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Ocular Diagnostics

Ocular Diagnostics. Dilating Agents. Mydriatics. Bartlett & Jaanus Chapter 8. Sympathetic Innervation of the Eye. Preganglionic portion 1.) Starts from the posterior & lateral nuclei of the hypothalamus. 2.) Descends through lateral portion of the brainstem.

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Ocular Diagnostics

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  1. Ocular Diagnostics Dilating Agents

  2. Mydriatics Bartlett & Jaanus Chapter 8

  3. Sympathetic Innervation of the Eye Preganglionic portion 1.) Starts from the posterior & lateral nuclei of the hypothalamus. 2.) Descends through lateral portion of the brainstem. 3.) Myelinated fibers exit the spinal cord at the level of C8 – T2 anteriorly. 4.) Ascends over the top of the lung through the stellate ganglion and finally synapse in the superior cervical ganglion (SCG).

  4. Sympathetic Innervation of the Eye Postganglionic Portion: 1.) Unmyelinated fibers exit the SCG and form the carotid plexus next to the carotid artery. 2.) When in the cavernous sinus the fibers cross over the 6th CN and link up with ophthalmic division of the Trigeminal. 3.) Fibers parallel the long ciliary nerves to the Iris dilator and Mueller’s muscle.

  5. Sympathetic Innervation of the Eye:

  6. Other Sympathetic Innervation to the Eye • Some evidence of fibers associated with the uveal vessels leading to the ciliary muscle. • Trabecular meshwork and Schlemm’s canal. • Convergence mechanism associated with the Lateral rectus. • Some receptors in the cornea, lens and retina.

  7. Sympathomimetic: Phenylephrine: • Similar to epinephrine. • Activity primarily at α1 receptors. • Available in 2.5% and 10% solutions. • Trade names include AK-Dilate, Mydfrin & Neosynephrine.

  8. Clinical Uses of Phenylephrine 1.) Mydriasis – Maximum dilation in 45 to 60 minutes. • Duration is 6 to 7 hours. • 2.5% and 10% solutions give nearly equal dilation. • Seems less effective in dark eyes. • Concentrations as low as 0.125% can dilate some eyes. • Corneal epithelial defects and local anesthetics can enhance the penetration.

  9. Clinical Uses of Phenylephrine 2.) Sometimes (rarely) used to break a Posterior synechiae. 3.) To prevent cyst formation from use of Echothiophate. 4.) Help diagnose the source of Horner’s Syndrome. 5.) Ocular decongestant – Whiten the eye.

  10. Posterior Synechiae:

  11. Horner’s Syndrome: 1.) Ptosis 2.) Miosis 3.) Anhydrosis

  12. Ocular Side Effects: 1.) Discomfort 2.) Watery Eye (Lacrimation) 3.) Keratitis 4.) Hypersensitivity reaction 5.) Pigmented aqueous floaters 6.) Rebound hyperemia (Visine…)

  13. Systemic Side Effects: 1.) Acute increase in Blood Pressure (especially in infants). 2.) Cardiac events in patients at risk. 3.) Severe occipital Ha. 4.) Ventricular arrhythmias. 5.) Tachycardia 6.) Paling of the Skin. ***Almost exclusively from the 10% concentration.

  14. Contraindications: • 10% should be avoided. • Proper history should guide the careful use of 2.5% • Patients taking MAO inhibitors, tricyclic antidepressants, reserpine, guanethidine, or methyl dopa. • Patients on Atropine (tachycardia & HBP).

  15. Sympathomimetic: Hydroxyamphetamine: • Similar to norepinephrine. • An indirect-acting agonist. • No effect on accommodation. • Maximum dilation in 60 minutes & lasts about 6 hours. • 1% concentration is equal to 2.5% phenylephrine. • 1% hydroxyamphetamine with 0.25% tropicamide = Paremyd

  16. Clinical Usefulness of Paremyd • A pupil dilation equal to 1% tropicamide but without the cycloplegic effects. • Effect is independent of age or iris color. • Rapid recovery from dilation (6 hours)

  17. Side Effects: 1.) Minimal ocular irritation 2.) Tachyphylaxic effect on blood pressure. 3.) Safer dilating agent than phenylephrine. 4.) Less strongly contraindicated in high-risk patients. Tachyphylaxis -

  18. SympathomimeticCocaine: • Acts as an anesthetic after local application - acts by blocking the initiation and conduction of the nerve impulse. • Blocks reuptake of norepinephrine - CNS stimulation

  19. Cocaine • Ocular effects include: 1) anesthesia 2) mydriasis *depends on the presence of a functioning adrenergic innervation * begins to dilate in 15 to 20 minutes. * maximum effect (2 mm) in 40 to 60 minutes 3) vasoconstriction

  20. Cocaine • Clinical uses: - limited due to corneal toxicity - Horner's syndrome - loosen the epithelia for debridement ** Topical application causes serious corneal epithelial damage.

  21. Horner’s Pupil

  22. H. Simplex Debridement

  23. Cycloplegics Bartlett & Jaanus Chapter 9

  24. Cycloplegics • Inhibit the action of acetylcholine. Cholinergic antagonists, Anticholinergics… • Will result in cycloplegia & mydriasis.

  25. Parasympathetic Innervation to the Eye • Begins in the Edinger-Westphal nucleus. • Preganglionic fibers exit the CNS with the Third Cranial nerve and continue to the Ciliary ganglion where they synapse. • Postganglionic fibers enter the eye via the short posterior ciliary nerves. • Synapse at the iris sphincter and ciliary muscle.

