Cataract PDF

APPROACH TO CATARACT Dr. Fatima Walid Al-Rawi, M.B., Ch. B. , C.A.B.M.S.O.,F.R.C.S. (G),M.R.C.S.I.,I.C.O. Duhok College of Medicine, Duhok University. Specialist Ophthalmologist at Duhok Eye Hospital.  Cataract...

APPROACH TO CATARACT Dr. Fatima Walid Al-Rawi, M.B., Ch. B. , C.A.B.M.S.O.,F.R.C.S. (G),M.R.C.S.I.,I.C.O. Duhok College of Medicine, Duhok University. Specialist Ophthalmologist at Duhok Eye Hospital.  Cataract ava Spi OPILY The name given to any light-scattering opacity within the lens. When it lies on the visual axis or is extensive, it gives rise to visual loss The commonest cause of treatable blindness in the world. retired Ludo The majority of cataracts occur in older subjects and are referred to as age related. They result from a cumulative exposure of the lens to environmental and other influences, such as diabetes, UV and ionizing radiation, corticosteroids and smoking. Age of onset is lower in countries with the highest prevalence of cataract, reflecting the influence of special cataractogenic factors such as high UV exposure, poor diet and chronic disease. A smaller number of cataracts are associated with specific ocular or systemic diseases or defined physicochemical mechanisms. Some congenital, infantile and even adult cataracts may be inherited. CLASSIFICATION ACCORDING TO MORPHOLOGY VE S  O Ocular causes of cataract Ocular trauma –penetrating injury, but also blunt trauma to the globe, ionizing radiation, infrared,electrical shock o Uveitis – unilateral, if the uveitis affects one eye only. High myopia. Topical medications (such as steroid eye drops). Intraocular tumour – ciliary body tumours (((mpinge impinge physically on the lens))). Follows acute angle-closure glaucoma Glaukomflecken on anterior capsule.  Traumatic Cataract Concussion (Blunt) 0 ‘Vossius’ ring from imprinting of iris pigment Flower-shaped Penetration Other causes Ionizing radiation Electric shock Lightning a  Drugs Systemic or topical steroids posterior subcapsular I Chlorpromazine HATE - central, anterior capsular granules 0 Other drugs Long-acting miotics Amiodarone Busulphan  Secondary (complicated) cataract Posterior subcapsular Glaukomflecken O Chronic anterior uveitis Follows acute angle- O closure glaucoma  Systemic causes of cataract Diabetes. Metabolic disorders (galactosaemia and hypocalcaemia). Systemic drugs (steroids, chlorpromazine, Amiodarone). X-radiation. Infection (congenital rubella). Atopy (accompanying atopic dermatitis). Inherited (congenital cataracts and some adult cataracts as in myotonic dystrophy, Neurofibromatosis 2). Syndromes (Down syndrome, Lowe syndrome). Motropis  Diabetes M Myotonic Dystrophy IP Juvenile Adult Atopic Dermatitis CLASSIFICATION ACCORDING TO LOCATION  Nuclear Cataract Myopia Starts as an exaggeration of the normal ageing changes involving the lens nucleus. It is often associated with myopia due to an increase in the refractive index of the nucleus, and also with increased spherical aberration. Some elderly patients may consequently be able to read without spectacles again ('second sight of the aged’). Nuclear sclerosis is characterized in its early stages by a yellowish hue due to the deposition of urochrome pigment Aging → presbyopia → need magnifier glasses to read. Nuclear sclerosis → cancel the presbyopia → may not need magnifier to read → second sight of aged (seems a good thing but this is the initial stage of nuclear cataract) Spherical abberation is when the outer parts of a lens do not bring light rays into the same focus as the central part  Nuclear cataract Progression Exaggeration of normal nuclear Increasing nuclear opacification ageing change Causes increasing myopia Initially yellow then brown  Cortical Cataract Complainof Grave May involve the anterior, posterior or equatorial cortex. The opacities start as clefts and vacuoles between lens fibres due to hydration of the cortex. wedgeshaped sporeline Subsequent opacification results in typical cuneiform (wedge-shaped) or radial spoke-like opacities, often initially in the inferonasal quadrant. Patients with cortical opacities frequently complain of glare due to light scattering.  