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Effects of radiation and glare in eye
Radiation and glare can affect the eye in various ways. Ionizing radiation like x-rays and gamma rays can directly damage eye tissues on a cellular level by ionizing atoms. This can lead to conditions like keratitis, cataracts, and retinal damage. Ultraviolet radiation is associated with pterygium, pinguecula, cataracts, and age-related macular degeneration due to its photochemical effects. Infrared radiation poses a thermal damage risk and can cause retinal burns. Visible light also carries photochemical risks like solar retinopathy from short exposures to intense brightness. Glare reduces image contrast and quality, causing disability or discomfort, and is tested for using devices like the BAT tester in
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Overview of radiation, its types, and effects on the eye, including the molecular damage mechanisms.
Characteristics of ionizing radiation and its damaging effects including conditions like cataract and retinal degeneration.
Understanding non-ionizing radiation's effects, including photochemical and thermal impacts on ocular tissues.
Concentration of radiant energy absorbed by different ocular tissues and their responses.
Effects of UVR on the eye, leading to conditions like pterygium, pinguecula, and photophthalmia.
Lens opacity formation due to UV exposure leading to cataracts and retinal damage implications.
Various tumors of the eyelids and conjunctiva induced by UV radiation, with emphasis on skin cancers.
Impact of visible radiation on visual performance and long-term effects such as solar retinopathy.
Damage caused by infrared radiation, affecting ocular structures and potential risks.
Definition and classification of glare, including its effects on vision and conditions requiring glare testing.
Factors indicating the need for glare testing and resources used for assessing glare-related impacts.
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Effects of radiation and glare in eye
- 1. Effects of radiation andglare in eye Hira Nath Dahal Optometrist Drishti Eye Care System
- 2. Radiation • Physical termdefining the transfer of energy through space from and emitter or radiator to a receiver • Light emission and absorption • Net transfer of energy
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- 4. 10/06/17 4 Electromagnetic Spectrum FGFigure 7-2 ULTRA- VIOLET RADIATION
- 5. 10/06/17 5 Electromagnetic Spectrum FGFigure 7-2 ULTRA- VIOLET RADIATION INFRARED RADIATION
- 6. Radiation effects • Mechanismof radiation hazards • Molecular level • Photo-absorption increased energy level unstable state electron ejection combine with oxygen superoxide molecule formation (free radical)disrupt cell membrane, mitochondrial membrane and nucleic acid tissue destruction • Tissue level
- 7. Classification of radiationeffects • Draper’s law • For an effect the radiation must be absorbed by the substance • Vision?? • Effects of radiation • Ionizing radiation • Non-ionizing radiation
- 8. Ionizing radiation • Interactswith matter to form ions • High-energy electromagnetic radiation and particle radiation are capable of producing ions in their passage through matter. • Types • Alpha and beta particles, • X-rays, gamma rays • Ionizing radiation thorough living tissue wreaks havoc on the atoms and molecules in its path chain of events destruction of living cells with functional abnormality
- 9. Ionizing radiation: Effects •Damage depends on • Exposure time • Concentration • Type • Direct effect • Cellular anomalies or death • Indirect effect • Damage to blood vessels • Low levels of radiation • Engorged conjunctival vessels • Loss of corneal lusture • High levels of radiation • Exfoliation of epithelial cells • Keratitis • Corneal ulcer • Cataract • Retinal degeneration
