In the name of ALLAH, most gracious, most merciful
MYOPIA  BY: SUMAYYA NASEEM     Internee Optometrist
AIMS & OBJECTIVES OF TODAY’S LECTURE  •   Myopia and its etiology  •   Mechanisms of production  •   Clinical types  •   S...
HUMAN EYE:OPTICAL CONDITIONS                     Emmetropia                                   Ametropia                   ...
•    EMMETROPIA     Parallel incident rays come to a focus on    the retina when the accomodation is fully    relaxed so f...
OPTICS OF EMMETROPIA
•    AMMETROPIA    Parallel incident rays do not come to a focus    on the retina when the accomodation is fully    relaxe...
MYOPIA     (short sightedness, hypometropia) A type of refractive error in which Parallel incident light is brought to a f...
AETIOLOGY •   Hereditary (Genetic Factor) •   Role of diet •   Theory of excessive near work •   Reading posture •   Racia...
MECHANISMS OF PRODUCTION 1. Axial myopia • Increased length of eyeball • 1mm=3D 2. Curvature myopia • Increased curve of c...
3. Positional myopia•   Anterior displacement of lens e.g. trauma4. Index myopia• Increase in ref index of lens e.g. nucle...
MYOPIA: REFRACTIVE vs AXIAL Refractive Myopia                Axial Myopia                                  (Eye too long) ...
Image of distant object & near object
CLINICAL VARIETIES OF MYOPIA  1. Congenital myopia  2. Simple or developmental myopia  3. Pathological or degenerative myo...
CLINICAL VARIETIES OF MYOPIA 1. Congenital myopia •   Present since birth •   Diagnosed at 2-3 years •   Common in childre...
2. Simple myopia•   Commonest•   Not associated with any eye disease•   Error usually does not exceed 6D•   Usually begins...
CLINICAL PICTURE Symptoms• Poor vision for distance
• Asthenopic symptoms    (due to dissociation b/w accomodation and convergence)• Change in physiological outlook of  child...
SIGNS •   Myopic eyes are large •   Anterior chamber is deeper than normal •   Pupil is dilated and sluggish •   Fundus is...
3. PATHOLOGICAL MYOPIA • Rapidly progressing error • Associated with degenerative changes in posterior   segment • Rapid a...
CLINICAL PICTURE Symptoms •   Defective distant vision •   Defective near vision if degeneration starts •   Muscae volitan...
MUSCAE VOLITANTES
SIGNS •   Prominent eyes •   Proptosis if error exceeds 20D •   Cornea large •   a/c deep •   Pupil large and sluggish •  ...
PosteriorSubcapsular Cataract                                       Open-Angle Glaucoma Idiopathic Retinal    Detachment  ...
OPHTHALMOSCOPICALLYChanges in vitreous• Liquefication• Floaters• Vitreous detachment
POSTERIOR VITREOUS DETACHMENT
VITREOUS DETACHMENT
CHOROIDAL AND RETINAL CHANGES•   Degeneration of choroid•   Choroidal hemorrhage•   White atrophic patches•   Tilted disc•...
POSTERIOR STAPHYLOMA
TILTED DISC
CHOROIDAL AND RETINAL DEGENERATIONS
MYOPIC CRESCENT
HIGHLY MYOPIC FUNDUS
COMPLICATIONS•   Retinal tears•   Retinal detachment•   Hemorrhages•   Complicated cataract•   Vitreous hemorrhage•   Prim...
RETINAL DETACHMENT
RETINAL DETACHMENT
VISUAL FIELD LOSS
4. ACQUIRED MYOPIASome causes are as follows:1.   Index myopia (diabetic, nuclear sclerosis)2. Curvature myopia (conical c...
5. Night myopia (as pupil dilates)                    6. Drug induced myopia(pilocarpine, steroids)7. Pseudo myopia (exces...
REFRACTION PROCEDURE •   VA with and without correction monocularly •   Pinhole VA •   Cover test with and without correct...
DISTANCE VA CHART                     University of WaterlooBailey-Lovie Chart     distance VA chart
RETINOSCOPIC FINDINGSDuring retinoscopy of amyopic patient, ‘against’movement of reflex is seen ascompared to retinoscopic...
