Pattern Dystrophy

Introduction

Typically has an onset around the 4th to 5th decade, with a typically good prognosis, but typically misdiagnosed as AMD.
- VA is usually stable, though complications can occur such as neovascularisation and retinal atrophy, which impacts vision

Pathophysiology:
- Occurs due to PRPH2 variations
- Encodes peripherin-2 found on the outer segment of rods and cones
- Required for the stabilisation of the outer segment discs
- Mutations lead to disorganised outer segments and discs, lipofuscin accumulation in the RPE.

Dead Giveaways

There are no direct giveaways due to the 5 different groups:

Dystrophy	Retinal Presentation
Adult-Onset Vitellifor Dystrophy	Bilateral, circular, 1/3 - 1 DD
Butterfly-Shaped Pigment Dystrophy	Bilateral, triradiate, hyperpigmentation
Reticular Dystrophy	Bilateral, fishnet/chicken wire, hyperpigmentation, 4-5 DD
Multifocal Pattern Dystrophy	Bilateral multiple yellow fleck-like lesions
Fundus Pulverulentus	Bilateral, coarse macular pigment mottling

diagnostic features

Adult Onset Vitelliform Dystrophy
1. Most common type
2. Yellowish round or oval shaped deposits
3. Located in the fovea or peri-foveal region
4. Often has central pigmentation
5. Usually bilateral but can be asymmetrical
6. Lesions represent vitelliform material --> They are lipofuscin rich, and OCTs show hyper-reflective material above RPE + FAF and hyper-AF
7. The fovea is very hyper-reflective
Butterfly Pattern Dystrophy
1. Yellowish pigmentary material distributed in 3-5 arms that resemble the wings of a butterfly
2. Sort of like a butterfly
Multifocal Pattern Dystrophy Simulating Stargardt's/Fundus Flavimaculatus
1. Multiple yellow retinal flecks similar to those found in Stargardt's disease are found in the posterior pole
2. These flecks can become confluent and atrophic overtime
3. OCT may reveal focal thickening at the level of the RPE, and disturbances to the ELM and EZ
4. FAF shows flecks to be initially hyper-AF, however hypo-AF if atrophy occurs
5. Distinguishing factors:
  1. AD inheritance, with latter age of onset.
  2. Good visual prognosis
  3. Absence of dark choroid on FA
6. Similar flecks to Stargardt's
7. Focal thickenings in the RPE can be seen, along with disrupted ELM and EZ layer
Reticular Dystrophy
1. Characterised by a fishnet with knot appearance of hyperpigmentation networks.
2. These fishnets appear hyper-AF over FAF
Fundus Pulverulentus
1. Is the rarest type
2. Granular or punctiform appearance with coarse mottling of the RPE
3. Pigment mottling seen from 1 to 4 o'clock