All are true about retinitis pigmentosa EXCEPT

B i.e. Early diagnosis & treatment prevents progression - Retinitis pigmentosa may be associated with Usher's syndrome, NARP (= Neuropathy, Ataxia, RP) syndrome, Bassen Karzweig syndrome (a beta lipoproteinaemia = deficiency of Beta lipoproteins), Friedreich's ataxia, Bardet Biedl syndrome, Cockayne's syndrome, Refsum disease (phytanic acid alpha hydrolase deficiency), Kearns-Sayre syndrome, and HaXgren's syndrome. Mn-"Use No Basse (1141) Fried Cock Bird Relief (Fight) in Shared Hall" Retinitis pigmentosa is a b/1 progressive degenerative disease of rods & cones beginning in childhood & resulting in blindness in middle or advanced age. No treatment is effective in preventing progression(2. It may be sporadic, AD or X-linked with visual acuity not dimishine till late in courseQ. Pigmentary Retinal Dystrophy/ Retinitis Pigmentosa (R.P.) RP encompasses clinically and genetically diverse group of diffuse retinal dystrophies that affect the photoreceptors (rodes more than cones) and retinal pigment epithelium (RPE), involving entire fundus. Although initial geographical involvement begin either in periphery or macula. Death of rod photoreceptors impaired vision in dim light, cause tunnel vision and prolonged dark adaptation. This primary pigmentary retinal dystrophy is hereditary disorder affecting rodes more than cones and characterized by night blindness, tubular vision, annular (ring) scotoma bony spicule pigmentation, aeriolar attenuation and waxy pallor of optic discQ Etiology Many cases are d/t mutation of pro-23-his rhodopsin gene. RP may occur as isolated sporadic disorder, or be inherited in an autosomal dominant (AD has best prognosis) > X-linked usually recessive (least common but most severe. Female carriers may have normal fundi or exhibit a golden metallic tapetal reflex temporal to the macula & atrophic & pigmentary peripheral irregularities). - Male:Female = 3:2 Associated Syndromes 1. Bassen Karzweig Syndrome (AR)Q is d/t deficiency of betalipoproteinQ resulting in intestinal malabsorption (jejunal biopsy is diagnostic) + RP, ataxia (spinocerebellar) & acanthocytosis. Treatment is vitamin E 2. Refsum Disease is an AR deficiency of enzyme phytanic acid 2 hydroxylaseQ resulting in accumulation of phytanic acid + polyneuropathy, cerebellar ataxia, deafness, anosmia, cardiomyopathy, icthyosis & elevated CSF protein in the absence of pleocytosis (cytoalbuminous inversion) + RP with salt pepper changes. Usher's Syndrome (AR)Q is RP & sensoryneural labrynthine deafness 4. Kearns- Sayre syndrome Q is mitochondrial cytopathy (d/t mitochondria DNA deletion) characterized by atypical RP (coarse pigment clumping in central fundus) with chronic progressive ophthalmoplegia (ocular myopathy eg. ptosis) & hea block.. 5. Bardet-Biedl/Laurence Moon Biedl Syndrome (ARQ) is characterized by RP, obesity, hypogenitalism, polydactyly and mental retardationQ. 6. Cockayne's Syndrome is RP dwarfism, deafness, mental retardation, nystagmus, ataxia, bird like facies, premature aging & flexion contracture of limbs. Hallgren's syndrome is RP, deafness, cerebellovestibular ataxia & mental retardation. Friedreich's ataxia is RP, posterior column disease, ataxia, nystagmus & subaoic stenosis. 9. NARP (Neuropathy, Ataxia and RD syndrome Treatment No treatment is effectiveQ. Vitamin A may be useful. X-linked usually recessive (least common but most severe. Female carriers may have normal fundi or exhibit a golden metallic tapetal reflex temporal to the macula & atrophic & pigmentary peripheral irregularities). - Male:Female = 3:2 Associated Syndromes 1. Bassen Karzweig Syndrome (AR)Q is d/t deficiency of betalipoproteinQ resulting in intestinal malabsorption (jejunal biopsy is diagnostic) + RP, ataxia (spinocerebellar) & acanthocytosis. Treatment is vitamin E 2. Refsum Disease is an AR deficiency of enzyme phytanic acid 2 hydroxylaseQ resulting in accumulation of phytanic acid + polyneuropathy, cerebellar ataxia, deafness, anosmia, cardiomyopathy, icthyosis & elevated CSF protein in the absence of pleocytosis (cytoalbuminous inversion) + RP with salt pepper changes. 