Which is the commonest cause of ocular morbidity globally?
**Core Concept**
The question is testing knowledge on the most common cause of ocular morbidity worldwide, which is a key aspect of ophthalmology and public health. The correct answer involves a condition that affects a significant portion of the global population, resulting in substantial visual impairment.
**Why the Correct Answer is Right**
The correct answer is **Cataract**, which is the leading cause of ocular morbidity globally. Cataracts are characterized by the clouding of the lens in the eye, leading to vision impairment. This condition is often age-related, but it can also be caused by trauma, diabetes, or other systemic diseases. The prevalence of cataracts increases with age, making it a significant public health concern in many countries.
**Why Each Wrong Option is Incorrect**
* **Option A:** Glaucoma is a significant cause of ocular morbidity, but it is not the most common cause. Glaucoma is characterized by increased intraocular pressure, which can damage the optic nerve and lead to vision loss.
* **Option B:** Age-related macular degeneration (AMD) is a leading cause of visual impairment in developed countries, but it is not the most common cause globally. AMD is characterized by the degeneration of the macula, which is the part of the retina responsible for central vision.
* **Option D:** Diabetic retinopathy is a common complication of diabetes, but it is not the most common cause of ocular morbidity globally. Diabetic retinopathy is characterized by damage to the blood vessels in the retina, leading to vision impairment.
**Clinical Pearl / High-Yield Fact**
The World Health Organization (WHO) estimates that approximately 43 million people worldwide are blind, and 314 million people have low vision. Cataracts are the leading cause of blindness in people aged 50 and older.
**Correct Answer: C. Cataract.**