Cycloplegic refraction lecture Flashcards
What is min. pre-installation workup?
Hx, VA, Pupils, Slit lamp, Van Herick angles, Tonometry
Color of Cap indicates
Clear = anesthetic (Proparacaine/Altacaine) red = mydriatic/cycloplegic (Tropicamide,phenylephrine,cyclo) green = miotic
Why punctal occlude?
Prevent system absorption
Vasovagal syncope
transient, temporary loss of consciousness and posture
Action: keep pt safe, lower head and raise feet, open alcohol pad to smell, allow pt to rest 15-30 min
“if face is red, raise head. if face is pale, raise tail (feet)”
Standard Dilation drops?
1 drop 0.5% proparacaine/altacaine
1 drop 1% tropicamide
1 drop 2.5% phenylephrine
Anesthetics
prevents generation and conduction of nerve impulses by binding to specific receptors that control gating of Na channels
Anesthetic classification
Esters: cocaine, proparacaine, tetracaine, benzocaine
Amides: lidocaine and bupivacaine
Topical Anesthetics (Use, Side effects/adverse effects, Contraindications,)
Proparacaine or tetracaine
1 gtt 0.5% sol.
Duration: 10-20 min
USE: prevents sting, dec. blink rate & tearing, inc. drug penetration
Side effects: burning/stinging/lacrimation, punctate keratitis, corneal edema, conj. hyperemia, delayed corneal healing, blurred vision, tear film instability (dec. tbut, dec. mucous adherence), dec. reflex tearing, epithelial toxicity (sloughing inc.), endothelial toxicity, microbial contamination
2nd adverse effects:
hypofluorescence of fluorescein, variability in schirmer test, reduction of microbial recovery in culturing, surface keratopathy
contraindication: hypersensitivity
Cycloplegia Vs. Mydriasis
Cycloplegia: paralysis of ciliary muscle by anti-muscarinics
Mydriasis: dilation of pupil through dilator contraction by adrenergic agonists OR sphincter relaction by muscarinic antagonists.
Iris dilator and Iris sphincter
Iris dilator: sympathetic imput - pupil dilates when contracted (mydriasis)
Iris sphincter - parasympathetic input - cholinergic muscarinic (mydriasis and cycloplegia)
Mydriatics dilation (phenylephrine)
Stimulate adrenergic division of ans (bind and activcate alpha receptors)
sympathomimetics: increase pupil size - contracts iris dilator, widen palpebral fissure, constriction of blood vessels ‘blanching’, spares accommodation
Cycloplegia dilation (tropicamide)
inhibit cholinergic division of ans (block muscarinic receptors on ciliary muscle and prevent acetylcholine)
parasympatholytics: inhibit accommodation - ciliary muscle paralysis
Mydriatics indications
occurs within minutes and lasts 4-6 hours
indications: floaters, flashing lights, dec. va, unexplained vf, unknown etiology ocular pain, post trauma to eye, hx diabete, hx ret. disease, pupil defect or miosis, media opacities
mydriatic effects - age
older patients have release of pigment granules from iris neuro-epithelium after phenyelphrine
elderly - less mydriasis with phenyl and hydroxyamphetamine is less effective
Alpha agonists
visine and clear eyes
- causes rebound hyperemia and inc. conj injection
- conj. blanching “get the red out”
- more drug is required for same effect
- use caution in pt: taking inhibitors, tricyclic antidepressants, antihypertensive medications
phenylephrine (2.5%)
direct-acting alpha-adrenergic agonist - dilation and conj. vasoconstriction/blanching hyperemia -spares accommodation -pupil will constrict bright light max dilation = 45-60 min duration of dilation = 4-6 hrs
phenyl precautions, contraindications, side effects
systemic htn; dm1; heart disease; adv arteriosclerosis
contraindications: narrow angles, hypersensitivity, iris IOL, or pt taking MAO inhibitors, tricyclic antidepressants, reserpine, guanidine, methyldopa
side effects: ocular - lacrimation, keratitis, pigmented aqueous floaters, rebound miosis, rebound conj. congestion
systemic - systemic htn, occipital h/a, subarachnoid hemorrhage, ventricular arrhythmia, tachycardia, reflex bradycardia, blanching of skin - due to vasoconstriction
Type of Cycloplegia drugs
- Atropine (longest recovery mydriasis and cycloplegia)
- Scopolamine
- homatropine
- cyclopentolate
- tropicamide (shortest recovery mydriasis 6hrs and cycloplegia 6hrs)
indications for cycloplegia
- esotropia - determine accom. component
- suspected latent hyperopia
- suspected pseudomyopia
- young children
- inconsistent subj. responses
- malingerers/unreliable pts
- hysterical pts / uncommunicative pxs
- pt do not correct 20/20 - no patho
- high heterophoria
- accommodative asthenopic symp.
