Mydriatic

Aka: Mydriatic, Cycloplegic, Eye Dilating Drop, Tropicamide, Mydriacyl, Ak-Dilate, Mydfrin, Cyclopentolate, Cyclogyl, Homatropine hydrobromide, Atropisol, Atropine-care, Isopto Atropine, Isopto Hyoscine

1. Definition
   1. Topical Medications that cause Pupil Dilation (Mydriasis)
2. Mechanism
   1. Agents based on Atropine which blocks muscarinic acetylcholine receptors
   2. Blocks pupillary constriction
3. Indications
   1. Retinal Exam
   2. Eye Pain (prevents ciliary muscle spasm)
4. Contraindications
   1. Narrow Angle Glaucoma
   2. Following pupillary signs after Head Injury
   3. Iris supported intraocular lens implantation (square/hexagonal pupil 'sputnik')
5. Adverse Effects
   1. Narrow Angle Glaucoma
      1. Precipitating Narrow Angle Glaucoma is rare with Mydriatics used for diagnostic exam
      2. Wolfs (1997) Invest Ophthalmol Vis Sci 38(12): 268307 +PMID:9375589 [PubMed]
6. Preparations: Eye Dilation for Retinal Exam (rapid onset, shorter duration preferred)
   1. Tropicamide 0.5% - 1% (Mydriacyl)
      1. Onset: 20-40 minutes
      2. Duration: 4-8 hours in most cases (may last as long as 24 hours)
      3. Blue eyes more sensitive, lasts longer
      4. Start with 0.5% concentration
   2. Phenylephrine hydrochloride 2.5% (Ak-Dilate, Mydfrin)
      1. Onset: 30-60 minutes
      2. Duration: 3-5 hours
      3. Unlike other agents, results in Mydriasis, but no cycloplegia
      4. Risk of Chemical Eye Injury
7. Preparations: Eye Pain management to reduce ciliary spasm (longer duration preferred)
   1. Cyclopentolate 0.5 to 2% (Cyclogyl)
      1. Typically use 1% in adults and 0.5% in children
      2. Rapid onset with peak activity at 25-75 min
      3. Duration: 6 to 24 hours (mean 12 hours); up to 2 days in some cases
   2. Scopolamine 0.25% (Isopto Hyoscine)
      1. Onset 30-60 minutes
      2. Duration 4-7 days
   3. Homatropine hydrobromide 2%
      1. Onset: 30-60 minutes
      2. Duration: 3 days
      3. Avoid in children
   4. Atropine sulfate (Atropisol, Atropine-care, Isopto Atropine)
      1. Onset: 45-120 minutes
      2. Duration: Up to 1-2 weeks
8. References
   1. Fishbaugh (1994) J Am Soc Ophth Reg Nurs 19(1):30-2
      1. http://ir.uiowa.edu/cgi/viewcontent.cgi?article=1003&context=eye_pubs