- 10. Non-ionizing radiation • Electromagneticradiation that is not of sufficient energy to ionize matter, though it is capable of damaging the human body. • Cause photochemical and thermal effects • By exciting electrons in atoms to higher energy levels, and by producing molecular excitation. • Examples • Lasers, radio-frequency and microwave radiation, IR radiation, and UV radiation
- 11. Non-ionizing radiation: Effects •Thermaleffects • Heating effect • Solar retinopathy •Photochemical effects • Visual sensation • Photokeratitis
- 12. Concentration of radiantenergy by eye
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- 14. Absorption of theradiation by the ocular tissue Tissue Ultraviolet (nm) Visible (nm) Infrared (nm) Tear layer 290-380 380-760 760-3000 Cornea 290-380℗ 380-760 760-3000℗ Aqueous 290-380℗ 380-760 760-3000℗ Lens in child 310-380℗ 380-760 760-2500℗ Lens in adult 375-380℗ 380-760℗ 760-2500℗ Vitreous 290-380℗ 380-760 760-1600℗
- 15. Absorption of radiationby various ocularAbsorption of radiation by various ocular tissuestissues
- 16. Effect of ultravioletradiation (UVR) •Pinguecula • Small yellowish elevated concretion of bulbar conjunctiva • Fibro-fatty degenerative change within the palpebral fissure • Typically located nasally • Due to light reflecting off the nose onto the nasal conjunctiva • a/w long continued exposure to the solar radiation
- 17. Pterygium A fibrovasculargrowth which appears on the cornea and looks as if it is continuous with the conjunctiva ◦ ?Degeneration or proliferation ◦ Rich in blood vessel growth which appears to pull the lesion toward he cornea. ◦ An orange-brown ferric deposition line (Stocker’s line) may be seen at the leading edge of the pterygium on the cornea More on nasal side
- 18. Pterygium Greater frequencyin tropical areas near the equator rather than in milder climates ◦ UVR as an risk factor Pathophysiology ◦ Elastoid degeneration of deep conjunctival tissue ◦ fibrovascular proliferation ◦ over growth of conjunctivally derived epithelium onto the limbus and cornea
- 19. Band shaped keratopathy White or cream colored opacities b/w the epithelium and Bowmann’s layer ◦ Distributed symmetrically in the inter- palpebral portions of two cornea Spheroid degeneration or climatic droplet keratopathy Limited geographic prevalence
- 20. Photophthalmia ◦ Absorption ofUV<300 nm ◦ Photochemical damage to corneal epithelium ◦ Photokeratoconjuctivitis ◦ Latent periods of 30 minutes to 24 hrs ◦ Cumulative effects ◦ Intermittent exposure prevents healing
- 21. Photophthalmia Clinical features ◦Foreign body sensation ◦ Photophobia ◦ Lacrimation and blepharospasm ◦ Redness ◦ Edema ◦ Similar features as in snow blindness and welder’s keratitis • Self limiting • Symptomatic treatment • antibiotic coverage • NSAIDS
- 22. Uveitis • UV wavelengthsbetween 295nm and 310nm cause anterior uveitis. • Usually this is only a temporary problem.
- 23. Cataract Any formof lens opacity ◦ Adversely affecting vision or visual function Continuous exposure Cumulative effect ◦ Formation of lens pigments causing yellow coloration of the lens nucleus ◦ Pigments mainly produced by the nucleus ◦ UV-B (290-320) ◦ Brown cataract Nuclear, PSCC and cortical cataract
- 24. Retinal damage Usuallyprotected ◦ ? aphakia UVR absorption by RPE and choroid potential photochemical and thermal effect Cystoid macular edema Decline in short wavelength sensitive cones in rapid manner Retinal degenerative changes ◦ ARMD
- 25. Age related maculardegeneration • Prolonged sun exposure: risk factor
- 26. Tumors of eyelidsand conjunctiva • Basal cell carcinoma • Mainly lower lids on medial sides • More incidence in the countries with high sunlight exposure (Australia) • Squamous cell carcinoma • Invasive epithelial malignancy showing keratinocytic differntiation • Lower lid
- 27. Tumors of eyelidsand conjunctiva • Sebaceous carcinoma • Malignant melanoma • Squamous cell carcinoma of the conjunctiva
- 28. Effects of visibleradiation Transparent media ◦ Transmisssion of the visible spectrum Photoreceptors ◦ Absorption visual sensation Higher level of visible light ◦ Harmful photochemical and thermal injury to the retina ◦ Converged radiation to the retina ◦ Even at normal level, prolonged exposure undesirable visual effects such as increased dark adaptation time
