Source: Health Products and Food Branch (CA) Revision Year: 2018
MYDFRIN is recommended as a vasoconstrictor, decongestant, and mydriatic in a variety of ophthalmic conditions and procedures. Some of its uses are for pupillary dilatation in uveitis (to prevent posterior synechia formation), for multiple ophthalmologic surgical procedures (including phacoemulsification, intracapsular and extracapsular cataract extraction, vitrectomy, etc.), and for refraction without cycloplegia (as an adjunct to increase pupillary dilatation). MYDFRIN may also be used for fundoscopy, multiple ophthalmic diagnostic procedures and examination.
MYDFRIN is especially useful when rapid and powerful dilatation of the pupil and reduction of congestion in the capillary bed are desired. A drop of a suitable topical anesthetic may be applied, followed in a few minutes by 1 drop of MYDFRIN on the upper limbus. The anesthetic prevents stinging and consequent dilution of the solution by lacrimation. It may occasionally be necessary to repeat the instillation after one hour, again preceded by the use of the topical anesthetic.
Posterior Synechia: MYDFRIN may be used in patients with uveitis when synechiae are present or may develop. The formation of synechia may be prevented by the use of MYDFRIN and atropine to produce wide dilatation of the pupil. For recently formed posterior synchiae, one drop of MYDFRIN may be applied to the upper surface of the cornea and may be repeated in one hour as necessary. Treatment may be continued the following day, if necessary, employing topical atropine sulfate and applying hot compresses as indicated.
MYDFRIN may be used with miotics in patients with open angle glaucoma. It reduces the difficulties experienced by the patient because of the small field produced by miosis, and still it permits and often supports the effect of the miotic in lowering the intraocular pressure. Hence, there may be marked improvement in visual acuity after using MYDFRIN in conjunction with miotic drugs.
When a short-acting mydriatic is needed for wide dilatation of the pupil before intraocular surgery, MYDFRIN may be applied topically from 30 to 60 minutes before the operation.
Prior to determination of refractive errors, MYDFRIN may be used effectively with homatropine hydrobromide, cyclopentolate hydrochloride, tropicamide and topical atropine sulfate.
One drop of the preferred cycloplegic is placed in each eye, followed in 5 minutes by one drop of MYDFRIN.
Since adequate cycloplegia is achieved at different time intervals after the instillation of the necessary number of drops, different cycloplegics will require different waiting periods to achieve adequate cycloplegia.
Topical atropine sulfate is the preferred cycloplegic for children. Usually atropine sulfate ointment is placed into the interior cul-de-sac twice daily for 3 days prior to refraction.
For a “one application method,” MYDFRIN may be combined with the preferred rapid acting cycloplegic to produce adequate cycloplegia.
One drop of MYDFRIN is placed in each eye. Sufficient mydriasis to permit examination is produced in 15 to 30 minutes. Dilatation lasts from one to three hours.
Provocative Test for Angle Closure Glaucoma: MYDFRIN may be used as a provocative test when interval narrow angle closure glaucoma is suspected.
Intraocular tension and gonioscopy are performed prior to and after dilatation of the pupil with phenylephrine hydrochloride. A “significant” intraocular pressure (IOP) rise combined with gonioscopic evidence of angle closure indicates an anterior segment anatomy capable of angel closure. This pharmacological induced angle closure glaucoma may not simulate real life conditions and other causes for transient elevations of IOP should be excluded.
When dilatation of the pupil without cycloplegic action is desired for the shadow test, MYDFRIN may be used.
One or two drops of MYDFRIN should be applied to the infected eye. After five minutes, examine for perilimbal blanching. If branching occurs, the congestion is superficial and probably does not indicate iridocyclitis.
In case of accidental ingestion, phenylephrine may cause hypertension, headache, seizures, cerebral hemorrhage, palpitations, paresthesia or vomiting. Pulmonary edema or cardiac arrest may occur.
Phenylephrine has a rapid and short duration of action; treatment of toxicity is supportive. The use of beta blockers and calcium channel blockers for the treatment of acute hypertension secondary to vasoconstriction should be avoided.
© All content on this website, including data entry, data processing, decision support tools, "RxReasoner" logo and graphics, is the intellectual property of RxReasoner and is protected by copyright laws. Unauthorized reproduction or distribution of any part of this content without explicit written permission from RxReasoner is strictly prohibited. Any third-party content used on this site is acknowledged and utilized under fair use principles.