Reflex motion seen during retinoscopy     “ w ith ”   “ n e u tr a lity ”   “ a g a in s t”
Retinoscopy Reflex
RETINOSCOPY: SET-UP
DUOCHROME TEST Letters    Circles
COVER/UNCOVER TEST
MADDOX ROD
PHOROPTER (MANUAL REFRACTOR)
VISUAL FUNCTIONS ASSESSMENT
OPTICAL CORRECTION OF MYOPIA Options are as follows: • Spectacles and LVD’s • Contact lenses • Refractive surgeries • Lase...
SPECTACLES • Minus lenses (CONCAVE) are used to correct myopia • In high numbers glasses are not cosmetically attractive  ...
EXTREME MYOPIA
CONTACT LENS
Contact lens is a better option for correction of highmyopia both optically and cosmetically..
C/L INSERTION & REMOVAL
A SOFT C/L
LOW VISION DEVICES (LVD’s)         READING GLASSES
HAND MAGNIFIERS & STAND MAGNIFIERS
DOME/PAPERWEIGHT MAGNIFIER
FILTERS
TELESCOPES
ORTHOKERATOLOGY• Orthokeratology is defined as, the reduction,  modification, or elimination of visual defect by  the prog...
• Orthokeratology uses hard Contact Lenses to  remould the Cornea, to reduce or correct Myopic  (short-sighted) and Astigm...
• Once the desired level of V.A has been  achieved a of retainer lens wear is initiated  until cornea reaches the level of...
ORTHOKERATOLOGY CONTACT LENS
SURGERYClear lens extraction:• For myopia of greater than 15-20 D, cataract  surgical procedure is applied and non-  catar...
CATARACT SURGICAL PROCEDURE
LASER AND SURGERIES
Photorefractive keratectomy PRK:• Uses Excimer laser to change ant. curvature of  cornea.• Tissue is ablated centrally 3.5...
PHOTOREFRACTIVE KERATECTOMY PRK
LASER ASSISTED IN SITU KERATOMILEUSIS                           LASIK• A mechanical keratotome is used to dissect through ...
LASER ASSISTED IN SITU KERATOMILEUSIS                  LASIKFlap creation   Laser intervention   Flap repositioning
CORRECTION WITH LASIK & PRK Myopia     • -1D to -6D --------- PRK     • -6D to -12D -------- LASIK(better to wait till the...
EXCIMER SYSTEM
LASIK
EPIKERATOPHAKIA • This uncommon surgical technique creates a   new corneal surface with a different surface   curvature by...
EPIKERATOPHAKIA
KERATOMILEUSIS • It is the use of microkeratotome to remove   lamella of ant. corneal stroma which is then   reshaped on a...
KERATOMILEUSIS
PREVENTION & CONTROL OF MYOPIA• Many people believe that too much close work, such  as reading or sitting too close to the...
• Nutritional Factors• Since the eye has a collagenous structure, it seems  likely that the same nutrients which strengthe...
VISUAL HYGEINE• We should insist that our children use good lighting  and good posture when reading, take frequent eye  re...
REFERENCES • Theory and practice of optics and refraction   by A K Khurana • Duke Elders Practice of refraction (Tenth   e...
Myopia lecture By Sumayya Naseem
Myopia lecture By Sumayya Naseem
Myopia lecture By Sumayya Naseem
Myopia lecture By Sumayya Naseem
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  • Human Eye: Optical Conditions There are a number of optical conditions of the eye which require correction. Some are refractive errors and some are age-related conditions. The refractive errors, i.e. myopia and hyperopia with or without astigmatism, as well as astigmatism itself uncomplicated by myopia or hyperopia will be dealt with in detail in the following sections. Presbyopia, an age-related condition, with and without ametropia, will be dealt with separately.
  • Ametropia An emmetropic eye focuses light from a distant object on the retina resulting in a clear image. An ametropic eye is one in which light from distant objects is not focused on the retina. The light rays may be focused either in front of or behind the retina.
  • Myopia Myopia is the refractive error resulting from lights rays from a distant object being brought to a focus in front of the retina. The greater the refractive error the further in front of the retina this focus is located. This situation means that, regardless of the accommodative state, unaided clear distance vision cannot be achieved. Applying accommodation only makes the situation worse by bringing the focus position further forward thereby increasing the blur perceived. NOTE: In this and subsequent diagrams, a simplistic approach to the optics of each situation is taken. In the interests of clarity, light rays are shown for an unrealistic pupil size. Thus light appears to pass through the iris, an impossibility in the real world. Further, light is shown being refracted by the anterior corneal surface only, rather than being refracted progressively by each surface. In the case of hyperopia, light rays are shown being focused behind the retina, also an impossibility in the real world since light cannot pass through the posterior pole of the eyeball. When illustrating the forms of astigmatism, even the crystalline lens is omitted from the diagrams.
