The Human Eye

The Human Eye

Uitwendige Struktuur (External Structure)

• Oogbal geleë in benige oogholte (Eyeball located in bony eye socket): The eyeball is situated within the bony eye socket for protection.

• Bindweefsel en vet omring oogbal vir beskerming (Connective tissue and fat surround the eyeball for protection): This provides cushioning and further protection.

• Ooglede met wimpers keer dat vreemde deeltjies binnedring (Eyelids with eyelashes prevent foreign particles from entering): This acts as a barrier against debris.

• Pupil: Ronde opening van oog; laat lig deur (Round opening of the eye; allows light to pass through).

• Iris: Gekleurde deel; beheer pupil, reguleer hoeveelheid lig wat binnekom deur om die grootte van die pupil te verander (Colored part; controls the pupil, regulates the amount of light entering by changing the size of the pupil).

• Sklera: Buitenste sterk onelastiese laag wat bestaan uit bindweefsel; dien as punte van vashegting en ondersteun oog en is verantwoordelik vir vorm van oog (Outer strong inelastic layer consisting of connective tissue; serves as points of attachment and supports the eye and is responsible for the shape of the eye).

Inwendige Struktuur (Internal Structure)

• Kornea (Cornea): deursigtige voortsetting van sklera aan voorkant van oog; dit is konveks (bult uitwaarts) (Transparent continuation of the sclera at the front of the eye; it is convex (bulges outward)). Aanpassing: deursigtigheid laat lig toe om oog binne te dring; die konvekse vorm veroorsaak ligbreking van inkomende ligstrale (Adaptation: transparency allows light to enter the eye; the convex shape causes refraction of incoming light rays). Funksie: laat lig deur na die oog; veroorsaak breking (buiging) van inkomende lig om beeld op retina te vorm (Function: allows light through to the eye; causes refraction (bending) of incoming light to form an image on the retina).

• Watervog (Aqueous humor): waterige vloeistof wat in ruimte tussen kornea en lens aangetref word (Watery fluid found in the space between the cornea and lens). Funksie: behou vorm van kornea; speel klein rol in die breking van inkomende lig (Function: maintains the shape of the cornea; plays a small role in the refraction of incoming light).

• Lens (Lens): elastiese, bikonvekse struktuur agter pupil van iris; word deur suspensoriese ligamente in posisie gehou (Elastic, biconvex structure behind the pupil of the iris; held in position by suspensory ligaments). Deurskynend (Transparent). Funksie: verander van vorm om oog toe te laat om op naby- en verafgeleë voorwerpe te fokus; laat lig deur (Function: changes shape to allow the eye to focus on near and far objects; allows light through).

• Glasvog (Vitreous humor): jellieagtige stof wat agter lens aangetref word (Jelly-like substance found behind the lens). Funksie: behou vorm van oogbal; speel klein rol in die breking van inkomende lig (Function: maintains the shape of the eyeball; plays a small role in the refraction of incoming light).

• Sklera (Sclera): taai, wit, onelastiese laag wat oog aan agterkant bedek (Tough, white, inelastic layer covering the eye at the back). Aanpassing: beskerming van oog omdat dit onelasties is (Adaptation: protection of the eye because it is inelastic). Funksie: beskerm strukture binne oog; laat die oog sy vorm behou (Function: protects structures inside the eye; allows the eye to maintain its shape).

• Choroïed (Choroid): donkerkleurige laag wat bloedvate en pigmente bevat (Dark-colored layer containing blood vessels and pigments). Funksie: pigmente absorbeer lig om weerkaatsing van lig te verhoed; bloedvate voorsien voedingstowwe en suurstof aan retinaselle (Function: pigments absorb light to prevent reflection of light; blood vessels provide nutrients and oxygen to retinal cells).

• Retina (Retina): binneste laag van oog wat stafies en keëltjies, wat ligsensitief is, bevat (Innermost layer of the eye containing rods and cones, which are light-sensitive). Funksie: stafies reageer wanneer ligintensiteit laag is, is verantwoordelik vir nagvisie sowel as periferale visie; keëltjies reageer op helder lig en verskaf skerp, duidelike kleurvisie; neurone gelei impulse van stafies en keëltjies deur optiese senuwee na serebrum (Function: rods respond when light intensity is low, are responsible for night vision as well as peripheral vision; cones respond to bright light and provide sharp, clear color vision; neurons conduct impulses from rods and cones through the optic nerve to the cerebrum).

• Geelvlek (Yellow spot/Macula): klein induiking aan agterkant van oogbal, bevat meeste keëltjies (Small indentation at the back of the eyeball, contains most cones). Funksie: area met duidelikste (skerpste) visie (Function: area with the clearest (sharpest) vision).

