Ординатура / Офтальмология / Английские материалы / Clinical Ophthalmology A Systematic Approach 7th Edition_Kanski, Bowling_2011

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1Presentation is with painless mild progressive visual deterioration which may be associated with floaters.

2Signs

•Low-grade anterior uveitis, sometimes with mutton-fat keratic precipitates (Fig. 9.20A).

•The inflammation initially responds well to topical steroids (Fig. 9.20B), but recurs when treatment is stopped and eventually becomes steroid resistant (Fig. 9.20C).

•Vitritis is common but hypopyon infrequent.

•An enlarging capsular plaque composed of organisms sequestrated in residual cortex within the peripheral capsular bag is characteristic (Fig. 9.20D).

•Gonioscopy under mydriasis may identify an equatorial plaque.

3Initial management involves a 10–14 day course of oral moxifloxacin; clarithromycin is an alternative.

4Investigations consisting of cultures or aqueous and vitreous should be considered, if oral antibiotics are ineffective. Anaerobic culture should be requested if P. acnes infection is suspected, and isolates may take 10–14 days to grow. The detection rate can be greatly improved with the use of polymerase chain reaction (PCR).

5Treatment if persistent

•Intravitreal antibiotics alone are usually unsuccessful in resolving the infection.

•Removal of the capsular bag, residual cortex and IOL, requiring pars plana vitrectomy. Secondary IOL implantation may be considered at a later date. Intravitreal antibiotics are combined: vancomycin (1 mg in 0.1 mL) is the antibiotic of choice and can also be irrigated into any capsular remnant. P. acnes is also sensitive to methicillin, cefazolin and clindamycin.

Fig. 9.20 Delayed-onset postoperative endophthalmitis. (A) Anterior uveitis with mutton-fat keratic precipitates; (B) fewer keratic precipitates following topical steroid therapy; (C) severe recurrence 2 weeks following cessation of steroid therapy; (D) white plaque within the capsular bag

Posterior capsular opacification

Visually significant posterior capsular opacification (PCO) is the most common late complication of uncomplicated cataract surgery. Apart from reducing visual acuity, PCO may impair contrast sensitivity, cause difficulties with glare or give rise to monocular diplopia. The incidence of PCO is reduced when the capsulorhexis opening is in complete contact with the anterior surface of the IOL. PMMA (and probably to a lesser extent hydrogel) IOLs are particularly prone to PCO, but otherwise implant design is more important than material; notably, a square edge to the optic appears to inhibit PCO.

Signs

1Elschnig pearls (bladder cells, Wedl cells) are caused by the proliferation and migration of residual equatorial epithelial cells along the posterior capsule at the site of apposition between the remnants of the anterior capsule and the posterior capsule. They impart a vacuolated appearance to the posterior capsule, best visualized on retroillumination (Fig. 9.21A). This is the most frequently seen type of opacification and is related to the patient's age. It is extremely common in children if a posterior capsulorhexis is not performed at the time of surgery.

2Capsular fibrosis (Fig. 9.21B), due to fibrous metaplasia of epithelial cells, is less common and usually appears earlier than

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Elschnig pearls.

Fig. 9.21 Posterior capsular opacification. (A) Elschnig pearls; (B) capsular fibrosis; (C) appearance following laser capsulotomy; (D) laser pitting of the IOL

(Courtesy of P Gili – figs A and B; R Packard – fig. C; R Curtis – fig. D)

Treatment

Treatment involves the creation of an opening in the posterior capsule with the Nd:YAG laser.

1Indications for capsulotomy include:

•Diminished visual acuity.

•Diplopia or glare secondary to capsular wrinkling.

•Inadequate fundus view impairing diagnosis, monitoring or treatment of retinal pathology.

2Technique. Safe and successful laser capsulotomy involves accurate focusing and using the minimum energy required. Laser power is initially set at 1 mJ/pulse, and may be increased if necessary. A series of punctures are applied in a cruciate pattern using single-pulse shots, the first puncture aimed at the visual axis. An opening of about 3 mm is usually adequate (Fig. 9.21C), but larger capsulotomies may be necessary for retinal examination or photocoagulation.

3Complications are not usually associated with identifiable risk factors. The number of laser pulses and the energy level are probably not related to their development, although it is prudent to use minimum possible total energy.

