REFRACTION DISORDERPURNAMANITA SYAWAL

BKMM MAKASSAR

REFRACTIONProcess to measure a patients refractive errorDetermine optical correction needed to focus light rays from distant & near objects onto retinaProvide the patient with clear & comfortable vision

REFRACTIVE MEDIAKORNEA - Contribute 2/3 of refracting power of the eye 43 D2. THE LENS - Contribute 1/3 of refractive power of the eye 20 D - Total convergence power of the eye 58,7 D (not 43 20 D) due to the distance between the cornea & the lens (deep of anterior chamber) that substract 4 D ( 63 4 D = 58,7 D)

REFRACTIVE MEDIA, cont..3. THE PUPIL - Reduce amount of light enters the eye - Decrease aberrations - Increases the depth of focus when costricting

REFRACTIVE STATES OF THE EYEEmmetropiaAmmetropia 1. Myopia 2. Hyperopia 3. Astigmatism

EMMETROPIAEmmetropia (normal vision) Eye focusing power perfectly matched to globe lengthImage focused precisely on retinaNormal vision confers focal length of infinity

AMMETROPIAMismatch between the optical power & length of the eye

Etiology :

AmmetropiaRefractive apparatus (cornea and lens) isAxial length isAxial myopiaNormalToo longRefractive myopiaToo strongNormalAxial hyperopiaNormalToo shortRefractive hyperopiaToo weakNormal

MYOPIA (Nearsighness)

Focused image in front of the retina

CAUSE OF MYOPIA1. Causes Autosomal dominant inheritance Mild Myopia (-0.5 to -2.0 D) by age 5 to 8 yearsModerate Myopia (-2.0 to -5.0 D) by age 8-14Severe Myopia (

CAUSE OF MYOPIA cont..Structural or axial myopia Antero-posterior (AP) diameter longer than normal (N)Curvature myopia AP diameter is normal, but corneal curvature steeper than NIncreased index of refractionAnterior displacement of the lens

SYMPTOMS OF MYOPIABlurred vision for distanceSquint (due to blepharospasm- like action to act as a pinhole)Headache

Myopic school usually detected at 9-10 yo, increase till mid-teens (stable at S-5,00D)Progressive myopia, increase up to -4 D/year,may reach up to -10 D or 20 D predispose to retinal detachment & primary open angle glaucoma

HYPEROPIAHyperopia (Farsightedness) Normal in infants (+0.50 to +2.50 Diopters) Vision normalizes by age 5 to 8 years old Light rays focus behind corneaCornea too flat or lens too weak for globeNear objects not seen clearly Correction: Convex lenses (convergent, plus power)

CAUSE OF HYPEROPIAStructural or axial hyperopia AP diameter shorter than N2. Curvature hyperopia3. Index of refraction hyperopia

LATENT HYPEROPIA : part of the refractive error completely corrected by accomodation, only be measured by cycloplegic refraction & not manifest refractionMANIFEST OR ABSOLUTE HYPEROPIA : part of hyperopia not corrected by accomodationFACULTATIF HYPEROPIA = MANIFEST HYPEROPIA ABSOLUTE HYPEROPIA

HYPEROPIAEx : Patient 25 yo, visual acuity 6/20- Correction with S + 2,00 D 6/6Correction with S + 2,50 D 6/6Correction with cycloplegik S +5,00 D 6/6So, this patient have :Absolute hyperopia S +2,00 DManifest hyperopia S + 2,50 DFacultatif hyperopia = S +2,50 S+2,00 = S+0,5DLatent hyperopia S +5,00 D S +2,50 D = S +2,50 D

SYMPTOMS OF HYPEROPIABlurred vision for distanceFrontal headache prolonged use of near visionAsthenopia : fatigue, burning eye sensasion & periorbital pain when fixing at an object for prolonged periods of timeLight sensitivityDecreased in near visual acuity at a younger age than in emmetropic eyes

ASTIGMATISMAstigmatism Non-spherical corneal surfaceParts of surface (meridians) are steeper than othersObjects blurry at any distance The curvature of the optical systrm varies in different meridians thus refracting the incident ligth differently in those meridians

