4Electric shock0a. Very rare cause of cataract, 5% to 20% major electrical injury patients.b. Most often follows shock to head.c. Usually more than 1,000-V current.d. Initial anterior cortical vacuoles, replaced by white opacities.e. PSCcataract less common.f. Cataract may present many months after injury.g. Cataract matures within few years after injury.
5What are ultraviolet rays? Ultraviolet (UV) rays are part of electro-magnetic radiation. They are invisible rays lying beyond the violet end of the visible spectrum.Low intensity ofUV rays are also emitted from fluorescent lamps, TV and computer monitors.
6Are there different types of UV rays? As different intensity (wavelength) ofUV has different effect on us, they are commonly categorized as UV-A, UV-B and UV-c.UV-C (wavelengths from 200nm - 290nm) is present above the earth'satmosphere and also given out from welding arcs. It also arises from sunlight's reflection from snow at high altitude.UV-B (wavelengths from 290nm - 320nm) and UV-A (wavelengths from 320nm - 390nm) are present in our living environment, from direct sunlight or reflection from snow, water, sands, glass windows, walls etc
7Ultraviolet Radiation Inju I. Clinical featuresA. Synonyms.1. Snowblindness.2. Welder's arc burn.3. Keratitis photoelectrica.4. Ultraviolet (UV) keratopathy)B. Ocular features.1. Onset of symptoms usually 8 to 24 hours after exposure and characterized by pain, photophobia, and foreign body sensation.
82. Signs may include eyelid erythema; tearing,conjunctivalinjection, corneal epithelialirregularities, edema, andpunctate epithelial erosions.
9C. Course/prognosis.1. Signs and symptoms should resolve over to hours.2. Prognosis for visual recovery is excellent.3. Chronic UV exposure can lead to pterygia, pingueculae, an cataracts.D. Complications/sequelae.1. Any breakdown of corneal epithelium causes eye to be more susceptible to infection, ulceration, and scarring.2. Also, association exists with conjunctival squamous cell carcinoma.
10A. Pathogenesis1. Clinical findings result from excessive exposure to radiation with wavelength of approximately 290 nm.2. Exposure to UV radiation results in characteristic changes in cells produced by changes in proteins, including inhibition of mitosis and loss of cellular adhesion.3. Clinical and pathologic changes evident after 6 to 8 hours of , exposure.
11B. Risk factors1. Physical factors.a. Snow can reflect UV light, welder's lamps, and othersources such as sunlamps, malfunctioning mercury vapor lamps2. Iatrogenic factorsphototherapy for psoriasis or other medical conditions can cause keratopathy.3. Use of tanning bed without protective goggles increases risk.C. Epidemiology.1. Fairly common, especially among welders.
13DiagnosisA. Slitlamp examination with instillationof fluorescein reveals typical punctate epithelial changes.B. Palthologic findings.1. uv waves generally absorbed by conjunctiva and cornea, 'leading to conjunctivitis and keratitis.C. Differential diagnosis1. Other causes of punctate staining include dry eye(keratoconjunctivitis sicca), floppy eyelid syndrome
14Management/treatment A. Oral alnalgesics and pressure patching with antibiotic ointment .Bandage contact lenses also aid with healingB. Consider treating as corneal abrasion if significant number of punctate epithelial erosiqns present.C. Preventionl avoidance .1. Use UV-absorbing glasses or goggles and proper eyewear when welding to prevent this condition,
15D. Monitoring1. Follow up patients every few days until corneal epithelial defect resolved.E. Patient education1. Signs and symptoms generallyresolve in 24 to 48 hours.2. Remind patient to use UV-protectiveeyewear.
16Radiation Retinopathy I. Clinical featuresA. Clinical description.1. Findings resemble diabetic retinopathy.B. Signs and symptoms.1. Reduced visual acuity secondary to macular edema andnon perfusion occurs 6 to 36 months after treatment.
172. Bilateral in one third of.external beam irradiation cases. 3. Early features.a. Microaneurysms.b. Telengiectasia.c. Cotton-wool spots.d. Intraretinal hemorrhages.e. Capillary non perfusion. -f. Retinal edema.g. Hard exudates.
18Microaneurysmal changes telangiectasias Edema ; andhemorrhages are temporal to the fovea in OS
194. Late features.a. Vascular sheathing.b. Hard exudates.c. Cystoid macular edema.d. Neovascularization.e. Rubeosis and neovascular glaucoma.f. Ischemic optic neuropathy.
21BasicsA. Pathogenesis.1. On retinal vascular endothelial cellular level, mitosis arrested and nucleus may degenerate.2. Initial vascular changes include early swelling withdegeneration of intima and endothelial cells.3. Subsequent changes include vascular occlusion by thrombus formation and fibrosis.