•Damage to the IOL (‘pitting’ – Fig. 9.21D) may occur if the laser is poorly focused. Although undesirable, a few laser marks on the IOL do not alter visual function or impair ocular tolerance of the IOL.

•Cystoid macular oedema is an occasional complication and may develop months after capsulotomy. It is less common when capsulotomy is delayed for 6 months or more after cataract surgery.

•Rhegmatogenous retinal detachment is rare, though more common in high myopes, and may occur several months after capsulotomy.

•Intraocular pressure elevation, which is mild and transient, is usually innocuous. However, sustained elevation above precapsulotomy levels may occur, especially in patients with established glaucoma or those who manifest significant ocular hypertension within hours of the capsulotomy.

•Posterior IOL subluxation or dislocation is rare but may occur, particularly with plate haptic silicone and hydrogel IOLs.

•Chronic endophthalmitis due to release of sequestered organisms into the vitreous is very rare.

Anterior capsular fibrosis and contraction

Since the advent of continuous curvilinear capsulorhexis, contraction of the anterior capsular opening (capsulophimosis) has become a relatively common postoperative complication. It can occur as early as several weeks after surgery and is accompanied by prominent subcapsular fibrosis (Fig. 9.22). The contraction typically progresses for up to three months, and if severe, may require Nd: YAG laser anterior capsulotomy. The severity of contraction is related to the optic material; the highest rate is with plate-haptic silicone IOLs and the lowest with 3-piece acrylic optic-PMMA haptic IOLs. A small capsulorhexis may also predispose to contraction.

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Fig. 9.22 Anterior capsular contraction and fibrosis

Miscellaneous postoperative complications

Malposition of IOL

Although uncommon, malposition may be associated with both optical and structural problems. Annoying visual aberrations include glare, haloes, and monocular diplopia if the edge of the IOL becomes displaced into the pupil.

1Causes

•Primary malposition may occur during surgery due to zonulodialysis, capsular rupture or when one haptic is inserted into the capsular bag and the other into the ciliary sulcus or rarely the angle (Fig. 9.23A).

•Postoperative causes include trauma, eye rubbing and capsular contraction.

2 Treatment. Significant malposition (Fig. 9.23B) may require repositioning or replacement.

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Fig. 9.23 (A) Decentred optic with one haptic in the angle and the other in the bag; (B) inferior subluxation of IOL

(Courtesy of P Gili – fig. B)

Cystoid macular oedema

Symptomatic CMO is relatively uncommon following uncomplicated phacoemulsification and in most cases it is mild and transient. It occurs more often after complicated surgery and has a peak incidence at 6–10 weeks, although the interval may be much longer.

1Risk factors for visually significant CMO include a history of CMO in the other eye, operative complications such as posterior capsular rupture, particularly with vitreous incarceration into the incision site (Fig. 9.24A), AC-IOL (Fig. 9.24B), secondary IOL implantation, prior topical prostaglandin treatment, diabetes and uveitis.

2Presentation is with blurring of vision, especially for near tasks, and sometimes distortion. Subtle CMO may not be readily visible clinically, but is well demonstrated on OCT (see Ch. 14).

3Treatment involves correction of the underlying cause, if possible. For example, vitreous incarceration in the anterior segment may be amenable to anterior vitrectomy or YAG laser disruption. As a last resort it may be necessary to remove an AC-IOL. If a correctable cause is not present, treatment can be difficult although many cases resolve spontaneously within a few months. Treatment of persistent CMO involves the following:

aTopical NSAIDs such as ketorolac 0.5% (Acular®) administered q.i.d. may be beneficial even in long-standing cases. Topical treatment may have to continue for an extended period. Intravitreal NSAID injection is a promising new modality.

bSteroids given topically or by posterior periocular injection may be effective.

c Carbonic anhydrase inhibitors given systemically and topically may be beneficial in some cases. d Intravitreal triamcinolone may be effective in those unresponsive to periocular injections.

eIntravitreal anti-VEGF agents show some promise for the treatment of pseudophakic CMO but remain under investigation at present.

fPars plana vitrectomy may be useful for CMO refractory to medical therapy, even in eyes without apparent vitreous disturbance.

