Module 4: Refraction and Ocular Health Flashcards by RaeAnne H.

-case history
-analysis of visual needs/work
-Visual acuity
-depth percenption
-colour vision
-slit lamp/ophthalmoscope/ DFE
-neurological assessment
-glaucoma screening
-refraction

Exams inculde

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-light rays bent/focused
-each eye has different refractive ability
-light bending relies on curve or cornea+ lens
-relies on clarity and density of cornea + lens
-ability of retina to recieve and transmit info
- length of eyeball (axial) changes refraction power

Refraction

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-length from cornea to posterior pole
- average length 23-25mm (size of quater)
-light should focus at the fovea

Axial length

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-cornea
-aqueous humor
-crystalline lens
-vitreous humour

Refracting system

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-normal eye
-image lands right on the fovea
-no correction required

Emmetropia

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-abnormal eye
- 3 types (myopia/hyperopia/astig)

Ametropia

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-out of focus on the retina
-images land behind the retina
-farsightedness (blurry up close)
-cornea too flat/axial too short
-all babies start off this way
-corrected with convex lens (plus power)
-kids can accommodate/focus through

Hyperopia/Hypermetropia

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-magnify objects
-objects seem bigger and closer
-px eyes look bigger
-can make “pincushion” effect(lines caved in)
-can alter depth perception

convex lenses

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light focused infront of retina
-near-sightedness (blurry distance)
-physiologic (steep corneas/long axial)
-requires concave lenses (minus power)
-uncommon at birth

Myopia

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-minifying
-objects appear smaller/further away
-px eyes look smaller
-can cause “barrel” distortion (lines look round)

Concave lenses

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-parallel light rays equally not focused
-cornea unevenly shaped/unsymmetrical
-football shape
-weeakest curve & strongest curve

Astigmatism

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-reduction in ability to accommodate upclose
-ciliary muscles cannot buldge the lens enough
-additional plus power
-contact lenses MF/monovision

Presbyopia

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-focussing ability
-muscle tight/contracts = bulges= near
-muscle rest/pulls = flat= distance

Accommodation

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at least one diopter diference between OS/OD

Anisometropia

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unequal size/image on the retina between OS/OD

Aniseikonia

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-breakage of blood vessel
-blood pools/covers white sclera
-resolves in a few weeks

Subconjunctival Haemorrhage

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-commonly referred “pink eye”
-bactieral
-viral
-allergy
-tocicity

Conjunctivitis

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-progressive disease
-thinning cornea
-conical shape
-induces irregular astigmatism
-treated with rigid CL
-possibly hereditary

Keratoconus

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-styes
-infection of glands/eyelids
-whitehead-like

Hordeolum

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-clear lens becomes cloudy
-capsule holds transparent lens like enevelope
-lens is size of aspirin
-cloudy = light distorted/blocked out
-vision reduced
-lens continually grows/becomes hard

Cataracts

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-natural part of aging

Senile Catartacts

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-injury/lens is disturbed
- medications/steroids
-chemicals
-UV
-radiation
-smoking
- eye diseases
-diabetes

Traumatic Cataracts

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Congenital cataracts

-babies born with them

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-colour vision loss
-hazzing
-dark spots in vision
-needing brighter lighting
-glare at night
-near-sighted
-double vision
-better without glasses
-yellow/white pupil

Signs of cataracts

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-slit lamp biomicroscope -ophthalmoscope -DFE

Detecting Cataracts

-sunglasses -vitamins A,C,E,Zinc, Selenium, Magnesium

Cataract prevention

- surgery -removal of cloudy part -replacement of lens

Cataract treatment

-opening front of capsule -pocket of side and back capsule left alone -insert loop and pull out (still common) -ultrasonic probe, 3mm incision (phacoemulsification)

Cataract extraction

-3mm incision -probe vibrates at 40,000 times/second -breaks up hard/cloudy lens -suctioned out with vacuum -femtosecond laser (bladeless)

Phacoemulsification

- if not replaced becomes aphakic -intraocular lens (IOL) - IOL fits into capsule pocket left behind - made of plexiglass -use tiny spring loops to hold in place -clear vision immediate

Replacing lens

- caspule pocket becomes yellow/cloudy -fixed with YAG laser capsulotomy -beams of light energy shot into eye -quick pulses of laser energy

