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SYMPTOMS
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Nyctalopia (most common symptom), Vision loss, Visual field defects, Color vision defects, Photophobia, Flashes
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SIGNS
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Bilateral
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Early signs: Arteriolar narrowing with fine pigmentary changes in the mid-peripheral retina
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Late signs: Bone spicule pigment clumping with areas of chorioretinal atrophy that start in the mid-periphery and spread to the far periphery and posterior pole, Extensive arteriolar narrowing, Visible large choroidal vessels, Waxy optic nerve pallor
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Other signs associated with retinitis pigmentosa include Cystoid macular edema, Epiretinal membranes, Vitreous cells, Posterior subcapsular cataracts
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WORK-UP
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Pupils, Color vision (abnormal), Full eye exam with dilation, Visual field, OCT of the macula, Fundus Autofluorescence, Fluorescein Angiography, Fundus photos, Infrared photos, Electrodiagnostic testing (ERG: Abnormal / EOG: Abnormal), Dark adaptation (abnormal), Watzke-Allen test, Macular photostress test, Amsler grid
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TREATMENT
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Give take home Amsler grid in order to monitor for change
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Retinitis pigmentosa with no evidence of cystoid macular edema: Monitor
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There is no clear evidence that Vitamin A supplementation is actually beneficial but 15,000 IU/day of Vitamin A palmitate is still commonly recommended to these patients (Need to be aware of complications and contraindications if recommending high dose Vitamin A. Patient should be co-managed with PCP)
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Omega-3 (DHA) and 12mg of lutein may be beneficial to patients with retinitis pigmentosa
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Consider Luxturna gene therapy if retinitis pigmentosa occurs due to a mutation of the RPE65 gene but unfortunately this therapy is very expensive
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Recommend genetic counseling for other family members
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If the patient develops poor vision, refer to low vision
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Retinitis pigmentosa with cystoid macular edema: Begin oral acetazolamide 125mg 1 tab bid or topical dorzolamide 1gtt TID for 2 months (Need to be used with caution due to the potential complications of long-term use especially if patient is using oral acetazolamide. Always keep in mind the contraindications and side effects before prescribing these medications). If not effective, refer the patient to a retinal specialist ASAP for further evaluation and treatment
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If the patient presents with a visual significant posterior subcapsular cataract, refer for cataract surgery
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FOLLOW-UP
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If the patient presents with retinitis pigmentosa without any evidence of cystoid macular edema, the patient should be seen back in 6-12 months
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If the patient presents with retinitis pigmentosa with cystoid macular edema and is being monitored while using topical dorzolamide, the patient should be seen back every month (If the patient is using oral acetazolamide, the patient would need to be monitored on an even more frequent basis)
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After patient is evaluated and treated by a retinal specialist and the retina/macula is stable, the patient should be seen back every 6 months
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ADDITIONAL LAB | TESTS
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Genetic testing
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Rule out other syndromes that may be associated with retinitis pigmentosa
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Serum Vitamin A levels
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If patient is using long-term carbonic anhydrase inhibitors (especially oral acetazolamide), the patient needs to have kidney and liver function monitored
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ETIOLOGY
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Progressive apoptosis of the photoreceptors (rods before cones) with subsequent damage to the RPE
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Mode of inheritance can be sporadic (most common), autosomal dominant, autosomal recessive, or X-linked
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DIFFERENTIAL DX
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Choroideremia, Gyrate atrophy, Cone dystrophy, Thioridazine retinopathy, Ocular syphillis
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NOTES
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Retinitis pigmentosa is the most common inherited retinal condition in the world
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Patients with retinitis pigmentosa tend to be myopic
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Peripheral vision loss is typically first noted during adolescence. By the fifth decade of life, patients will typically have tunnel vision and VA that is around 20/200 to 20/400
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The classic “triad” associated with retinitis pigmentosa is bone spicules, arteriole attenuation, and waxy optic nerve pallor
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Retinitis pigmentosa can be isolated or associated with other syndromes which includes Usher Syndrome (most common syndrome associated with retinitis pigmentosa that also involves deafness and possible abnormal vestibular function)
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Atypical forms of retinitis pigmentosa include: Retinitis punctata albescens (presence of punctate white dots in the mid-periphery), Sector retinitis pigmentosa (confined only to one or two quadrants of the retina), Pericentric retinitis pigmentosa (confined only to the mid-periphery), Retinitis pigmentosa sine pigmento (little to no pigmentary changes noted in the retina)
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The autosomal dominant form of retinitis pigmentosa has the best prognosis and the x-linked form of retinitis pigmentosa has the worst prognosis
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