眼科學(xué)課件：02 角膜病白內(nèi)障

1、Chen Tao MD PhD.Ophthalmology Department Renji HospitalShanghai Jiaotong UniversityThe cornea is the eyes optical window that makes it possible for humans to see The ophthalmologist is only able to discern structures in the interior of the eye because the cornea is transparentAt 43 diopter, the corn

2、ea is the most important refractive medium in the eyeShape and LocationThe corneas curvature is greater than the scleras curvatureIt fits into the sclera like a watch-glass with a shallow sulcus (the limbus of the cornea) marking the junction of the two structures.EmbryologyThe corneal tissue consis

3、ts of five layers The cornea and the sclera are formed during the second month of embryonic development The epithelium develops from ectoderm, and the deeper corneal layers develop from mesenchyme.Morphology and HealingThe surface of the cornea is formed by stratified nonkeratinized squamous epithel

4、ium that regenerates quickly when injured An intact epithelium protects against infectionMorphology and HealingA thin basement membrane anchors the basal cells of the stratified squamous epithelium to Bowmans layerThis layer is highly resistant but cannot regenerateInjuries to Bowmans layer usually

5、produce corneal scarringMorphology and HealingThe corneal stroma , Beneath Bowmans layer, many lamellae of collagen fibrils form the corneal stromaThe stroma is a highly dedydrate and avascular tissue It represents90% of the corneal thinknessMorphology and HealingDescemets membrane is a relatively s

6、trong membrane. It will continue to define the shape of the anterior chamber even where the corneal stroma has completely meltedMorphology and HealingThe corneal endothelium is responsible for the transparency of the cornea The corneal endothelium does not regenerate; defects in the endothelium are

7、closed by cell enlargement and cell migration.Specular microscopy permits a precise endothelial cell count (CD = 2159 endothelial ells per mm2) while simultaneously measuring the thickness of the cornea pachymetry = 572 mKeratitisKeratitis occupies an important place in keartopathyOne of main causes

8、 of blindnessAlmost all keratities are caused by external infectionsKeratitislPathogenic factorExternal：Trauma, Infection，Viruses, Bacteria ,Acanthamoeba, Fungi.Internal：self-immunoreactionlClassification: classification of keratitis isnt unified yetlThe nomenclatures used in clinic at present depen

9、ds on etiology, ill site and shape Protective Mechanisms of the CorneaReflectivity eye closingFlushing effect of tear fluid (lysozyme)Its hydrophobic epithelium forms a diffusion barrierEpithelium can regenerate quickly and completelycorneaReaction of corneal limbus bold vesselEdema and infiltration

10、 of corneal stromaCorneal ulcerUlcer perforatesEndophthalmitisSecondary glaucomaCorneal anterior adhesive leucomaCorneal staphylomaRepair, heal, scar leftReactive iridocyclitisNo tissue necrosisInflammation develops, surface layer necrosis, exfoliatedhypopyonAnterior, posterior synechia of irissmall

11、largeFistula formation, bacteria enter the eyePathogenic factorThe pathogenic process of corneal inflammationDiagnosis of keratitislHistory：trauma, influenza, local or systemic immunosuppression , systemic diseaselSymptoms：visual decrease, pain, tearing, photophobia, blepharospasmSign：ciliary/mixed

12、congestion、corneal eadema and infiltration、corneal ulcer、2%fluorescein positive corneal stain FL(+)，reactive iridocylitis、secondary glaucomaLab examinationIdentifying the pathogen and testing its resistance. This is done by taking a smear from the base of the ulcer to obtain sample material and inoc

13、ulating culture media for bacteria and fungi Wearers of contact lenses should also have cultures taken from the lenses to ensure that they are not the source of the bacteria or fungiLab examinationSlides of smears, unstained and treated with Gram and Giemsa stains, are examined to detect bacteriaWhe

14、re a viral infection is suspected, testing corneal sensitivity is indicated as this will be diminished in viral keratitisPrinciple of treatmentPahogenic cause must be eliminatedSelect suitable antibiotic or antiviral agentsTopical instillation frequently or bulbar subconjunctival injection are ratio

15、nal way to use these medicinesMydriasis with atropineSecondary disease treatmentDercease corneal scarNebula :thin and translucent scarCorneal macula: relative thick oneLeukoma: very thick whitish oneSecondary disease treatmentSecondary glaucoma should be treated by surgerySeverely impairs vision, op

16、tical iridectomy or corneal grafting should be doneBacterial KeratitisOver 90% of all corneal inflammations are caused by bacteriaThe pathogens listed are among the most frequent causes of bacterial keratitis in the urban population in temperate climates.Staphylococcus aureus Infection progresses sl