• Blinde vlek (Blind spot): klein area op retina, onder geelvlek; geen stafies of keëltjies, dus geen visie (Small area on the retina, below the yellow spot; no rods or cones, therefore no vision). Area waar bloedvate oog binnedring (Area where blood vessels enter the eye). Area waar optiese senuwee oog verlaat (Area where the optic nerve leaves the eye). Funksie: area van geen visie; binneste dele van oog word van suurstof en voedingstowwe voorsien; impulse word na serebrum geneem vir interpretasie (Function: area of no vision; inner parts of the eye are supplied with oxygen and nutrients; impulses are taken to the cerebrum for interpretation).

• Optiese senuwee (Optic nerve): Dra elektriese impulse vanaf retina na brein (Transports electrical impulses from the retina to the brain). Veroorsaak blindevlek waar daar geen keёltjies en stafies op area is nie (Causes a blind spot where there are no cones and rods in the area). Brein neem omgekeerde beeld en draai dit om sodat ons dit kan sien (The brain takes the inverted image and flips it so we can see it).

• Siliaarliggaam (Ciliary body): bevat siliaarspier en is verdikte voorste gedeelte van choroïed (Contains the ciliary muscle and is the thickened anterior portion of the choroid). Funksie: siliaarspier trek saam of ontspan om trekkrag op suspensoriese ligamente te verander (Function: The ciliary muscle contracts or relaxes to change the pulling force on the suspensory ligaments).

• Suspensoriese ligamente (Suspensory ligaments): ligamente wat aan siliaarliggaam verbind is (Ligaments that are connected to the ciliary body). Funksie: suspensoriese ligamente hou lens in posisie tydens akkommodasie; trekkrag (spanning) op suspensoriese ligamente verander om die vorm van die lens te verander (Function: suspensory ligaments hold the lens in position during accommodation; pulling force (tension) on suspensory ligaments changes to change the shape of the lens).

• Iris: gekleurde deel, met opening in middel, word pupil genoem; iris bevat twee soorte spiere om grootte van pupil te beheer (Colored part, with an opening in the middle called the pupil; the iris contains two types of muscles to control the size of the pupil). Funksie: beheer hoeveelheid lig wat oog binnedring deur middel van pupilmeganisme (Function: controls the amount of light that enters the eye through the pupil mechanism).

• Pupil: Opening in iris (Opening in the iris). Funksie: Laat lig oog binnegaan (Function: Allows light to enter the eye).

Binokulêre Visie (Binocular Vision)

• Wat dit is (What it is): Verwys na vermoë om te fokus op voorwerp met beide oë, wat enkele beeld vorm (Refers to the ability to focus on an object with both eyes, which forms a single image). Gedurende binokulêre visie stel drie pare spiere aan buitekant van elke oog, oog instaat om drie dimensioneel te sien (During binocular vision, three pairs of muscles on the outside of each eye enable the eye to see three-dimensionally). Vermoë om diepte te sien is bekend as stereoskopie of stereoskopiese visie (The ability to see depth is known as stereoscopy or stereoscopic vision).

• Belangrikheid (Importance):

  • Diepte persepsie stel ons instaat om op en af op trappe te loop (Depth perception enables us to walk up and down stairs).

  • Dit gee wyer veld van visie (It gives a wider field of vision).

  • Gee presiese diepte persepsie (Gives precise depth perception).

  • Binokulêre visie help met vaardighede soos vang, gryp en beweging (Binocular vision helps with skills such as catching, grabbing, and movement).

Akkommodasie (Accommodation)

• Vermoë van oog om vorm van lens te verander om te verseker dat duidelike beeld altyd op retina val, ongeag of voorwerp naby of ver is (Ability of the eye to change the shape of the lens to ensure that a clear image always falls on the retina, regardless of whether the object is near or far).

