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HYPERMETROPIA & PRESBYOPIA

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

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HYPERMETROPIA & PRESBYOPIA

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

  2. 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

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

  4. Hypermetropia POSITIONAL POSTERIORLY LOCATED LENS ABSENCE-LENS CONGENITAL/SURGICAL

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

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

  7. Clinical types FUNCTIONAL Paralysis of accomodation-3rd nerve palsy

  8. Hypermetropia LATENT FACULTATIVE ABSOLUTE MANIFEST

  9. 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

  10. Hypermetropia • 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

  11. Hypermetropia Total Latent Manifest Facultative Absolute

  12. 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 -

  13. 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

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

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

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

  17. TREATMENT Principles total amount of hypermetropia is corrected under complete cycloplegia error <1D, 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- 6monthly

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

  19. 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 2.5D • Epithelium is removed. BM and ant stroma is lasered • Heals in 48-72 hours

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

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

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

  23. ACCOMODATION

  24. 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

  25. 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

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

  27. 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

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

  29. TREATMENT • Convex lens • rough estimate 40 years -1D 45 years -1.5D 50 years - 2D 55 years - 2.5D • Single vision, bifocal,trifocal glasses

  30. 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

  31. THANK YOU

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