Lecture 1 Visual functions in different age. Main diagnostic criteria in ophthalmology. Blidness. Term

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Lecture 1Visual functions in different age.
Main diagnostic criteria in ophthalmology.
Blidness. Term norm pathology of visual
organ. Refraction. Types of clinical refraction.
Progressive myopia. Prophylaxis, methods of
surgical and conservative treatment. Presbyopia.
Lecture is delivered by Ph. D., assistant of
professor Tabalyuk T.A.
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• Visual organ consists from
• 1) peripheral part eyeball with ocular adnexa
• 2) guiding pathway optic nerve, chiasm, optic
  tract
• 3) undercortex centers lateral geniculare
  nucleus and optic radiation
• 4) higher visual centers in the occipital cortex.

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Structure of Visual Analisator

• 1 - retina,
• 2 - optic nerve (non-crossed fibers),
• 3 -  optic nerve (crossed fibers),
• 4 - optic tract,
• 5 -  lateral geniculare nucleus,
• 6 - radiatio optici,
• 7 - lobus opticus

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• EYEBALL
• I. External (structural) layer cornea sclera
• II. Middle (vascular) layer iris, ciliary body
  choroid
• III. Internal layer retina.
• Internal nucleus of the eye includes lens,
  vitreous aqueous humor, which fill in eye
  chambers.
• The eyes lie within two bony cavities, or orbits.
• OCULAR ADNEXA
• Lacrimal gland excretory system
• Oculomotor apparatus
• Eyelids
• Conjunctiva
• OPTICAL SYSTEM of the EYE
• Cornea
• Aqueous humor
• Lens
• Vitreous

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VISUAL FUNCTIONS

• Peripheral vision (rods are response) includes
• Light sensitivity
• Field of vision
• Central vision (cones are response) includes
• Visual acuity
• Colour vision

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Light sensitivity

• Eye adaptation to light lasts till 1 minute.
• Eye adaptation to dark lasts till 1 hour.
• Adaptometr is a special equipment
• with the help of which we can measure
• dark adaptation of the human eye.
• The investigation durates 1 hour.
• Hemeralopia is a light sensitivity disorder.
• Functional hemeralopia is usually
• caused by hypovitamonosis A.
• Symptomatic hemeralopia is an index
• of rods condition and may be a
• symptom of retinitis pigmentosa,
• optic neuritis or glaucoma.

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Field of vision is a space which is seen by
non-moving eye (one eye, not both).

• Perimetry projection of visual field on
  spherical concave space,
• which is concetric to retina.
• Left picture ancient perimetr of Ferster
• Right picture modern automatic computerized
  spheroperimetr

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Campimetry is a projection of visual field on a
plane

• This method is useful to reveal and measure
  phisiological scotoma blind spot projection
  in a space optic disc.
• Usually blind spot is found in temporal part of
  visual field 12-18 degrees of point of fixation
  (controposite nasal location of optic disc). Its
  vertical size - 8-9 degrees (10-11 sm), its
  horizontal size 5-7 degrees
• (8-9 sm).

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Normal bounders of visual field for objects of
different colour
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Visual field defects

• 1.Narroving of visual field bounders
• concetric (retinitis pigmentosa, optic atrophy,
  final glaucoma)
• local (usual hemianopsia homonim - dextra or
  sinistra heteronim - binasal or bitemporal)
• 2. Patch loosing of visual field - scotoma
• positive (with complaints) negative (without
  complaints)
• absolute relative
• physiological pathological
• I.e. blind spot is physiological, absolute
  negative scotoma

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Visual acuity

• Visual acuity is measured in relative units.
• visusd/D,
• where d-distance of investigation D-distance,
  from each normal eye can definite signs of this
  line (is written in the left of each line of
  Sivtcev table).
• For example, the person reads first line of
  Sivtcev table from 5 m. Normal eye definites the
  signs of this line from 50 m. So, visus5 m/50
  m0,1.
• If the person does not see optotypes of first
  line of Sivtcev table from 5 m, we ask him to
  come more near to the table.
• For example, the person reads first line of
  Sivtcev table from 3 m. Normal eye definites the
  signs of this line from 50 m. So, visus3 m/50
  m0,06.
• If the person does not see optotypes of first
  line of Sivtcev table even from 0,5 m, we project
  the light to his or her eye from different
  direcrion. If the person gives correct answers,
  then his visus1/8 pr.l.certa. If the person see
  light, but gives not correct answers even in one
  direction, then his visus1/8 pr.l.incerta.
• If the person does not see light, then his
  visus0. In such cases usually direct light
  reaction of pupil is absent during objective
  measuring of visual acuity with the help of
  nystagmoaparat optokinetic nystagmus is absent.