17、owly with little painStaphylococcus epidermidis As in Staphylococcus aureus infectionStreptococcus pneumonia Typical serpiginous corneal ulcer: the cornea is rapidly perforated with early intraocular involvement; very painfulPseudomonas aeruginosa Bluish green mucoid exudate, occasionally with a rin

18、g shaped corneal abscess. Progression is rapid with a tendency toward melting of the cornea over a wide area painfulMoraxella Painless oval ulcer in the inferior cornea that progresses slowly with slight irritation of the anterior chamberSerpiginous corneal ulcerAn acute suppurative corneal ulcerCom

19、monly seen in aging or weak persons or someone with chronic dacryocystitisSuppurative bacteria such as hemolytic streptococcus, staphylococcus aureauHave corneal abrasion history for example damaged by paddy, nail or by twigClinical findingsAcute onset, sudden ophthalmalgia, photophobia, tearing, se

20、vere blurred vision after corneal injury within 24-48 hoursMixed congestion, grey-yellow dense infiltrative focus with surrounding corneal eademaThe ulcer margin extends to surroundings and deep with creeping developmentThe toxin has infiltrated into the anterior chamber, iridocyclitis and fibrinous

21、 exudate lead to hypopyon, pupil contracts and produces adhesion to lensIt is easy to lead to perforation and endophthlmitisTreatmentTopical administration: sensitive antibiotic drops such as Levofloxacin eye drop every half an hoursystemic administration: Penicillin 800-120010000u, iv. Drop, Qd.Myd

22、riasis with atropine should be done as early as possilbeImportant ！As soon as the results of bacteriologic and resistance testing are availablethe physician should verify that the pathogens will respond to current therapy Failure of keratitis to respond to treatment may be due to one of the followin

23、g causes, particularly if the pathogen has not been positively identified1. The patient is not applying the antibiotic (poor compliance).2. The pathogen is resistant to the antibiotic.3. The keratitis is not caused by bacteria but by one of the following pathogens:! Herpes simplex virus.! Fungi.! Ac

24、anthamoeba.! Rare specific pathogens such as Nocardia or mycobacteriaPseudomonas corneal ulcerSevere purulent keratitis caused by pseudomonas aeruginosaComplicated with corneal injury, especially after extraction of corneal foreign bodyUsing of polluted by pseudomonas aeruginosa operative instrument

25、s or eye dropsPolluted contact lens or cleaning solutionClinical findingsAfter corneal injury several hours or within 1-2 daysExtreme pain and palpebral swollen, bulbar conjunctival hyperemia and eademaClinical findingsWhite-yellow necrotic focus occurred on the cornea, quickly extendingSoon hypopyo

26、n appears with much quantityCornea will perforated within 1-2days Smear examination: gram-negtive bacteriaTreatmentPolymyxin B gentamycin are most effectivePolymyxin B 50000u/ml is dropped topically with 30 minutes interval during day in acute stageGentamycin 40000u subconjunctival injectionMydriasi

27、s with atropineFungal keratitisEpidemiology: Mycotic keratitis was once very rare, occurring almost exclusively in farm laborers However, this clinical syndrome has become far more prevalenttoday as a result of the increased and often unwarranted use of antibiotics andsteroids.EtiologyThe most frequ

28、ently encountered pathogens are Aspergillus and Candida albicansThe most frequent causative mechanism is an injury with fungus-infested organic materials such as a tree branchSymptomsPatients usually have only slight symptoms，pain, hotophobia, tearing Accompanied by secondary bacterial infection, is

29、 difficult for diagnosis The ulcer is in white tint, a little elevated on surfaceAround the central focus, sometimes there may be seen “satellite focus”Hypopyon is often existed and cheesy, thickHistologic findings include hyphae inthe corneal stromaDiagnosisScraping and inoculation of media should

30、be performedIt is important to scrape multiple sites in the ulcer craterGram stain may identify some fungal forms such as Candida albicansTreatmenttopical treatment with antimycotic agents such as natamycin, nystatin, and amphotericin BThe cornea should be cleaned of debris to enhance drug penetrati

31、onCycloplegics such as atropine should be used to prevent posterior synechiae and help reduce uveal inflammation.Surgical therapy corneal transplantationViral KeratitisViral keratitis is frequently caused by: Herpes simplex virus. Varicella-zoster virus. Adenovirus.Herpes Simplex KeratitisEpidemiolo

32、gy and pathogenesis the more common causes of corneal ulcerAbout 90% of the population are carriers of the herpes simplex virusMany people remain carriers of the neurotropic virusRecurrences may be triggered external influences (such as exposure to ultraviolet light), stress, menstruation, generaliz

33、ed immunologic deficiency, or febrile infectionsSymptomsusually very painful and associated with photophobia, lacrimation, and swelling of the eyelids Vision may be impaired depending on the location of findings, for example in the presence of central epitheliitis.Forms and diagnosis The following f

