Cycloplegic Refraction

Yasuna's Method

1) place distance correction in the phoropter 2) add +3.00 D OU 3) occlude 1 eye 4) target= 0.5 M at 33 cm 5) add plus power in 0.25 D steps to blur 6) replace +3.00 add OU again 7) reduce plus power in 0.25 D steps to blur 8) measure the dioptric distance between the 2 (this is the residual accommodation)

Duane's Method

1) place distance correction in the phoropter 2) add +3.00 D OU 3) occlude 1 eye 4) target = 0.5 M at 33 cm 5) determine near blur point (pull in and measure) 6) determine far blur point (pull out and measure) 7) measure the dioptric distance between the 2 (this is the residual accommodation)

Pascal's Method

1) static retinoscopy at distance 2) static retinoscopy at retinscope plane (sphere power only) 3) measure the dioptric distance between the 2 (this is the residual accommodation)

What to do in the Case of a Vasovagal Syncope Event

1) stay calm 2) keep the patient safe (so not leave them) 3) lower the head and raise the feet 4) can use an ammonium capsule or alcohol pad to wake them up 5) do not move the patient, let them rest 6) document

Pascal's Method, Duane's Method, Yasuna's Method

3 methods of measuring residual accommodation

Facultative Hyperopia and Absolute Hyperopia

add up to manifest hyperopia

Idiosyncrasy

adverse reaction in response to a drug that is genetically determined, unexpected, and occurs in a small percentage of patients

Decreased Blink Rate

adverse side effect of anesthetics that resulting in increased evaporation off the surface of the eye

Tear Film Instability

adverse side effect of anesthetics that results from the disruption of surface microvilli of epithelial cells and decreased mucous adherence

Epithelial Toxicity

adverse side effect of anesthetics that results from the increased sloughing rate of epithelial cells and slow healing rate (due to decreased motility)

Manifest Hyperopia

amount of hyperopia that CAN be measured by relaxation of accommodation with plus lenses (amount found by traditional dry subjective refraction)

Facultative Hyperopia

amount of hyperopia that CAN be overcome by accommodation

Absolute Hyperopia

amount of hyperopia that CANNOT be compensated for by accommodation (affects acuity, is present when hyperopia is greater than the patient's accommodative amplitude)

Latent Hyperopia

amount of hyperopia that CANNOT be readily relaxed in a routine refractive exam (must cycloplege the patient to find it)

Lidocaine, Bupivacaine

anesthetics that are classified as amides

Cocaine, Procaine, Proparacaine, Tetracaine, Benzocaine

anesthetics that are classified as esters

Ocular Cycloplegic Reactions

angle closure glaucoma, transient IOP elevation, decreased aqueous outflow from iris blocking angle

Iris Dilator and Iris Sphincter

antagonistic muscles that control the size of the pupil

Cyclopentolate

better cycloplegic agent than homatropine, will result in 1.5 D of residual accommodation within 40-60 minutes (involves prolonged recovery period, less desirable for routine dilation) dosage: 0.2%, 0.5%, 1%, 2% solution onset: 30-60 min (max cycloplegia and mydriasis) duration: 1 day

Alpha Receptor Agonists (Sympathomimetics)

bind to and activate alpha receptors, stimulating the adrenergic division of the autonomic nervous system of the eye, contracting the iris dilator, and increasing pupil size without affecting accommodation

Ocular Anticholinergic Effects

blurred vision, loss of near vision, photophobia, mydriasis, dry eye, transient IOP elevation, acute angle closure glaucoma

Sympathomimetic

broad class of drugs that includes alpha receptor agonists

Parasympatholytic

broad class of drugs that includes anticholinergics

Minimum Amplitude of Accommodation

can be determined by this equation: 15-0.25(age)

Average Amplitude of Accommodation

can be determined by this equation: 18.5-0.3(age)

