How dyes are used in ophthalmic purpose.

1. Ophthalmic Dyes
Introduction:
In late 18th century the dyes are came in use for
ophthalmic care followed by Baeyer’s synthesis of
Fluorescein sodium in 1871. In ophthalmology the dyes are
used for variety of diagnostic and therapeutic aids in the
clinic based on out-patient. Dyes enable the physician to
better view the ocular surface and the retinal or choroidal
vasculature. There are several types of dyes used in
ophthalmic care such as fluorescein sodium, fluorexone, rose
bengal etc., In clinical practice, the used of individually
wrapped, sterile, dyes impregnted paper strips is the
preferred staining technique.

2. Types of ophthalmic dyes:
Fluorescein
Sodium Fluorexone Indocyanine
green
Rose Bengal Lissamine
green
Methylene
Blue
Dyes

3. Fluorescein sodium:
Fluorescein sodium, a water soluble dibasic acid dye, is the
most essential and commonly use in ophthalmology. Several
factors contribute to its utility, including its hydrophilicity, low
toxicity, and excellent fluorescent properties in the visible
spectrum, even in very dilute concentration.
Fluorescein may be applied topically to the eye in the form
of solution or by fluorescein-impregnated filter paper strips. It
is also available in injection form for intravenous use.
Fluorescein in solution is highly susceptible to bacterial
contamination, especially by Pseudomonas aeruginosa, which
grows easily in the presence of fluorescein. Major methods of
reducing the possibility of bacterial growth include sterile
formulation and air-tight seal of solutions, use of effective
preservatives in fluorescein solution, and the development of
sterile fluorescein impregnated strips.

4. Both injection fluorescein and sterile strips are used once
and discarded, fluorescein-anesthetic combination solutions are
used repeatedly on sequential patients.
Uses:
* Corneal staining to detect abrasion and ulcers. Epithelial
defect of cornea stain bright green in white light and opaque
green with cobalt blue light and thus are easily visualized.
* Applanation tonometry is the most frequent procedure in
which tear film is stained for measuring IOP.
* Lacrimal tests includes tear film break up time(TBUT) for
any eye and Jane’s test for watering eye.
* Seidel’s test- Tear film is stained to detect leakage of
aqueous from the anterior chamber in postoperative shallow
anterior chamber, perforating trauma and perforation of
corneal ulcer.

5. * Rigid contact lens fitting is the best judged with
fluorescein pattern of tear film.
Fluorescein strips
* Intravenous fluorescein(10% & 25%) is used for:
1. Fundus fluorescein angiography
2. Iris angiography for evaluation of vasculature
3.Vitreous fluorophotometry.
Fluorescein staining of cornea
as seen with cobalt blue filter

6. Side effects:
* Topical – unconsciousness and hypertensive reactions.
* Rare side effects.
* Intravenous injection – with increased concentration
adverse effects in about 10% of patients receiving IV injections.
* Less frequently – respiratory effects like laryngeal or
pulmonary edema.
* Cardiovascular toxicity in form of severe hypotension and
shock.
Fluorescein Angiography

7. Fluorexon:
It is a high molecular weight fluorescent solution (N-bis-
aminomethyl fluorescein tetrasodium). Fluorexon, a molecule
similar in fluorescent characteristics to that of fluorescein, is less
readily absorbed by the soft lens material, which renders it
useful in fitting and evaluating soft and hybrid design lenses.
It is a hydrophilic dye due to its multiple polar moieties.
Compared with sodium fluorescein, fluorexon has a paler
yellow-brown color. Its staining properties are similar to those
of flurorescein, although the fluorescence is much less (due to
lower quantum yield) and thus it must be used at greater
concentration.
Like sodium fluorescein, fluorexon is vulnerable to bacterial
contamination, but it appears to support bacterial growth longer
than does a comparable solution of fluorescein sodium. For
clinical use, therefore, it is dispensed as single-dose sterile
pipettes, a preserved

8. solution with benoxinate, or recently as fluorexon-impregnated
sterile strips.
Uses:
* Fluorexone does not stain most of the soft contact lenses
and thus used in eyes when fluorescein is contraindicated to
avoid staining of soft contact lenses:
1. Evaluation of corneal integrity of patients wearing
hydrogel contact lenses.
2.Tear film BUT test
3. Applanation tonometry without removing soft
contact lens.
4. For detecting lathe-cut index marking of toric soft
contact lenses.

9. Side effects:
* Fluorexon stains the soft lens if it remains in contact
with the lens for more than a few minutes. However,
repeated rinsing with saline usually removes the dye from
the lens.
* Occasional conjunctival injection may occur.
* Topical application to the eye of a fluorexon-
benoxinate combination solution for tonometry has been
suggested to produce less stinging and burning compared
with a standard fluorescein-benoxinate solution.

10. Rose Bengal:
It is widely used in the diagnosis of ocular surface disease,
the understanding of the staining characteristics of rose bengal
has evolved. Relatively recent evidence suggests that it is not a
vital dye but one that may actually cause toxicity and cell death
under certain circumstances.
It is a dye commonly used in ophthalmic diagnosis.Tissues
stained with rose bengal display a vivid pink or magenta color
when viewed with white light.
It has been formulated as a 1% solution and in the form
of sterile impregnated paper strips that require moistening
with sterile saline or extraocular irrigation solution.When
using a rose bengal–impregnated strip a variable volume of dye
is delivered to the eye based on differing strip soak times.

