HYPERMETROPIA

K.K.D.SECOND YEAR

Emmetropia

Myopia

Hyperopia

Astigmatism

aberropia

AMMETROPIA

The term hypermetropia is derived from hyper meaning “In excess” met meaning “measure” & opia meaning “of the eye”.

First suggested in 1755 by KASTNER

HYPERMETROPIA

DEFINATION

etiology

Axial hypermetropia

Curvatural hypermetropia

Index hypermetropia

Positional hpermetropia

aphakia

ETIOLOGY

AXIAL HMseen in cases like orbital tumour, inflammatory mass , oedema, coloboma and microphthalmos.

CURVATUAL

Result (trauma)

INDEX HMChange in refractive index with age

Pathologically in diabetics under treatment

POSITIONAL

Result of trauma

APHIKIA

the refractive power will lower than required

Far point will be in behind of the eye(retina)

more amount of accommodation (uncorrected)

optics of hypermetropia

Clinical types

Simple/developmental

pathological

functional

Clinical classification of hypermetropia

Commonest formResults from normal biological variations in

the development of eyeballInclude axial and curvatural HMMay be hereditary

SIMPLE/DEVELOPMENTAL

• Congenital/acquired

• Index hypermetropia(cortical sclerosis)• Positional hypermetropia(postr subluxn of

lens)• Aphakia• Consecutive (overcorrection of myopia)

pathological

PATHOLOGICAL HYPERMETROPIA

FUNCTIONAL HYPERMETROPIA

Paralysis of accommodation in pts with3rd nerve palsy

Latent

hypermetro

pia

Manifest

hypermetro

pia

Total hypermet

ropia

COMPONENTS OF HYPERMETROPIA

It is the total amount of refractive error,estimated after complete cycloplegia with atropine

Divided into latent & manifest

TOTAL HYPERMETROPIA

Corrected by inherent tone of ciliary muscleHigh in children Decreases with ageRevealed after abolishing tone of ciliary

muscle with atropine

LATENT HYPERMETROPIA

Remaining part of total hypermetropiaCorrect by accommodation and convex lensMeasure by add strongest lens with max. visionConsists of facultative & absoluteFACULTATIVE HYPERMETROPIACorrected by patients accommodative effort ABSOLUTE HYPERMETROPIAResidual part not corrected by patients

accommodative effortAbsolute hypermetropia can be measured by the weakest convex lens with which maximum visual acuity

MANIFEST HYPERMETROPIA

• Manifest HM – absolute HM = Facultative HM

(Strongest lens) – (weakest lens)• Total HM – Manifest HM = Latent HM

MANIFEST HYPERMETROPIA

CONT…

1. Asymptomatic2. Asthenopic symptoms

3. Defective vision with asthenopic symptoms4. Defective vision only

Associated with near work & increase in evening• Tiredness of eyes• Frontal / frontotemporal head

ache• Watering• photophobia

Not fully corrected with voluntary accomodation

SYMPTOMS

Size of eye ball may appear small as a wholeCornea may be flatternAnterior chamber is comparatively shallowFundus examinationsmall optic disc

pseudopapilitisretina as a whole may shine due to greater

brilliance of light reflections (shot silk appearance).

signs

• SPECTACLES

• CONTACT LENS

• SURGICAL

Optical treatment

MODE OF TREATMENT

Basic principlePrescribe convex lenses(Plus lenses) so that rays are brought to focus on the retina

Advantages• Comfortable• Easier method• Less expensive• Safe idea

SPECTACLES

ADVANTAGESCosmetically good

Increased field of view

Less magnification

Elimination of aberrations & prismatic effect

CONTACT LENS

Refractive surgery is not as effective as in myopia

TYPES:1) LASER THERMAL KERATOPLASTY(LTK)2) PHOTOREFRACTIVE KERATECTOMY(PRK)3) LASER IN SITU KERATOMILEUSIS(LASIK)4) PHAKIC IOL AND CLEAR LENS

EXTRACTION5) VISUAL HYGIENE

REFRACTIVE SURGERY

Images are taken from the google imageDuke-Elder’s PRACTICE OF REFRACTION REVISED BY David Abrams TENTH EDITION

REFERENCE

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