Ординатура / Офтальмология / Английские материалы / Pediatric Ophthalmology Current Thought and A Practical Guide_Wilson, Saunders, Trivedi_2008

Contents

26.2.1Albinism  . . . . . . . . . . . . . .   389

26.2.2Congenital X-linked Retinoschisis  . . . .   390

26.2.3Heredodegenerative Retinal Degeneration    391

26.2.4Best’s Disease  . . . . . . . . . . . .   393

26.2.5Stargardt’s Disease/Fundus Flavimaculatus    393

26.3Vasoproliferative Vitreoretinopathies  . . .   394

26.3.4Norrie’s Disease  . . . . . . . . . . .   396

26.3.5Incontinentia Pigmenti  . . . . . . . .   396

26.3.6Pediatric Choroidal Neovascularization  . .   397

26.4Pediatric Rhegmatogenous Retinal

Detachment  . . . . . . . . . . . . .   397

26.4.1 Stickler Syndromes  . . . . . . . . .   398

26.4.2Marfan Syndrome  . . . . . . . . . .   398

26.4.3Colobomatous Rhegmatogenous Retinal Detachment  . . . . . . . . . . . . .   398

Core Messages

Albinism

•The various subtypes of oculocutaneous albinism are typically inherited in

an autosomal recessive fashion, whereas ocular albinism is inherited in an X-linked pattern.

•Decreased visual acuity occurs as a consequence of foveal hypoplasia.

•Misrouting of optic nerve fibers is common with temporal retina fibers inappropriately routed contralaterally instead of ipsilaterally, resulting in impaired stereopsis and strabismus.

Congenital X-linked Retinoschisis

•Congenital X-linked retinoschisis (CXLRS) is the most common cause of juvenile macular degeneration in males.

•Retinal splitting occurs in all layers of the retina.

•Foveal schisis is seen in all forms of CXLRS, while lamellar and peripheral bullous schisis are variably present.

•A selectively reduced b-wave electroretinogram (ERG) is characteristic of CXLRS, and is useful in differentiating CXLRS from other disease entities.

•Apart from foveal schisis, vision may also be compromised by amblyopia due to vitreous hemorrhage, a schisis bulla which interrupts the visual axis or extends through the macula, or a combined schisis-rhegmatogenous retinal detachment (RRD).

Heredodegenerative Retinal Degeneration

•Retinitis pigmentosa (RP) is a heterogeneous group of inherited diseases that typically results in bilateral, symmetric, progressive degeneration of photoreceptor and retinal pigment epithelial (RPE) cells.

•Pigmentary changes in the retinal midperiphery, waxy pallor of the optic nerve, retinal arteriolar attenuation, visual

field abnormalities, and a flat scotopic

ERG are the characteristic features.

•Syndromic causes of RP should be excluded by careful family history, medical history, and physical examination.

Best’s disease

•Best’s disease is characterized by an abnormal electrooculogram.

•The clinical appearance of Best’s disease is highly variable even within the same family.

Stargardt’s Disease/Fundus Flavimaculatus

•Stargardt’s disease/fundus flavimaculatus (STGD1/FF) is the most common recessively inherited macular degeneration.

•It is characterized histopathologically by the accumulation of lipofuscin pigment in the RPE cells.

•The phenomenon of lack of choroidal fluorescence (“dark choroid”) during the fluorescein angiogram is present in at least 50% of STGD1/FF patients.

Familial Exudative Vitreoretinopathy

•Familial exudative vitreoretinopathy

(FEVR) is a hereditary retinal vascular disorder characterized by an avascular peripheral retina, exudation, and traction retinal detachment.

•Eighty-five percent of eyes are bilaterally involved, and asymmetric bilaterality is common.

•Infants presenting in the first year of life usually have a worse prognosis.

Persistent Fetal Vasculature Syndrome

•The term refers to a spectrum of structural changes in which the hyaloid vessels

and tunica vascular lentis persist in an eye following birth, resulting in lens and/or posterior pole abnormalities.