Secondary clouding

-produced in ciliary tissue -fliud passes through space between lens&iris -goes through the pupil -collects in anterior chamber -drains into trabecular meshwork -then released into canal of schlemm -goes into bloodstream via blood vessels in sclera

Aqueous Humour route

-blocked passage of aqueous humour -causes IOP pressure to rise -nerve fibers/ optic nerve damage under pressure -when destroyed suport tissue sinks back=cupped position -dreakdown of messages sent to brain -leading to blindness -asymptomatic in early stages

Glaucoma

-over 40 years old -family history -near-sighted -diabetes -african american -injuries

Risks of glaucoma

- eye exam -tonometry -inspect drainage angles -check ONH cup - disc ratio -check peripheral vision

Dectecting glaucoma

- most common type -gradual clogging of trabecular meshwork -fluid cannot drain -reason/cause unknown -dangerous/slow &no warning -irreversible

Chronic Primary Open Angle Glaucoma (POAG)

- no ONH changes - no peripheral changes - not glaucoma - at risk to develope glaucoma

Ocular Hypertension

- can't unclog meshwork - prescription drops/ pills limits fluid production or increase drainage -surgery thinning the walls (trabeculectomy)

Glaucoma treatment

- small flap created under top lid - removes some sclera & meshwork - moves into anterior chamber - punctures small hole in iris -flap stitched closed -filtering bleb forms and absorbed into blood vessels

TrabeculeCTOMY

- alternate surgery - uses argon laser (gas) energy - aimed at meshwork -clear clogged cannals -temporary -excimer laser (UV) new technology

TrabeculoPLASTY

- build-up eye pressure 1)blockage behind iris -space between iris & lens too small 2)enlarged pupil makes iris bunch up -no space between iris & cornea -needs emergency laser surgery - unlikely to return again

Acute Glaucoma

-severe headaches -nausea -eye pain -redness -distorted vision -limited action time

Acute Glaucoma symptoms

-uncommon - babies born defective drainage - resolved with laser surgery

Congenital Glaucoma

-caused by injuries, drugs, inflammation - possibly temporary - medication or surgery treatments

Secondary Glaucoma

- ONH damage with normal IOP - possibly from hardend arteries that supple OHN - medication to drop IOP lower

Low-tension Glaucoma

- eye unable to lubricate naturally - seem too moist/too many tears - low qaulity tears - common over 50 years old - increased by screen time

Dry Eye Diesease

- questionaires DEQ-5/OSDI -tear meniscus height -tear break0up time -blink evaluation -meibography

Diagnosing Dry Eye

- invasive dry eye test -uses dyes fluoresence/lissamine green - stains cornea and conjunctiva - tear break-up time

Meibomian gland expression

- invasive dry eye test -tests the amount of salt in tears -checking inflammatory markers - InflammaDry

Osmolarity

1)-tear deficiency or excessive evaporation -inner muscus layer not covering eye/creates dry patches -common as we get older 2)- diseases -medications -infections -CL wear -blepharitis -environmental (wind/AC/dry) -arthritis -Sjogren's syndrome (mouth too)

Causes of Dry Eye

- irritating condition of eyelids -infect/plug meibomian glands (sebaceous) -interrupts oil layer production - sometimes causes by injury - use lid hygeine (wipes/ABMax/BlephEX) removes plaque in 10 mins. For only 4-6 months

Blepharitis

- Tiredness (end of day) -Redness -foreign body/burning -blurry vision -excessive tearing -pulling/pressure behind eyes -loss of lustre -corneal deterioration

Symptoms of Dry Eye

- no known cure 1) blink often (18-20 blinks/minute) 2) conserve natural tears (avoid wind & fans/ drink water/humidifier) -3) artificial tears daytime(use when needing to focus) -ointment/gel (at night before bed) distorts vision 4) omega 3 (anti-inflammatory/ improve meibomian gland production) 5) Special treatments -punctal plugs/ laser closure - prescription drops (restasis/Xiidra) - antiboitics/steroids -vitamin A

Treatment of Dry Eye

-most common dry eye type -glands inflammed/clogged -dont produce enough oil -glands need to be drained/expressed -warm compress treatment - O.D. forceps & squeeze/ thermal pulsation (lipiflow/iLux) - new options (amniotic membranes/autologous serums)

Meibomian Gland Dysfunction (MGD)

-breakdown of the macula - 100 times more senstive than rest of retina - macula contains most cones (detailed/colour vision) - mono or binocular - results in completes loss of central vision (peripheral is fine) -leading cause of vision loss (1/3 over 65years) - Dry AMD -Wet AMD -blisters/birthdefects/ injuries/infection/inflammation

