I dag dykker vi ned i øjets anatomi og hvordan synet egentlig virker. 1: Hvordan synet virker 2: Hvad er langsynet / kortsynet 3: Grå stær 4: Laser Eye Surgery 5: Nat linser 6: Elektrisk omformning af øjet 7: Guld i Øjet 8: Chip i øjet ---------- 1: Hvordan synet virker Hjerne / Synet forbindelse https://videnskab.dk/krop-sundhed/oejet-kigger-men-hjernen-ser/ 2: Hvad er langsynet / kortsynet Øjets form 3: Grå stær Hvad er det? 4: Laser Eye Surgery LASIK For those who want do do away with corrective lenses, the main option is LASIK (Laser-Assisted In Situ Keratomileusis) surgery, which uses a laser to reshape the cornea by removing microscopic amounts of tissue beneath a thin flap, allowing light to focus properly on the retina. While, for those suitable for treatment, LASIK has a high success rate – around 95% of patients go on to ditch their glasses only a few days after recovering from surgery – it’s expensive and invasive, and cutting into the cornea alters the structural integrity of the eye.“LASIK is just a fancy way of doing traditional surgery,” said lead researcher and presenter Michael Hill, a professor in chemistry at Occidental College. “It’s still carving tissue – it’s just carving with a laser.” 5: Nat linser https://www.city-optik-muenchen.de/en/orthokeratologie-muenchen-ortho-k-nachtlinsen/ Orthokeratology, or Ortho-K, offers a revolutionary way to correct vision without the need for glasses or daytime contacts. By wearing special contact lenses overnight, users can reshape the cornea and experience clear vision throughout the day. This method challenges the conventional approach to eyesight correction, offering a non-invasive alternative for those seeking freedom from corrective lenses. The cornea is the transparent part of the eye on which the contact lens is placed. It consists of five layers of different thicknesses. However, only the uppermost layer, the so-called epithelium, is important for us. Corneal epithelium Bowman membrane stroma Descement’s membrane endothelium The corneal epithelium is about 0.04mm to 0.06mm thick. It is the uppermost layer of the cornea and renews itself completely once in 7 days. Such an epithelium as it occurs on the eye, there is similarly also on the “normal” skin on the human body. Such an epithelium scales itself off and is thus a protection for the underlying tissue. The Ortho-K contact lens makes use of this process by pushing the top layer of the epithelium from the middle of the cornea (directly above the pupil) to the edge by adhesive forces (tensile forces). Since only the top layer of the epithelium is moved here, the natural protective mechanism of the eye is fully preserved. In addition, this effect of orthokeratology is reversible due to the rapid regeneration time of the epithelium. This means that if the contact lens is no longer worn, it will take another 7 days for the old shortsightedness to be restored. Orthokeratology is in no way harmful to the eye compared to laser eye surgery, which destroys tissue in much deeper layers (stroma) in order to achieve a lasting effect. Recent studies from the USA, on the other hand, have even pointed out that the eye dioptres in orthokeratological contact lenses remain very constant, i.e. do not change. For this reason, Ortho-K contact lenses are also used with children who are already very shortsighted at a young age. In general, there is no age limit for orthokeratology. 6: Elektrisk omformning af øjet https://bli.uci.edu/laser-free-vision-correction-uses-electrical-current-to-reshape-eye/ Electric Eye Treatment (EMR - electromechanical reshaping) Denne teknik er stadigvæk ikke godkendt til mennesker, men de er i gang med kliniske forsøg. Scientists have developed a novel, non-invasive technique that reshapes the cornea using only a mild electric current and a temporary pH shift. The cornea is the clear, dome-shaped surface at the front of the eye, acting as a transparent window that helps focus incoming light. It’s made of tightly packed collagen fibers and is designed to be strong and smooth. When light enters the eye, the cornea is the first lens it hits – and it’s here that most of light-bending (refraction) occurs in order to focus the light onto the retina at the rear of the eye. However, if the cornea has an irregular curve, it results in conditions such as nearsightedness (myopia) and farsightedness (hyperopia).What Hill and colleagues propose is instead working with the composition of the cornea to reshape the dome without removing any material from it. Made primarily of collagen, the cornea maintains its shape thanks to the arrangement of charged molecules and proteins. The researchers discovered that by applying a low-level electrical current through a specially designed platinum “contact lens” electrode, they could change the pH of the tissue, increasing the acidity of the corneal tissue, which would make it pliable just long enough to reshape – like fitting something into a mold. In this case, the mold is the platinum lens.Then, once the current stops and the pH returns to normal, the cornea hardens again and holds its mold-fitted shape. The whole process takes about a minute, requires no cutting or removal of tissue, and, so far, has shown no structural damage or cell death in the tested samples. 7: Guld i Øjet https://www.sciencealert.com/gold-injections-in-the-eye-may-be-the-future-of-vision-preservation The macula is responsible for the central, high-resolution, color vision that is possible in good light. This kind of vision is impaired if the macula is damaged, as in macular degeneration (AMD). AMD: Sygdommen ødelægger de celler i nethinden, der opfanger lys, og gør det svært at se skarpt. 20-30 procent af befolkningen over 70 år får denne sygdom. Biomedical engineer Jiarui Nie, from Brown University in Rhode Island: This is a new type of retinal prosthesis that has the potential to restore vision lost to retinal degeneration without requiring any kind of complicated surgery or genetic modification. We believe this technique could potentially transform treatment paradigms for retinal degenerative conditions. How: very fine gold nanoparticles, thousands of times thinner than a human hair, are laced with antibodies to target specific eye cells. They're then injected into the gel-filled vitreous chamber between the retina and the lens. Next, a small infrared laser device is used to excite these nanoparticles and activate specific cells in the same way photoreceptors do. If the treatment makes it to us humans as well, that laser could be embedded in a pair of glasses. So far it looks like the nanoparticles could help bypass damaged photoreceptors (in Mice). Dette er endnu ikke blevet testet på mennesker 8: En microchip i Øjet https://videnskab.dk/krop-sundhed/lille-traadloes-chip-i-oejet-kan-potentielt-genskabe-synet-hos-aeldre-med-oejensygdom/ En anden behandling af AMD. En trådløs chip kan måske give ældre mennesker med fremskreden øjensygdom noget af synet tilbage. Opfindelsen bygger på en ny teknologi kaldet PRIMA-systemet, der består af to dele: Første del er en fleksibel, trådløs chip på 2×2 millimeter, som erstatter de ødelagte sanseceller. Den anden del er et par specielle briller, der opfanger billeder og sender dem som usynligt infrarødt lys til chippen, der omdanner signalerne til elektriske impulser, som sendes videre til hjernen. Forskerne forventer ikke at kunne genskabe helt normalt syn med chippen alene, men de arbejder videre på at forbedre livskvaliteten for patienterne. »Jeg tror ikke, vi nogensinde vil kunne genskabe fuldt 20/20-syn (normal synsstyrke, red.) med implantatet alene [...], men et af de største ønsker, vi hører fra patienter, er at kunne genkende ansigter og følelser igen - og det arbejder vi hen mod,« siger han i pressemeddelesen. Indtil videre er chippen kun godkendt til forskningsbrug, men firmaet Science Corporation har ansøgt om godkendelse til klinisk brug i Europa. Der er allerede forsøg med mennesker. 38 deltagere over 60 år på 17 klinikker i fem europæiske lande. Efter et års brug af systemet havde 26 ud af 32 deltagere, der gennemførte hele forløbet, opnået tydelige forbedringer i synet.