•Persistent fetal vasculature syndrome (PFVS) is unilateral 90% of the time, and the eye may range

from small to normal in size.

Coats’ Disease

•Typically a unilateral retinal vascular disorder occurring predominantly in young males in the first decade of life.

•Infants presenting in the first year of life usually have a worse prognosis.

Norrie’s Disease

•Patients often present as infants with bilateral profound visual impairment, retinal dysplasia, and leukocoria.

•Sensorineural hearing loss and mental impairment occur in approximately 30% of patients.

Incontinentia Pigmenti

•Inherited as an X-linked dominant trait typically seen in only females, as it is usually lethal in males.

•Ocular findings consist of peripheral retinal non-perfusion and vitreoretinal neovascularization.

•Cutaneous involvement is characteristic with skin vesicles beginning at birth and hyperand hypopigmented papular lesions on the trunk and extremities.

•Skin, dental, central nervous system, and skeletal involvement are associated features.

Pediatric Choroidal Neovascularization

•Typically occurs as a complication of infectious conditions, hereditary conditions, inflammatory conditions, or traumatic choroidal rupture.

Pediatric Retinal Detachment

•Though uncommon, pediatric RRD has a high rate of vision-threatening pathology in the companion eye.

•Non-traumatic retinal detachments in children are often syndromic.

•Retinal detachment is usually detected otherwise either on routine examination or routine follow-up to a prior surgical procedure.

26.1 Introduction

Pediatric retinal diseases often present with striking clinical features, and can have a profound impact on visual outcome. Alternatively, both clinical findings and visual impact can be subtle. Some of these conditions are covered elsewhere in this text: retinopathy of prematurity (ROP) (Chap. 25), retinoblastoma (Chap. 27), and pediatric uveitis (Chap. 28). The pages that follow will provide practical insight into the current thinking and practice regarding the more common heredodegenerative retinal disorders, vasoproliferative retinopathies, and retinal detachment syndromes occurring in children.

26.2 Medical Pediatric Retina

26.2.1 Albinism

Albinism is comprised of a group of clinically and genetically heterogeneous disorders characterized by

Clinical Findings

Diagnosis of albinism is typically based on the clinical presentation of ocular and/or systemic findings.

Both types of OCA1 are born with white hair and skin, whereas OCA2 has a variable amount of visible pigmentation at birth. Clinically, the phenotype of

OA is similar to that of the ocular findings observed in OCA but with normal skin and hair pigmentation. Carrier females of OA, however, may have a fundu-

26.2.2Congenital X-linked Retinoschisis

Congenital X-linked retinoschisis (CXLRS) is predominantly inherited in an X-linked recessive distribution. It is the most common cause of juvenile macular degeneration in males affecting 5,000–25,000 live births worldwide. Affected individuals have a 96% incidence of a mutation in the XLRS1 gene, resulting in expression of an aberrant retinoschisin protein.

Mothers are typically asymptomatic obligate carriers of the disease with normal retinal examinations and normal electroretinograms (ERG), but often have a positive family history of male members in the family with a history of vision loss [14].

Clinical Findings

Patients may present in infancy with a diagnosis of amblyopia, strabismus, or nystagmus, but most patients will present between 5 and 10 years of age with difficulties in school. The disease is characterized by structural deficits in the retinal layers resulting in foveal schisis and peripheral bullous schisis cavities most commonly affecting the inferior retinal periphery. Retinal splitting was previously thought to occur primarily in the nerve fiber layer.Analysis of the retinal layers by OCT has revealed that schisis occurs in all layers of the retina, most commonly in the outer plexiform layer. The finding on OCT of fine, coalescing extramacular intraretinal schisis cavities is referred to as lamellar schisis. Foveal schisis is seen in all forms of CXLRS, while lamellar and peripheral bullous schisis are variably present [11]. Electroretinography (ERG) typically shows an “electronegative” waveform, consisting of a normal a-wave amplitude and a selectively reduced b-wave amplitude.