  • Myopia lecture By Sumayya Naseem

    1. 1. In the name of ALLAH, most gracious, most merciful
    2. 2. MYOPIA BY: SUMAYYA NASEEM Internee Optometrist
    3. 3. AIMS & OBJECTIVES OF TODAY’S LECTURE • Myopia and its etiology • Mechanisms of production • Clinical types • Signs & symptoms • Complications • Diagnosis • Correction • Prevention
    4. 4. HUMAN EYE:OPTICAL CONDITIONS Emmetropia Ametropia Index Axial Presbyopia Curvature Myopia Hyperopia Astigmatism Parallel incident light is Parallel incident light is We get 2 focal points focused in front of the retina focused behind the retina
    5. 5. • EMMETROPIA Parallel incident rays come to a focus on the retina when the accomodation is fully relaxed so far point is at infinity.
    6. 6. OPTICS OF EMMETROPIA
    7. 7. • AMMETROPIA Parallel incident rays do not come to a focus on the retina when the accomodation is fully relaxed so far point is not at infinity.
    8. 8. MYOPIA (short sightedness, hypometropia) A type of refractive error in which Parallel incident light is brought to a focus in front of the retina when eye is at rest. So far point is at finite distance.
    9. 9. AETIOLOGY • Hereditary (Genetic Factor) • Role of diet • Theory of excessive near work • Reading posture • Racial (Chinese and Japanese highest) • Environmental Factors
    10. 10. MECHANISMS OF PRODUCTION 1. Axial myopia • Increased length of eyeball • 1mm=3D 2. Curvature myopia • Increased curve of cornea e.g. conical cornea • Increased curve of lens e.g. lenticonus • 1mm=6D
    11. 11. 3. Positional myopia• Anterior displacement of lens e.g. trauma4. Index myopia• Increase in ref index of lens e.g. nuclear sclerosis in diabetes• Increase in ref index of aqueous humor• Decrease in ref index of vitreous humor e.g. vitreous liquefication5. Myopia due to excessive accomodation• Patients with excessive accomodation
    12. 12. MYOPIA: REFRACTIVE vs AXIAL Refractive Myopia Axial Myopia (Eye too long) (Optics of the eye too strong)
    13. 13. Image of distant object & near object
    14. 14. CLINICAL VARIETIES OF MYOPIA 1. Congenital myopia 2. Simple or developmental myopia 3. Pathological or degenerative myopia 4. Acquired myopia
    15. 15. CLINICAL VARIETIES OF MYOPIA 1. Congenital myopia • Present since birth • Diagnosed at 2-3 years • Common in children born with Marfan’s syndrome • Mostly unilateral and anisometropic • Rarely bilateral • Usually 8-10 D and constant • May be associated with aniridia, megalocornea and congenital separation of retina
    16. 16. 2. Simple myopia• Commonest• Not associated with any eye disease• Error usually does not exceed 6D• Usually begins at age of 7 to 10 years• Stabilizes around midteens
    17. 17. CLINICAL PICTURE Symptoms• Poor vision for distance
    18. 18. • Asthenopic symptoms (due to dissociation b/w accomodation and convergence)• Change in physiological outlook of children
    19. 19. SIGNS • Myopic eyes are large • Anterior chamber is deeper than normal • Pupil is dilated and sluggish • Fundus is normal • Does not exceed 6D • Normal near vision • Defective distant vision
    20. 20. 3. PATHOLOGICAL MYOPIA • Rapidly progressing error • Associated with degenerative changes in posterior segment • Rapid axial growth of eyeball • Usually Hereditary in nature • Can exceed till 30 D • Ref error increases 4D yearly • Also known as degenerative myopia.
