**4. Retinitis pigmentosa**

Retinitis pigmentosa (RP) is a heterogeneous group of diffuse retinal dystrophies characterized by a progressive dysfunction affecting the rod more than the cone photoreceptors (a rod-cone dystrophy). It is the most common hereditary fundus distrophy with a prevalence of approximately 1:5000. All forms of RP can present in the first or second decade of life (Kanski, 2011).

#### **4.1 Inheritance and systemic associations**

RP can be inherited as an autosomal dominant (ADRP), autosomal recessive (ARRP) or Xlinked recessive (XLRP) pattern. RP can occur as an isolated sporadic disorder with no family history. The age of onset, rate of progression, eventual visual loss and associated ocular/systemic features are related to the type of inheritance (Khani, 2011). Approximately 20% of these cases are ADRP, and 6% to 9% are XLRP. The remaining 71% to 84% are either ARRP or isolated simplex cases. Up to 40% of recessive cases are associated with other systemic pathologies or syndromes and 18% have associated hearing loss. The most common forms of ADRP appear to have a later onset and less severe clinical course than XLRP. Significantly reduced visual function usually occurs at a younger age in XLRP than in other forms of RP. Most patients with XLRP are legally blind by age 30. Important systemic associations are Basen-Kornzweig syndrome (abetalipoproteinaemia), Refsum disease, Bardet- Biedl syndrome and Usher syndrome (Drack, 2006).

#### **4.2 Symptoms and diagnosis**

Typically patients present with night blindness and visual field constriction. Central vision may or may not be involved. Classical retinal signs include bone-spicule pigmentation, arteriolar narrowing and disc pallor. Cystoid macular edema may occur. The fundus may be normal in the early stages of disease and this is often the case in young children. Electroretinography (ERG) is essential in the workup of inherited retinal dystrophies. Bright flash scotopic ERGs show a reduced a-wave, indicating rod photoreceptor dysfunction with less severe photopic ERG abnormalities. Perimetry is useful in monitoring the progression of disease. Perimetry initially demonstrates small mid-peripheral scotomas that gradually coalesce to form the classical annular scooma that correlates in location and shape to the extent of fundus pathology (Kanski, 2011).

#### **4.3 Treatment**

6 Complementary Pediatrics

patients with papilloedema. Horizontal diplopia due to 6th nerve palsy may accompany

Optic nerve glioma is the most common primary neoplasm of the optic nerve. A low-grade form of this neoplasm, called benign optic glioma, occurs most often in the pediatric patients. On the other hand, the aggressive form of optic glioma, is most common in adults. Many children with optic nerve glioma are also known to have neurofibromatosis type 1. Another optic nerve tumor is meningioma. Meningiomas are believed to arise from

Optic atrophy is the final common morphologic endpoint of any disease process that causes axonal degeneration in the optic nerve. There are two types; primary and secondary. Primary optic atrophy may be caused by lesions affecting the visual pathways from the retrolaminar portion of the optic nerve to the lateral geniculate body. Secondary optic

Retinitis pigmentosa (RP) is a heterogeneous group of diffuse retinal dystrophies characterized by a progressive dysfunction affecting the rod more than the cone photoreceptors (a rod-cone dystrophy). It is the most common hereditary fundus distrophy with a prevalence of approximately 1:5000. All forms of RP can present in the first or second

RP can be inherited as an autosomal dominant (ADRP), autosomal recessive (ARRP) or Xlinked recessive (XLRP) pattern. RP can occur as an isolated sporadic disorder with no family history. The age of onset, rate of progression, eventual visual loss and associated ocular/systemic features are related to the type of inheritance (Khani, 2011). Approximately 20% of these cases are ADRP, and 6% to 9% are XLRP. The remaining 71% to 84% are either ARRP or isolated simplex cases. Up to 40% of recessive cases are associated with other systemic pathologies or syndromes and 18% have associated hearing loss. The most common forms of ADRP appear to have a later onset and less severe clinical course than XLRP. Significantly reduced visual function usually occurs at a younger age in XLRP than in other forms of RP. Most patients with XLRP are legally blind by age 30. Important systemic associations are Basen-Kornzweig syndrome (abetalipoproteinaemia), Refsum disease,

Typically patients present with night blindness and visual field constriction. Central vision may or may not be involved. Classical retinal signs include bone-spicule pigmentation, arteriolar narrowing and disc pallor. Cystoid macular edema may occur. The fundus may be normal in the early stages of disease and this is often the case in young children. Electroretinography (ERG) is essential in the workup of inherited retinal dystrophies. Bright flash scotopic ERGs show a reduced a-wave, indicating rod photoreceptor dysfunction with

arachnoid cap cells, and they are usually attached to the dura.

atrophy is preceded by long-standing swelling of the optic nerve head.

the clinical picture.

**4. Retinitis pigmentosa** 

decade of life (Kanski, 2011).

**4.2 Symptoms and diagnosis** 

**4.1 Inheritance and systemic associations** 

Bardet- Biedl syndrome and Usher syndrome (Drack, 2006).

Although the photoreceptor cell death of retinitis pigmentosa cannot at be arrested or reversed currently, some vision threatening complications (cataract and macular edema) can be successfully managed. Additional molecular and surgical therapies targeting various stages of the disease are under investigation. (gene and stem cell-based therapies, prosthetic retinal implants, germ and somatic cell gene replacement, allele-specific targeting strategies and retinal transplantation etc.)