• Naby visie (Near vision) (minder as 6 m van die voorwerp) (less than 6 m from the object):

  • siliaarspier trek saam (ciliary muscle contracts)

  • suspensoriese ligamente ontspan (suspensory ligaments relax)

  • spanning op die lens verminder (tension on the lens decreases)

  • lens word meer konveks (bult uit) (lens becomes more convex (bulges out))

  • dit veroorsaak dat ligstrale meer gebuig word (this causes light rays to be bent more)

  • ‘n duidelike beeld word op die retina gefokus (a clear image is focused on the retina)

• Ver visie (Far vision) (meer as 6 m van die voorwerp) (more than 6 m from the object):

  • siliaarspier ontspan (ciliary muscle relaxes)

  • suspensoriese ligamente trek styf (suspensory ligaments tighten)

  • spanning op die lens verhoog (tension on the lens increases)

  • lens word minder konveks (platter) (lens becomes less convex (flatter))

  • dit veroorsaak dat ligstrale minder gebuig word (this causes light rays to be bent less)

  • ‘n duidelike beeld word op die retina gefokus (a clear image is focused on the retina)

Pupilmeganisme (Pupillary Mechanism)

• Verwys na proses waardeur deursnit van pupil verander word om hoeveelheid lig wat oog binnedring te beheer (Refers to the process by which the diameter of the pupil is changed to control the amount of light entering the eye).

• Ligintensiteit is stimulus wat grootte van pupil verander (Light intensity is the stimulus that changes the size of the pupil).

• Iris beheer hoeveelheid lig wat pupil binnedring (The iris controls the amount of light that enters the pupil).

• Dit het kring- en radiale spiere wat antagonisties werk om grootte van pupil te verander (It has circular and radial muscles that work antagonistically to change the size of the pupil).

• In dowwe lig (In dim light):

  • Die radiale spiere van die iris trek saam (The radial muscles of the iris contract).

  • Die kringspiere ontspan (The circular muscles relax).

  • Die pupil verwyd / word groter (The pupil dilates / becomes larger).

  • Die hoeveelheid lig wat die oog binnedring word verhoog (The amount of light entering the eye is increased).

• In helder lig (In bright light):

  • Die kringspiere van die iris saamtrek (The circular muscles of the iris contract).

  • Die radiale spiere ontspan (The radial muscles relax).

  • Die pupil vernou/word kleiner (The pupil constricts/becomes smaller).

  • Die hoeveelheid lig wat die oog binnekom word minder (The amount of light entering the eye is reduced).

Defekte (Defects)

• BYSIENDHEID (Myopia/Nearsightedness):

  • Bysiendheid word veroorsaak deur ‘n oogbal wat te lank is of (Nearsightedness is caused by an eyeball that is too long or)

  • Die lens kan nie platter word of minder konveks word nie (The lens cannot become flatter or less convex)

  • Sukkel om voorwerpe ver weg te sien (Difficulty seeing objects far away)

  • Afstand tussen lens en retina is te groot (Distance between lens and retina is too large)

  • Lig word voor die retina gefokus (Light is focused in front of the retina)

  • Word met divergerende lense gekorrigeer (Is corrected with diverging lenses)

• VERSIENDHEID (Hyperopia/Farsightedness):

  • Versiendheid kan veroorsaak word deur die oogbal wat te rond is (Farsightedness can be caused by the eyeball being too round)

  • Die lens kan nie meer konveks word nie of is te plat. Dit is meer algemeen onder ouer mense (The lens can no longer become convex or is too flat. It is more common among older people)

  • Sukkel om naby voorwerpe te sien (Difficulty seeing objects up close)

  • Afstand tussen lens en retina is te klein (Distance between lens and retina is too small)

  • Lig fokus agter die retina (Light focuses behind the retina)

  • Word gekorrigeer deur konvergerende lense (Is corrected by converging lenses)

• ASTIGMATISME (Astigmatism):

  • Oog kan nie ‘n voorwerp se beeld op ‘n enkele punt op die retina fokus nie(The eye cannot focus an object's image on a single point on the retina)

  • Gewoonlik is die kornea glad en rond in al die rigtings (Normally the cornea is smooth and round in all directions)

  • Dit beteken dat lig die kornea binnedring en fokus in al die rigtings (This means that light enters the cornea and focuses in all directions)

  • Somtyds is die voorkant van die kornea oneweredig, en een deel is meer gerond as die ander (Sometimes the front of the cornea is uneven, and one part is more rounded than the other)

  • Dit gee die kornea ‘n vorm van ‘n voetbal (This gives the cornea the shape of a football)

  • Veroorsaak dowwe vissie (Causes blurry vision)

  • Sommige tipes kan gekorrigeer word met lense (Some types can be corrected with lenses)

• KATARAKTE (Cataracts):

  • Lens wat dof word agv die denaturering van die lens proteїene (Lens that becomes cloudy due to the denaturation of the lens proteins)

  • Dit is in die pad van lig en voorkom dat lig deurkom (It is in the path of light and prevents light from passing through)

  • Word deur ouderdom, chroniese blootstelling aan UV, of deur trauma veroorsaak (Caused by age, chronic exposure to UV, or trauma)

  • Verwyder deur chirurgie (Removed by surgery)