Green

cap color that indicates the bottle contains a miotic agent

Red

cap color that indicates the bottle contains a mydriatic/cycloplegic agent

Clear

cap color that indicates the bottle contains a topical anesthetic

Esters and Amides

chemical classifications of anesthetics

Anti-Muscarinics

class of drugs that facilitate cycloplegia

Adrenergic Agonists and Muscarinic Antagonists

classes of drugs that facilitate mydriasis

Alpha Agonists

common ingredient in OTC ocular decongestants (such as visine and clear eyes) and can cause conjunctival blanching and rebound hyperemia with chronic use

Dilation, Contact Lens Insertion, Application Tonometry, Gonioscopy, Punctal Plug Insertion/Removal, Foreign Body Removal

common trigger factors of vasovagal syncope in optometric practice

Atropine, Scopolamine, Homatropine, Cyclopentolate, Tropicamide

cycloplegic drugs

Atropine and Cyclopentolate

cycloplegic drugs that are primarily used to determine the accommodative component of an esotropia (also can be used to treat anterior segment inflammation)

Peripheral Blood Vessels

dilate in response to overstimulation of the vagus nerve and cause a decrease in blood pressure and heart rate (decreasing ability of the body to pump blood to the brain)

Mydriatics

dilate lighter irises faster and more completely, effect can occur within minutes and can last up to 4-6 hours, effect is increased by the use of a local anesthetic, can cause increased lacrimation and keratitis

Mydriasis

dilation of the pupil by means of dilator contraction by adrenergic agonists or sphincter relaxation by muscarinic antagonists (aids in the periphery of the retina)

Phenylephrine

direct acting alpha adrenergic agonist that results in dilation and conjunctival vasoconstriction/blanching of hyperemia while sparing accommodation (pupil will constrict with bright light) dosage: available in 0.125%, 2.5%, 10% solution (use 1 gtt of 2.5% for routine dilation) onset: 45-60 min (for maximum dilation) duration: 4-6 hours

Rebound Hyperemia

effect of chronic use of ocular decongestants with alpha agonists

Total Hyperopia

equals manifest hyperopia + latent hyperopia

18.5-0.3(Age)

equation that can be used to find average accommodation

15-0.25(Age)

equation that can be used to find minimum accommodation

Indications for Cycloplegia

esotropia, suspected latent hyperopia, suspected pseudo-myopia, young children, inconsistent subjective responses, malingerers/uncommunicative patients, patients that do not correct to 20/20 (no pathology), patients who have visual signs that do not correlate with refractive error, high heterophoria, accommodative asthenopic symptoms, anterior segment inflammation treatment

Phenylephrine and Hydroxyamphetamine

examples of alpha receptor agonists (sympathomimetics) that cause mydriasis

Tropicamide and Atropine

examples of anticholinergics (parasympatholytics)

Elderly Patients

exhibit less mydriasis with phenylephrine than cycloplegic agents (hydroxyamphetamine is also less effective due to loss of sympathetic tone in the muscle)

Systemic Anticholinergic Effects

fever, inability to sweat, facial flushing, tachycardia, dry mucous membranes, CNS toxicity, delirium (incidence of these are related to duration of action- thus atropine has the greatest incidence of side effects and tropicamide has the fewest)

Asian Eye

has greater prevalence of angle closure glaucoma

10% Phenylephrine

highest available dosage of phenylephrine, is contraindicated in people with type I diabetes mellitus, systemic hypertension, cardiac disease, advances arteriosclerosis, aneurysms, idiopathic orthostatic hypertension, and infants/elderly (because of metabolism)

Esotropia

indication for cycloplegia (atropine is the drug of choice to determine the accommodative component)

Pseudo-myopia

indication for cycloplegia that involves an intermittent and temporary shift in refraction of the eye toward myopia in which the focusing of light in front of the retina is due to a transient spasm of the ciliary muscle (characterized by static refraction with more plus power than subjective, low accommodative amplitude, fluctuating vision, and near point symptoms)

Suspected Latent Hyperopia

indication for cycloplegia that is characterized by 2 or more esophoria at distance, near point blur, small pupils, high FCC results, decreased accommodative amplitude, and NRA>+2.50 D

