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Hypermetropia
- 1.
- 2. hyperopia / long-sightedness •The term hypermetropia is derived from hyper meaning “In excess” met meaning “measure” & opia meaning “of the eye”. • First suggested in 1755 by KASTNER • Later by DONDERS 1858 hyperopia • HELMHOLTZ - hypermetropia
- 3. DEFINITION • parallel raysof light coming from infinity are focused behind retina with accommodation being at rest • The posterior focal point is behind the retina which receives a blurred image
- 5. ETIOLOGY 1) AXIAL • Mostcommon • Total refractive power of eye is normal • Axial shortening of eyeball (<2mm) • 1mm short- 3 D of HM • Physiologically >6D HM are uncommon • At birth +2.5 – 3 D of HM (physiologically) • Pathologically seen in cases like orbital tumour, inflammatory mass , oedema, coloboma and microphthalmos.
- 6. 2) CURVATURAL • Flatteningof cornea, lens or both • 1mm increase in roc - 6D of HM • Never exceed 6D HM physiologically • Congenitally flattened (cornea plana) • Result (trauma and disease ) 3) INDEX • Change in refractive index with age • Physiologically in old age • Pathologically in diabetics under treatment
- 7. 4)POSITIONAL • Posteriorly placedcrystalline lens • Occurs as congenital anomaly • Result of trauma or disease 5)ABSENCE OF LENS • Seen in aphakia
- 8. CLINICAL TYPES • SIMPLEHYPERMETROPIA, • PATHOLOGICAL • FUNCTIONAL HYPEROPIA
- 9. SIMPLE HYPERMETROPIA • Commonestform • Results from normal biological variations in the development of eyeball • Include axial and curvatural HM • May be hereditary
- 10. PATHOLOGICAL HYPERMETROPIA • Anomalieslie outside the limits of biological variation • Acquired hypermetropia – Decrease curvature of outer lens fibers in old age – Cortical sclerosis • Positional hypermetropia • Aphakia • Consecutive hypermetropia
- 11. FUNCTIONAL HYPERMETROPIA • Resultsfrom paralysis of accommodation • Seen in patients with 3rd nerve paralysis & internal ophthalmoplegia
- 12. OPTICAL CONDITION • Parallelrays focus behind retina • Diffusion circles produce blurred & indistinct images • Retina is nearer to nodal point • Image is smaller than in emmetropic • Rays diverge from retina • Formation of clear image is possible only when converging power of eye is increased
- 15. NOMENCLATURE • TOTAL HYPERMETROPIA= LATENT + MANIFEST (facultative + absolute)
- 16. TOTAL HYPERMETROPIA • Itis the total amount of refractive error, estimated after complete cycloplegia with atropine • Divided into latent & manifest
- 17. LATENT HYPERMETROPIA • Correctedby inherent tone of ciliary muscle • Usually about 1D • High in children • Decreases with age • Revealed after abolishing tone of ciliary muscle with atropine
- 18. MANIFEST HYPERMETROPIA Correct byaccommodation and convex lens FACULTATIVE HYPERMETROPIA • Corrected by patients accommodative effort ABSOLUTE HYPERMETROPIA • Residual part not corrected by patients accommodative effort
- 19. • Manifest HM– absolute HM = Facultative HM (Strongest lens) – (weakest lens) • Total HM – Manifest HM = Latent HM
- 20. NORMAL AGE VARIATION At birth +2 +3D HM • Slightly increase in one year of life, • Gradually diminished In old age after 50 year again tendency to HM 1) Lens grows, converging power decreases 2) Change in refractive index Some amount of latent HM become manifest More amount of facultative HM become absolute Practically after 65 year all of it become absolute
- 21. SYMPTOMS • Principal symptomis blurring of vision for close work • Symptoms vary depending upon age of patient & degree of refractive error ASYMPTOMATIC • small error produces no symptoms • Corrected by accommodation of patient
- 22. ASTHENOPIA • Refractive errorare fully corrected by accommodative effort • Sustained accommodation produces symptoms • Asthenopia increases as day progresses • Increased after prolonged near work SYMPTOMS Tiredness Frontal or fronto temporal headache Watering Mild photophobia
- 23. DEFECTIVE VISION WITHASTHENOPIA • Not corrected by accommodation • Defective vision for near more than distance • Asthenopia due to sustained accommodation • Refractive error more(>4D)
