Case 22: Nyctalopia Flashcards
6 signs associated with RP
- waxy optic disc pallor 2. mid-peripheral pigment clumping 3. attenuated arterioles 4. hyaline bodies within the optic nerve 5. PSC cataracts 6. keratometry findings suggestive of keratoconus
RP is characterized by progressive loss of _____ and ____ ____
Photoreceptor & RPE function
In RP, ____ ____ is MC form of inheritance
Autosomal dominant
What are the most common complains of pts w/ RP?
Night blindness & peripheral vision loss
What is the avg age of dx for RP?
9-19
___% of RP pts are symptomatic by 30 yrs
75
RP Triad
Retinal bone-spicule pigmentation (pigment clumping in the mid-periphery), anteriolar attenuation, waxy optic disc pallor
In the early stages of RP, the ___ ERG is reduced, while the ___ ERG is normal
Scotopic, photopic
Gyrate atrophy
Very rare, bilateral, autosomal recessive chorioretinal degeneration due to deficiency in mitochondrial enzyme ornithine aminotransferase
What is the classical clinical appearance of gyrate atrophy?
Multiple, well-defined, scalloped areas of peripheral choroioretinal atrophy. In childhood, the lesions begin in the mid-periphery & then coalesce to engulf most of the posterior pole, with the macula being spared until 40-70s
Gyrate atrophy sx
Prevalent in most pts by age 10: nyctalopia, decreased vision, constricted VF. Decreased vision usually a result of posterior subcapsular cataracts, macular chorioretinal degen or CME
Choroideremia
Very rare condition, characterized by diffuse & progressive atrophy of the choriocapillaris & overlaying RPE. Cause appearance of blond fundus. As atrophy worsens the deep choroidal vessels become prominent & underlying sclera becomes visible. Macula spared until later stages of disease.
Choroidermia results from a deficiency in what?
Rab geranylgeranyl transferase, an enzyme utilized in membrane metabolism
Choroidermia has what kind of genetic inheritance?
X-linked. Only males are affected all daughters are carriers. Most commonly presents in 1st decade of life
Choroidermia sx
MC initial symptom is nyctalopia. By late childhood, pts will also report photophobia & peripheral vision loss & will have constricted VF
In males w/ choroidermia, night blindness occurs early in life & progresses to total night blindness in ___ yrs
10
In choroidermia, legal blindness occurs by age ____
50-60 yrs
Fundus albipunctatus
Autosomal recessive congenital disorder that causes stationary (non-progressive) night blindness
Fundus albipunctatus signs
Numerous, small, yellow-white dot-like lesions at the level of the RPE; the lesions are in the mid-periphery & spare the macula
What is the difference between fundus albipunctatus & retinitis punctata albenscens?
Retinitis punctata albescens results in slow progression of night blindness
What is the MC retinal dystrophy?
RP
What is the MC assoc syndrome w/ RP?
Usher’s
What are some additional systemic conditions assoc w/ RP?
Abetalipoproteinemia (lack of serum betalipoprotein), Alstrom’s disease, Cockayne’s syndrome, Kearns-Sayre syndrome, Laurence-Moon/Bardet-Biedl, Neuronal ceroid lipofuscinosis (lipopigments accumulate w/i neurons, resulting in CNS degen)
RP Tx
Vit A supplementation. Adults 15,000 IU QD. Children 5,000 IU/day for 6 yr olds and 10,000 IU/day for 10 yr olds