22B. Risk factors1. Neoplasm involving eye, orbital, periorbital, nasopharyngeal, face, brain, or other adjacent tissue, with subsequent irradiation and inadequate shielding by technical staff.a. Fifty percent of patients treated for nonocular neoplasm.
232. Radiation retinopathy develops after total doses of 30 to 35 Gy within 3 to 36 months (mean time, 18 months).a. If more than 80 Gy administered, 85% of patients develop radiation retinopathy within few months.
243. Higher the fraction size, greater the risk of radiation retinopathy. a. Usual dose for external beam therapy 200 to 300 cGy/day, given over 1- to 2-month periodfor total dose of 35 to 72 Gy.b. Twice as many patients develop radiation retinopathy with 250-cGy fractions than with200-cGy fractions.
254. Local plaque therapy (brachytherapy) requires higher doses to produce damage than external beam therapy(teletherapy).5. Diabetes mellitus and administration ofchemotherapy, whether concomitant or not, additive to retinopathic effects of radiation.
26DiagnosisA. Clinical diagnosis.1. Consider when head or neck radiation given for any reason including metastatic CNS tumors, orbital treatment for thyroid disease, and orbital pseudotumor.
27B. Imaging1. Fluorescein angiographyshowscapillary nonperfusion.A.Early phase(1) Dilated and telangiectatic retinal vessels.(2) Blocked fluorescence secondary to retinal hemorrhages.
28(3) Hypofluorescence secondary to capillary nonperfusion.b.laet phase(1) Leakage from affected retinal vessels and from neovascularization if presentC. Pathologic findings.1. Preferential damage to inner retinal layers resulting in paucity of ganglion cells.Photo receptors relatively resistant.
29Fluorescein angiogram of the left eye demonstrates large areas of capillarynonperfusion. The foveal avascular zone isenlarged, and the microaneurysms showleakage.
302. Eosinophilic exudate in outer plexiform layers.3. Retinal capillary changesincluding fusiform dilations,microaneurysms, and focal lossof endothelial cells andpericytes.4. Capillary closure
315. Thickening of retinal blood vessel walls.6. New blood vessels on surface ofretina or optic disc.7. Intraretinal blood or blood invitreous cavity.8. Peripheral anterior synechiaeand fibrovascular membrane onsurface of iris in eyes withneovascular glaucoma.
32D. Differential diagnosis. 1. Diabetic retinopathy.2. Multiple branch retinal artery obstruction and embolic disease.3. Multiple episodes of venousocclusive disease.
35Managementltreatment A. Medical therapy.1. Apply guidelines of Early .Treatment Diabetic RetinopatpyStudy for macular edema and neovascularization.
362. Macular photocoagulation effective in decreasing macularedema; may improve vision.3. Consider pars plana vitrectomy for nonclearing vitreous hemorrhage.
37B. Prevention.1. Adequate shielding of eye during radiation treatment.2. If satisfactory shielding not achieved, patient will receive far larger dose than prescribed by radiation oncologist .3. Inadequate shielding considered responsible for cases of retinopathy after radiation thought of safe dose or in area thought to pose no threat to ocular tissue .
38C. Monitoring.1. Monitor frequently for development of retinal changes.
40Solar Retinopathy I. Clinical features A. Synonyms. 2. Eclipse burn.3. Eclipse blindness.4. Eclipse retinopathy.5. Solar retinitis.6. Solar chorioretinal burn.7. Photoretinitis.8. Foveomacular retinitis.
41B. Clinical description. 1. Signs and symptoms.a. Initial features.(1) Browache.(2) Positive central scotoma.(3) Afterimage.(4) Chromotopsia.(5) Metamorphopsia(6) Decreased visual acuity, usually to 20/200 level.(7) Small, yellow-grayish
42b. Chronic features(1) Yellow-grayish lesion fades over 2 weeks; replaced by "lamellar hole" or "cyst,“ which produces permanentred foveal appearance. Red reflex permanent and pathognomonic.(2) Foveolar depression.(3) Macular pigmentary disruption can occur with significant solar phototoxicity
43b. Chronic features Yellowish pigment epithelial lesions are seen in the fovea.The OS demonstrates a yellowish lesionat the level of the retinal pigment epitheliumcentered on the fovea.
44Two months later the yellowish lesion has been replaced by a small, focaldepression.Fluorescein angiogram demonstrates aCentra window defect in the macula.
45BasicsA. Pathogenesis.1. Blue light largely responsible for producing photochemical injury by initially damaging apical melanosomes in retinal pigment.2. Subsequent release of lysosomalenzymes may occur, with resultant cell damage and degeneration of photoreceptors and RPE.
46B. Risk factors.1. Sun gazing.a. Illicit drug use.b. Viewing solar eclipsec. Occupational (ie, astronomers,military personnel).