Bullous peripheral schisis cavities may cause amblyopia when they extend superiorly to interrupt the visual axis. Disruption of the thin inner wall of schisis bullae may result in interruption of a retinal vessel and amblyogenic vitreous hemorrhage. Rhegmatogenous retinal detachment (RRD) is uncommon, and may be difficult to diagnose in CXLRS.

Clinical Course and Management

The clinical course is variable with severity in visual loss ranging from 20/50 to no light perception. Currently there is no treatment for foveal or lamellar schisis in CXLRS. Vitreoretinal surgery may be necessary when bullous CXLRS results in interruption of the visual axis or threatens to extend through the fovea, to address an amblyogenic vitreous hemorrhage, and to repair combined schisis-RRD. Laser retinopexy can create a mechanical barrier to prevent progression of bullous retinal schisis, but there

is risk of iatrogenic full-thickness retinal break. Correction of refractive errors and early intervention with amblyopia therapy are vital during the entire visual development of the child. Low-vision aids in conjunction with a low-vision specialist can be invaluable as the child gets older. Protective eyewear is recommended.

26.2.3Heredodegenerative Retinal Degeneration

Pigmentary retinopathy is a generalized reference to a panretinal deterioration of the retina and retinal pigment epithelium (RPE). The pigmentary retinopathies can be divided into primary retinitis pigmentosa

(RP), in which the disorder is exclusively found in the eyes without any other systemic manifestations, and secondary pigmentary retinopathy, in which the retinal degeneration is associated with a multiorgan syndrome.

26.2.3.1Primary Retinitis Pigmentosa

Retinitis pigmentosa is a heterogeneous group of inherited diseases that typically results in bilateral, symmetric, progressive degeneration of photoreceptor and RPE cells.

Inheritance Pattern

Retinitis pigmentosa is a heterogeneous assembly of gene mutations affecting various molecular pathways, and with diverse inheritance patterns [3].Autosomal dominant (AD) RP has been estimated to comprise 10% of cases, is usually the mildest form, and is often undiagnosed until the second to fourth decade. Autosomal recessive (AR) RP comprises 84% of cases, is often more severe, usually present in the first two decades of life with significant loss of peripheral visual field and visual acuity deterioration to worse than 20/200. Forty percent of cases are associated with some form of systemic syndrome. X-linked (XL) cases constitute only 6% of all cases, yet tend to have the most severe phenotype of RP. Clinically,

affected males show early onset and present within the first decade of life with severe retinal degeneration. Carrier females can have no clinical effect to severe dysfunction depending on the lyonization of their retina and RPE cells [8].

Clinical Findings

Children with RP typically present either asymptomatic with a known family history or symptomatic with a variety of symptoms and signs: night blindness and symptoms of difficulty with dark adaptation, poor vision, nystagmus, and strabismus are common. The scotopic ERG is typically flat. Kinetic (Goldmann) visual field (VF) testing may reveal a classic “ring scotoma” caused by mid-peripheral rod degeneration early in the disease. Central vision is preserved until relatively late.

The classic triad of RP is “bone spicule” pigmentary accumulations in the mid-periphery, waxy pallor of the optic nerve, and retinal arteriolar attenuation. Older patients may develop vitreous cells, cystoid macular edema, macular pucker, and/or macular pigment migration. Optic nerve drusen and posterior subcapsular cataract may occur as well.

Clinical Course and Management

As the disease progresses, central visual acuity decreases as cone function deteriorates. A thorough history, including a detailed family history, physical examination, ERG, and kinetic visual field testing should be performed in the workup of any pigmentary retinopathy. Fluorescein angiography and OCT are useful to detect and monitor cystoid macular edema, a potentially reversible cause of vision loss in RP patients when treated with systemic or topical carbonic anhydrase inhibitors. Posterior subcapsular cataract may be disproportionately symptomatic due to the impact on central vision. Early cataract surgery is commonly necessary to maintain visual acuity. Periodic monitoring of lens and macular status, serial perimetry, genetic counseling, and working with a low-vision specialist are appropriate management considerations.