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VISUAL ACUITY TEST (UKRAINIAN FOREIGN ONE)
Left picture Snellen chartRight picture
Sivtcev table
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Visual acuity transcription
20 feet equivalent (USA) 6 meter equivalent (Great Britain) 5 meter equivalent (Ukraine)
20/20 6/6 1,0
20/25 6/7.5 0,8
20/40 6/12 0,5
20/60 6/18 0,3
20/200 6/60 0,1
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Normal data of visual acuity in children
Newborns 0,005 4 months 0,01 1 year
0,1-0,3 2 years 0,2-0,5 3 years 0,3-0,6 4
years 0,4-0,7 5 years 0,5-0,9 6 years
0,7-1,0 7-15 years 1,0
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Colour vision

• Polichromatic Rabkins tables are used for
  investigation
• Normal colour vision according to this method is
  called
• normal trichromasia

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Colour vision disorders

• Congenital usually bilateral
• Aquired usually monolateral
• Defect of one of three main colours is called
  dichromasia
• White black perceprion is called monochromasia
• Anomal perception of red protanomaly
• Anomal perception of green deyteranomaly
• Anomal perception of blue - tritanomaly

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• PHYSICAL REFRACTION of the EYE
• average refractive power of the eye is
  approximetly 60 D
• individual indices fluctuate from 52 till 71 D
• Average refractive power of optical mediums of
  the eye
• Cornea 40 D
• Lens - 19-20 D
• Aqueous humor vitreous less then 1 D
• In sum 60 D

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CLINICAL REFRACTION of the EYEcorrelation
between refractive power of the eye its length

• EMMETROPIA AMMETROPIA
• MYOPIA
• HYPERMETROPIA
• ASTIGMATISM

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• Emmetropia (E or Em) refractive power of the
  eye corresponds with its length, thus main focus
  is located on retina
• Ammetropia refractive errow, abnormal
  correlation between refractive power length of
  the eye
• Myopia (M or My) main focus is before
  retina due to incresed refractive power or length
  of the eye
• Hypermetropia (H or Hy) - main focus is
  behind retina due to decresed refractive power or
  length of the eye
• Astigmatism different refractive power in
  two perpendicular planes. Combination of
  different clinical refraction or different
  degrees of one type of clinical refraction in one
  eye is usually named astigmatism.

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Myopia is subdivided into Light degree till
minus 2,75 D Middle degree from minus 3,0 till
5,75 D High degree minus 6,0 D and
more Hypermetropia is subdivided into Light
degree till plus 1,75 D Middle degree from
plus 2,0 till 4,75 D High degree plus 5,0 D
and more Anisometropia is different refraction
of both eyes more then 1,0 dptr
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• TYPES of ASTIGMATISM
• 1. Simple combination of emmetropia in one
  meridian ammetropia in perpendicular one.
• A. Simple myopic - combination of
  emmetropia myopia in two perpendicular planes
• B. Simple hypermetropic - combination
  of emmetropia hypermetropia in two
  perpendicular planes.
• 2. Complex combination of different degrees
  of one type of ammetropia in two meridians.
• A. Complex myopic - combination of
  different degrees of myopia in two perpendicular
  planes
• B. Comlex hypermetropic - combination of
  different degrees of hypermetropia in two
  perpendicular planes.
• 3. Mixt combination of myopia
  hypermetropia in perpendicular planes of one eye.
• II. 1. Direct refractive power of vertical
  meridian is stronger then horizontal one
• 2. Indirect - refractive power of horizontal
  meridian is stronger then vertical one
• III. 1. Regular - refractive power of hole
  meridian is the same
• 2. Irregular - refractive power in one
  meridian is different due to corneal diseases,
  i.e. keratoconus, scars etc.

