Absence of the red reflex is seen in all of the following conditions EXCEPT:

A. Cataract is incorrect because cataracts are opacities of the lens. When performing an ophthalmoscopic examination, light cannot pass through a dense cataract to reach the retina, which results in the absence of the red reflex. Cataracts are a common cause of an abnormal or absent red reflex in both children and adults. Detecting this early is important for preventing amblyopia in children and for identifying vision-impairing lens changes in adults. B. Detached retina is incorrect because a retinal detachment separates the retina from its underlying structures, disrupting the normal reflection of light back through the pupil. This can produce a partial or complete absence of the red reflex. Early recognition of absent red reflex due to retinal detachment is critical because retinal detachment is a vision-threatening emergency that requires prompt referral to an ophthalmologist. C. Conjunctivitis is correct because conjunctivitis affects only the conjunctiva, which is the thin, transparent membrane covering the sclera and lining the eyelids. It does not affect the lens or retina, so light can still reach the retina and reflect back, preserving the normal red reflex. While the eye may appear red and inflamed externally due to conjunctival blood vessel dilation, the internal structures responsible for the red reflex remain intact. D. Retinoblastoma is incorrect because retinoblastoma is a malignant tumor of the retina. The tumor can obstruct light from reflecting normally off the retina, resulting in leukocoria, a white pupillary reflex. Absence of the red reflex in a child is a classic sign of retinoblastoma and requires immediate ophthalmology referral.