Classification of C.S.R
RPE – Retinal pigment epithelium – This is the layer of cells that support the photoreceptors (light sensitive cells of the retina). Without healthy RPE cells the overlying photoreceptors cannot stay healthy for very long.
CSR can be classified in several ways – at Bettersight we prefer to use the classification described below as it helps us to create a personalised management plan for patients suffering from this condition. In essence we describe CSR into the following categories:
- Sick RPE syndrome
- Acute CSR
In acute CSR there is a clear indication of recent onset of symptoms that are likely to be caused by CSR. Examination findings will show signs of CSR but little or no signs of tiny “pigment scars” left behind by previous episodes of CSR. In such cases it would be reasonable to suggest regular observations and OCT scans to chart the progress of this episode.
Many cases will resolve within four months. If an episode has not resolved after six months then this could be re-classified as chronic and treatment could be considered.
This may be an example of a patient who either has symptoms going back over more than 6 months or where there is documented evidence of CSR features of a similar length of time. It is in cases of chronic CSR where treatment is most likely to be considered.
- Recurrent CSR
This is where there is either documented evidence of previous episodes of CSR or where both the patients symptoms and examination findings suggest the likelihood of previous episodes of CSR.
If the pattern of recurrence is frequent and especially if the duration of each episode tends to be prolonged (lasting more than four months at a time) then recurrent CSR may also benefit from treatment with either argon laser or visudyne photodynamic therapy depending on the precise nature of the condition.
- Sick RPE Syndrome CSR
This type of CSR is perhaps the most feared type. It is thought to be a unusual variant of chronic CSR. Its thought that repeated, prolonged episodes of CSR in a patient may eventually lead to so much cumulative damage to the sensitive layer of cells called the retinal pigment epithelium (RPE) that these cells eventually start ‘wearing’ away.
Loss of the RPE cells either generally or in patchy areas across the macula is strongly associated with significant vision impairment. Its not known whether there may be other triggers for the sick RPE variant of CSR. Fortunately sick RPE syndrome CSR is generally pretty uncommon but unfortunately treatment of sick RPE CSR can be extremely challenging.