- 29. Effects of visibleradiation • Short wavelength • Higher energy more photochemical damage • Long wavelength • Less energy both photochemical and thermal damage • Infra-red radiation thermal damage
- 30. Effects of visibleradiation • Age related macular degeneration • Long term exposure to the visible radiation and UVR • RPE and photoreceptor damage •Solar retinopathy •Eclipse burn •Presentation • Reduced vision • Small dense central scotoma • Chromatopsia and metamorphopsia
- 31. Effects of visibleradiation •Solar retinopathy • Cause • ?IR thermal burn • Photochemical trauma (blue light hazard)- short term exposure to the high energy short wavelength visible spectrum (400-500nm) • Thermal injury - Long term exposure to the long wavelength visible radiation and IR radiation
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- 33. Effects of IRradiation Damage by 780-2000 nm >1400 nm absorbed by tear film and cornea Sources ◦ Solar radiation ◦ Carbon, tungsten and xenon lamps ◦ Photoflood lamps ◦ Some laser sources Immediate effects after IR exposure Population at risk ◦ Glass blowers ◦ Blast furnace operators
- 34. Effects of IRradiation Cornea ◦ Coagulation and opacification Iris ◦ Congestion ◦ Depigmentation ◦ Atrophy Lens ◦ Exfoliation of lens capsule ◦ Coagulation of lens protein ◦ Cataract production : ASCC, PSCC Retina ◦ Necrotic burns
- 35. Other forms ofradiation • Long wave microwaves • Diathermy • Ionizing radiation • X-ray and gamma rays
- 36. Glare Refers tothe presence of one or more areas in the field of vision that are of sufficient brightness to cause discomfort in vision. Visual perception created by external light Glare source : Axial / Peripheral Reduces the quality of the image ◦ an unpleasant sensation ◦ a temporary blurring of vision ◦ a feeling of ocular fatigue
- 37. Classification • Veiling ordisability glare • Discomfort glare • Specular reflection glare
- 38. Veiling or disabilitygalre Arises from stray light falling on the retina, usually from scatter by the media of the eye. Scattered light falls as a patch of veiling illuminance on the fovea ◦ Reduces the contrast of the retinal image. ◦ Reduces visibility and visual performance. E.g. sky, sand, brightly illuminated walls etc.- ◦ the reflected images are large in angular subtense leading to reduction in contrast observed in the visual field.
- 39. Glare in Cataract NormalCataract
- 40. Discomfort glare • Occurswhen the illumination in a part of the visual field is much greater than the level of illumination for which the retina is adapted. • Highest level of illumination in the visual field and background illumination exceeds a ratio of 3 :1 • During night driving-causes extreme discomfort. • Importance of having background illumination while watching television
- 41. Specular reflection glare Occurs when patches of bright light are reflected form smooth, shiny surface into the eye. ◦ Typical reflecting surfaces include expanses of water, snowfields, roadways etc. Reflections are not only annoying but interfere with visibility, at times seriously. Can be well controlled by using polaroid glasses.
- 42. Glare testing •Objective : •quantify the deleterious effects of light scatter on visual performance • Reduce the effect on impairment of vision •When? • Corneal opacities • Corneal dystrophies/ Degeneration • Cataract
- 43. Indications for glaretesting Pre-operative ◦ Cornea Infectious scarring Traumatic scarring Degenerative scarring Dystrophic scarring ◦ Lens Age-related cataract Traumatic cataract Drug-induced cataract Disease-induced cataract Post-operative ◦ Cornea PK Epikeratophakia Keratomileusis Repaired laceration ◦ Lens PCO following ECCE, IOL
- 44. Glare Testers • BrightnessAcuity Tester (BAT) • Optec 1500 Glare Tester • Terry Vision Analyzer (TVA) • Miller-Nadler Glare Tester
- 45.