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 Table of Contents  
INSTRUMENT CORNER
Year : 2019  |  Volume : 31  |  Issue : 1  |  Page : 72-74

Ocular surface analyzer


Department of Cornea and Refractive Surgeries, Giridhar Eye Institute, Kadavanthra, Kochi, Kerala, India

Date of Web Publication15-Apr-2019

Correspondence Address:
Rose Mary George
Giridhar Eye Institute, Kadavanthra, Kochi - 682 020, Kerala
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/kjo.kjo_26_19

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How to cite this article:
George RM, Mohan P. Ocular surface analyzer. Kerala J Ophthalmol 2019;31:72-4

How to cite this URL:
George RM, Mohan P. Ocular surface analyzer. Kerala J Ophthalmol [serial online] 2019 [cited 2019 Aug 24];31:72-4. Available from: http://www.kjophthal.com/text.asp?2019/31/1/72/256266




  Introduction Top


Dry eye disease (DED) is defined as a “multifactorial disease of the ocular surface characterized by a loss of homeostasis of the tear film and accompanied by ocular symptoms, in which, tear film instability and hyperosmolarity, ocular surface inflammation and damage, and neurosensory abnormalities play etiological roles.”[1]

The accurate diagnosis and classification of dry eye are complicated by the heterogeneous nature of the disease and the variability of signs and symptoms.[2] Various diagnostic assessments have been proposed to qualitatively and quantitatively characterize the entire ocular surface system.[3] However, to date, no universally accepted diagnostic workup for the diagnosis of dry eye has been established. The tests which are available before are invasive, requiring direct contact with the ocular surface, and subjective, which leads to the possibility of significant observer bias because of a low degree of standardization.[4]

Ocular surface analyzer (OSA) is the new instrument of individual analysis of tear film that allows to do a quick detailed structural research of the tear composition and research on all the layers, that is, lipid, aqueous, and mucin. OSA also helps to identify the type of DED and determine which layers can be treated with a specific treatment, in relation to the type of deficiency [Figure 1].[5]
Figure 1: Ocular surface analyzer

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The following parameters can be measured by OSA, and each parameter plays an important role to identify the type of DED.

  1. Interferometry: It is a technique that studies the surface reflection pattern and dynamics of the lipid layer of the tear film, thus allowing the measurement of the tear film stability and the thickness of the lipid layer. The OSA can evaluate the quantity and the quality of the lipid component on the tear film. The device enlights the lipid layer and the pattern defined can be compared with the reference grading scale. Using the device, it is possible to do an interferometric analysis of the lipid layer in 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 like any of the following: amorphous structure; marble appearance; wavy appearance; and yellow, brown, blue, or reddish interference fringes [Figure 2]. When the tool shows a matt white pattern, it means that there are no lipids; if it shows a white and quick movement of the image, the lipid layer is present and in a borderline condition; when the resulting image is full of colors, it means there are many lipids
  2. Tear meniscus: The size of the tear meniscus formed on the eyelid borders provides useful information on the volume of produced tears. The tear meniscus can be examined considering its height, regularity, and shape. Evaluation of the tear film quantity is with the help of magnification tools; you can measure the tear meniscus height and evaluate its characteristics along the lower lid margin [Figure 3]. The result of this examination is comparable to the Schirmer's test one, with the difference that it is not invasive and lasts 3 s instead of several minutes
  3. Noninvasive breakup time (NIBUT): The measurement of BUT with a noninvasive technique eliminates the disturbance on the tear film caused by instillation of fluorescein dye. The stability of the mucin layer and the whole tear film is measured through NIBUT using grids that are projected onto the cornea you are able to evaluate manually or automatically the time when the tear breakup occurs [Figure 4]
  4. Meibography: It images the morphology of the glands in order to diagnose any  Meibomian gland More Details dropout which would lead to tear dysfunction. Meibography is the visualization of the glands through transillumination of the eyelid with infrared light. Dysfunction of the meibomian glands destabilizes tears resulting in evaporative dry eye. The posterior lamella of the eyelid hosts a fleet of meibomian glands situated between the palpebral conjunctiva and tarsal plate. A normal meibomian gland is approximately linear and 3–4 mm in length, traversing the posterior eyelid perpendicularly from the lid margin to the opposite edge of the tarsus [Figure 5]
  5. Blepharitis: This test helps in detection of blepharitis and demodex, which can be performed on the outer surface of the eye and eyelids
  6. Ocular redness classification: Once you have captured the image of the blood vessels of the conjunctiva, it will be possible to compare them to the classification sheets of bulbar and limbal redness degree
  7. Pupillometry: Measurement of the pupil reaction to light with and without glare; measurement mode: scotopic, mesopic, and photopic
  8. White-to-white (WTW) measurement: Evaluation of corneal diameter from limbus to limbus (WTW distance).
Figure 2: Interferometry

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Figure 3: Tear meniscus

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Figure 4: Noninvasive breakup time

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Figure 5: Meibography

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  Osa Plus Top


Additional uses

  1. Three-dimensional (3D) meibomian gland imaging: The revolutionary introduction of 3D meibomian gland imaging provides the clinician with two clear advantages. First, it enables you to confirm the presence of abnormal glands versus that of a healthy individual in a 3D format, and second, it provides a clear image to share with the patient to help explain the potential cause of their discomfort
  2. Blink rate: It has been established that efficient blinking plays an important role in ocular surface health
  3. Tear meniscus height measurement: Have the possibility to acquire up to five measuring points.


[Figure 6] depicts graphical reporting showing the parameters of OSA, which is self-explanatory and easily understood both by the examiner and the patient.
Figure 6: Ocular surface analyzer reporting

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Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Craig JP, Nichols KK, Akpek EK, Caffery B, Dua HS, Joo CK, et al. TFOS DEWS II definition and classification report. Ocul Surf 2017;15:276-83.  Back to cited text no. 1
    
2.
Ji YW, Lee J, Lee H, Seo KY, Kim EK, Kim TI, et al. Automated measurement of tear film dynamics and lipid layer thickness for assessment of Non-Sjögren dry eye syndrome with meibomian gland dysfunction. Cornea 2017;36:176-82.  Back to cited text no. 2
    
3.
Baudouin C, Messmer EM, Aragona P, Geerling G, Akova YA, Benítez-del-Castillo J, et al. Revisiting the vicious circle of dry eye disease: A focus on the pathophysiology of meibomian gland dysfunction. Br J Ophthalmol 2016;100:300-6.  Back to cited text no. 3
    
4.
Roy NS, Wei Y, Kuklinski E, Asbell PA. The growing need for validated biomarkers and endpoints for dry eye clinical research. Invest Ophthalmol Vis Sci 2017;58:BIO1-9.  Back to cited text no. 4
    
5.
Giannaccare G, Vigo L, Pellegrini M, Sebastiani S, Carones F. Ocular surface workup with automated noninvasive measurements for the diagnosis of meibomian gland dysfunction. Cornea 2018;37:740-5.  Back to cited text no. 5
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]



 

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