Introduction
Family Dominant Drusen:
- Naturally AD inheritance
- Onset 3rd to 4th decade
- Due to single missense mutation in the EFEMP1 gene -> fibrillin-like ECM protein expressed in RPE and retina
X-linked Retinoschisis
- Naturally X-linked, and so affects males more often
- Onset around age 10-20
- Associated with poor VA, strabismus and anisometropia + unexplained vision loss
- Poor prognosis if RD or VH
- Female carries are unaffected and asymptomatic
- Retinoshisin1 gene encodes retinoschisin which maintains the integrity of the retina by binding to the surface of PR and bipolar cells.
- Phororeceptors and bipolar cells are thus impacted
Dead Giveaways
Family Dominant Drusen
There are symmetrical distribution of drusen in the form of radial, mosaic or honeycomb
The family dominant drusen typically found at the macular are larger , and if the patterns become confluent, they form a honeycomb pattern.
Under OCT
Evident with the drusen forming just under the retina
X-linked Retinoschisis
The biggest giveaway is the spoke-wheel like pattern which radiates from the fovea in all affected Px, and even present in FAF
Spoke-wheel pattern seen. Schisis also seen in the multiple retinal layers, ranging from RNFL to nuclear, but mainly INL and ONL.
diagnostic features
For X-linked Retinoschisis:
50% present with peripheral retinal changes
Retinoschisis is more predominant in the inferotemporal
They can be a metallic sheen seen, with pigmentary changes, white spicules and vitreous veils
Additionally, the ERG yields a negative wave due to the loss of connection between PR and bipolar
5% will present with vitreous haemorrhages and retinal detachment can also occur which will lead to a worse prognosis.