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Fig. 9.24 Predispositions to cystoid macular oedema. (A) Vitreous incarceration in the incision; (B) anterior chamber IOL

(Courtesy of C Barry – fig. B)

Retinal detachment

Rhegmatogenous retinal detachment, although uncommon following uneventful ECCE or phaco, may be associated with the following risk factors:

1Preoperative

•Lattice degeneration or retinal breaks should be treated prophylactically prior to cataract surgery or laser capsulotomy if fundus view permits, or as soon as possible thereafter.

•High myopia.

2Operative

•Disruption of the posterior capsule.

•Vitreous loss, particularly if managed inappropriately, is associated with approximatly a 7% risk of retinal detachment. Myopia of over 6D increases the risk to 15%.

3Postoperative laser capsulotomy, if performed within a year of cataract surgery.

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Congenital cataract

Aetiology

Congenital cataracts occur in about 3 in 10 000 live births. Two-thirds of cases are bilateral and the cause can be identified in about half of those affected. The most common cause is genetic mutation, usually autosomal dominant (AD); other causes include chromosomal abnormalities, metabolic disorders and intrauterine infections. The underlying aetiological factors in unilateral cases remain less clear and the cause can be identified only in approximately 10%. Unilateral cataracts are usually sporadic, without a family history or systemic disease, and affected infants are usually full-term and healthy.

Inheritance

Isolated hereditary cataracts account for about 25% of cases. The mode is most frequently AD but may be autosomal recessive (AR) or X- linked (X-L). The morphology of the opacities and frequently the need for surgery are usually similar in parent and offspring. Isolated inherited congenital cataracts carry a better visual prognosis than those with coexisting ocular and systemic abnormalities.

Morphology

The morphology of congenital cataract is important because it may indicate a likely aetiology, mode of inheritance and effects on vision.

1Nuclear opacities are confined to the embryonic or foetal nuclei of the lens. The cataract may be dense or composed of fine pulverulent (dust-like) opacities (Fig. 9.25A). They may be associated with microphthalmos.

2Lamellar opacities affect a particular lamella of the lens both anteriorly and posteriorly (Fig. 9.25B) and in some cases is associated with radial extensions (‘riders’ – Fig. 9.25C). Lamellar opacities may be AD, occur in isolation as well as in infants with metabolic disorders and intrauterine infections.

3Coronary (supranuclear) cataract lies in the deep cortex and surrounds the nucleus like a crown (Fig. 9.25D). They are usually sporadic and only occasionally hereditary.

4Blue dot opacities (cataracta punctata caerulea – Fig. 9.25E) are common and innocuous, and may coexist with other types of lens opacity.

5Sutural in which the opacity follows the anterior or posterior Y suture. It may occur in isolation or in association with other opacities (Fig. 9.25F).

6Anterior polar cataract may be flat (Fig. 9.26A) or project as a conical opacity into the anterior chamber (pyramidal cataract – Fig. 9.26B). Flat anterior polar opacities are central, less than 3 mm in diameter, bilateral in one-third of cases and visually insignificant. Pyramidal opacities are frequently surrounded by an area of cortical opacity and may affect vision. Occasional associations of anterior polar cataracts include persistent pupillary membrane (Fig. 9.26C), aniridia, Peters anomaly and anterior lenticonus.

7Posterior polar cataract (Fig. 9.26D) may be occasionally associated with persistent hyaloid remnants (Mittendorf dot), posterior lenticonus and persistent hyperplastic primary vitreous.

8 Central ‘oil droplet’ opacities (Fig. 9.26E) are characteristic of galactosaemia.

9Membranous cataract is rare and may be associated with Hallermann–Streiff–François syndrome. It occurs when the lenticular material partially or completely reabsorbs leaving behind residual chalky-white lens matter sandwiched between the anterior and posterior capsules (Fig. 9.26F).

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Fig. 9.25 Congenital cataracts. (A) Nuclear; (B) lamellar; (C) dense lamellar with ‘riders’; (D) coronary; (E) dense blue dot; (F) sutural and fine blue dot

(Courtesy of R Bates – fig. E)

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Fig. 9.26 Congenital cataracts. (A) Flat anterior polar; (B) pyramidal anterior polar; (C) anterior polar with persistent pupillary membrane; (D) posterior polar associated with Mittendorf dot; (E) ‘oil droplet’; (F) membranous

(Courtesy of J Schuman, V Christopoulos, D Dhaliwal, M Kahook and R Noecker, from Lens and Glaucoma, in Rapid Diagnosis in Ophthalmology, Mosby 2008 – fig. D; K Nischal – fig. E)

Systemic metabolic associations

Many systemic paediatric conditions may be associated with congenital cataract. The vast majority are extremely rare and of interest only to paediatric ophthalmologists. The general ophthalmologist should, however, be aware of the following conditions:

Galactoasemia

1Pathogenesis. Galactosaemia is an AR condition characterized by severe impairment of galactose utilization caused by absence of the enzyme galactose-1-phosphate uridyl transferase (GPUT).