Macular Degeneration (AMD)

- age -smoking -female -UV -family history -high blood pressure -diabetes -obesity/poor diet -light eye colour

Risks for AMD

-most common type 90% cases - tissue becomes thin/stops working - vision loss via size/#/location of drusen - vision loss gradual and moderate - treated with vitamins/lifestyle

Dry AMD

-small yellowish lesions that accumulate in the retinal layers

Drusen

- less common - more visually devastating -abnormal blood vessel growth behind macula causing choroidal neovascular membrans (CNVM) -blood vessels break>bleed>heal> scar tissue -new blood vessels in scar tissue>push retina away from wall -new blood vessels fragile> distorts/damages macula - the longer this continues= more damange -1/10 moves into both eyes -treated with injections

Wet AMD

-symptoms may vary -gradual loss of sharp vision -distorted vision (shape/size/straight lines) - gradual colour loss - dark spot central vision

AMD symptoms

- Amsler grid test (card@ 30 cm> look at dot> wavy lines) - colour vision test -fluorescein Angiography Exam(OMD injects in arm>take pictures) -Fundus Photos -Digitial Imaging -DNA testing

Diagnosing AMD

- use UV protection - have good nutrition (limit fatty food) - maintain good blood pressure -don't smoke - food with vitamin A,E,Zinc,Lutein,Zeaxanthin,Selenium, Omega3

AMD prevention

- diabetes mellitus (inability to produce insulin) - changes blood vessles that nourish retina -leakage of fluid/blood > big/disctructive branch vessels - retina cannot recieve/send clear images -leading cause blindess under age 65 (25% prone) -length of diabetes is most damaging (15% with under 4 years), (90% with 15 years +)

Diabetic Retinopathy

- non-proliferative -most common/ least seerious (80% cases) - first stage of blood vessel deterioration - only 20% progress further -blood vessels in retina weak/change -vessels small or big (balloon-like sacs) - burst and leak serum/exudate (fatty material) - appear as yellow flecks - leaks cause retina wet & swollen -bloodstream normally reabsorbs= swelling temporary - can be both peripheral or macular - only symptom = blurred vision -typically dont need treatment -serves cases need laser (focal/grid)

Background Diabetic Retinopathy

- leakage not extensive - targets only certain spots - cauterizes tissue>creates healing scar tissue -scar tissue shuts/stops leak

Focal laser treatment

-too many leakages -uses grid over the entire surface - doesnt restore vision -prevents further damage by drying retina - may need serveral treatments/ can reopen

Grid laser treatment

- 20% of background progress to this - leads to blindness when not caught early -vessels close = no nutrients to areas of retina - happens in peripheral = narrow sight/poor night vision -creates new blood vessels/very dangerous -vessels increase rapidly -bleeding into vitreous cavity/blocking light -scar tissue>detach retina from choroid -distort iris> blocks fluid > glaucoma - no pain/symptoms

Proliferative Diabetic Retinopathy

- lasers/ injections -detroys/inhibits new vessels - panretinal laser photocoagulation (destroys new blood vessels growing), honey comb pattern, sacrifice peripheral vision to save detail and colour -vitrectomy= last resort (prevents detatchment), suctions out vitreous> removes vessels> replace with air/gases until vitreous returns

Treatment Proliferative DR

- complication of diabetic retinopathy - leaking = swelling of macula - blurry vision/gradual loss -occurs at any stage -affects 2.5% diabetics - treamtent= focal laser/corticosteriods

Diabetic Macular Edema (DME)

- intact retina is crucial for vision -1/10,000 effects by RD every year - various causes - tears lead to detachments - can also detach without a tear -vision saved by immediate medical attention

Retinal Tears/Detachments

- age> vitreous shrinks> pulls away>pull retina> tear peripheral> fluid behind retina> detach from wall> no longer sensitive to light= blindness - can thin and deteriorate= detach on its own -serious hit/injury - eye surgeries - increased in ner-sighted (grow oblong=pulling) -severse internal inflammation -tumours - diabetes

Causes of RD/Tears

-sudden flashes (response to trauma) -increased floaters (impurties from tear) - haze/strands - sometimes no symptoms until detaching -detachment= dark growing shadow peripheral (can become permenant without treatment)