Iris Sphincter

inner iris muscle, has cholinergic muscarinic receptors, when blocked the pupil will dilate and accommodation will be reduced (mydriasis and cycloplegia)

Secondary Anesthetic Adverse Effects

interference with diagnostic tests (hypo fluorescence of fluorescein, variability in Schirmer testing, reduction of microbial recovery in culturing, surface keratopathy)

Standard Dilation

involves 0.5% proparacaine or tetracaine, 1% tropicamide, and 2.5% phenylephrine

Atropine Overdose

involves effects that would make you "hot as a hare (increased temperature, decreased sweating), mad as a hatter (confusion, delirium), red as a beet (flushed face, tachycardia), dry as a bone (decreased secretions, increased thirst), and blind as a bat (blurred vision)"

Anesthetic Classification

is based on chemical structure (esters vs amides)

Drug Penetration

is increased by the use of an anesthetic and results in better dilation of the pupil

Anesthetic Action

is reversible (complete recovery of nerve function will occur with no evidence of damage to the nerve fibers)

Cocaine

local anesthetic with vasoconstrictive (onset is 5 minutes and effect may last up to 2 hours)

Older Patients

may exhibit a release of pigment granules from the iris neuroepithelium after phenylephrine (can appear 30 minutes after administration of mydriatics and generally subside 12-24 hours after)

Preterm Infants

may experience episodes of abdominal distention and vomiting 24 hours after administration of mydriatics (because there is inhibition of duodenal motor activity)

MAOIs, Tricyclic Antidepressants, Antihypertensive Medications

medications that indicate you should take caution in prescribing alpha antagonists

History, Visual Acuity, Pupils, Slit Lamp, Van Herick Test, Tonometry

minimum pre-instillation workup before using cyloplegic drops

2 D

minimum residual accommodation (indicates the patient is adequately cyclopleged)

Hyperopia

most common refractive error (which is why we should always look for it even if the patient is seeing well

Disadvantages of Cycloplegia

not always complete, not always equal between eyes, not always properly timed with DFE, alters the AC/A, decreased depth of focus, increased aberrations in retinoscopy, inconvenience to the patient, blurred vision, photophobia, potential for toxic/allergic reaction

Acute Angle Closure

occurs when there is forward movement of the lens-iris diaphragm with functional apposition between the iris border and anterior lens surface and restriction of aqueous flow

Narrow Angles, Known Allergy to Drug, Iris-Fixed IOL, Down Syndrome

ocular contraindications for cycloplegic drugs

Fixed IOL, Shallow Anterior Chamber

ocular contraindications for use of alpha antagonists (2)

Age-Related Mydriatic Effects

older patients may have a release of pigment granules from iris neuroepithelium after phenylephrine, elderly patients have less mydriasis with phenylephrine or hydroxyamphetamine than cycloplegic agents , preterm infants may have episodes of abdominal distention and vomiting 24 hours after administration

Tropicamide

one drop of this cycloplegic agent will produce variable cycloplegia and a second drop will give reasonable cycloplegia (less than 2 D residual accommodation usually 20-25 minutes later) dosage: 0.5%, 1% solution onset: 30-45 min (max cycloplegia), 20-35 min (max mydriasis) duration of max cycloplegia: 6 hours

Change in IOP Greater than 5 mmHg

only occurs in 3.6% of patients dilated routinely with tropicamide or phenylephrine

Iris Dilator

outer iris muscle that receives sympathetic input, has alpha receptors, and will dilate the pupil when contracted (mydriasis)

Cycloplegia

paralysis of the ciliary muscle of the eye by anti-muscarinics resulting in a loss of accommodation

23%

percent of patients with primary open angle glaucoma that experience a significant increase in IOP following topical instillation of cycloplegic agents

Anesthetics

prevent the generation and conduction of nerve impulses by blocking sodium influx into the neuronal membrane (by blocking specific receptors that control the gating of sodium channels) and thus blocking most sensation on the ocular surface