Cortical cataract Progression Initially vacuoles and clefts Progressive radial spoke-like opacities  Subcapsular Cataract Anterior subcapsular cataract lies directly under the lens capsule and is associated with fibrous metaplasia of the lens epithelium. Posterior subcapsular opacity lies just in front of the posterior capsule and has a vacuolated, granular, or plaque-like appearance and appears black (on retroillumination). DM, steroid, uveitis Due to its location at the nodal point of the eye, a posterior subcapsular opacity has a more profound effect on vision than a comparable nuclear or cortical cataract. Near vision is frequently impaired more than distance vision. Because with near vision, there is miosis (↓ pupil diameter), so the visual axis left for the light is more opacified (the cataract obstructs light from center) but in distant vision, there is mydriasis (↑ diameter) so there is more room for the light to pass through periphery of capsule and so better vision  Subcapsular cataract Anterior Posterior CLASSIFICATION ACCORDING TO MATURITY  Cataract Maturity 1. Immature cataract is one in which the lens is partially opaque. 2. Mature cataract is one in which the lens is completely opaque. 3. Hypermature cataract has a shrunken and wrinkled anterior capsule due to leakage of water out of the lens 4. Morgagnian cataract is a hypermature cataract in which liquefaction of the cortex has allowed the nucleus to sink inferiorly Immature Mature Hypermature Morgagnian (a) A nuclear cataract (b) a cortical spoke cataract, silhouetted against the red reflex andThe location of different types of Christmas tree cataract (c) a posterior subcapsular cataract. cataract. Polychromatic, needle-like opacities  SIGNS AND SYMPTOMS Symptoms painless loss of vision. glare – due to light scattering. a change in refraction – for example, a myopic shift with nuclear cataract. In neonates and infants, cataract causes amblyopia, a failure of visual maturation (may be profound) which occurs when the retina is deprived of a formed image at a critical stage of visual development. Signs Reduced visual acuity affects reading at all distances including the interpretation of road signs when driving. Driving at night may be a particular problem, because of the glare of oncoming headlights. In some patients the acuity, if the test is carried out in bright light or sunlight, the acuity falls as a result of glare and loss of contrast. Small pupils in bright light may restrict light entry. A cataract appears as a dark silhouette against the red reflex when the eye is examined with the direct ophthalmoscope. Slit-lamp examination allows the precise location, type and morphology to be examined in detail.  Preoperative considerations Indications for surgery 1. Visual improvement is by far the most common indication for cataract surgery. Operation is indicated only if and when the opacity develops to a degree sufficient to cause difficulty in performing essential daily activities. 2. Medical indications are those in which a cataract is adversely affecting the health of the eye, for example, phacolytic or phacomorphic glaucoma. 3. To Facilitate Fundus Examination Cataract surgery to improve the clarity of the ocular media may also be required in the context of fundal pathology (e.g. diabetic retinopathy) requiring monitoring or treatment. Ophthalmic Preoperative Assessment Just have an idea 1 Visual Acuity.is usually tested using a Snellen chart. 2 Cover Test. A heterotropia may indicate amblyopia, which carries a guarded visual prognosis, or the possibility of diplopia if the vision is improved. A squint, usually a divergence, may develop in an eye with poor vision due to cataract, and lens surgery alone may straighten the eye. 3. Pupillary Responses. Because a cataract never produces an afferent pupillary defect, its presence implies substantial additional pathology likely to influence the final visual outcome and requires further investigation. 4. Ocular Adnexa. Dacryocystitis, blepharitis, chronic conjunctivitis, lagophthalmos, ectropion, entropion and tear film abnormalities may predispose to endophthalmitis and require effective preoperative resolution. 5. Cornea. Eyes with decreased endothelial cell counts (cornea guttata) have increased vulnerability to postoperative decompensation secondary to operative trauma. Specular microscopy and pachymetry.  6. Anterior Chamber. A shallow anterior chamber ,poorly dilating pupil allows intensive preoperative mydriatic drops, planned mechanical dilatation prior to capsulorrhexis and/or intracameral injection of mydriatic. A poor red reflex compromises the creation of an adequate capsulorrhexis. 7. Lens. Nuclear cataracts tend to be harder and may require more power for phacoemulsification, while cortical opacities tend to be softer. Black nuclear opacities are extremely dense (superior option : extracapsular cataract ). Pseudoexfoliation indicates a likelihood of weak zonules (look for phakodonesis), a fragile capsule and poor mydriasis. 8. Fundus Examination. Pathology such as age-related macular degeneration may affect the visual outcome. Ultrasonography (U/S) may be required, principally to exclude retinal detachment and staphyloma. 