26.2.3.2Secondary Pigmentary Retinopathies

Usher disease is a heterogeneous autosomal recessive disease, and usually manifests clinically as initial bilateral sensorineural hearing loss followed by vision loss secondary to RP in late childhood or adolescence. Total blindness can occur by the third or fourth decade. Type I Usher disease patients have severe hearing loss with vestibular dysfunction and an earlier onset of vision loss compared to type II Usher disease patients who have a milder course with normal vestibular function. Type III has a variable course with regard to onset of vision loss, vestibular dysfunction, and progressive hearing loss [6].

Leber’s congenital amaurosis (LCA) presents in the first year of life with severely affected vision, poor pupillary reactions, and sensory nystagmus. Visual acuity ranges from 20/200 to no light perception when older. Clinical findings are varied as well, and patients may have a normal-appearing fundus, colobomas, bull’s eye maculopathy, peripheral bone spicules, or diffuse peripheral fine white dots. Keratoconus, cataract, and hyperopia can also be associated with LCA. A markedly attenuated or non-recordable

ERG in an infant is characteristic [1].

The infantile or late-infantile form of neuronal ceroid lipofuscinosis (NCL), or Batten’s disease, is one of the most common neurogenic lysosomal storage diseases of childhood, and can present with visual inattention and nystagmus. Hypotonia, seizure disorder, developmental delay, vision loss, and poor motor control are trademarks of NCL.

Other syndromic causes of RP include BardetBiedl syndrome (polydactyly, intellectual developmental delay, hypogonadism, obesity, renal dysfunction), Kearns-Sayre syndrome (chronic progressive external ophthalmoplegia, ataxia, ptosis, sensorineural hearing loss, heart block cardiomyopathy, white matter brain disease with a mitochondrial inheritance pattern), Friedrich’s ataxia (ataxia, sensory loss, cerebellar dysfunction that is associated with vitamin E deficiency), and abetalipoproteinemia, also known as Bassen-Kornzweig syndrome (characterized by ataxia, fat intolerance, sensory neuropathy, and acanthocytosis). Patients with abetalipoproteinemia should be on a fat-free diet and receive supplemental vitamin E, A, and K.

A detailed family and medical history, and physical examination should identify systemic involvement associated with a pigmentary retinopathy, and the diagnosis needs to be made such that treatable and potentially life-threatening systemic conditions can be managed.

Best’s disease is characterized by an abnormal

EOG (most affected patients have an Arden ratio of less than 1.5, as compared to a normal value of greater than 1.7), with a normal ERG and dark adaptation. The EOG measures the standing electric potential that exists across the RPE, which oscillates depending on illumination intensities.

Best’s disease is inherited in an autosomal dominant manner with variable expressivity, with phenotypes ranging from an opthalmoscopically normal-appear- ing fundus (seen in 5–32% of carriers) to an orangeyellow vitelliform lesion to a gliotic macular scar. The penetrance of Best’s disease, however, is complete as all patients with the genetic disorder have an abnormal electrooculogram (EOG), the hallmark of this macular dystrophy. The disease locus has been mapped to 11q13, and the defective gene in Best’s disease is VMD2, which encodes for the RPE transmembrane chloride channel, bestrophin [9].

Clinical Findings

The clinical appearance of Best’s disease is highly variable even within the same family. The most characteristic appearance is the orange-yellow “egg-yolk” (vitelliform) lesions in the central macula. Vitelliform lesions may have a variety of appearances depending on the resorption of lipofuscin pigment. Choroidal neovascularization (CNV), a well-demarcated gliotic scar, and macular RPE atrophy may also occur. Vitelliform lesions have been reported in infants as early as 1 week old, and may persist into late adulthood. Multiple lesions have also been described in the same eye, referred to as multifocal Best’s disease.

Fluorescein angiographic findings depend on the type of fundus lesion present. Lipofuscin blocks fluorescein transmission early. Resorption of lipofuscin in the vitelliform lesion and subsequent RPE atrophy results in RPE transmission defects, early hyperfluorescence that fades in the late phase of the angiogram. When present, CNV demonstrates typical early hyperfluorescence followed by late, expanding leakage.