Anesthetic Adverse Effects

punctate keratitis, corneal edema, conjunctival hyperemia, stinging/lacrimation, delayed corneal healing, tear film instability, decreased reflex tearing, reduced blink rate, epithelial toxicity, endothelial toxicity, microbial contamination

Punctal Occlusion

putting pressure over the inner canthus to prevent systemic absorption of drops and keep them on the surface of the eye

Hypersusceptibility

quantitatively different (greater than normal) response to a drug that is due to biologic variation, disease, or other medications

Indications for Mydriatics

recent onset of floaters, recent onset of flashing lights, sudden decrease in visual acuity, unexplained loss of visual field, ocular pain or redness of unknown etiology, post trauma to eye/face/head, history of diabetes, presence of media opacities, history of retinal disease/detachments, pupil defect or miosis

Acute Belladonna Poisoning

results from a lethal dose of atropine (10-30 mg in children or 80-130 mg in adults), involves peripheral muscarinic blockage (dry mouth, difficulty swallowing, thirst, tachycardia, palpitations, inhibition of sweating, dilation of pupils, blurred vision, photophobia, urinary urgency, difficult micturition, urinary retention, rash on face/neck/upper trunk), and central actions (excitement, restlessness, confusion, hallucinations, mania, delirium, motor incoordination, slurred speech, memory disturbance, coma, and paralysis of respiratory center)

Interference with Diagnostic Tests

secondary adverse effects of topical anesthetics

Heart Disease, Hypertension, Diabetes, Narrow Angles, Hyperthyroidism

systemic contraindications for use of alpha antagonists (5)

Systemic Side Effects of Phenylephrine

systemic hypertension, occipital headache, subarachnoid hemorrhage, ventricular arrhythmia, tachycardia, reflex bradycardia, blanching of skin (due to vasoconstriction)

Systemic Side Effects of Alpha Agonists

tachycardia, elevated blood pressure, headache, arrhythmia, cardiovascular effects with higher concentrations (10% phenylephrine)

Proparacaine

topical anesthetic that is better tolerated by patients but is more expensive ($32)

Tetracaine

topical anesthetic that is not tolerated as well by patients but is less expensive ($8)

Proparacaine/Tetracaine

topical anesthetics that prevent the stinging of other drops, decrease blink rate and tearing (allowing prolonged contact time), and roughen the corneal epithelium (allowing increased drug penetration) dose: 1 get of 0.5% solution onset: 10-20 sec duration: 10-20 min pt education: don't rub eyes for next 30 min

Adverse Cycloplegic Reactions

toxicity, idiosyncrasy, hyper susceptibility, allergy

Ocular Side Effects of Phenylephrine

transient stinging/lacrimation, keratitis, pigmented aqueous floaters, rebound mitosis, rebound conjunctival congestion

Vasovagal Syncope

transient, temporary loss of consciousness and posture that results when the vagus nerve is overstimulated and the body's peripheral blood vessels dilate which lowers blood pressure and heart rate, decreasing the ability of the heart to pump blood upward to the brain causing fainting (body can correct this and restore normalcy within seconds)

Congenital, Youth-Onset, Early Adult-Onset, Late Adult-Onset

type of myopia (by age)

Youth-Onset

type of myopia that occurs between age 6 and teen years, comprises 18% of all myopia

Early Adult-Onset

type of myopia that occurs between ages 20 and 40, comprises 10% of all myopia

Congenital Myopia

type of myopia that someone is born with (may persist through entering school), comprised 2% of all myopia

Allergy

unpredictable or unexpected response due to a previous sensitizing exposure (ex. eye may become red, itchy, and swollen, may be due to the preservative in the bottle)

Anterior Segment Inflammation Treatment

use for cycloplegia that involves extending mydriasis, decreasing pain due to iridocyclitis, stabilizing and restoring the blood-aqueous barrier, reducing the amount of inflammatory cell and flare reaction in the anterior chamber in uveitis, and decreasing the possibility of posterior synechiae

Angle Closure

very rare ocular reaction to cycloplegic drugs (chance is 1:183,000) but we should still assess history and chamber depth, advise patient of symptoms, and check IOP)