Physiology of the eye

Imagine your eyes as a camera

Sagital View of the eye

1. Image Focusing  Refractive media Cornea Humor akuos Crystallin Lens Vitreous Body

Refractive media  CORNEA Media refrakta yang terpenting Barrier penting dari isi bola mata Kekuatan refraksi ± 43 Dioptri Indeks bias 1.376

Cornea Physiology sel epitel dpt hidup rata-rata 4-8 hr epitel dpt beregenerasi lengkap dlm 7 hr epitel dan LAM  permukaan optik halus Pompa endotel mempertahankan kondisi dehidrasi relatif

Physiology cont’d Innervated by N V.1 corneal sensitivity Tear film  maintain the smooth corneal surface, and protection effect

Refractive Media  Aquos Humor Produced by the ciliary body Refractive Media Nutrition and O2 supply for cornea, lens etc. Maintain the ocular pressure Refractive index 1.336

Refractive Media  The Lens biconvex, avascular, and transparent 66% water Other  Proteins Protein Can be degenerated  cataract Other function Accommodations UV absorption (protecting the retina)

Refractive Media  Vitreous Body

Struktur seperti gel 80% terdiri air Index bias 1.334. Beratnya sekitar 4g, volumenya 4 cc Ukuran sekitar 2/3 dari seluruh volume bola mata

Refractive Indices of Refractive Media   Refractive Indices of Refractive Media Element Surface Radius (mm) Thickness (mm) Refractive Index Position (mm) Air   1.000 Cornea Anterior 7.7 0.50 1.376 0.0 Posterior 6.8 Aqueous 3.10 1.336 Anterior lens cortex 10.0 0.546 1.386 3.60 7.911 Lens core 2.419 1.406 4.146 Posterior lens cortex -5.76 0.635 6.565 -6.0 7.20 Vitreous 16.80 Retina -12.0 24.0

The receiver RETINA

Transparant, Histology 10 layers Photoreseptor : rod & cones Supporting : Glial cells, amacrine, Muller cells

Comparison of Rods and Cones Used for night vision Used for day vision Very light sensitive; sensitive to scattered light (have more pigment than cones) At least 1/10th of the rods light sensitive;sensitive only to direct light Loss causes night blindness Loss causes legal blindness Low visual acuity High visual acuity; better spacial resolution Not present in fovea centralis Concentrated in fovea Slow response to light, stimuli added over time Fast response to light, can perceive more rapid change in stimuli Stacks of membrane-enclosed disks are unattached to cell membrane Disks are attached to outer membrane 20 times more rods than cones in the retina One type of photosensitive pigment (monochrome vision) Three types of photosensitive pigment in human (color vision) Confer achromatic vision Confer color vision

Fovea central for visual acuity Perifovea  peripheral vision

The Conversion Phototransduction Process of conversion from image in to neural impulse

The Pathway  Retina into visual cortex Start from the retinal photoreceptors , through the optic nerve, chiasma and optic tract into the LGN Ends in the visual cortex (LGN) Striate Cortex

The Pathway Optic Nerve (C.N.II) Merupakan Perpanjangan dari Otak Terdiri dari 4 bagian Intra ocular, intra orbita, intra canalicular, intra cranial

Cortex visual Visual Perception Area Visual Primer Area Visual Sekunder Jalur Ventral / What stream V1-V2-V4-Lobus temporal informasi warna,bentuk&tekstur –mengenali benda Jalur Dorsal / where stream V1-V2-V3-V5/MT-lobus parietal. Informasi pergerakan,orientasi ruang dan lokasi

Optic Nerve field of vision

Pembagian daerah visual field saat serabut saraf berjalan ke otak

Neural pathways direct reflex 7 Neural pathways direct reflex

Neural pathways consensual reflex 8 Note: Ada 2 tempat dimana information bersilangan - the optic chiasm the pretectal nucleus to the Edinger-Westphal nucleus .

RELATIVE AFFERENT PUPILLARY DEFECT (RAPD) Menggambarkan adanya kelainan patologis pada jalur afferent refleks pupil Membandingkan refleks pupil 2 mata dengan melihat r.c.langsung dan tidak langsung kelainan harus unilateral Sederhana, mudah dan obyektif Dapat dievaluasi meskipun pasien dalam kondisi tidak sadar

BAGAIMANA RAPD TERJADI ? Penyinaran pada mata yang sakit penerimaan cahaya kurang pada mata sakit dan juga ke mata sehat otak akan menginterpretasikan adanya penurunan penerimaan cahaya otak merespon dengan pupil berdilatasi supaya cahaya lebih banyak masuk ke 2 mata, walau hanya 1 mata yang sakit.

KONDISI DGN PENURUNAN PENGLIHATAN ADA TIDAKNYA RAPD.....: Neuritis optik Walau neuritis optik yang sedang dan kehilangan penglihatan yang ringan, memberi RAPD berat. Ischemic Optic Neuropathies Ada Glaucoma Akan muncul jika satu mata lebih berat dari yang lain Traumatic optic neuropathy Optic Nerve Tumor Optic Nerve Inflamation (sarcoidosis) Ischemic Retinal Disease (CRVO,CRAO, etc) Ischemic Ocular Disease Chiasmal Disease Jarang Optic Tractus Disease Ada dan biasanya kontralateral dengan tempat lesi krn jumlah serabut yang bersilangan lebih banyak. Retinal Detachment Akan timbul jika makula ablasi atau dua kuadran retina ablasi Severe Macular Degeneration Timbul jika keadaan berat atau unilateral Retinal or Choroidal Tumor Timbul jika keadaan berat Amblyopia Refractif Error Tidak ada walau keadaan berat Cerebral disease Tidak ada Media Opacity

The Supporting structure of the Eye Palpebra Conjunctiva cover most exposed part of the eye Sclera  the sceleton of the eye Uveal Tract  Iris, Ciliary Body and Choroid Nutrition, circulation, immune system Lacrimal Gland  tear film production Extra ocular muscles  Ocular movement

The Extraocular Muscles 7 extraoculer muscles 6  Ocular Movement

Eye Movements I. Monocular eye movements (ductions) Sherrington’s law 1. Adduction is movement of the eye nasally. 2. Abduction is movement of the eye temporally 3. Elevation (supraduction) is an upward rotation of the eye. 4. Depression (infraduction) is a downward rotation of the eye. 5. Intorsion (incicloduction)is a nasal rotation of the superior portion of the vertical corneal meridian. 6. Extorsion (excycloduction) is a temporal rotation of the superior portion of the vertical cornea meridian Sherrington’s law Pada gerakkan monookular impuls syaraf akan dialirkan secara aktif untuk otot-otot sinergis sedangkan untuk otot-otot antagonis impuls syaraf akan dihambat. II. Binocular eye movements (versions) Innervasi yang seimbang dan simultan mengalir ke otot-otot yang berpasangan Hering’s law

Parese n.III

right cranial nerve VI palsy

Penutup Mata merupakan satu kesatuan sistem optik Jalur penglihatan meliputi pembiasan cahaya, reseptor, neurotransmisi dan persepsi Keseluruhan struktur bola mata berfungsi untuk menunjang fungsi visual

Terima kasih

JALUR NEAR REFLEKS : AKOMODASI KONVERGENSI