    21. 21. CLINICAL PICTURE Symptoms • Defective distant vision • Defective near vision if degeneration starts • Muscae volitantes (Flying Flies) • Night blindness
    22. 22. MUSCAE VOLITANTES
    23. 23. SIGNS • Prominent eyes • Proptosis if error exceeds 20D • Cornea large • a/c deep • Pupil large and sluggish • Sclera is thin
    24. 24. PosteriorSubcapsular Cataract Open-Angle Glaucoma Idiopathic Retinal Detachment Chorioretinal Degeneration
    25. 25. OPHTHALMOSCOPICALLYChanges in vitreous• Liquefication• Floaters• Vitreous detachment
    26. 26. POSTERIOR VITREOUS DETACHMENT
    27. 27. VITREOUS DETACHMENT
    28. 28. CHOROIDAL AND RETINAL CHANGES• Degeneration of choroid• Choroidal hemorrhage• White atrophic patches• Tilted disc• Posterior staphyloma• Myopic crescent (temporally)• Forster-Fuchs flecks (subretinal neovascularisation & pigmented lesion at or near the fovea)
    29. 29. POSTERIOR STAPHYLOMA
    30. 30. TILTED DISC
    31. 31. CHOROIDAL AND RETINAL DEGENERATIONS
    32. 32. MYOPIC CRESCENT
    33. 33. HIGHLY MYOPIC FUNDUS
    34. 34. COMPLICATIONS• Retinal tears• Retinal detachment• Hemorrhages• Complicated cataract• Vitreous hemorrhage• Primary open angle glaucoma• Visual field shows contraction• Scotoma can be seen
    35. 35. RETINAL DETACHMENT
    36. 36. RETINAL DETACHMENT
    37. 37. VISUAL FIELD LOSS
    38. 38. 4. ACQUIRED MYOPIASome causes are as follows:1. Index myopia (diabetic, nuclear sclerosis)2. Curvature myopia (conical cornea & corneal ectasias)3. Positional myopia (ant. Subluxation of lens)4. Consecutive myopia (surgical overcorrection)
    39. 39. 5. Night myopia (as pupil dilates) 6. Drug induced myopia(pilocarpine, steroids)7. Pseudo myopia (excessive & spasm of accomodation)
    40. 40. REFRACTION PROCEDURE • VA with and without correction monocularly • Pinhole VA • Cover test with and without correction • Quick ophthalmoscopy • Retinoscopy Subjective verification: • Duochrome test • Muscle balance- Maddox rod for distance
    41. 41. DISTANCE VA CHART University of WaterlooBailey-Lovie Chart distance VA chart
    42. 42. RETINOSCOPIC FINDINGSDuring retinoscopy of amyopic patient, ‘against’movement of reflex is seen ascompared to retinoscopiclight or streak.Against movement isneutralized by negative orconcave lenses.
    43. 43. Reflex motion seen during retinoscopy “ w ith ” “ n e u tr a lity ” “ a g a in s t”
    44. 44. Retinoscopy Reflex
    45. 45. RETINOSCOPY: SET-UP
    46. 46. DUOCHROME TEST Letters Circles
    47. 47. COVER/UNCOVER TEST
    48. 48. MADDOX ROD
    49. 49. PHOROPTER (MANUAL REFRACTOR)
    50. 50. VISUAL FUNCTIONS ASSESSMENT
    51. 51. OPTICAL CORRECTION OF MYOPIA Options are as follows: • Spectacles and LVD’s • Contact lenses • Refractive surgeries • Laser Others: • Visual hygiene • Prophylaxis • General measures
    52. 52. SPECTACLES • Minus lenses (CONCAVE) are used to correct myopia • In high numbers glasses are not cosmetically attractive and minify actual pt eye size for others • Myopes are usually kept under corrected so that there accomodation is not stimulated. Otherwise, they will complain of Asthenopic symptoms
    53. 53. EXTREME MYOPIA
    54. 54. CONTACT LENS
    55. 55. Contact lens is a better option for correction of highmyopia both optically and cosmetically..
    56. 56. C/L INSERTION & REMOVAL
    57. 57. A SOFT C/L
    58. 58. LOW VISION DEVICES (LVD’s) READING GLASSES
    59. 59. HAND MAGNIFIERS & STAND MAGNIFIERS
    60. 60. DOME/PAPERWEIGHT MAGNIFIER
    61. 61. FILTERS
    62. 62. TELESCOPES
    63. 63. ORTHOKERATOLOGY• Orthokeratology is defined as, the reduction, modification, or elimination of visual defect by the programmed application of contact lenses
    64. 64. • Orthokeratology uses hard Contact Lenses to remould the Cornea, to reduce or correct Myopic (short-sighted) and Astigmatic (irregular surface) errors of the eye.• In some ways this is similar to the use of dental braces by an Orthodontist to straighten crooked teeth.• The main difference is that if a tooth position is corrected for some months it will stay in the new position. However the Cornea is highly elastic, and always returns to its original shape.• For this reason the lenses are worn nightly or on alternate nights after the ideal Corneal shape has been achieved and removed in the morning giving perfect vision without the need for spectacles or contact lenses.
