I think we can safely say that dry eye disease is no longer considered by any practitioner as a single disease entity which can be addressed with a single drop. Indeed, if it were needed, the latest TFOS DEWS2 reports have emphasised that the condition has a wide variety of causes, both external and internal, and expresses itself in a range of ways, from corneal staining and tear break up time reduction through to tear osmolarity changes and fluctuations in inflammatory markers within the tears.
The condition itself may be of an evaporative or aqueous deficient nature, and usually a combination of the two in a ratio that might be anywhere along a spectrum of combinations of the two. Furthermore, the condition may have significant numbers of signs with few symptoms and vice versa.
No wonder, then, in order to provide an effective management plan, which is likely to involve a number of components to tackle the problem, it is necessary to carry out a range of assessments, to look at each result as part of an overall profile, and then to decide on the best remedial approach.
It should also be possible to review the patient regularly, be able to easily access their profile, and then see how effective any intervention has been and decide upon any adjustment to the care plan, either by looking at the patient’s compliance or by changing one or more of the interventions.
At the start of this year, I tried out the Ocular Surface Analyser (Optician 02.03.18) which brought together a wide range of tests and data in one easy to use slit-lamp top mounted unit. This month, Grafton Optical is launching the latest version of this system – the IDRA.
Figure 2
The IDRA
Like the OSA, the IDRA is essentially a 5MP digital imaging system (figures 1 and 2) that can be fitted into the central pivot hole (figure 3) of any slit-lamp and is capable of both multi-shot and video image capture.
Figure 3
The unit has two links (one USB2 and the other USB3) to link with any laptop with the ports and onto which the licensed software has been downloaded (you pay for the unit and a license for software on one laptop). The unit, wiring and the linked laptop are easily contained within a carry case (figure 4) making the system portable between clinics.
Figure 4
The new system has some interesting improvements. Firstly, there is no longer the need for the slightly awkward insertion of curled up Perspex grading pattern sheets into the head of the instrument. Gratings are already embedded into the inner wall of the unit (figure 5).
Figure 5
Secondly, the software has been streamlined such that, once patient data has been input, selection of the specific test to be used is simple and made from a list down the left hand side of the screen (figure 6).
Figure 6
Table 1 shows a comparison of tests available with the OSA and the IDRA. This shows a number of new tests available.
Auto interferometry
When this mode is selected, the image needs to be focused such that, after each blink, interference fringes are clearly seen on the tear film. The tear film plane must be focused, while the image of the bright circle must remain blurred. Depending on its thickness and regularity, the lipid layer may appear as one of the following descriptions:
- Amorphous structure
- Marble (marmoreal) appearance
- Wavy appearance
- Yellow, brown, blue or reddish interference fringes
When the tool shows a matt white pattern, it indicates that there are no lipids. If it reveals a white and rapidly moving image, then a lipid layer is present but of borderline integrity. When the resulting image is full of colours, a robust lipid layer is implied. The patency of the lipid layer helps to predict the stability of the tear film and the likelihood of evaporation. This function is automated so possible with minimal user input and reveals:
- Maximum thickness of lipid layer
- Average thickness
- Blinking rate
Figure 7
The results are presented in accordance with the original Guillon and Guillon research. The machine is also able to offer data on blink rates and blinking patterns. Figure 6 shows the capture for one eye and figure 7 a comparison between each eye. The lipid layer integrity is easily visualised as a colour coded scale plot (figure 8).
Figure 8
3D meibography
Meibography is a technique gaining popularity in dry eye assessments.
Figure 9
Infrared imaging clearly shows the patency of the meibomian glands when the lids are everted (figures 9 to 11), and the software is then able to define the contrasting regions and calculate a numerical representation of the meibomian gland structure (figure 12 and 13).
Figure 10
Figure 11
Figure 12
Figure 13
New to the IDRA is an option to view the meibomian gland structure in three dimensions (figures 14 to 17).
Figure 14
Figure 15
Figure 16
Figure 17
The advantages this offers both the clinical and the patient are summarised in table 2.
Report generation
The data reports have been simplified and are more flexible. It is possible to highlight individual data, for example just those of any interest or anomaly, display imported data, such as osmolarity results, as well as produce a composite report (figure 18).
Final thoughts
Having the ability to assess dry eye by a wide variety of techniques, import other relevant data, grade and compare data, and generate reports should be attractive to anyone with a desire to offer dry eye disease services. The ease of use and ergonomic appeal of the IDRA is a welcome addition to the consulting room.
For further information see www.graftonoptical.com