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METHODS of MEASURING the REFRACTION

• I. Objective methods
• sciascopy or retinoscopy
• refractometry
• autorefractometry
• ophtalmometry
• II. Subjective method
• according to improving the visual acuity with
  trial glasses

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Retinoscopy, refractometry, autorefractometry
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Ophthalmometry, corneal topography
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NORMAL DEVELOPMENT of REFRACTION in CHILDREN

• Newborns Hm 3,0-5,0 dptr
• 1 year Hm 3,5 dptr
• 2 years Hm 3,0 dptr
• 3 years Hm 2,5 dptr
• 4 years Hm 2,0 dptr
• 5 years Hm 1,5 dptr
• 6 years Hm 1,0 dptr
• 7-8 years Hm 0,75 dptr
• 9-15 years Hm 0,5 dptr

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EXAMPLES 1. The results of refractometry of
both eyes 90 degrees My (-) 5,0 dptr 180
degrees My (-) 5,0 dptr It's middle degree
myopia OU. 2. The results of refractometry of
both eyes 90 degrees Hm () 2,0 dptr 180
degrees Hm () 2,0 dptr It's middle degree
hypermetropia OU. Pay attention for patients'
age! It may be physiological refraction! 3. The
results of refractometry of right eye 90 degrees
My (-) 5,0 dptr 180 degrees Em It's simple
myopic direct astigmatism OD.
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EXAMPLES
4. The results of refractometry of left eye 90
degrees Hm () 5,0 dptr 180 degrees Hm ()
10, 0 dptr It's complex hypermetropic indirect
astigmatism OS. 5. The results of refractometry
of both eyes 90 degrees My (-) 2,0 dptr 180
degrees Hm () 3,0 dptr It's mixt direct
astigmatism OU. 6. The results of refractometry
of right eye 90 degrees My (-) 2,0 dptr 180
degrees My (-) 2,0 dptr The results of
refractometry of left eye 90 degrees Hm ()
5,0 dptr 180 degrees Hm () 5, 0 dptr It's
anisometropia. Light degree myopia OD. High
degree hyperopia OS.
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• METHODS of AMMETROPIA CORRECTION
• GLASSES
• CONTACT LENSES
• SURGICAL, i.e. EXIMER LASER
• ORTHOKERATOLOGY in light middle myopia

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Glasses is the most simple, most ancient method
of correction, but not always the most effective

• Sph concave for myopia
• Sph convex for hyperopia
• Cyl for simple astigmatism
• Sph-cyl for complex
• mixt astigmatism

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SOFT HARD CONTACT LENS
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Contact lenses give the better more natural
vision, but the patient have to be under a
special doctors control

• Medical indications for contact correction
• High myopia
• High astigmatism
• Aphakia
• Irregular cornea, i.e. in keratoconus
• Anisometropia

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Lasik surgery changing of cornea shape
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Implantation of phakic intraocular lenses in high
myopia astigmatism
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ORTHOKERATOLOGY changing of corneal shape in
light middle myopia with the help of special
contact lenses to stop myopia progression in
children in cases when laser surgery is
contrindicated (i.e. thin cornea)
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Accommodation -   adjustment of the eye for
vision in different distances

• .

In short distances - ciliary muscle contracts
zonula ciliaris relax lens becomes more convex
refractive power of lens increases In long
distances - ciliary muscle relaxes tensio of
zonula ciliaris increases lens becomes more
concave refractive power of lens decreases
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PRESBYOPIA age loosing of accommodation

• To correct it special multifocal glasses
  (progressive) or glasses for near distance are
  prescribed. Approximetly
• 40 years sph convex () 1,0 dptr
• 45 years sph convex () 1,5 dptr
• 50 years sph convex () 2,0 dptr
• 55 years sph convex () 2,5 dptr
• 60 years sph convex () 3,0 dptr
• over 60 years sph convex () 3,5 dptr

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STRABISMUS
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HIRSHBERG TEST is used to determine angle of
strabismus
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Differentiation of neurologycal
ophthalmological srabismus
Paralytic (nonconcominant) strabismus Concominant (nonparalytic) strabismus
Decreasing or absence of eye movements in any direction Full amount of eye movements
Primary secondary angle of strabismus are different Primary secondary angle of strabismus are equal
Diplopia Diplopia is absebt
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Types of concominant srabismus
Accommodative strabismus Nonaccommodative strabismus
Angle of srabismus is visible only for near distance (if it is esotropia) or only for far distance (if it is exotropia) Angle of srabismus is present constantly (for far near distances)
Using of cycloplegic agents (S. atropini, Mydriacili or Tropicamide) corect angle of srabismus (if it is esotropia) or increases it (if it is exotropia) Using of cycloplegic agents (S. atropini, Mydriacili or Tropicamide) does not influence on angle of srabismus
Glasses corect angle of srabismus sph convex if it is esotropia sph concave if it is exotropia Glasses does not influence on angle of srabismus
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TREATMENT of NONACCOMMODATIVE STRABISMUS only
SURGICAL

• Recession
• (weakening of eye muscle)
• Resection
• (strenthening of eye muscle)

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THANK YOU FOR ATTENTION!