- 24. DEFECTIVE VISION ONLY •Refractive vision more than 4D • Adults usually do not accommodate • Marked defective vision for near and distance
- 25. SIGNS • VISUAL ACUITY: Defective • EYEBALL: small or normal in size • CORNEA : may be smaller than normal. There can be CORNEA PLANA • ANTERIOR CHAMBER : may be shallow • LENS: could be dislocated backwards • A Scan ultrasonography (biometry) reveal short axial length
- 26. FUNDUS: A) DISC: Darkreddish color, irregular margins ,confused with Papillitis so termed as PSEUDO-PAPILLITIS B) MACULA: Situated further from the disc than usual, large positive angle alpha, apparent divergent squint C) BLOOD VESSELS: Show undue tortuosity & abnormal branchings D) BACKGROUND: SHOT- SILK RETINA
- 27. COMPLICATION • Recurrent styes, blepharitis or chalazia • Accommodative convergent squint • Amblyopia – Anisometropic – Strabismic – Uncorrective bilateral high hypermetropia • Predisposition to develop primary narrow angle glaucomas Care should be taken while instilling mydriatics
- 28. TREATMENT BASIS FOR TREATMENT •No Treatment Error is small Asymptomatic Visual acuity normal No muscular imbalance
- 29. Young children(<6 or7yrs) Some degree of hypermetropia is physiological so no correction Treatment required if error is high or strabismus is present working in school small error may require correction refraction should be carried out every six month
- 30. ADULTS If symptoms ofeye-strain are marked,we correct as much of the total hypermetropia as possible,trying as far as we can to relieve the accommodation Some patients with hypermetropia do not initially tolerate the full correction indicated by manifest refraction so we undercorrect them Exophoria hyperopia should be under correct by 1 to 2D
- 31. Patients with absolutehypermetropia are more likely to accept nearly the full correction because they typically experience immediate improvement in visual acuity In pathological hypermetropia the underlying cause rather than the hypermetropia is chief concern
- 32. MODE OF TREATMENT •SPECTACLES • CONTACT LENS • SURGICAL
- 33. SPECTACLES Prescribe convex lenses(Plus lenses) Advantages • Comfortable • Easier method • Less expensive • Safe idea
- 35. CONTACT LENS ADVANTAGES Cosmetically good Increasedfield of view Less magnification Elimination of aberrations & prismatic effect
- 36. REFRACTIVE SURGERY • Refractivesurgery is not as effective as in myopia TYPES: 1) HEXAGONAL KERATOTOMY 2) LASER THERMAL KERATOPLASTY 3) PHOTOREFRACTIVE KERATECTOMY 4) LASER IN SITU KERATOMILEUSIS(LASIK) 5) PHAKIC IOL AND CLEAR LENS EXTRACTION
- 38. LASER THERMAL KERATOPLASTY(LTK) •Procedure done using laser energy to heat the cornea (contraction of collagen) and increase its curvature • Central heating of cornea results in central corneal flattening thereby resulting in hyperopic shift
- 39. PHOTOREFRACTIVE KERATECTOMY(PRK) • Direct laserablation of corneal stroma after removal of corneal epithelium mechanically • Done using EXCIMER LASER
- 40. LASER IN SITUKERATOMILEUSIS(LASIK) • Anterior flap of cornea lifted with keratome and excimer laser is used to sculpt the stromal bed to change the refractive error of eye • It can correct up to 4D of hypermetropia and 8D of astigmatism
- 41. PHAKIC IOL ANDCLEAR LENS EXTRACTION • Done by Phaco technique • Clear lens extraction with the implantation of an IOL-----Preferably foldable IOL or a Piggyback IOL is implanted
- 42. VISUAL HYGIENE • Whilereading or doing intensive near work take a break about every 30 min • When reading maintain proper distance that is the book should be at least as far from your eyes as your elbow when you make a fist and hold it against your nose • Sufficient Illumination • Place a limit spent watching television & watching videogames • Sit 5-6 feet away from the television
- 43. • Younger childrenwho have significant hyperopia associated with amblyopia, strabismus,or anisometropia require treatment, starting as early as 3-6 months of age
- 44. BIBLIOGRAPHY 1) DUKE –ELDER’S PRACTICE OF REFRACTION 2) OPTICS AND REFRACTION BY KHURANA
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