Post on 20-Mar-2017
Embed Size (px)
MR.JAYDIP J.NINAMALECTURERMEDICAL SURGICAL NURSING DEPARTMENT
Its crystalline.Histology:CapsuleSubcapsular epithelium (simple cuboidal).Synthesize protein for lens fiber
Maintains a cation pump to keep the lens clearLens fibers
Ciliary muscleFunction:Constricts ciliary bodyRelaxes tension on lensLens become spherical, which increase the refractive power
Ciliary processAttaches to the lenses by suspensory ligament (zonular fibers)Secrete the Aqueous humor into the post. chamber
DEFINITIONAny congenital or acquired opacity(dullness) in the lens or lens capsule is called as cataract
EpidemiologyCataracts remain the leading cause of blindness.Age-related cataract is responsible for 48% of world blindness, which represents about 18 million peopleCataracts are also an important cause of low vision in both developed and developing countries.
Causes of cataractOld age (commonest)Ocular & systemic diseasesDMUveitisPrevious ocular surgerySystemic medicationSteroidsPhenothiazinesTrauma & intraocular foreign bodiesIonizing radiationX-rayUV
CongenitalPart of a syndromeAbnormal galactose metabolismHypoglycemiaInherited abnormalityMyotonic dystrophyMarfans syndromRubellaHigh myopia
Any physical or chemical cause Disturbs the intracellular and extracellular equilbrium of water and electrolytes Deranges the colloid system in lens fibres Aberrant fibres are formed from germinal epithelium of lens Epithelial cell necrosis Focal opacification of lens epithelium (glaucomflecken) Opacification of lens
Opacification of lens takeplace by 3 biochemical changes.
Hydration 2.Denaturation of 3.Slow lens protein sclerosis
Abnormalities of lens proteins & Disorganisation of lens fibres
Loss of transparency of lens
CataractDivided to :Acquired cataract
Age - related cataract(Senile Cataract)Presenile cataractTraumatic cataractDrug induced cataractSecondary cataractCongenital Cataract
Systemic associationNon-systemic association
Age -related cataract It is the Most commonly occurred.Classified according to:Morphological ClassificationNuclearCorticalSubcapsularChristmas tree uncommonMaturity classificationImmature Cataract Mature Cataract Hypermature Cataract
Nuclear cataractMost common typeAge-relatedOccur in the center of the lens.In its early stages, as the lens changes the way it focuses light, patient may become more nearsighted or even experience a temporary improvement in reading vision. Some people actually stop needing their glasses.Unfortunately, this so-called 2nd sight disappears as the lens gradually turns more densely yellow & further clouds vision.As the cataract progresses, the lens may even turn brown. Advanced discoloration can lead to difficulty distinguishing between shades of blue & purple.
Cortical cataract Occur on the outer edge of the lens (cortex).Begins as whitish, wedge-shaped opacities or streaks.Its slowly progresses, the streaks extend to the center and interfere with light passing through the center of the lens.Problems with glare are common with this type of cataract.
Subcapsular cataractOccur just under the capsule of the lens.Starts as a small, opaque areaIt usually forms near the back of the lens, right in the path of light on its way to the retina.Its interferes with reading visionReduces vision in bright lightCauses glare or halos around lights at night.
Posterior Subcapsular CataractsBegins at the back of the lens (posterior pole) & spreads to the periphery or edges of the lens.It can be developed when:Part of the eye are chronically inflamed.Heavy use of some medications (steroids).Affects vision more than other types of cataracts because the light converges at the back of the lens.Anything constrict the pupils (bright light) makes it very difficult for people with this type of cataract to see.Dilating drops useful in this type by keeping the pupils large and thus allow more light into the eye.
Immature Cataract Lens is partially opaqueTwo morphological forms are seen:Cuneiform Cataract:Wedge shaped opacities in the peripheral cortex and progress towards the nucleus.Vision is worse in low ambient illumination when the pupil is dilated.
Cupuliform Cataract:A disc or saucer shaped opacities beneath the posterior capsule.Vision is worse in bright ambient illumination when the pupil is constricted.
