HYPERMETROPIA PRESBYOPIA Dr Cynthia arunachalam Professor and head

HYPERMETROPIA & PRESBYOPIA Dr Cynthia arunachalam Professor and head Dept of Ophthalmology Yenepoya medical College Yenepoya University

Hypermetropia The refractive state of the eye where in parallel rays of light coming from infinity are focussed behind the retina with accomodation at rest

Hypermetropia AXIAL Common 1 mm short-3 D increase CURVATURE Curvature of cornea /lens –flat 1 mm increase in radius of curvature 6 D INDEX Change in RI in old age and diabetics

Hypermetropia POSITIONAL POSTERIORLY LOCATED LENS ABSENCE-LENS CONGENITAL/SURGICAL

Clinical types SIMPLE Common Variation in the normal development of the eye Axial / curvatural

Clinical types PATHOLOGICAL SENILE POSITIONAL APHAKIC CONSECUTIVE CURVATURAL-decreased curvature of outer lens fibre INDEX-acquired cortical sclerosis Posteriorly displaced lens Congenital or acquired absence of lens Surgical / overcorrected myopia

Clinical types FUNCTIONAL Paralysis of accomodation-3 rd nerve palsy

Hypermetropia LATENT FACULTATIV E ABSOLUTE MANIFEST

Hypermetropia TOTAL HYPERMETROPIA total amount of hypermetropia estimated after complete cycloplegia LATENT HYPERMETROPIA Amount of hypermetropia corrected by inherent tone of ciliary muscle • high in children • decreases with age

Hypermetropia Ø MANIFEST Which is not corrected by inherent tone of ciliary muscle • FACULTATIVE-corrected by patients accommodative effort ABSOLUTE-cannot be corrected by patients accommodative effort

Hypermetropia Total Latent Manifest Facultative Absolute

Clinical features • Asymptomatic - small error, corrected by mild accommodative effort, young patient • Asthenopic - symptoms with normal vision tiredness of eyes, frontal head ache, watering • Defective vision - with asthenopia • Defective vision -

SIGNS • • Size of the eye ball - small Cornea - flat AC - shallow VA - varies with degree of hypermetropia and accommodation • Fundus • A scan - short anteroposterior length

Fundus in hypermetropia Small disc, ill defined margin, simulates papillitis Shiny retina - shot silk appearance Vessel reflexes accentuated

Complication recurrent stye, blepharitis, chalazion? accomadativeconvergent squint amblyopia predisposition to develop angle closure glaucoma

TREATMENT OPTICAL Convex lens is placed to focus the rays on the retina

TREATMENT Principles total amount of hypermetropia is corrected under complete cycloplegia error <1 D, correction is given if patient is symptomatic gradual increase the correction at 6 m interval assess amblyopia - full correction with occlusion hypermetropia may decrease with child growth 6 monthly

TREATMENT • Contact lens • Surgical EXCIMER LASER PHTOKERATECTOMY LASIK NON CONTACT LASER THERMAL KERATOPLASTY

EXCIMER LASER KERATECTOMY • • • Reshaping the ant cornea with pulsed laser Accurately ablate corneal tissue Minimal disruption of surrounding tissue In hypermetropia - periphery is ablated Upto 2. 5 D Epithelium is removed. BM and ant stroma is lasered • Heals in 48 -72 hours

LASIK SUCTION RING IS APPLIED MICROKERATOME INSERTED THIN FLAP IS RAISED EXCIMER LASER APPLIED FLAP REPOSITED BACK

LASIK Advantages • absence of post operative pain - early rehabilitation Complications incomplete cutting of flap over correction decentration

Non contact laser heat thermoplasty • Laser heat is used to alter corneal stroma • Steepens the corneal curvature

ACCOMODATION

OCULAR CHANGES IN ACCOMODATION • Slackening of zonules • Change in the curvature of the lens surface(anterior) • Increase in axial thickness of the lens • Pupillary constriction and convergence Ciliary ring CM

AA FP NP RA NEAR POINT NEAREST POINT AT WHICH THE SMALL OBJECTS CAN BE SEEN CLEARLY FAR POINT FARTHEST POINT AT WHICH THE SMALL OBJECTS CAN BE SEEN CLEARLY RANGE OF ACC DISTANCE BETWEEN NEAR AND FAR POINT

AMPLITUDE OF ACCOMODATION DIFFERENCE BETWEEN THE DIOPTERIC POWER NEEDED TO FOCUS THE DISTANCE AND NEAR 10 years-7 cm 40 years-25 cm 45 years -33 cm Far point is infinity Near point varies with the age of the pt Amp of accommodation =100/7=14 D Amp of accommodation =100/25=4 D

PRESBYOPIA FAILING NEAR VISION DUE TO DECREASE IN THE AMPLITUDE OF ACCOMMODATION CAUSES Decrease in elasticity of the lens Decrease in the power of ciliary muscle

symptoms • Difficulty in near vision (start evening, later -good light) • asthenopia

TREATMENT • Convex lens • rough estimate 40 years -1 D 45 years -1. 5 D 50 years - 2 D 55 years - 2. 5 D • Single vision, bifocal, trifocal glasses

principles Correct refractive error for distance Find presbyopic correction needed for each eye separately Weakest convex lens which can be seen clearly is selected Presbyopic add should leave 33% of the accommodation as reserve Profession of the pt should be considered

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