Retinitis pigmentosa

Question 1

what is RP prevalence?

what is Usher prevalence?

what is the highest RP populaton incidence?

Answer 1

RP 1: 3000-5000

Usher 1:6000

Navajo Indians have the highest incidence of RP 1:1858

Question 2

other causes of nyctalopia?

Answer 2

• RP
• CSNB
• high myopia
• AMD
• birdshot chorioretinopaty and maybe other WDS?

Question 3

what is the age of onset of symptoms in AR and AD RP?

Answer 3

• AR is mroe agressive
• AR median 10.7 years-old
• AD median 23.4 yeas-old

AR at 10 years AD at 20

Question 4

what is the natural history of VF loss progression in RP?

which field is affected first?

Answer 4

• the superior VF is affected first (the inferior retina affected first)
• Some studies showed
  
  • 5% of remaining field lost per year (Berson et al all RP types)
  • 50% loss in 5 years (Massoff & flinkenstein all RP types)
• VF loss symmetric in both eye
  
  • execpt in X-linked female carriers
    
    • due to lyonization
      
      • this is a RANDOM event determining on each cell which of the 2 X chromosomes mutant or normal will be expressed)

Question 5

what is Lyonization?

Answer 5

• its a RANDOM process occuring in each cell by wich one of the 2 X chromosomes (the mutans or the normal) will be expressed)

Question 6

what is the VF deffinition of legal blindness in the US?

Answer 6

less than 20 degrees

in better seeing eye

with III 4e

Question 7

what is the natural history of central visual loss in RP?

and what is the best prognostic factor?

Answer 7

• Best prognostic factor?
  
  • scotopic b-wave >100 microvats
    
    • these patient in Marmor 1979 study showed to have the less symptoms and best VA independently of RP type
• RP with best vision long term is
  
  • #1 sectorial :) (BEST)
  • # 2 AD-RP usually retain vision beyond 60 yo
  • # 3 AR-RP
  • #4 X-linkedRP (WORSE) leg blind by 30-40 y
• once vision starts to decrease it reaches a 20/200 level in 4-10 years

Question 8

what is the best prognostic factor of retaining good central vision?

Answer 8

scotopic b-wave >100 microvats

these patient in Marmor 1979 study showed to have the less symptoms and best VA independently of RP type

Question 9

what are the color vision changes in RP?

Answer 9

pretty much none.

We test that to help in the differential diagnosis

color affected in cases of rod-cone with cones affected

Question 10

doctor…. I have seen some

tiny,

blinking or shimmering

lights

always in the same place

(patient with RP)

Do I have a retinal detachment?

Answer 10

• these are RP photopsias (present in ~35% of RP pts by Heckenlively et all)
• midperipheral
• similar to ocular migraines
  
  • ut in RP they are in the same place
• The disease continues but the photopsias remain similar
• eventually they dissapear in late stages of disease
• BUT ALWAYS CHECK THE PERIPHERY AS THIS COULD BE RD!!!!

Question 11

is RP sine pigmento a subtype of RP

Answer 11

no longer considered a subtype

it is just a stage of disease through which many patients pass.

Question 12

what are the first fundus changes in RP?

Answer 12

vascular attenuation

RPE mottling and granularity in mid and far periphery

Question 13

what is the progression of optic nerve pallor in RP?

Answer 13

• waxy pallor is a late sign “usually”

1. first sign is the golden ring (white halo)
2. the pigment PPA
3. finally waxy pallor

Question 14

RP due to MERTK mutation

Answer 14

• MERTK mutaitons cause
  
  • AR-RP
  • symptoms develop VERY EARLY DURING CHILDHOOD
  • macula involved early
  • its a rod-cone dystrophy
• MERTK gene encondes for a surface receptor requiered for POS photoreceptor outer segment disc RPE internalization.
• Ch 2q14.1