Symptoms of RD/tears

-direct ophthalmoscopes = magnified small area of retina -indirect ophthalmoscope= less magnified but larger area -DFE

Diagnosing RD/tears

- can be reversed depending on intial damage - tears easier than detachment -40% regain vision - up to 6 months to fully heal 1) tears= laser beam/freezing cryoprobe> heat/cold>burn/freeze area>scar tissue>forms bond. 2) RD= A)remove fluid behind retina> press wall inward with pressure pad/silicone band> laser makes scar tissue (cryoprobe/radio freq diathermy)>bond tissue. B)seperated far back/shrunk/puckered= vitreous broken up>suctioned out> air/gas replace (vitrectomy)

RD/tear treatments

- eye vision problems related to near work via computer -50-90% of computer users -22% have musculoskeletal disorders - greater risk in presbyopes (PAL = tilting head back/leaning foward= neck issues) - presbyopia happening younger via computer use

Computer Vision Syndrome (CVS)

- eyestrain - blurred vision - headaches - dry/irritated eyes - light sensitivity - double vision (diplopia) - poor ergonomics

Computer Vision Syndrome symptoms

- condition of the px eyes - visual ergonmics - SV reading for low add px -advanced presbyope =intermedaite/near bifocal -PAL is good for intermittent computer use - best is task/computer lens (occupational lens) - boost/antifatigue/bump add +0.50-0.75 - 20-20-20 rule - adjust your chair (90 degrees/ floor to knee 2"-4") -set up your workspace (leg room 25"/ monitor height 26") -monitor/keyboard (16-30" from eyes/tilt away 10-20 degrees) -Lighting (match room brightness 20-70 candles)

CVS treatment

- previously used to correct myopia - reduced curvature of cornea - tiny cuts with diamond blade - temprorally relaxes peripheral cornea > allowing slight buldge out

Radial Keratotomy

- newest = wavefront analysis (no aberrations with pupil dilation) - custom corneal ablation (removal of tissue)

Laser surgery

- excimer laser - removes corneal tissue = curve change - UV rays without heat= breaking molecule bonds - computer controls energy required - at depth of 10% corneal thickness - takes 1 minute -px wears CL lens/ drops 2-3 days post-op - stroma does not regenerate= permentant results - 3 months for deeper layers to stablize - mild to moderate myopia and thinner corneas

Photo-refractive keraectomy (PRK)

- epithelium/bowmans peeled back with flap -excimer laser same as PRK - flap put back - less healing involved - faster clear vision - moderate-severe myopia & astig -less post-op haze/pain - newest form = sub-bowmans keratomileusis (SBK)> flap with cold laser = thinner/smaller flap

Laser in-situ keratomileusis (LASIK)

- Intracorneal rings "phakic IOL" (behind cornea) for low myopia -Thermokeratoplasty (TKP)= heat to periphery>cornea steepens> reducing hyperopia -Conductive keratoplasty (CK) newer = controlled release radio-freq -Refractive/Clear Lens Exchange (RLE) = some process cataract surgery -Implantable Contact Lens (ICL)= small CL inside eye -KAMRA Inlay= small ring/pinhole into ONE eye

Other Refractive Surgeries

- 1/10 risk of undiagnosed vision problems -1/30 amblyopia (lazy eye) -1/3 refractive error -1/100 eye disease

Children

- Amblyopia (lazy eye) - congenital strabimus (eye turn) -Anisometropia (uneven refractive error) -high or oblique astig -retinopathy of prematurity - congenital cataracts - congenital glaucoma - retinoblastoma (cancer) -Nystagmus -Coloboma (hole in iris/retina) - dislocated cyrstalline lens -blindness

Childhood disorders

- first exam at 6 months (sooner if concerns) - 80% hyperopic> intermittent strabismus -common blocked tear ducts

Infants/Toddlers (birth-2 years)

- next exam at 3 years old (better idea of refraction) - test depth perception/ colour vision

Pre-School (3-5 years)

-annual exams - farsightedness stabilizes at age 7/8 -myopia can increase - delayed learing could be visual

School age (6-18 years)

- Chemicals - sudden loss of vission/veil -penetrated injury -forceful trauma/blow -sudden halos/red, eye/brow pain - sudden eye pain -foreign body -sudden flashing lights/floaters - sudden droopy lid - sudden red eye/crusting

Emergencies

- blurred vision gradual -CL wearer discomfort - lost/broken CL in eye

Urgent issues