9. Current Refractive Status. To guide intraocular lens implant (IOL) selection. The keratometry readings should be noted in relation to the refraction, particularly if it is planned to address astigmatism by means of targeted wound placement or a specific adjunctive procedure. It is particularly important to obtain a postoperative refractive result from an eye previously operated upon so that any ‘refractive surprise’ can be analyzed and taken into account.  Biometry Skip Biometry facilitates calculation of the lens power likely to result in the desired postoperative refractive outcome; in its basic form this involves the measurement of two ocular parameters, keratometry and axial (anteroposterior) length. Keratometry ( K-readings) involves determination of the curvature of the anterior corneal surface (steepest and flattest meridians), expressed in dioptres or in mm of radius of curvature. This is commonly carried out with the interferometry apparatus ((axial length)) or manual keratometry. Optical coherence biometry is a non-contact method of axial measurement that utilizes two coaxial low-energy laser beams which are partially coherent and produce an interference pattern (partial coherence interferometry). The Zeiss IOLMaster (((complete biometry system which also readily performs keratometry, anterior chamber depth and corneal white-to-white measurement, and is able to calculate IOL power using a range of formulae, Aphakic, pseudophakic and silicone-filled eyes can be measured, with variable tailored settings)). IOL power calculation formulae. The SRK-T (keratometry , axial length and anterior chamber depth) , is an example of a commonly used formula for eyes of axial length greater than 22.0 mm. Specific formulae may be superior for very short (generally the Hoffer Q) or long eyes. Previous refractive surgery. Contact lenses. may need to be left out for up to a week or three weeks prior to biometry to allow corneal stabilization. Personalized A-constant of IOL.  4150 The optical power of the lens implant is calculated prior to surgery by measuring the length of the eye ultrasonically and the curvature of the cornea (and thus its optical power) optically (keratometry). The power of the lens is generally calculated to provide good distance acuity without glasses (i.e. emmetropia). The choice of implant power is influenced by curative of cansby 1. The refraction of the fellow eye restantry 2. Whether it too has a cataract that will require surgery. Where surgery on the fellow eye is likely to be delayed, it is important that the patient is not left with a major difference in the refractive state of the two eyes (anisometropia), since the difference in retinal image size (aniseikonia) may not be tolerated visually. anisometorf Multifocal intraocular lenses, which provide good distance and near vision without glasses now in use, although there may be a reduction in contrast sensitivity with such lenses.  Intraoperative Considerations Just have an idea 1. Corneal Astigmatism : Surgery may sometimes induce a degree of corneal astigmatism. Where sutures were used, their postoperative removal may reduce this. This is done pre-existing astigmatism. This can also be treated Thurstone prior to measuring the patient for new glasses but after the wound has healed and steroid drops have been stopped. 2. Astigmatism Excessive corneal curvature can be induced in the line of a tight suture. Removal usually solves this problem and is easily accomplished in the clinic under local anaesthetic with the patient sitting at the slit lamp. 3. Sutureless phacoemulsification through a smaller incision avoids these complications. 4. Furthermore, a modified entry site or relaxing incisions at the periphery of the cornea may allow correction of a pre-existing astigmatism. Postopertive Considerations 1. Postoperative Presbyopia ::: Since the patient cannot accommodate, a spectacle correction is usually required postoperatively for close work. 2. Presbyopia agino hyperopia Loose sutures must be removed to prevent infection but it may be necessary to re-suture the incision if healing is imperfect.  Postoperative Considerations Just have an idea Postoperative Refraction 1 Emmetropia is typically the ideal postoperative refraction, though with spectacles needed for close work since a conventional IOL cannot accommodate. 