refractive errors (gangguan refraksi)
TRANSCRIPT
REFRACTIVE ERRORS
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Z A L D I
FAKULTAS KEDOKTERAN
UNIVERSITAS ISLAM SUMATERA UTARA
MEDAN
2014
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Dengan menyebut nama Allah
Yang Maha Pengasih Maha Penyayang.
I. TUJUAN INSTRUKSIONAL UMUM
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Setelah Proses Belajar Mengajar mahasiswa
mampu menegakkan diagnosa kelainan refraksi
dan dapat memberikan koreksi terbaik bagi pasien
dengan melakukan pemeriksaan sederhana yang
akan dipelajari selama masa perkuliahan secara
baik dan benar .
II. TUJUAN INSTRUKSIONAL KHUSUS
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Setelah Proses Belajar Mengajar mahasiswa
mampu menegakkan diagnosa dan memberikan
koreksi kacamata yang sesuai bagi pasien miopia ,
hipermetropia , astigmatisma dan presbiopia
dengan baik dan benar sesuai dengan
kompetensinya
VISUAL EXAMINATION
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VISUAL ACUITY
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SNELLEN CHART = 6/6 – 6/60
FINGER COUNTING ( FC ) = 5/60 – 0,5/60
HAND MOVEMENT ( HM ) = 1/300
LIGHT PERCEPTION ( LP ) = 1/∞
NO LIGHT PERCEPTION ( NLP ) = 0
MAGNITUDE OF VISUAL
IMPAIRMENT
(Visual Acuity <6/18)
153 Million
Uncorrected
Refractive Errors
161 Million
Eye Diseases
= 314 Million
People severely visually impaired
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517million uncorrected presbyopes
In addition, recent studies indicate that there are:
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EMMETROPIA
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REFRACTIVE ERRORS
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= REFRACTIVE DISORDERS
= ANOMALI REFRAKSI
= KELAINAN REFRAKSI
CLASSIFICATION
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REFRACTIVE ERRORS :
A. FAR VISION
1. MYOPIA
2. HYPERMETROPIA
3. ASTIGMATISM ( 5 )
B. NEAR VISION : PRESBYOPIA
FOCUS NODE IN MACULA
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THE ROLE OF OPTICAL DEFOCUS
Optically Imposed MyopiaTo compensate, the eye must
become more hyperopic.
Optically Imposed
HyperopiaTo compensate, the eye must
become more myopic.
Positive Treatment
Lens
Negative Treatment
Lens
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EMMETROPIA
Is the condition when the
parallel rays focused
exactly on the macula of
the eye in relax condition
---> the visual acuity is
maximum
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MYOPIA
Refractive condition in which, with accommodation completely relaxed, parallel rays are brought to a focus in front of the macula.
Myopic eye :refractive state overplus power
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ETIOLOGY
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Axial : The antero-posterior axis of the eye ball > normal
in this case, the refraction power of the cornea, lens and the lens position
are normal. The eye usually looks like proptosis
Curvature :
The size of the eye ball ---> normal, but there is a increasing of the
cornea/lens curvature
The change of the lens e.g. : intumescens cataract
Increasing of the refraction index
could occur on Diabetic patient
Changes of the lens location
changes of the lens position to the anterior after glaucoma surgery
lens subluxation
SIGNS & SYMPTOMS
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Clinical findings :
Farsightedness are blurred, nearsightedness are normal
Asthenopia
On high myopia : hemeralopia occurred caused by periphery
retinal degeneration
Floating spots visualization caused by vitreous degeneration
screw up the eye lids together, in order to get a better vision
On high myopia -> proptosis simulation, deep Anterior Chamber
COMPLICATIONS
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Commonly occurred on high myopia
1. Degenarated and liquefied vitreous
2. Retinal detachment
3. Pigmentation changes + Macular bleeding
4. Strabismus
5. Amblyopia
CLASSIFICATION
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Myopia classification :
< 3.00 D = low myopia
3.00 - 6.00 D = moderate myopia
> 6.00 D = high myopia/gravis
MANAGEMENT
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Treatment :
Low and moderate myopia : full correction with weakestspherical lens that give the best visual acuity
Example : VOD = 5/60 S -2.50 D = 6/7
S -2.75 D = 6/6
S -3.00 D = 6/6
S -3.25 D = 6/7
The glasses are ???