Disciform scars will stain with dye in the late phases of the angiogram.

Vision may be normal or mildly reduced even with a large subfoveal vitelliform lesion. Most (75%) patients maintain 20/40 vision or better in at least one eye through middle age. All family members of affected patients should undergo dilated funduscopic examination, and be offered genetic testing and counseling. There is no treatment for Best’s disease apart from CNV, which is infrequent.

26.2.5Stargardt’s Disease/ Fundus Flavimaculatus

Stargardt’s disease/fundus flavimaculatus (STGD1/

FF) is the most common recessively inherited macular degeneration, affecting roughly 1 in 10,000 people. Dominant inherited pedigrees have been reported. Although controversial, Stargardt’s disease (STGD) and fundus flavimaculatus (FF) are considered as part of a spectrum of the same disease entity, STGD1/FF, with different allelic expressions. Autosomal recessive STGD is caused by a mutation in the ABCA4 (ABCR) gene, which encodes the ATP-binding cassette transporter on chromosome 1p. FF maps to this same region. The pathologic accumulation of toxic lipofuscin pigment in the RPE cells suggests a disorder in lipopigment metabolism leading to RPE cell dysfunction, subsequent photoreceptor death, and severe vision loss in affected patients [15].

Clinical Findings

Stargardt’s disease/fundus flavimaculatus is typically a bilaterally symmetric progressive retinal degeneration. The classic Stargardt phenotype is a central

beaten-bronze bull’s eye maculopathy with yellowwhite flecks at the level of the RPE or deep retina, usually concentrated in paracentral macula and the posterior pole. Children with STGD will usually present with visual complaints and central macular involvement in the early to mid-teens, although onset of symptoms typically starts several years prior to presentation. Patients with the FF phenotype–par- acentral and more diffuse peripheral flecks as compared to STGD patients without atrophic macular involvement—will typically present in early or midadult life. The peripheral flecks are transitory and may appear in the second decade, and disappear and reappear over decades. The FF phenotype, however, tends to have a more severe deterioration of retinal and visual function as compared to patients with the STGD phenotype with or without typical central lesions.

Fluorescein angiography is often useful for diagnosis. The phenomenon of a “dark” or “silent” choroid describes the lack of choroidal fluorescence during the fluorescein angiogram, and this finding is present in at least 50% of STGD1/FF patients. The absence of this sign does not exclude the diagnosis of

STGD1/FF. The dark choroid effect has been thought to be due to blockage of the choroidal flush by the lipofuscin-laden RPE cells. This theory has been challenged by little or lack of correlation between lipofuscin concentration and presence or absence of a dark choroid on fluorescein angiography. Flecks may be hypofluorescent, presumably because of blockage, or display adjacent hyperfluorescence secondary to

RPE transmission defect.

Clinical Course and Management

Early in the disease, loss of central vision may be out of proportion to funduscopic examination. Visual dysfunction can range from mild to expanding central scotoma over time, or have peripheral degeneration with accompanying loss of peripheral visual field and ERG loss. Visual acuity typically ranges from 20/50 to 20/200. There is currently no treatment for STGD/ FF.

26.3Vasoproliferative Vitreoretinopathies

26.3.1Familial Exudative Vitreoretinopathy

Familial exudative vitreoretinopathy (FEVR) is an inherited retinal vascular disorder characterized by an avascular peripheral retina, extraretinal fibrovascular proliferation, exudation, an abnormal vitreoretinal interface, and traction retinal detachment. Patients with the FEVR mutation may present with an avascular retinal periphery without exudation or vasoproliferative findings, or with a clinically normal retina

(incomplete penetrance although mutation present). The disease may be inherited in an autosomal dominant, autosomal recessive, or X-linked manner. Family history can be instrumental in making a diagnosis. In 55% of cases there is no known family history of the disease, though on peripheral fundus examination vascular abnormalities are commonly uncovered in an asymptomatic parent. Earlier reports of retinopathy of prematurity (ROP) in full-term infants were likely, in reality, infants with FEVR and a negative family history [18].