2 Contralateral eye. The postoperative target for the operated eye might be set for within less than 2.0 D of its fellow, to avoid problems with binocular fusion 3 ‘Monovision’ is a concept in which the (usually) non-dominant eye is left at or just less than –2.0 D myopic to allow reading whilst emmetropia is targeted in the dominant eye. 4 Multifocal lens options use a variety of optical means to attempt to achieve satisfactory near, distance and intermediate vision. (problem : glare, needs greater likelihood of tolerance, highly accurate refractive outcomes). Toric intraocular lenses, which incorporate astigmatic correction in the lens. 5 Younger patients. than about 50 need to be aware that they will experience the sudden loss of active focusing (( take some time to adjust)).  TREATMENT Although much effort has been directed towards slowing the progression of or preventing cataract, management remains surgical. mature There is no need to wait for the cataract to ‘ripen’ and cause major visual loss. The test is whether or not the cataract produces sufficient visual symptoms to reduce the quality of life. Patients may have difficulty in recognizing faces, reading, carrying out their occupation or achieving the driving standard. Some patients may be greatly troubled by glare. Prior to surgery, patients must be informed of any coexisting eye disease which may influence the outcome of cataract surgery and the visual prognosis. Incivion Small cisio inner  Cataract Surgery The operation requires access to the lens via an opening in the anterior part of the lens capsule, removal of most of the lens fibres and epithelial cells and insertion of a plastic lens implant of appropriate optical power. The implant (IOL) is held in place within the capsular bag’. Surgery is usually performed under local rather than general anaesthesia. Local anaesthetic is infiltrated around the globe and lids or given topically. Usually the patient can attend as a day case, without admission. Emulsification of the lens, using an ultrasound probe introduced through a small incision at the limbus (phacoemulsification or phaco). Usually no suture is required. This is now the preferred method in the developed world. The use of the femtosecond laser to make incisions in the cornea and anterior capsule as well as to partially emulsify the lens is a developing field in cataract surgery. Alternatively, an extended incision at the limbus, or a smaller incision in the sclera, followed by extracapsular cataract extraction (ECCE) Here, after opening the capsule, the bulk of the lens substance is expressed from the eye with gentle pressure and residual material is aspirated with a cannula. The incision must be sutured and the sutures removed postoperatively. I  Postoperatively, the patient is given a short course of steroid and antibiotic drops. New glasses, if required, can be prescribed after a few weeks, once the incision has healed. Visual rehabilitation and the been stopped. Excessive corneal curvature can be the incision has healed. Visual rehabilitation and the prescription of new glasses is much quicker after months. complications of cataract surgery capsule removal of posterior 1 vitreous loss 2 This prolapse 3Endophthalmitif  Complications of cataract surgery Just have an idea 1. Vitreous loss. If the posterior capsule is accidentally torn during the operation, the vitreous gel may prolapse forward into the anterior chamber. A. A risk for glaucoma by obstructing aqueous outflow via the trabecular meshwork. B. Retinal traction and increase the risk of retinal detachment. The gel requires careful aspiration and excision (vitrectomy) at the time of surgery and placement of the intraocular lens may need to be deferred to a secondary procedure. 2 Iris prolapse. The iris may protrude through the surgical incision in the immediate postoperative period, appearing as a dark elevation at the incision site accompanied by pupil distortion. This requires prompt surgical repair. 3 Endophthalmitis. A serious , rare infective complication of cataract extraction (less than 0.3%). Patients usually present within a few days of surgery with: A. a painful red eye; B. reduced visual acuity; C. a collection of white cells in the anterior chamber (hypopyon). This is an extreme ophthalmic emergency. The patient requires urgent sampling of the aqueous and vitreous for microbiological analysis and an intravitreal, broad-spectrum, antibiotic injection at the time of sampling (e.g. vancomycin and ceftazidime) to provide immediate cover. Further injections are dependent on the microbiological report and clinical response. Use of intravitreal corticosteroids in conjunction with the antimicrobials (( debated)).  