3. Usher's Syndrome (AR)Q is RP & sensoryneural labrynthine deafness 4. Kearns- Sayre syndrome Q is mitochondrial cytopathy (d/t mitochondria DNA deletion) characterized by atypical RP (coarse pigment clumping in central fundus) with chronic progressive ophthalmoplegia (ocular myopathy eg. ptosis) & hea block.. 5. Bardet-Biedl/Laurence Moon Biedl Syndrome (ARQ) is characterized by RP, obesity, hypogenitalism, polydactyly and mental retardationQ. 6. Cockayne's Syndrome is RP dwarfism, deafness, mental retardation, nystagmus, ataxia, bird like facies, premature aging & flexion contracture of limbs. 7. Hallgren's syndrome is RP, deafness, cerebello-vestibular ataxia & mental retardation. 8. Friedreich's ataxia is RP, posterior column disease, ataxia, nystagmus & subaoic stenosis. 9. NARP (Neuropathy, Ataxia and RD syndrome Treatment No treatment is effectiveQ. Vitamin A may be useful. " v:shapes="_x0000_s1027">Clinical Features - Diagnostic criteria for RP include bilateral involvement (mostly) with loss of peripheral and night vision along with classical tried of RP (1) aeriolar attenuation (2) retinal bone spicule pigmentation and (3) waxy disc pallor - Nyctalopia (night blindness) i.e. impaired vision in dim light is earliest feature, most commonly seen in young adults (2nd - 3,d decade). - Prolonged (defective) dark adaptation i.e. slowed adaptation to decreased (or even increased) lighting. Patients have problem in dimly lit theaters, restaurants and when they come indoors from bright sun light - Visual field constriction i.e. slowly progressive loss of peripheral vision or concentric contraction of visual field results in characteristic tubular (tunnel) vision. It occurs in midstage of disease and there is poor correlation between acuity and extent of tunnel vision. Patient may appear clumsy & colloid with objects b/ o unrecognized tunnel vision. - Ultimately central vision is also lost by 50-60 years of age. Later manifestations (complications) include posterior sub capsular cataract (in middle age), cystoids macular edema. Both reduce central acuity even when the RP affects the peripheral retina only. Choroidal bodies (sclerosis), progressive chorioretinal atrophy and epiretinal membrane may be other latge complications Fundus Examination - Classical key features include atrophy and thinning of RPE, narrowing (attenuation) of retinal aerioles and bone spicule intraretinal pigmentary changes (typically perivascular and resembling bone corpuscles). These changes are initially found in mid peripheral (equatorial) regions f/b far peripheral retina with relative preservation of macula. - There is gradual increase in density with anterior and posterior spread, resulting in tessellated fundus appearance (d/t RPE atrophy) and unmasking of choroidal vessels. - Gliotic waxy nerve pallor of optic disc (waxy pale optic disc) from reactive gliosis, macular atrophy, epiretinal membrane & CMG are late features. Perimetry - Small mid peripheral scoloma (earliest) that gradually coalesce to form the classical annular or ring scotoma (complete or paial), which expands both peripherally & centrally. It leaves tiny central island of vision which may eventually be lost. - Useful in monitoring progression of disease Dark Adaptometry - Prolonged dark adaptation is useful for diagnosing early unceain cases ERG - In early RP, scotopic rod and combined response is reduced (i.e. ERG is subnormal) Gradually photopic response becomes reduced and eventually ERG is extinguished EOG - Markedly subnormal with absence of light rise (peak) - Retinitis pigmentosa sine pigmento is characterized by all clinical features except there is no visible pigmentary changes in the fundus - Retinitis punctata albescens is characterized by multiple scattered white dots mostly between posterior pole & equator. Other findings are same to R.P. Sectorial R.P. Involvement of only one quadrant (usually nasal) of the fundus - Pericentric R.P. All features are similar except that pigmentary changes are confined to an area, immediately around the macula.