- ant. segment inflammation treatment (dec. pain due to iridocyclitis, stabilize/restore blood-aqueous barrier, dec. possibility of post. synechiae)
cycloplegic effects
2 drops of tropicamide gives reasonable cyclo (less than 2D resid. accommodation)
cyclopentolate: residual accommodation 1.5 D
cycloplegic side effects
ocular: blurred vision, loss of near vision, photophobia, mydriasis, dry eye, transient IOP elevation, acute angle closure glaucoma
systemic: fever/unable to sweat, facial flushing, tachycardia, dry mucous membranes, CNS toxicity, delirium
cycloplegia disadvantages and adverse reactions
not always complete/equal, alters AC/A, decreased depth of focus, photophoibia, inconvenience to pt
toxicity, idiosyncrasy, hypersusceptibility (intolerance), allergy (unpredictable, red,itchy, swollen)
Atropine (usually 0.5% ointment bid x 2 d)
- use min. amt needed
- 1.0% sol. for ET BID 3 days before exam
- duration of cyclo = 24 hours
- contraindications = glaucoma, narrow angles, hypersensitivity, iris-fixed IOL, down syndrome
- SE = acute angle closure, allergic rxn, toxic rxn (dry mouth, facial flushing, fever, tachycardia, irritability, delirium)
cyclopentolate (1 gtt 1% q 5 min x 2; drug of choice for routine cyclo exam)
- usual usage 1 gtt 1% q 5 min x 2
- max cyclo: 30-60 min
- max cyclo: 2 hrs
- duration of cyclo: 1 day
Tropicamide (1 gtt 1%; drug of choice for routine dilated exam)
- rapidly-acting, short duration mydriatic/cycloplegic
- 1 gtt 1% x 1 for dilation
max cyclo = after 30-45 min
duration of cyclo = 6 hrs
max mydriasis = after 20 - 35 min
duration fo mydriasis = 6 hrs
Okay to dilate with narrow angles?
Any medication with anticholinergic properties should be used in caution with narrow angles.
should acute angle-closure attack occur, suspected medication must be d/c
acute angle closure glaucoma
restriction in aqueous flow creates excessive pressure in post. chamber, which bows peripheral iris forward and closes the angle
greatest risk: asian ethnicity, advanced age, female, hyperopia, pos. family hx, narrow iridocorneal angle, and shallow ant. chamber depther
does IOP change after std. dilation?
yes, about 96% pt has change in IOP less than 5 mmHg and 4% has change in IOP greater than 5 mmHg
cycloplegic refractive techniques
- measure residual accommodation (min. res acc. = 2D)
- perform retinoscopy (central 4mm)
- subj refraction
Measuring residual accommodation
- Pascal’s method: diff. between static at D and retinoscope plane
- Duane’s method: add +3 ou and determin near blur point and far blur point (monocular, target 0.5 M at 33cm)
- Yasuna’s Method: add +3 ou over rx and add 0.25 to blur and reduce 0.25 to blur (monocular, target 0.5 M at 33cm)
Total Hyperopia
manifest (amt measured by relaxation of accommodation with plus lenses AKA dry refraction) + latent (amt hyperopia not readily relaxed AKA wet reffraction)
Types of hyperopia
Absolute: cannot be compensated for by accommodation
facultative: can be overcome by accommodation
What is total hyperopia? +3 D sphere on ret and +2 D subj refraction. patient has 12 D AA
Manifest hyperopia: 2 D
facultative hyperopia = 2 D
absolute hyperopia = 0
latent hyperopia = 1 D
Total = 3 D
egger’s rule?
20/50 = -1.00 20/100 = -2.00
Average amplitude accommodation?
18.5 - 0.3 * age
min. amplitude accommodation?
15 - 0.25 * age
Myopia management - children
- 16 males/15 females age of cessation
- progression rates 0.42 males/0.48 females
- RX based on near phoria = expected 3-5 XP; if EP = consider BF or removing for near
Myopia management - YA
- Either stabilizes, slow progression, continuation, or acceleration (least prevalent; seen with corneal steepening)
- RX least minus with best VA (watch for EP, consider CL)
Myopia management - Late adults
- myopia stable, change +-.50 per 10 years
- cause: nuclear cataracts
- RX least minus with best VA
Myopic cycloplegic RX
IF wet is = or more minus than dry, give DRY RX
If wet is more +, RTC for post-cuclo exam
Challenges of hyperopia
- undetected b/c accommodation
- excessive amt of accommodation can result in ET
- prolonged near work can result in eyestrain
Uncorrected Hyperope
untreated eyter will result in suppression and then amblyopia
Hyperopia management
depends on 3 factors:
- age
- amt of hyperopia
- pt complaints
cycloplegic refraction should be done
wet - dry = latent hyperopia
RTC if latent exists
Hyperope Rule of thumb for RX
Amt of latency/Add to dry 0 to +0.50/ 0D \+0.75 to +1.00/ +0.25 D \+1.25 to +2.00/+0.50 D above +2.00/ 0.25*latent amt
Hyperope consideration
Consider near RX for hyperopes
- reading spec
- bifocals (large segmemt)
- recheck 2-4 months
- repeat dry refraction
What to do at end of cyclo exam?
- Pt ed. on blur/driving/photphobia
- dispense sunglasses (paper ones if needed)
- don’t use miotic drops