4 Cystoid Macular Oedema. The macula may become oedematous following surgery, particularly if surgery was accompanied by vitreous loss or inflammation. It may settle with time but can produce a severe and permanent reduction in acuity. The release of prostaglandin from inflamed intraocular tissues. Prompt treatment with topical NSAIDs and steroid can alleviate the oedema in a proportion of patients. Sometimes, in addition, it may be necessary to inject steroids into or around the eye. 5. Retinal detachment. Modern techniques of cataract extraction are associated with a low rate of detachment, but the risk is increased if there has been vitreous loss. 6. Opacification of the posterior capsule.Normally, the thin capsular layer that lies behind the implant is crystal clear. However, in approximately 20% of patients, clarity of the posterior capsule decreases in the months following surgery, when residual epithelial cells migrate across its surface to form an opaque scar. Vision then becomes blurred and there may be problems with glare. If no The treatment is YAG laser capsulotomy, using a neodymium yttrium garnet (Nd-YAG) laser to create a small central opening in the capsule as an outpatient procedure. ((Small risk of cystoid macular oedema or retinal detachment)). Lens implant material, the shape of the lens edge and overlap of the intraocular lens by a small rim of anterior capsule are important factors in preventing this complication. 7. If fine nylon sutures are placed but not removed after surgery, they may break in the following months or years, causing irritation or infection. Symptoms are relieved by removal. If nylon straitened Congenital cataract Just have an idea  Causes 1- Isolated hereditary cataracts 2- Metabolic cataract a- galactosaemia b- Lowe's (oculocerebral) syndrome. 3- Prenatal infections: TORCH a- Congenital Rubella: cataract presents in 15% of cases. b- Others: Cytomegalovirus, Herpes simplex and Varicella. 4- Chromosomal abnormalities: a- Down syndrome (Triosomy 21). OOWOV b- Other: Patau syndrome (Triosomy 13), Edward syndrome 5- Genetic; Marfan syndrome, Alport syndrome, myotonic dystrophy, NF-2.  Infants with a family history of congenital cataract should be assessed by an ophthalmologist shortly after birth as a matter of urgency. The presence of congenital, or infantile cataract is a threat to sight, not only because of the immediate obstruction to vision but also because of the disturbance to retinal image formation during the sensitive period of visual development the first 5 years) that impairs visual maturation and leads to amblyopia. This in turn triggers the onset of a squint If bilateral cataract is present and has a significant effect on retinal image formation in both eyes, this will cause bilateral amblyopia, squint and nystagmus, a horizontal oscillation of the eyes. oscillation Nystagmus Horizontal There is also a significant risk of subsequent glaucoma in infants undergoing surgery for congenital cataract, particularly when this is performed prior to 1 year of age Amby upin Cataract----- require urgent surgery (( maximize the chances of success)) treatment must be performed within the first few weeks of life Fitting of contact lenses to correct the aphakia (((requires considerable input and motivation from the parents of the child)). Intraocular lenses are being implanted in children over 2 years old. A coordinated patching routine to the fellow eye to stimulate visual maturation in the amblyopic eye and minimize the risk of squint. Increasingly, The eye, however, becomes increasingly myopic as the child grows, making the choice of lens implant power difficult. O  Disorders of lens shape Abnormal lens shape is very unusual. In Alport’s syndrome((bilateral, conical anterior protrusion of the anterior lens surface)) (anterior lenticonus). Posterior lenticonus ((non-syndromic, unilateral condition)). An abnormally small lens may be associated with short stature and other skeletal abnormalities. Disorders of lens position---------(ectopia lentis) Position of lent Ectopialentis Weakness of the zonule causes lens displacement, which is termed subluxation if minor, or dislocation when more advanced. The lens takes up a more rounded form and the eye becomes more myopic. Homocytinarianov tons After ocular trauma. trauma Inherited disorders: – Homocystinuria is a recessive disorder with ectopia lentis ((displaced downwards)). – Marfan syndrome ((displaced upwards))). --defect in the zonular protein(mutation in the fibrillin gene). The irregular myopia and astigmatism of subluxation can be corrected optically. If the lens is substantially displaced from the visual axis, an aphakic correction may be required. Surgical removal may be indicated, particularly if the displaced lens has caused 1. A secondary glaucoma 2. vision cannot be corrected optically.