Lens appears grayish white in color.Iris shadow can be seen on the opacity with oblique illumination.
Mature Cataract Lens is completely opaque.Vision reduced to just perception of lightIris shadow is not seenLens appears pearly white
Right eye mature cataract, with obvious white opacity at the centre of pupil
Hypermature CataractShrunken and wrinkled anterior capsule due to leakage of water out of the lense.
This may take any of two forms:
Liquefactive/Morgagnian TypeSclerotic Cataract
Liquefactive/Morgagnian TypeCortex undergoes auto-lytic liquefaction and turns uniformly milky white.The nucleus loses support and settles to the bottom.
Sclerotic CataractThe fluid from the cortex gets absorbed and the lens becomes shrunken.There may be deposition of calcific material on the lens capsule.Iridodonesis: Anterior chamber deepens and iris becomes tremulous.The zonules become weak, increasing the risk of subluxation / dislocation of lens.
SymptomsA cataract usually develops slowly, so: Causes no pain.Cloudiness may affect only a small part of the lensPeople may be unaware of any vision loss.Over time, however, as the cataract grows larger, it:Clouds more the lensDistorts the light passing through the lens.Impairs vision
Reduced visual acuity (near and distant object)Glare in sunshine or with street/car lights.Distortion of lines.Monocular diplopia.Altered colours ( white objects appear yellowish)Not associated with pain, discharge or redness of the eye
SignsReduced acuity.An abnormally dim red reflex is seen when the eye is viewed with an ophthalmoscope.Reduced contrast sensitivity can be measured by the ophthalmologist.Only sever dense cataracts causing severely impaired vision cause a white pupil.After pupils have been dilated, slit lamp examination shows the type of cataract.
History collection Visual acuity testDilated eye examTonometry
TreatmentGlasses: Cataract alters the refractive power of the natural lens so glasses may allow good vision to be maintained.Surgical removal: when visual acuity can't be improved with glasses.
Surgical techniquesPhacoemulsification method.Extracapsular method.Intracapsular method
Pre-op assesmentsGeneral health evaluation including blood pressure checkAssessment of patients ability to co-operate with the procedure and lie reasonably flat during surgeryInstruction on eye drop instillationThe eyes should have a normal pressure, or any pre-existing glaucoma should be adequately controlled on medications.An operating microscope is needed, in order to reach the lens, a small corneal incision is made close to the limbus for the phaco-probe.It is important to appreciate anterior chamber depth and to keep all instruments away from the corneal endothelium in the plane of the iris.
Phacoemulsification in cataract surgery involves insertion of a tiny, hollowed tip that uses high frequency (ultrasonic) vibrations to "break up" the eye's cloudy lens (cataract). The same tip is used to suction out the lens.
Intra-capsular Cataract ExtractionIntracapsular Cataract Extraction. From the late 1800s until the 1970s, the technique of choice for cataract extraction was intracapsular cataract extraction (ICCE). The entire lens (ie, nucleus, cortex, and capsule) is removed, and fine sutures close the incision. ICCE is infrequently performed today; however, it is indicated when there is a need to remove the entire lens, such as with a subluxated cataract (ie, partially or completely dislocated lens).
Extra-capsular Cataract Extraction (ECCE)Extracapsular Surgery. Extracapsular cataract extraction (ECCE) achieves the intactness of smaller incisional wounds (less trauma to the eye) and maintenance of the posterior capsule of the lens, reducing postoperative complications, particularly aphakic retinal detachment and cystoid macular edema.
Postoperative care after cataract surgerySteroid drops (inflammation)Antibiotic drops (infection)AvoidVery strenuous exertion (rise the pressure in the eyeball)Ocular trauma.
Complications of cataract surgeryInfective endophthalmitisRare but can cause permanent severe reduction of vision.Most cases within two weeks of surgery.Typically patients present with a short history of a reduction in their vision and a red painful eye.This is an ophthalmic emergency.Low grade infection with pathogen such as Propionibacterium species can lead patients to present several weeks after initial surgery with a refractory uveitis