472. Without sun gazing.a. Increased ocular pigmentation.b. Increased body temperature,warm climate, exercise, or infection.c. Clear ocular mediad. Environmental conditions suchas highly reflective surroundings and reduced atmospheric ozone.
48Diagnosis A. Imaging. 1. Fluorescein angiography. a. In early stages, leakage of dye occurs through RPE;clinically may appear as yelloWish abnormality seen in fovea·b. In severe cases, window defectmay be present.
49The right macula reveals an abnormal foveal reflex with a smallreddish facet-like eccentric defectwithin the fovea.Fluorescein angiogram demonstratesa verysubtle window defect centeredon the fovea.
50B. Pathologic findings.1. Focal loss of rod and cone nuclei.2. Disruption of receptor elements in foveola.3. In severe cases. RPEdepigmented but intact.4. Choriocapillaris intact.
51C. Differential diagnosis. 1. Early stage-yellow lesion.a. Central serous chorioretinopathy.b. Choroidal neovascular membrane.c. Impending macular hole.d. Chorioretinal inflammatory disorders.
522. Late stage-red spot.a. Storage diseases.b. Macular hemorrhage.c. Macular hole.d. Central retinal artery occlusion.e. Berlin edema.f. Acute macular neuroretinopathy.g. Sickle cell retinopathy.
53D. Clinical course/prognosis. 1. Vision usually returns to 20/40or better within 4 to 6 months.2. Fifty percent of patients regain20/20 visual acuity.3. Permanent foveal or juxtafoveallesion well defined andproduces paracentral scotoma.4. Metamorphopsia may persist.
55Management/treatment A. Medical therapy-' -none.B. Prevention.1. Avoid sun gazing andobservation of solar eclipse.
56Operating Microscope light-induced Retinopathy Clinical features1. Signs and symptoms.a. Initial features.(1) On first or second postoperative day, patients may report paracentral scotoma and decreased vIsion.(2) Within 24 to 48 hourspostoperatively, oval or round, yellow-white retinal lesion, 1/2 to 2 DD present.
57(3) Lesions located at level of RPEand outer layers of retina; may be associatedwith overlying serous retinal detachment.b. Chronic feat(1) Speckled pattern of pigment clumping and focal areas ofRPEatrophy develop.(2) Occasionally chorioretinal folds develop.
58C. Fiberoptic light pipe produces lesion with pigmentary disruption that is diffuse and lacks well-defined borders of phototoxic lesions produced by coaxial illumination of operatingmicroscope.
591 month after cataract surgery.OD Visual acuity is 20/ Mottledpigmentation is present inferior to the fovea.Choroidal folds extended horizontallythrough the area of pigmentation. Thesefolds can result from contracture of theretinal pigment epithelium from lightinduceddamage.OS in the same patient had Cataractsurgery performed 10 months previously.Vision IS 20/20. Mottled pigmentation ispresent inferior and nasal to fovea.
602. Photochemical damage secondary to toxicity produced by absorption of light and production of oxygen free radicals that destroy cell membranes and inactivateenzymes.B. Risk factors.1. Exposure to operating microscope during ocular surgery and fiberoptic illuminators used during vitrectomy procedures.
612. Important variables in producing these macular lesions are intensity of light used and duration of exposure.a. Ophthalmoscopically visiblelesions created in pseudophakic rhesus monkeys in 4 to 7.5 minutes using highintensity coaxial illumination.3. Greatest risk of photic injury occurs after insertion of IOL because media clear andoperating microscope focused on retina.
62C. Epidemiology.1. Operating microscopemaculopathy reported to occurin 7% of patients undergoingcataract surgery.
64Diagnosis lagnosls A. Imaging. 1. Fluorescein angiography. a. Focal area of hyperfluorescencesecondary to leakage seen earlyb. Results from disturbance of RPEtight junctions, producingbreakdown of outer BRB.
652. With time, window defects become apparent. 3. Occasionally, chorioretinal folds seen angiographicallyB. Differential diagnosis.1. Aphakic/pseudophakic cystoidmacular edema.2. Choroidal neovascular membrane.
66Fluorescein angiogram of the right eye demonstrates choroidal folds and pigmentarydisturbance.
67Pigment epithelial changes are seen at the site of photic injury.
68C. Pathologic findings.1. Histopathologic findings inanimals exposed to operatingmicroscope show evidence ofphotoreceptor and RPEdamagegreater in macula thanelsewhere.2. Rods more susceptible than cones.
693. Histologic studies of early photic lesions showphotoreceptor inner and outersegment damage, swollen RPE, and disrupted RPEtightjunctions.
70Managementltreatment A. Medical therapy-none.B. Prevention-despite followingprecautions, retinal injury stillpossible.
711. Use lowest illumination necessary. 2. Filter light at wavelengths below450 nm.3. Reduce length and duration ofpatient's exposure to coaxial illumination by using occluderwhen coaxial illumination not essential.