  26. Clinically Useful Anticholinergics 1.) Atropine 2.) Homatropine 3.) Scopolamine 4.) Cyclopentolate 5.) Tropicamide **Effectiveness may be dependent on the number of muscarinic receptors they block.

  27. Atropine: • A nonselective muscarinic antagonist. • Most potent mydriatic and cycloplegic. • Can dilate for 10 days and cycloplegia for 7 to 12 days. • Available in 1% solution and ointment.

  28. Uses of Atropine: 1.) Cycloplegic refractions: • Especially useful for accommodative esotropia. • Can reveal more hyperopia than weaker drugs. 2.) Uveitis: • Eases the pain by relaxing ciliary muscle spasms • Prevents posterior synechiae. • Stabilizes the Blood-Ocular barrier.

  29. Uses of Atropine: 3.) Treatment of Myopia: • By placing the ciliary muscle at rest the axial elongation slows. • Too many side effects. 4.) Treatment of Amblyopia: • Referred to as “penalization” of the preferred eye. • Shown to be as effective as occlusion therapy.

  30. Ocular Side Effects from Topical Atropine 1.) Allergic contact dermatitis 2.) Angle-closure glaucoma 3.) Increased IOP in POAG patients • Possibly from a decrease in outflow facility.

  31. Allergic Contact Dermatitis • Lesions appear within 24-96 hours. • Main symptom, in addition to the lesion, is pruritus.

  32. Systemic Side Effects of Topical Atropine 1.) Dry Mouth (low doses) 2.) Facial Flushing & Anhydrosis (moderate doses) 3.) Convulsions in children (20x min. dose) 4.) Confusion & delerium in the elderly (20x min. dose) 5.) Deaths reported: • Young children (3 y.o.) • Lightly pigmented, spastic paralysis • Down’s Syndrome?

  33. Contraindications of Topical Atropine 1.) Known hypersensitivity 2.) Pts. With POAG or Angle-closure glaucoma. 3.) Caution in infants, children & elderly. 4.) Down’s children may show hyperreactive pupil. 5.) Caution in nursing mothers.

  34. Homatropine: • One-tenth as potent as Atropine. • Available in 2% and 5% solution. • 1% concentration gives dilation in 40 min. and lasts 1 to 3 days. • Cycloplegia in 30 to 60 min. and lasts about 1 to 6 days. • Primarily used in Uveitis treatment. • Side effects and contraindications are the same as atropine

  35. Scopolamine: • Currently available only in a 0.25% solution. • Dilation occuring in 20 to 30 minutes and lasting 3 to 7 days (0.5% solution). • Cycloplegia in 30 to 60 minutes and lasting 3 to 7 days. • Low doses produce CNS effects. • Only used in patients sensitive to atropine.

  36. Cyclopentolate: • Available in 0.5%, 1% and 2% solutions. • Dilation in 20 to 45 minutes with recovery in 1 day. • Cycloplegia in 20 to 45 min. with recovery in 6 hours to 1 day. • Longer onset and duration in dark eyes.

  37. Clinical Uses of Cyclopentolate: • The cycloplegic agent of choice for refractive procedures. • Quick onset and usually the patient can read in 6 to 12 hours. • Can be used in uveitis but must be used more often.

  38. Ocular Side Effects of Topical Cyclopentolate 1.) Stinging on insertion • Concentration dependent. 2.) Allergic reactions (rare) 3.) Increased IOP in POAG patients and may precipitate a closed angle.

  39. Systemic Side Effects of Topical Cyclopentolate 1.) Similar to that of atropine 2.) CNS effects are common with 2% solution. • Drowsiness, incoherent speech & restlessness. • Usually subsides in 2 hours in adults and 4 to 6 hours in children. 3.) Contraindications similar to atropine. Therefore use 0.5% in children. **Nasolacrimal Occlusion

  40. Tropicamide: • Available in 0.5% and 1% solutions. • Dilation in 20 to 35 minutes and duration of 6 hours. • Cycloplegia is minimal in 20 to 45 minutes and lasts 6 hours. • Fastest mydriatic onset. • The drug of choice for DFE.

  41. Tropicamide: • Not as dependent on iris color as other anticholinergics. • Clinically, diabetic patients do not dilate well. The addition of phenylephrine helps. • Topical side effects similar to other anticholinergics. • Has low affinity with systemic receptors. • Adverse reactions are rare. • Contraindications limited to hypersensitivities and angle closure.

  42. 1) New patient exams 2) Flashes & Floaters 3) Transient loss of vision 4) Visual acuity not corrected to 20/20 5) Myopia (-4 to -6 D) 6) Systemic diseases like diabetes 7) Presence of an APD 8) Miotic pupils 9) Media opacities 10) Blunt trauma 11) Suspected penetrating injury 12) Visual field loss or disturbances When Do I Dilate a Patient?

  43. Flashes & Floaters

  44. Transient Loss of Vision

  45. VA not corrected to 20/20

  46. High to Moderate Myopia

  47. Systemic Disease

  48. 13) Nystagmus 14) Headache 15) Hx of Retinal pathology 16) Drug use with known toxicity - Plaquenil 17) Retinal photography 18) Elevated IOP 19) Electrodiagnostic testing 20) Cycloplegic refraction - children - pre-LASIK When Do I Dilate a Patient?

  49. When Do I Not Dilate a Patient? 1) Iris-fixed IOL’s 2) Subluxated crystalline lens 3) Subluxated IOL 4) Extremely narrow anterior chamber angles. 5) History suggestive of angle-closure.

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