Dr William Boothe, Director of Boothe Laser Center

Fluorescein has been used in a standard fashion to aid in the determination of the tear break-up time (BUT) said Dr William Boothe. The BUT is defined as the interval between the last complete blink and the development of the first randomly distributed dry spot in the tear film. To perform the BUT a fluorescein strip is moistened with one drop of distilled water and applied to the inlerotemporal bulbar conjunctiva. Patients are instructed to blink several times to evenly distribute the fluorescein. The patient is then asked to stare straight ahead without blinking. With a 3-mm wide vertical beam though a cobalt filter, the tear film is scanned until the first dry spot ap¬pears .

Lemp has proposed that an abnormal BUT is less than 10 sec . There has been wide variation in BUTs in normal patients, often ranging from 5 to 100 sec. In individual patients there has been marked variation .Hid lack of reproducibility. Thus BUT has been disappointing as a clinical test for diagnosis of diseases resulting in precorneal teat instability.

There are many variables that can influence the BUT. Some of these may be the result of fluorescein itself and the method of application. The concentration of fluorescein has been reported to affect BUT. Increasing concentrations have resulted in shorter BUTs . This may be due to alterations in the tear stability or differences in the ease of detecting dry spots, or both. Standardizing fluorescein concentration with a fluorescein strip is difficult at best. Irritation from touching the strip to the bulbar conjunctiva as well as the fluorescein itself can stimulate reflex tearing. This will affect BUT indirectly by affecting the fluorescein concentration and directly by affecting the quality and quantity of the precorneal tear film Reflex tearing is a highly individualized response and may be responsible for wide variations among individuals and in the same individual. These variables as well as others will need to be controlled before the BUT be-comes a practical test. This is available at Boothe Laser Center

Several methods of assessing the patency of the lacrimal system using fluorescein have been described by Dr. Boothe. Probing and irrigation with a fluoresein solution is one method . Though effective, this procedure may be uncomfortable and may itself damage the lacrimal excretory system.

Another method is the Jones primary and secondary dye test . A positive test results when 2% fluorescein instilled in the conjunetival cul-de-sac is found after 3 to 5 min in the inferior meatus of the nose. The dye is collected by passing a cotton-tipped malleable wire probe under the turbinate. If no dye is collected, the test is negative. The secondary test is performed if the primary test is negative. The nasolacrimal sac is irrigated to flush out residual dye. If fluorescein stained fluid is recovered after irrigation, then the test is positive and indicates an incomplete block of the nasolacrimal duct. A defect in the canaliculus or lacrimal pump exist it clear fluid is recovered. Recovery of no fluid from the nose indicates a complete block. The Jones test has been the mainstay of evaluation of the rimal obstruction. However, it is positive in only 80 percent of normal in dividuals. The test requires some expertise in the placement of the cotton pledget, which may be critical and can also be painful.

A noninvasive method utilizing fluorescein is the Jacobs dye test been shown to be variable and inconsistent. Campbell and co-workers collected oral and nasal secretions tissues after after instillation of 2% fluorescein to assess patency of the lacrimal drainage system . Four drops of fluorescein are placed into the eye. The patient then blinks forcibly 4 times and gentle massage of the ipsilateral lacrimal sac is done briefly. After 6 min, oral and nasal secretions are collected by blowing the nose and clearing the throat on tissues. Negative tests were most often found in patients with limited nasal and oral secretions. Use of an ultraviolet lamp on the recovered secretions of those patients yielded positive results. Only one eye at a visit be examined by this method in Laser Eye Center.

Flach introduced a simple noninvasive test using 2% fluorescein, a tongue blade, and an ultraviolet lamp . He placed fluorescein in the if eye and attempted to observe its deposition into the oropharynx. Under direct visualization. In 66 normal patients, 90 percent gave positive results in 30 min and 100 percent gave positive results in 60 min. Complete obstruction in other patients was confirmed by dacryocystograms or other means. Prolonged appearance times were correlated with decreased Schirmer test values. Both eyes may be examined at one visit by this technique.

