All of the following can cause a white pupillary reflex except
**Core Concept**
A white pupillary reflex, also known as Leucocoria, is an abnormal white or silvery reflection from the retina of the eye, often visible in low light conditions. This phenomenon occurs due to the reflection of light from the surface of the retina, which can be caused by various factors including anatomical abnormalities, tumors, or other pathological conditions.
**Why the Correct Answer is Right**
The correct answer is related to the anatomical and physiological mechanisms that allow light to be reflected from the retina. In normal eyes, light enters through the cornea, pupil, and lens, and is then focused onto the retina. However, in conditions where the retina is abnormal or disordered, light can be reflected from the surface of the retina, causing a white pupillary reflex.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it is not a known cause of white pupillary reflex. However, conditions such as congenital cataracts or retinoblastoma can cause a white pupillary reflex.
**Option B:** This option is incorrect because it is not a known cause of white pupillary reflex. However, conditions such as retinal detachment or vitreous hemorrhage can cause a white pupillary reflex.
**Option C:** This option is incorrect because it is not a known cause of white pupillary reflex. However, conditions such as Coats disease or ocular melanoma can cause a white pupillary reflex.
**Clinical Pearl / High-Yield Fact**
A classic exam trap to remember is that conditions such as retinoblastoma, congenital cataracts, and Coats disease can all cause a white pupillary reflex. However, conditions such as retinal detachment or vitreous hemorrhage can also cause a white pupillary reflex, but are less likely to be associated with a white pupillary reflex.
**Correct Answer: None.**