Bahasan Kelainan Refraksi Ncit

7/31/2019 Bahasan Kelainan Refraksi Ncit

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Bahasan kelainan refraksi


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Will introduce some terminology before we

continue the next slide

Emmetropia: The ratio of the axial length of

the eye to the refractive power of the cornea

and lens is balanced. Parallel light rays that

enter the eye therefore meet at a focal point

on the retina and not anterior or posterior toit, as is the case in ametropia


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Ametropia: The most common disorders are

nearsightedness, farsightedness, and

astigmatism.


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Cornea, COA, Pupil, Lens, length of the eye,Humor Vitreus, Retina

The maximum total refractive power of an

emmetropic eye is 63 diopters with an axiallength of the globe measuring 23.5mm. Thecornea accounts for 43 diopters and the lens for1020 diopters, depending on accommodation,

accommodate for a near or far sight


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Parallel light rays that enter the eye thereforemeet at a focal point on the retina.

Cahaya memasuki mata melalui kornea danmelalui serangkaian cairan-cairan transparan danstruktur, yang secara kolektif disebut mediadioptrik. Cairan-cairan dan struktur itumerupakan kornea, humor akueous, lensa, danhumor vitreous. Secara normal, cahaya dari

sebuah objek difokuskan secara tajam ke retinaoleh kornea dan lensa dengan cara membiaskancahaya tersebut.


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There is a mismatch between the axial length of

the eye and the refractive power of the lens and

cornea. The ametropia is either axial, which is

common, or refractive, which is less frequentlyencountered.

The most common disorders are nearsightedness,

farsightedness, and astigmatism. . It is called Ametrophia that can be myopia,

hypermetropia, presbiopia atau astigmatism.


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The visual acuity always less from 6/6

Axial miopya: so the distance of cornea to

retina is longer than average.

Curvature myopia: refractive element (humor

aquous, lens)


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Correction: so the patient has a maximal visus

without accommodate.

Fungsi lensa disini hanya mengubah arah

perjalanan cahaya agar berkas yang tanpa

kacamata akan jatuh didepan retina dapat

dibiaskan dan jatuh tepat diretina


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In farsighted patients, the virtual far point of

the eye lies posterior to the retina.

Axial hyperopia is usually congenital and is

characterized by a shallow anterior chamber

with a thick sclera and well developed ciliary

muscle->predisposed to acute angle closure

glaucoma


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Symptoms: accomodative astenopia

If the patient use syclopegic, use the strongest

plus lens (S + Bb) to have a maximal visual

acuity. degre of total hypermetropia


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Berdasarkan faktor penyebabnya, astigmatisme jugadibedakan menjadi 2 jenis, yaitu:

Astigmatisme kornea

Astigmatisme ini disebabkan oleh kelengkungan permukaan

kornea yang tidak spherical(seperti lengkung bola), jadibisa dikatakan peyang.

The curvature of cornea not spheric correction with hardsoft lens

Astigmatisme internal

Astigmatisme ini disebabkan oleh adanya ketidaksamaandaya bias pada semua meredian di internal bolamata, baikpada lensa mata maupun pada badan kaca (vitreus humor).

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Bahasan Kelainan Refraksi Ncit