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)