34、orms of herpes simplex keratitis are differentiated according to the specific layer of the cornea in which the lesion is locatedRecurrences are more frequent in the stroma and endotheliumDendritic keratitisbranching epithelial lesions will be visible after application of fluorescein dyeCorneal sensi

35、tivity is usually reduced.Dendritic keratitis may progress to stromal keratitisStromal KeratitisSlit lamp examination will reveal central diskiform corneal infiltrates (diskiform keratitis) with or without a whitish stromal infiltrateCorneal opacity caused by herpes simplex infection (disciform kera

36、titis)Depending on the frequency of recurrence, superficial or deep vascularization may be presentReaction of the anterior chamber will usually be accompanied by endothelial plaques (keratic prcipitate KP)Slit picture of interstitial keratitis showing stromal hickening, opacity, abnormal corneal ves

37、sels not clearlyseenEndotheliitisEndotheliitis or endothelial keratitis is caused by the presence of herpes viruses in the aqueous humorSwelling of the endothelial cells and opacification of the adjacent corneal stromaInvolvement of the endothelial cells in the angle of the anterior chamber causes a

38、 secondary increase in intraocular pressure Inflamed cells and pigment cells in the anterior chamber（Tyndall phenomenon (tyn+)Endothelial plaques(KP+)TreatmentAntiviral agents 0.1% idoxuridine(IDU), 0.1% acycloguanosine(ACG), 1% trifluorothymidine, every 1-2 hours Inteferon may shorten the course ,

39、promote ulcerative healedMydriasis if any iridocyclitis existCoricosteroid is banned, but for stromal disciform keratitis or ulcer has been healed bacterial viral fugalstress trauma influenza tree branch scratchcourse acute chronic chronic no recurrent recurrent recurrent pain severe severe mildcong

40、estion mixed ciliary or mixed mixedexudate purulent water stickness purulentUlcer shape infiltration punctate infiltration whitish stromal infiltration grey-yellow dense white-yellow dry cheesy elevated infiltrative focus dendritci or geographic necrotic tissue satellite focushypopyon usually yellow

41、 purulent seldom usually thickness perforate usually seldom usuallypathogens bacteria virus fungitreatment antibacterial antivirus anti fungiCataractFunction of the lens: The lens is one of the essential refractive media of the eyeTotal refractive powerThe lens lies in the posterior chamber of the e

42、ye between the posterior surface of the iris and the vitreous body with the iris it forms an optical diaphragm that separates the anterior and posterior chambers of the eyeRadially arranged zonule fibers that insert into the lens around its equator connect the lens to the ciliary body These fibers h

43、old the lens in position and transfer the tensile force of the ciliary muscleMetabolism and aging of the lensThe lens is nourished by diffusion from the aqueous humorMetabolic activity is essential for the preservation of the integrity, transparency, and optical function of the lensTransparent lens

44、becomes opaque called cataract, one of the main cause of blindnessSenile cataract is the most common cataract, often occurred over the age of 50, with aging, the disease incidence increase. The metabolism and detailed biochemical processes involved in aging are complex and not completely understood.

45、 Because of this, it has not been possible to influence cataract development with medications.General symptomsseeing only shades of gray, visual impairment, blurred vision, distorted vision, glare or star bursts, monocular diplopia, altered color perception, etc.Visual image with a cataract: gray ar

46、eas and partial loss of image perceptionClassificationCataracts may be classified according to several different criteria1.Time of occurrence (acquired or congenital cataracts)2.Maturity immature, intumescent, mature hypermature3.Morphology nuclear cortical capsular subcapsular No one classification

47、 system is completely satisfactory.Senile CataractSenile cataract is by far the most frequent form of cataract, accounting for 90% of all cataracts. About 5% of all 70-year-olds and 10% of all 80-year-olds suffer from a cataract requiring surgeryCortical cataractIt is most common type, according to

48、its course , it is divided into 4 stagesHypermatureImmatureIntumescentmature Central cortical cataract. Visionworse in bright sunlight or whilereading when pupil constricts.Peripheral cortical cataract. Visionusually affected later.Mature cataract where entire lensbecomes opaque. Maturity can leadto

49、 complications.The nucleus of the lens has a yellowish brown color due to the pressure of peripheral lens fiber roductionA contusion rosette posterior to the anterior lens capsule develops following severe blunt trauma to the eyeball.The brown nucleus has subsided inthe liquified cortexHypermature c

50、ataract.Histologic image obtained at autopsy shows the position of the subsidednucleus and the shrunken capsular bagThe lens opacities (“riders”) are located in only one layer of lens fibers, often only in the equatorial region as shown hereThis variant of the lamellar cataract affects only the outer layer of the embryonic nucleus, seen here as a sutural cataractCongenital CataractThis diffuse opacity proceeds from the posterior subcapsular cataract. Inflammatory