11. Uses:
* Conjunctival staining
* Diagnosis of dry eye diseases
* Dysplastic or squamous metaplastic cells of
conjunctival squamous neoplasms.
* Corneal staining for herpetic corneal epithelial dendrites,
superficial punctate keratitis.
* Diagnosis of meibomian gland dysfunction.
Rose bengal strip & solution Rose bengal staining of
the ocular surface

12. Lissamine green:
Lissamine green is a vital stain degenerate cells, dead cells and
mucus in much the same way as rose bengal. It is also widely used
in the food industry as a colorant.
Lissamine green 1% stains in a fashion identical to that of 1%
rose bengal. It is currently available in sterile strips, which when
wetted with saline solution probably deliver variable
concentrations and volumes to the eye similar to that for rose
bengal. It may be useful when a patient is known to be sensitive to
rose bengal.
Uses:
* Diagnosis of Dry eye disease
* To ascertain proper fitting of contact lens, and to look for any
contact-lens induced conjunctival staining.

13. * In Sjogren’s syndrome suspects – to rule out
Keratoconjunctivitis sicca.
* In patients with symptoms of dry eye disease but no clinical
signs, can be used to assess lid margins for lid wiper epitheliopathy.
* Lissamine green stains membrane-damaged epithelial cells as
well as corneal stroma in a manner similar to that of fluorescein
and, like rose bengal, also binds to the nuclei of severely damaged
cells.
Lissamine green strips Lissamine green staining
in keratoconjunctivitis sicca

14. Indocyanine green:
Indocyanine green (ICG) has a high protien binding
capacity, near infrared fluorescence and peak spectral
absorption of 800-810 nm in blood.
40mg in 2ml for IV injections
0.05% to 0.5% for posterior segment surgeries, the
concentration of the dye used for ILM (internal limiting
membrane) staining depends upon the surgeon.
The dye comes in a 25mg vial of ICG, which is mixed with
5mL of the aqueous solvent that comes with it to yield the
5mg/mL (0.5%) concentration dye, which is used to stain the
anterior capsule in cataract surgeries.

15. The dye has a high affinity for collagen type IV and laminin.
Both of these are found in a high concentration in the internal
limiting membrane of the retina. Hence, the dye is the used for
staining the ILM during vitreoretinal procedures.
When injected intravenously, 98% of the dye remains
plasma protein bound. The dye can not diffuse out of the
intravascular compartment, and hence is used in imaging the
choroidal vasculature in ICGA.
The dye shows a phenomenon called decomposition,
where once it is diluted in any solvent and exposed to light,
ICG may undergo various chemical reactions by self-sensitized
oxidation because it is chemically unstable. This can cause
ocular toxicity, especially to the retina.

16. Uses:
* For staining the anterior capsule during cataract surgery.
* In chromovitrectomy to visualise the ILM.
* In ICGA, to visualise choroidal circulation, and help in the
diagnosis of conditions like polypoidal choroidal vasculopathy,
choroidal neovascular membrane, age related macular
degeneration and posterior uveitis.
* ICG-enhanced anterior capsulorrhexis using 0.5%
solution is useful in childhood cataracts and adulthood cataract
with no fundus glow.
* ICG-enhanced posterior capsulorrhexis using 0.5%
solution is useful in childhood cataracts.

17. Side effects:
* Mild nausea, vomiting
* Serious reactions are exceptionally rare.
* ICG contains a small amount of sodium iodide, it should
not be used in patients with sensitivities to iodine or shellfish
or in patients at high risk for anaphylactic reaction.
ICG solution ILM staining with ICG in macular hole surgery

18. Methylene blue:
Methylene blue, a vital stain (Urolene blue), has
properties similar to those of rose bengal. It can stain both
devitalized cells and mucus and corneal nerves. It is not a
specific stain when applied to the eye because the blue areas
may be either cells or mucus. Clinically, methylene blue is useful
for staining the lacrimal sac before dacryocystorhinostomy and
outlining glaucoma filtering blebs, and it may prove useful in
gonioscopic laser sclerostomy.
More recently it has been used in vitro to examine the
effects of artificial tear preparations on corneal integrity in dry
eye models.

19. The dye is usually used as a 5% solution, and benzalkonium
chloride may be added to the dye solution to enhance sterility.
Methylene blue precipitates in alkaline solutions.
Uses:
* Vital staining of corneal nerves requires up to three
instillations at 5-minute intervals.The bluish ocular
discoloration may remain for 24 hours.
* For staining of the lacrimal sac before surgery, the sac is
irrigated with methylene blue.The dye should remain in the sac
for several minutes.Before the beginning of surgery the dye
should be washed out of the sac, because it can spill out on
incision and stain the surrounding tissues.

20. * Methylene blue can also be administered intracamerally
to stain the crystalline lens capsule to aid in visualization during
cataract surgery.
Side effects:
* When topically applied methylene blue can be fairly
irritating to ocular tissue.
* A topical anesthetic may be used, because it enhances
penetration of the drug at the same time as it relieves the
discomfort.