Vasoconstriction and Pupil Dilation
Phenylephrine Hydrochloride Ophthalmic Solution USP, 2.5% is especially useful when rapid and powerful dilation of the pupil without cycloplegia 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 Phenylephrine Hydrochloride Ophthalmic Solution USP, 2.5% 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. Uveitis: Posterior Synechiae: Phenylephrine Hydrochloride Ophthalmic Solution USP, 2.5% may be used in patients with uveitis when synechiae are present or may develop. The formation of synechiae may be prevented by the use of this solution and atropine or other cycloplegics to produce wide dilation of the pupil. For recently formed posterior synechiae one drop of Phenylephrine Hydrochloride Ophthalmic Solution USP, 2.5% may be applied to the upper surface of the cornea and be repeated as necessary, not to exceed three times. Treatment may be continued the following day, if necessary. Atropine sulfate and the application of hot compresses should also be used if indicated.
Glaucoma
Phenylephrine hydrochloride ophthalmic solution may be used with miotics in patients with wide 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 phenylephrine hydrochloride in conjunction with miotic drugs.
Surgery
When a short-acting mydriatic is needed for wide dilatation of the pupil before intraocular surgery, 2.5 percent ophthalmic solution may be applied topically from 30 to 60 minutes before the operation.
Refraction
Prior to determination of refractive errors, phenylephrine hydrochloride 2.5 percent ophthalmic solution may be used effectively with homatropine hydrobromide, atropine sulfate, or a combination of homatropine and cocaine hydrochloride.
For adults, a drop of the preferred cycloplegic is placed in each eye, followed in five minutes by 1 drop of phenylephrine hydrochloride 2.5 percent ophthalmic solution and in ten minutes by another drop of the cycloplegic. In 50 to 60 minutes, the eyes are ready for refraction.
For older pediatric patients, a drop of atropine sulfate 1 percent is placed in each eye, followed in 10 to 15 minutes by 1 drop of phenylephrine hydrochloride 2.5 percent ophthalmic solution and in five to ten minutes by a second drop of atropine sulfate 1 percent. In one to two hours, the eyes are ready for refraction.
For a "one application method," phenylephrine hydrochloride 2.5 percent ophthalmic solution may be combined with a cycloplegic to elicit synergistic action. The additive effect varies depending on the patient. Therefore, when using a "one application method," it may be desirable to increase the concentration of the cycloplegic.
Ophthalmoscopic Examination
One drop phenylephrine hydrochloride 2.5 percent ophthalmic solution is placed in each eye. Sufficient mydriasis to permit examination is produced in 15 to 30 minutes. Dilatation lasts from one to three hours.
Diagnostic Procedures
Provocative Test for Angle Block in Patients with Glaucoma: The 2.5 percent ophthalmic solution may be used as a provocative test when latent increased intraocular pressure is suspected. Tension is measured before application of phenylephrine hydrochloride and again after dilatation. A 3 to 5 mm of mercury rise in pressure suggests the presence of angle block in patients with glaucoma; however, failure to obtain such a rise does not preclude the presence of glaucoma from other causes.
Shadow Test (Retinoscopy): When dilatation of the pupil without cycloplegic action is desired for the shadow test, the 2.5 percent ophthalmic solution may be used alone.
Blanching Test: One or 2 drops of the 2.5 percent ophthalmic solution should be applied to the injected eye. After five minutes, examine for perilimbal blanching. If blanching occurs, the congestion is superficial and probably does not indicate iritis.
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