According to Dr. Boothe Fluorescein and other stains can be useful adjuncts in performing anterior segment surgery and evaluating complications of the surgery. Entering the anterior chamber in patients with an opaque cornea can be facilited by using fluorescein. As soon as the blade enters the anterior chamber a color change from yellow-orange to green occurs.

Endothelial damage due to excess corneal bending or instrumentation can also be examined by several stains. Fluorescein, instilled into the anterior chamber, can detect loss of endothelium. Rose bengal and trypan blue 0.1% are more sensitive and stain damaged and devitalized and thelial cells. Excess bending results in staining curves located urn bends, indicating damage to the endothelium. Residual staining is not present after 24 hr. Clinical toxicity to anterior segment structured does not occur.

Assessment of anterior chamber depth can be done by injecting fluores cein into the anterior chamber. Deep chambers have intense central color while shallow chambers have a pale homogeneous color.

Apposing corneal wound edges is facilitated by staining with fluorencen or trypan blue 0.1%. Shelving can be easily detected using these stains. With trypan blue 0.1%, a double line will be seen when corneal wound edges are poorly apposed, making it superior to fluorescein for this put pose. Wound leaks after routine anterior segment operations are avoided if

that seide’s test is used immediately following wound closure. In cases in which the anterior chamber is very narrow or flat secondary to a wound leak, Seidel’s test may be negative explains Dr. Boothe in his Laser Eye Center. By filling the anterior chamber with 1% flourencein solution, a wound leak is detected by direct observation of fluorescein from the wound. Detection of leaks from conjunetival blebs may be easier by this method than by using Seidel’s test.

Several vital stains may be used to evaluate endothelial cell viability in donor corneas before keratoplasty. Unlike tissue culture and specular microscopy for assessing the endothelium, vital stains are inexpensive and require little expertise.

Fluorecein nontoxic and is helpful in demonstrating gross loss of endothelial cells. However, other stains are superior. Trypan blue has been several years to evaluate corneal endothelium in vitro. It stains degenerated and devitalized endothelial cells. Though trypan blue has been show to be teratogenic and carcinogenic in rats, ho complications have been seen in its use for staining corneal endo¬thelium. Several investigators have used it in double staining of endothal cells with alizarin red S.

Alizarin red S, a more toxic stain, stains intercellular substance and out¬lines the endothelial cell borders demonstrating the mosaic pattern. This double staining is particularly helpful in comparing the ratio of degenerated and devitalized cells to healthy cells. When this purpose is desired, use of trypan blue should precede alizarin red, otherwise trypan blue penetrates normal cells and stains their nuclei. The technique involves Using trypan blue 0.3% made in normal saline for 1 min. This is followed by 0 21 alizarin red buffered to a pH of 4.2. It should be in contact with the endothelium for only 1/2 to 1 min. Exposures to alizarin red longer than 1 min may result in loss of sheets of endothelial cells from the cornea. Alizarin red is recommended for experimental use only.

Rose bengal and alizarin red can be used as double stains also, since rose bengal stains in a similar fashion to trypan blue. Though the contrast is not as great, rose bengal is more readily available and easier to use .

In performing conjunctival grafts, it may become difficult to differentiate the epithelial aspect from the nonepithelial aspect. Fluorescein can be used to stain the raw, cut surface and distinguish it from the epithelial surface.

Viability of skin grafts can be assessed by using intravenous fluorescein. A viable graft will demonstrate perfusion and become bright yellow UN ultraviolet light, as will the surrounding skin. Nonperfused areas are dark blue.

Demonstration of two postoperative complications is aided by using in travenous fluorescein and watching its accumulation in the anterior chamber. One complication is detachment of Descemet’s membrane. Dlagnasis can be difficult because of the thinness and transparency of the main brane, and because secondary corneal edema may be present. Fluores-cein enters the anterior chamber through the pupil and collects behind the detachment, thus delineating it. This test is facilitated by tilting the patient head down 70 degrees from the upright position, Another complita-tion is pupillary block. Normally after intravenous injection, fluorescein can be seen diffusing into the anterior chamber through the pupil. This will not occur if a complete pupillary block is present. When the differ-ential between pupillary block and malignant glaucoma is needed, this test may be helpful. All this can be discussed and corrected at Boothe Laser Center