    65. 65. • Once the desired level of V.A has been achieved a of retainer lens wear is initiated until cornea reaches the level of stability new shape cornea. Lens wear is then gradually reduced to the minimum, required to attain good functional vision through out the day.• The amount of ametropia that can be corrected using orthokeratology is: –1 to –6 D myopia with 1.5 D of WTR astigmatism and 0.75 D of ATR astigmatism.
    66. 66. ORTHOKERATOLOGY CONTACT LENS
    67. 67. SURGERYClear lens extraction:• For myopia of greater than 15-20 D, cataract surgical procedure is applied and non- cataractous lens is removed and intra ocular lens of calculated power is inserted.Phakic IOL:• IOL is also placed in A/C or P/C of phakic eyes to correct the refractive error.
    68. 68. CATARACT SURGICAL PROCEDURE
    69. 69. LASER AND SURGERIES
    70. 70. Photorefractive keratectomy PRK:• Uses Excimer laser to change ant. curvature of cornea.• Tissue is ablated centrally 3.5-4mm and surface curvature is reduced.• After scarring, haloes, glare and reduction of best VA are the complaints of patient.
    71. 71. PHOTOREFRACTIVE KERATECTOMY PRK
    72. 72. LASER ASSISTED IN SITU KERATOMILEUSIS LASIK• A mechanical keratotome is used to dissect through the superficial corneal stroma and fashion a lamellar circular flap of uniform thickness.• The bared corneal stroma is reshaped using Excimer laser and hinged flap is replaced.• Better than PRK because of little scarring and better correction predictability.
    73. 73. LASER ASSISTED IN SITU KERATOMILEUSIS LASIKFlap creation Laser intervention Flap repositioning
    74. 74. CORRECTION WITH LASIK & PRK Myopia • -1D to -6D --------- PRK • -6D to -12D -------- LASIK(better to wait till the patient reaches the age of 21 years)
    75. 75. EXCIMER SYSTEM
    76. 76. LASIK
    77. 77. EPIKERATOPHAKIA • This uncommon surgical technique creates a new corneal surface with a different surface curvature by attaching a lenticule of pre- shaped donor corneal stroma to the surface of host cornea. • The eye is not entered and procedure is easily reversed by removal of lenticule.
    78. 78. EPIKERATOPHAKIA
    79. 79. KERATOMILEUSIS • It is the use of microkeratotome to remove lamella of ant. corneal stroma which is then reshaped on a cryolathe before being replaced. • High degrees of myopia till 15D can be corrected in this way. • Keratophakia is developed as a modification of keratomileusis and is used for aphakia.
    80. 80. KERATOMILEUSIS
    81. 81. PREVENTION & CONTROL OF MYOPIA• Many people believe that too much close work, such as reading or sitting too close to the television, causes nearsightedness. But there was little evidence to support this belief. However, one study suggested that people in professions that involve extensive reading have higher degrees of nearsightedness.• With regular instillation, topical 0.05% atropine is an effective agent for controlling myopia progression in a majority of school aged children.
    82. 82. • Nutritional Factors• Since the eye has a collagenous structure, it seems likely that the same nutrients which strengthen collagen might also be helpful in keeping the eye from becoming elongated. Calcium, magnesium, boron, silica, selenium, manganese and vitamin D all come to mind, as well as vitamin C. A strong ocular structure would likely be less prone to becoming elongated, as occurs in myopia. Low levels of calcium, fluoride and selenium were found to be related to increased risk of progressive myopia in an exploratory study.• Vitamin E, can slow the progression of myopia in children. Myopia in children was also significantly related to lower consumption of protein, fat, vitamins B1, B2 and C, phosphorus, iron, and cholesterol.
    83. 83. VISUAL HYGEINE• We should insist that our children use good lighting and good posture when reading, take frequent eye rest breaks during long study periods, and encourage them to be physically active.• Environmental visual stress may be lessened by taking these precautions while reading: frequently stretching and moving the eyes and looking away from the reading material at distant objects, removing distance eyewear(-) or using reading glasses for near tasks.• As it is usually hereditary in nature, so family marriages should be avoided.
    84. 84. REFERENCES • Theory and practice of optics and refraction by A K Khurana • Duke Elders Practice of refraction (Tenth edition) • Clinical Optics by Elkington, Frank and Greaney (Third edition) • www.visionlaser.com • www.orthokeratology.com and many other websites.
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