Excretory Tests

The goal of excretory tests is to describe the drainage function and lacrimal system patency.

3.3.3.1 Fluorescein Dye Disappearance Test

Fluorescein dye disappearance test (fluorescein dye retention test) is a very useful essential physiological test in which the lacrimal system is not instrumented and the marker fluorescein flows through the system mixed with tears [2, 18, 29, 30].

The principle of the test is in the evaluation of the residual fluorescein in the eye following instillation of one drop of fluorescein into the unanesthetized conjunctival sac [17, 29, 30].

The fluorescein dye test does not distinguish anatomical and functional defect [9]. There is not, in contrast to Jones II, a higher hydrostatic pressure in this test. The advantages of fluorescein dye test are higher sensitivity and ease of obtaining results with children [14, 17]. The presence of residual fluorescein gives no information on the localization of the obstruction, and that is why other anatomical tests, especially probing and syringing, must be carried out (Fig. 3.5).

Performance

One drop of 0.125-2% fluorescein is instilled into the unanesthetized lower fornix of each conjunctival sac. After 5 min, the thickness of the fluorescence of the tear meniscus is measured with the help of cobalt-blue filter. The tears normally drain down the system in 5 min. The test is positive if residual fluorescein is present. In infants, the child must be placed on a parent's knee or held in arms, and the head must be in a vertical position.

The fluorescein dye test grading scale is as follows [17]:

■ 0=no fluorescence in the conjunctival sac

■ 1=thin fluorescing marginal tear strip persists

■ 2=more fluorescein persists, between l and 3

■ 3=wide, brighly fluorescing tear strip

Grades 0 and 1 are considered to be normal, i.e., the drainage function is good. Grades 2 and 3 are considered to be abnormal and the lacrimal drainage system is not functional.

False-negative findings may occur due to a large lacrimal sac or mucocele, or a distal nasolacrimal duct block, where the dye with fluorescein can pool in the sac or duct [19].

If a drop of fluorescein is placed in the external canthus on the lower eyelid, its transport can be observed from lateral to medial across the eyelid and into each punctum, and the holes in the tear film can be observed (break-up time test).

Fluorescein may be sought in the nose if a patient is asked to blow the nose or the nose is examined endo-scopically.

In most patients with epiphora the history, palpation, and inspection, fluorescein dye disappearance

Eye Nosalcrimal Duct Labeling

Fig. 3.5. Fluorescein dye disappearance test. a Grade 0=no fluorescence in the conjunctival sac. b Grade 1=thin fluorescing marginal tear strips only. c Grade 2=between 1 and 2. d Grade 3=brightly fluorescing tear strip. e Asymmetry in test: retention of fluorescein on the left side in a congenital nasolacrimal obstruction. (From [14])

Fig. 3.5. Fluorescein dye disappearance test. a Grade 0=no fluorescence in the conjunctival sac. b Grade 1=thin fluorescing marginal tear strips only. c Grade 2=between 1 and 2. d Grade 3=brightly fluorescing tear strip. e Asymmetry in test: retention of fluorescein on the left side in a congenital nasolacrimal obstruction. (From [14])

test, diagnostic probing, and irrigation of the nasolac-rimal system is sufficient for the determination of the drainage function, location, and degree of anatomical block.

Jones tests are rarely used because of their false negativity and the fluorescein dye test is preferred [9, 20, 29, 30]. Jones tests can be performed only if the lacri-

mal system is patent for syringing, i.e., there is no complete obstruction in the lacrimal system. The primary dye test is a physiological test, and although it is limited, it has some benefit [9].

Saccharin test is a physiological test similar to fluorescein dye test [7]. A drop of saccharin is placed into the anesthetized conjunctival sac and the time is measured until the patient tastes saccharin (approximately 3.5 min; patients should not have any problem with tasting). As the test cannot be used in small children (in comparison with fluorescein dye test) and gives us no anatomical information, we do not use it.

3.3.3.2 Jones Fluorescein Tests and Saccharine Test

Tear Canaliculi

Fig. 3.6. Syringing and probing of the lacrimal system. a Syringing via lower canaliculus. Reflux through the upper punctum suggests obstruction at the common canaliculus or more distal structures. b Bowman probes. c Tapered punctum dilator inserted into punctum. d Diagnostic probing. The eyelid must be gently stretched laterally. e Examination with a pig-tail probe can help to assess the opposite canaliculus. (From [14])

Fig. 3.6. Syringing and probing of the lacrimal system. a Syringing via lower canaliculus. Reflux through the upper punctum suggests obstruction at the common canaliculus or more distal structures. b Bowman probes. c Tapered punctum dilator inserted into punctum. d Diagnostic probing. The eyelid must be gently stretched laterally. e Examination with a pig-tail probe can help to assess the opposite canaliculus. (From [14])

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