Toxic maculopathy
 

Crystal retinopathy which can occur in tamoxifen  or canthaxanthine retinopathy

Tamoxifen is now commonly used as an adjuncvitve treatment in women with breast carcinoma. As breast cancer is  common you may be given cases of tamoxifen retinopathy in the examination. However, tamoxifen is not the only  drug that causes crystalline retinopathy and you need to know the differenital diagnosis (see questions). There are bilateral intraretinal perifoveal refractile crystals (there may be associated macular oedema). Further examination: in women mention that you would like to know if there were any past history of breat problem. Also examine the  patient's arm for any evidence of lymphoedema (which can occur from lymph node removal during mastectomy)

Questions:

1. What are the causes of crystalline retinopathy apart from tamoxifen?

Answer
canthaxanthine (see picture above, it is used in colouring agents and also used as a tanning agent. Multiple yellow glistening spots are seen around the macula. The patient's vision is not affected.)
talc in intravenous drug users
secondary oxalosis can also lead to crystalline retinopathy and this include ethylene glycol and high dose aspirin (in patient with renal failure).

2. Should tamoxifen be stopped in patients with crystalline retinopathy?

Answer
Crystalline retinopathy alone is not an indication for stopping tamoxifen as patient may be visually asymptomatic. In those who are symptomatic, there are usually additional signs such as cystoid macular oedema or punctate RPE changes. It is important to liase with the oncologist looking after the patient to discuss future treatment.

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