2Systemic features, which become manifest during infancy, include failure to thrive, lethargy, vomiting and diarrhoea. ‘Reducing substance’ is found in the urine after drinking milk. Unless galactose, in the form of milk and milk products, is withheld from the diet, hepatosplenomegaly, renal disease, anaemia, deafness and mental handicap occur subsequently with early death.

3Ocular features. Cataract, characterized by a central ‘oil droplet’ opacity (see Fig. 9.26E), develops within the first few days or weeks of life in a large percentage of patients. The exclusion of galactose (in milk products) from the diet will prevent the progression of cataract and may reverse early lens changes.

Lowe syndrome

1Pathogenesis. Lowe syndrome is an X-L inborn error of amino acid metabolism.

2Systemic features include psychomotor retardation, Fanconi syndrome of the proximal renal tubules, muscular hypotonia, frontal prominence, chubby cheeks and sunken eyes (Fig. 9.27A). It is one of the few conditions in which congenital cataract and congenital glaucoma may coexist.

3Ocular features

•Cataract, which may be capsular, lamellar, nuclear or total, is universal. The lens is also small, thin and disc-like (microphakia) and may show posterior lentiglobus. Female carriers manifest micropunctate cortical lens opacities, usually without visual impact.

•Congenital glaucoma is present in 60% of cases.

•Other occasional findings include miosis and poor pupillary dilation, and posterior lenticonus.

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Fig. 9.27 Some syndromic associations of congenital cataract. (A) Lowe syndrome; (B) Down syndrome; (C) Hallermann–Streiff–François syndrome

(Courtesy of N Rogers – fig. C)

Fabry' disease

1Pathogenesis. Fabry disease is an X-L lysosomal storage disorder caused by deficiency of α-galactosidase A.

2Systemic features include periodic burning pain in the extremities, purple cutaneous telangiectasis (angiokeratoma corporis diffusum, see Fig. 6.67A), hypertrophic cardiomyopathy and renal disease.

3Ocular features

•Cataracts may consist of subtle minute dots along the suture lines or granular white subcapsular wedge-shaped opacities with the base at the equator.

•Other findings include vortex keratopathy (see Fig. 6.67B), conjunctival vascular tortuosity (see Fig. 6.67C) and retinal vascular tortuosity (especially venous).

Mannosidosis

1Pathogenesis. Mannosidosis is an AR disorder with deficiency of α-mannosidase and consequent excretion of mannose-containing oligosaccharides in the urine.

2Systemic features. There are two types:

aInfantile, which is characterized by early rapidly progressive mental deterioration, hepatosplenomegaly and bony deformities.

bJuvenile-adult in which mental deterioration does not occur until late childhood. Patients also manifest facial anomalies, deafness, muscular weakness and spinal abnormalities.

3Ocular features

•Punctate lens opacities arranged in a spoke-like pattern in the posterior lens cortex are common.

•Corneal clouding is less common.

Other metabolic disorders

These include hypoparathyroidism, pseudohypopara-thyroidism, hypoglycaemia and hyperglycaemia.

Associated intrauterine infections

Congenital rubella

1Pathogenesis. Congenital rubella (German measles) results from transplacental transmission of virus to the fetus from an infected mother, usually during the first trimester of pregnancy that may lead to serious chronic fetal infection and malformations. The risk to the fetus is closely related to the stage of gestation at the time of maternal infection. Fetal infection is about 50% during the first 8 weeks, 33% between weeks 9 and 12, and about 10% between weeks 13 and 24.

2Systemic features include spontaneous abortion, stillbirth, congenital heart malformations, deafness, microcephaly, mental handicap, hypotonia, hepatosplenomegaly, thrombocytopenic purpura, pneumonitis, myocarditis and metaphyseal bone lesions.