Clinical Findings

The clinical manifestations of FEVR include an avascular peripheral retina, neovascular buds at the junction of vascular and avascular retina, fibrovascular proliferation extending into the vitreous, and often a characteristic traction detachment producing a retinal foldwhichextendsthroughthemacula.Subretinalexudates, dragged retinal vessels, and retinal folds that can extend to the lens may also be seen. The clinical appearance may mimic not only ROP, but also Coats’ disease, Norrie’s disease, incontinentia pigmenti, and retinoblastoma. The diagnosis is usually made by clinical examination, patient history, birth history, and family history. In its most severe forms, a total retinal detachment due to exudation and fibrovascular proliferation can result, and render diagnosis more challenging. FEVR is usually, but not invariably, bilateral and asymmetric. Fluorescein angiography will often unmask peripheral non-perfusion in a seemingly normal-appearing companion eye.

Clinical Course and Management

Familial exudative vitreoretinopathy is a chronic life-long disease with periods of exacerbation and remission and frequent examinations are necessary for appropriate management. Patients who present with symptomatic FEVR (strabismus, amblyopia, or leukocoria most commonly) in infancy and early childhood often have a poor prognosis. Treatment of FEVR depends on the severity of the pathology. Exudation, even if asymptomatic, is initially treated with laser ablation of the avascular retina. Fluorescein angiography can be useful to identify the extent of the avascular retina and guide peripheral ablation. Tractional retinal detachment may be managed by vitrectomy in some cases. Family members of suspected patients with FEVR should have a thorough peripheral retinal examination to aid in the diagnosis.

26.3.2Persistent Fetal Vasculature Syndrome

Persistent fetal vasculature syndrome (PFVS), previously known as persistent hyperplastic primary vitreous (PHPV), refers to a spectrum of structural changes in which the hyaloid vessels and tunica vascular lentis (TVL) persist in an eye following birth.

The hyaloid system, or primary vitreous, fills the vitreous cavity and is more than just the hyaloid vessel connecting the optic nerve to the posterior lens. The

TVL extends both anterior and posterior to the lens, interweaving with the hyaloid system posteriorly and the ciliary processes as well. The hyaloid system typically regresses by 28–30 weeks of gestational age. Incomplete hyaloidal involution may result in a posterior lens opacity of variable severity, and a number of characteristic potential posterior pole abnormalities. No distinct genetic mutation has been associated for typical unilateral PFVS [19].

Clinical Findings

Ninety percent of the time PFVS is unilateral. Eyes with PFVS are typically, but not invariably, smaller compared to the normal fellow eye, with a posterior

lens opacity and a stalk that connects the posterior lens to the optic disc. Anterior or posterior changes may predominate in a given eye. Visual potential is most dependent on the extent of posterior involvement (especially optic nerve and peripapillary retina) and the size of the eye. Retinal dysplasia is found in varying amounts in PFVS, and may limit visual function as well.

Clinical Course and Management

When an eye is normal in size and leukocoria is the prominent ocular finding, the most important differential diagnostic consideration is retinoblastoma. Ultrasonographic and/or radiographic imaging (CT or

MRI) can be performed to detect intraocular calcifications and aid in the diagnosis.

Visual evoked potentials (VEP) are useful, comparing an affected eye to its normal companion, when trying to determine visual potential of the affected eye. If the visual evoked potential is positive, it is reasonable to consider surgical repair. With minor eccentric lens opacity, lens-sparing vitrectomy with interruption of the stalk is in order. Peripapillary retinal detachments will often resolve following vitrectomy, and the eye is allowed to grow more normally. Anatomic and visual results are variable following surgery, and depend not only on preoperative ocular anatomy but also timing of surgery, whether the lens was removed, and postoperative amblyopic therapy. Monocular precautions and the use of safety glasses lifelong are standard recommendations.

