 'Inferior-Superior Osmotic Difference', I-SOD, was the absolute osmolarity difference between these menisci. Concentrations of seven cytokines (IL-2, IL-4, IL-6, IL-10, IL-17A, IFN-gamma, TNF-alpha) were assayed from basal tears using multiplex cytometric bead array.

RESULTS

At baseline, there was no significant difference in key clinical signs between asymptomatic and symptomatic CL wearers (p > 0.05). The I-SOD was greater in symptomatic than asymptomatic CL wearers (23.1 ± 2.6 versus 11.3 ± 1.4 mOsmol/L, p = 0.001). People experiencing CL discomfort had higher tear IL-17A (122.6 ± 23.7 versus 44.0 ± 10.0 pg/mL, p = 0.02) and reduced tear stability (6.3 ± 1.1 versus 10.4 ± 1.6 s, p = 0.03) after several hours of CL wear. Tear IL-17A levels correlated with both the I-SOD (r = 0.43, p = 0.01) and CLDEQ-8 score (r = 0.40, p = 0.01).

CONCLUSIONS

CL discomfort occurs in individuals having no clinical dry eye signs, and is associated with higher tear levels of the pro-inflammatory cytokine IL-17A. These findings support an association between the discomfort response and low-grade, ocular surface inflammation.

Assessment of Tear Film Using Videokeratoscopy Based on Fractal Dimension

SIGNIFICANCE

The proposed automated approach for estimating the quality of the tear film closes the gap between the manual and automated assessment, translating the high-speed videokeratoscopy technology from scientific laboratories to a clinical practice.

PURPOSE

To develop and test a new method for characterizing Tear Film Surface Quality with high-speed videokeratoscopy utilizing a fractal dimension approach.

METHODS

The regularity of the reflected pattern in high-speed videokeratoscopy (E300; Medmont) depends on tear film stability. Thus, determining tear film stability can be addressed by estimating the fractal dimension of the reflected pattern. The method is tested on 39 normal subjects. The results of the fractal dimension approach are compared with those obtained using previously proposed automated method, based on a gray-level co-occurrence matrix approach, and with subjective results obtained by two operators that were assessing the video recordings in ideal conditions.

RESULTS

Fractal dimension method was less affected by eye movements and changes in the videokeratoscopic image background than gray-level co-occurrence matrix method. Median difference of the noninvasive break-up time between manual and automated methods was 0.03 s (IQR = 4.47 s) and 0.0 s (IQR = 2.22 s) for gray-level co-occurrence matrix and fractal dimension approaches, respectively. Correlation coefficient with manual noninvasive break-up time was r = 0.86 (P < 0.001) for gray-level co-occurrence matrix approach, and r = 0.82 (P < 0.001) for fractal dimension approach. Significant statistical difference was found between noninvasive break-up measurements of manual and gray-level co-occurrence matrix method (P = 0.008).

CONCLUSIONS

The proposed method has the potential to characterize tear film dynamics in more detail compared to previous methods based on high-speed videokeratoscopy. It showed good correlation with manual assessment of tear film.

Non-invasive pre-lens tear film assessment with high-speed videokeratoscopy

PURPOSE

To evaluate the effect of two types of daily contact lenses (delefilcon A and omafilcon A) on the tear film and establish whether it is dependent on pre-corneal tear film characteristics using a new method to analyse high-speed videokeratoscopy recordings, as well as to determine the sensitivity of the method in differentiating between contact lens materials on eye.

METHODS

High-speed videokeratoscopy recordings were analysed using a custom made automated algorithm based on a fractal dimension approach that provides a set of parameters directly related to tear film stability. Fifty-four subjects participated in the study. Baseline measurements, in suppressed and natural blinking conditions, were taken before subjects were fitted with two different daily contact lenses and after four hours of contact lens wear.

RESULTS

The method for analysing the stability of the tear film provides alternative parameters to the non-invasive break up time to assess the quality of the pre-corneal and pre-lens tear film. Both contact lenses significantly decreased the quality of the tear film in suppressed and natural blinking conditions (p<0.001). The utilised method was able to distinguish between contact lens materials on eye in suppressed blinking conditions. The pre-corneal tear film characteristics were not correlated with the decrease in pre-lens tear film quality.

CONCLUSION

High-speed videokeratoscopy equipped with an automated method to analyse the dynamics of the tear film is able to distinguish between contact lens materials in vivo. Incorporating the assessment of pre-lens tear film to the clinical practice could aid improving contact lens fitting and understand contact lens comfort.

Future directions in non-invasive measurements of tear film surface kinetics

PURPOSE

To review the methods for dynamic, non-invasive, and objective assessment of tear film surface quality and to outline their current state-of-the-art and their future potential.

METHODS

Among the methods available, high-speed videokeratoscopy, lateral shearing interferometry, and dynamic wavefront sensing are being considered.

RESULTS

The principles of operations, their advantages and disadvantages, and limitations of each method are being outlined. The possible future directions of each method are also discussed.

CONCLUSIONS

To gain a better understanding of tear film, its structure and function, it is essential to combine macroimaging technologies with those focusing on tear film microstructure. In this way, one can envisage a clinical device that could help, in future, early diagnosis of dry eye syndrome and development of better materials for contact lenses and eye lubricants.