3Ocular features

•Cataract occurs in about 15% of cases. After the gestational age of 6 weeks, the virus is incapable of crossing the lens capsule so that the lens is immune. Although the lens opacities (which may be unilateral or bilateral) are usually present at birth, they may occasionally develop several weeks or even months later. The opacity may involve the nucleus, with a dense pearly appearance or may present as a more diffuse opacity involving most of the lens. The virus is capable of persisting within the lens for up to 3 years after birth.

•Other ocular manifestations include microphthalmos, glaucoma, retinopathy, keratitis, anterior uveitis and iris atrophy, extreme refractive errors, pendular nystagmus and strabismus secondary to poor vision. Almost all microphthalmic eyes have cataracts and almost all cataractous microphthalmic eyes have glaucoma.

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Toxoplasmosis

1 Systemic features include seizures, hydrocephalus, microcephaly, hepatosplenomegaly, deafness and intracranial calcification.

2Ocular features apart from cataract include chorioretinitis, microphthalmos and optic atrophy.

Cytomegalovirus infection

1 Systemic features include jaundice, hepatosplenomegaly, microcephaly and intracranial calcification.

2Ocular features apart from cataract include chorioretinitis, microphthalmos, keratitis and optic atrophy.

Varicella

1Systemic features include mental handicap, cortical cerebral atrophy, cutaneous scarring and limb deformities; death in early infancy is common.

2Ocular features apart from cataract include microphthalmos, Horner syndrome, chorioretinitis, optic disc hypoplasia and optic atrophy.

Associated chromosomal abnormalities

Down syndrome (trisomy 21)

1Systemic features include mental handicap, stunted growth, upward-slanting palpebral fissures, epicanthic folds, flat midface with relative prognathism (Fig. 9.27B), brachycephalic skull with flattening of the occiput, broad short hands with a single transverse palmar (simian) crease, protruding tongue, small ears, excess skin on the back of the neck, thyroid dysfunction, cardiorespiratory disease (particularly Fallot tetralogy) and reduced life span.

2Ocular features

•Cataract of various morphology occur in about 75% of patients. The opacities are usually symmetrical and often develop in late childhood.

•Other features include iris Brushfield spots and hypoplasia, chronic blepharitis, myopia, strabismus, keratoconus and anomalous optic disc vasculature.

Edwards syndrome (trisomy 18)

1Systemic features include micrognathia, webbed neck, short digits and clenched hands, low-set ears, deafness, cardiac anomalies, mental handicap and very early demise.

2Ocular features apart from cataract include ptosis, microphthalmos, corneal opacity, uveal and disc coloboma and vitreoretinal dysplasia.

Cri du chat syndrome (partial deletion of 5p)

1Systemic features include microcephaly, growth retardation, low-set ears, cat-like cry and mental handicap.

2Ocular features apart from cataract include hypertelorism, down-sloping palpebral fissures and strabismus.

Associated skeletal syndromes

Hallermann–Streiff–François syndrome

1Systemic features of this sporadic condition include frontal prominence, small beaked nose, baldness (Fig. 9.27C), progeria, micrognathia and pointed chin, short stature, hypodontia and a narrow upper respiratory airway.

2Ocular features

•Cataract, which may be membranous (see Fig. 9.26F), occurs in 90% of cases.

•Other features include blue sclera, bilateral microphthalmos, disc coloboma, nystagmus and strabismus.

Nance–Horan syndrome

1Systemic features of this X-L condition include supernumerary incisors, prominent ears, anteverted pinnae and shortened metacarpals.

2Ocular features. Cataract may be dense and associated with mild microphthalmos. Female carriers may show a prominent Y suture or have Y suture opacities (see Fig. 9.25F).

Management

Ocular examination

Since a formal estimate of visual acuity cannot be obtained in the neonate, reliance is required on the density and morphology of the opacity, associated ocular findings and the visual behaviour of the child in order to assess the visual significance of the opacity. It is also important to examine parents and siblings.

1Density and potential impact on visual function is assessed on the basis of appearance of the red reflex and the quality of the fundus view on direct and indirect ophthalmoscopy; examination of the neonate has been made easier with the introduction of high quality portable slit-lamps. On ophthalmoscopy cataract density is graded as follows:

•A very dense cataract occluding the pupil will preclude any view of the fundus and the decision to operate is straightforward.

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