Contact Lens
Laser ( LASIK , PRK )
Clear Lens Extraction
Phakic IOL
HYPERMETROPIA
Is a refraction anomaly that
without accommodation parallel
rays will be focused behind the
retina
Divergent rays from near
object, will be focused farther
behind the retina
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ETIOLOGY
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Axial ---> eye ball diameter < N
Deminished convexity of cornea/lens curvature
Decreasing Refractive index
Changed lens position
CLINICAL MANIFESTASION
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H. Manifest ---> is detected without paralazing
accommodation and is represented by the strongest
convex glass needed , the patient sees most distinctly.
It correspons to the amount of accommodation which he
relaxes when a convex lens is placed before the eye.
Devided into two types :
Facultative : Can be overcome by an effort of accommodation
Absolute : Can not be overcome
CLINICAL MANIFESTATION
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Total Hipermetrop : detected after the accommodation
has been paralyzed with cylcopegic agents
Latent Hypermetrop : is the diference of the total
hypermetrop with the manifest hypermetrop
Latent Hypermetropia
Manifest Hypermetropia
Hypermetropia
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CLINICAL MANIFESTATION
CLINICAL FINDING
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Nearsightness are blurred
High hypermetropia at old age : farsightedness also
blurred
Astenophia accommodative (eye strain)
Children : high hypermetropia usually occurring
convergent strabismus (convergent squint)
* Treatment : Glasses !!!!!
ASTIGMATISM
Refractive condition ofthe eye in which there isa difference in degree ofrefraction in differentmeridian, each willfocused parallel rays ata different point.
The shape of theimages : Line, oval, circle, never
a point
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ETIOLOGY
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Etiology of Astigmatism :
Corneal curvature disturbances ---> 90%
Lens curvature disturbances ---> 10%
0
CLINICAL FINDING
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Nearsightness or farsightedness are blurred
Astenophia (eye strain)
Headache
TYPE OF ASTIGMATISM
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Ast. M. Simplex C-2.00 X 90
Ast. H. Simplex C+2.00 X 45
Ast. M Compositium S-1.50 C-1.00 X 60
Ast. H Compositium S+3.00 C+2.00 X 30
Ast. Mixtus S+2.00 C-5.00 X 180
Ast. M. Simplex Ast. H. Simplex
Ast. M Compositium Ast. H Compositium
Ast. Mixtus
CLINICAL MANIFESTATIONS
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MANAGEMENT
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Glasses
Contact Lens
LASIK
Refractive Surgery ( Keratotomi Radial )
PRESBYOPIA
Physiological changes because accommodation
capability is lowering at old age
Accommodation
Age
16
10
6
2
10 20 40 50 60
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PRESBYOPIA CORRECTION
Presbiopia additions :
40 years old S + 1.00 D
45 years old S + 1.50 D
50 years old S + 2.00 D
55 years old S + 2.50 D
60 years old S + 3.00 D
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GLASSES PRESCRIPTION
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FAR CORRECTION PLUS ADDITION
EXAMPLE ; MALE , 50 YEARS
RE : S -1,50 D AND LE : S +1,00 D
ADDITION : S +2,00 D
R/ RE : S -1,50 AND LE : S +1,00 D
NEAR CORRECTION : RE : S +0,50 D
AND LE : S +3,00 d
REFERENCES
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American Academy of Ophthalmology, Clinical
Refraction , 2011-2012
Khurana AK, Comprehensive Ophthalmology, Fourth
Edition , New Delhi, New Age Internasional (p) Limited
Publisher, 2007.
Vaughan & Asbury's : General Ophthalmology
17th Edition , Mc Graw- Hill’s Companies , May 2007
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Segala puji bagi Allah, Tuhan semesta alam.