26.3.3 Coats’ Disease

Coats’ disease is typically a unilateral retinal vascular disorder (90%) occurring predominantly (up to 90%) in young males in the first decade of life. Inheritance is primarily sporadic. Mildly affected individuals can present late in adulthood, typically with vitreous hemorrhage in the setting of posterior vitreous detachment. Patients who are younger at presentation are affected more severely. No racial or ethnic predisposition or environmental factors have been linked to

Coats’disease [12].

Clinical Findings

Children typically will present with strabismus, leukocoria, or poor vision on routine vision screening. Characteristic funduscopic findings in Coats’ disease are focal vascular telangiectasias and “light bulb-shaped” aneurysmal dilatations. It is generally held that breakdown of the blood–retinal barrier of the capillary endothelium causes plasma leakage into vessel walls and ultimately form dilatations and telangiectasias. Continued leakage into nearby retinal tissue results in the characteristic intraretinal and subretinal cholesterol exudates, hemorrhage, and subretinal fluid.

More severely affected patients have an associated serous detachment of the neurosensory retina which can be localized or total. Visual compromise occurs as a consequence of accumulation of exudative material in the macular area, secondary macular changes

(RPE atrophy or subfoveal fibrosis), exudative detachment involving the macula, and amblyopia.

Clinical Course and Management

If left untreated, eyes with Coats’ disease deteriorate.

Gomez Morales reported that 64% of untreated patients who were followed for 5 years developed total retinal detachments and 32% developed secondary glaucoma [5]. Not uncommonly, advanced unilateral

Coats’ disease must be differentiated from retinoblastoma. Funduscopic (microvascular dilatations), ultrasonographic, and radiographic (CT or MRI) findings

(intraocular calcification) can help in the diagnosis when serous detachment or disorganization is a prominent feature.

Fluorescein angiography is helpful in juvenile Coats’ disease in not only diagnosis but also identifying treatable areas. Discrete “light bulb-shaped” aneurysmal vessels hyperfluoresce early and leak late into the subretinal space. In addition, normal-appear- ing areas of non-perfused retina are more effectively identified for treatment.

All abnormal vasculature and areas of non-perfu- sion are treated with photocoagulation or cryotherapy ablation. Multiple treatment sessions are often needed to adequately treat the abnormal vasculature initially. Recurrences may occur long after successful treatment. Consequently, children with Coats’ disease

should be followed every 6 months to monitor for additional ablative therapy as needed. In cases of partial retinal detachment, scleral buckle may be performed with external drainage of subretinal fluid to facilitate peripheral retinal ablation and reduce exudative activity.

26.3.4 Norrie’s Disease

Norrie’s disease is a rare vitreoretinal dystrophy that is inherited in an X-linked recessive pattern. Patients with Norrie’s disease often present with bilateral profound visual impairment, retinal dysplasia, and leukocoria. Sensorineural hearing loss and mental impairment occur in approximately 30% of patients. Ocular findings include retinal dysplasia, traction retinal detachment, vitreous hemorrhage, and persistent fetal vasculature. The retina peripheral to posterior pole detachment is often avascular. The Norrie’s disease gene (NDP), originally known as the EVR2 gene, encodes for the norrin protein, a member of the cysteine knot proteins, which acts as a ligand in the canonical Wnt receptor/beta-catenin signal transduction pathway. Dysregulation in NDP has led to a unifying classification system of congenital vitreoretinopathies as

“NDP-related,” and includes PFVS, Coats’ disease,

X-linked FEVR, and ROP [20].

Clinical Course and Management

If the patient has visual potential as demonstrated by a visual evoked potential, vitrectomy surgery can be considered to relieve the traction between the retina and the lens. Visual potential is limited to hand motions to light perception vision, even with resorption of subretinal fluid, due to the severity of retinal dysplasia. Molecular genetic analysis should be performed, and families should receive genetic counseling.

26.3.5 Incontinentia Pigmenti

Incontinentia pigmenti (IP; Bloch-Sulzberger syndrome) is inherited as an X-linked dominant trait.