ASTIGMATISMWith the rule astigmatism : the vertical meridians is steeperAgaints the rule : the horizontal meridians is steeperRegular astigmatism : Principles meridians are 90 apartIrregular astigmatism : Principles meridians are not 90 apart, cant be completely corrected by spectacles, but with contact lens

REGULAR ASTIGMATISMSIMPLE ASTIGMATISMLens correction C +Lens correction C -

REGULAR ASTIGMATISMCOMPOUND ASTIGMATISMLens correction S (-) C (-)Lens correction S (+) C (+)

REGULAR ASTIGMATISMMIXED ASTIGMATISM

Lens correction S (-) C (+) S (+) C (-)

SYMPTOMS OF ASTIGMATISMBlurred vision for far and nearSquint (for pinhole effect)Asthenopic symptomsFrontal headachesTilting of the head

TRANSPOSITION OF SPHEROCYLINDRICAL NOTATIONEx : - 0,75 + 0,50 x 180 -0,25 -0,50 x 90Ex :

TRANSPOSITION OF SPHEROCYLINDRICAL NOTATIONNew sphere = old sphere + old cylinderNew cylinder = old cylinder, but with opposite signNew axis = old axis changed by 90

MANAGEMENT REFRACTIVE ERROR 1. Management: Refractive Error Correction Non-Surgical Options (Myopia : concave lens, hyperopia : convex lens, Astigmatism : cylinder lens) - Eye Glasses - Contact Lenses 2. Refractive surgery - Laser In Situ Keratomileusis (LASIK) - Intrastromal corneal ring (ICR) - Phakic Intraocular Lenses

AMBLYOPIADecreased visual acuity of one eye (uncorrectable with lenses) in the absence of : - Organic eye disease insufficient enough to explain the level of vision - Caused by visual deprivation due to any cause (congenital or acquired ) during the critical period of development (up to age 8-9 yo) that prevents the establisment of normal vision in the involved eye

CAUSES OF AMBLYOPIAStrabismus (most common cause)AnisometropiaHigh hyperopiaOpacities : corneal scars, cataractOptic nerve diseaseRetinal disease

LOW VISION

LOW VISION (WHO)

CAUSE OF LOW VISIONChildren : Optic atrophy, Congenital, cataract, Congenital idiopathic nystagmus, Congenital abnormalities of the brain & nerv systemEarly adult life : Stargards disease, Retinitis pigmentosaWorking years: Diabetic retinopathy (>>), Myopia,Uveitis, Corneal dystrophies, Degenerative condition (cataract & macular disease)Retirement : Cataract, AMD, Glaucoma, Retinal detachment

SYMPTOMS OF LOW VISIONDifficulty in : - reading - recognize peoples face - task fine detailed vision

Color vision deficitsContrast sensitivity variably affectedMobility not affected

LOW VISION AID

OPTICAL DEVICES : - Microscopic glassess - Hand magnifiers - Stand magnifiers - Telescope - Closed-circuit Television (CCTV)

LOW VISION AID

NON OPTICAL DEVICES - Typoscope - Standing reading book - Writing frame - Sunglassess lens - Large print - Contrast

ACCOMODATIONAccomodation mechanism the eye changes refractive power by altering the shape of its crystalline lensThe posterior focal point is moved forward in the eye during accommodation so far point moves closer to the eye

ACCOMODATIONIt is the process by the eye changes its refractive power to focus on near objects. It results from increased curvature of lens due to contraction of the ciliary muscle. The stimulus to accomodation is a blurred retinal image.

PRESBYOPIAIts physiologic disease in the amplitude of accommodation associated with agingThere is less bulging of the lens with accommodation due to a change in the crystalline lens that result in decrease in the elasticity of the lens fiber or hardening of the lens

SYMPTOMS OF PRESBYOPIALarger reading distance requiredInability to focus on close workExcessive illumination required for close work

TREATMENT OF PRESBYOPIAAdd positive lenses correction according to age - 40 yo : S + 1,00 D - 45 yo : S + 1,50 D - 50 yo : S + 2,00 D - 55 yo : S + 2,50 D - 60 yo : S + 3,00 D - > 60 yo : S + 3,00 D

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