Anatomy
1 questionsWhat is the longest part of the optic nerve?
NEET-PG 2013 - Anatomy NEET-PG Practice Questions and MCQs
Question 1061: What is the longest part of the optic nerve?
- A. Intracanalicular
- B. Intraorbital (Correct Answer)
- C. Intraocular
- D. Intracranial
Explanation: ***Intraorbital*** - The **intraorbital segment** is the **longest portion** of the optic nerve, measuring approximately **25-30 mm**. - It extends from the posterior pole of the eyeball to the **optic canal** and is characterized by a curved, **S-shaped course** within the orbit. - This excess length (approximately 8 mm more than the distance it spans) allows for **free eye movements** without putting tension on the nerve. *Intracranial* - The **intracranial portion** extends from the **optic canal** to the **optic chiasm**, measuring approximately **10-16 mm**. - While often mistakenly thought to be the longest, it is actually the **second longest segment**. - This segment is crucial for the formation of the **optic chiasm** where partial decussation of fibers occurs. *Intracanalicular* - The **intracanalicular portion** passes through the **optic canal** within the sphenoid bone, measuring approximately **4-10 mm**. - This segment is relatively short and constricted, making it vulnerable to compression in conditions like optic nerve gliomas or meningiomas. *Intraocular* - The **intraocular portion** (optic disc) is the **shortest segment**, measuring only about **1 mm**. - It passes through the **lamina cribrosa** of the sclera and is visible on fundoscopy as the optic disc.
Ophthalmology
8 questionsWhat are the characteristic features of Posner-Schlossman syndrome?
Which of the following is not a cause of exudative retinal detachment?
Which of the following is NOT a feature of CMV retinitis?
What condition is characterized by an "umbrella" configuration on fluorescein angiography?
Birdshot retinopathy is characterized by all except?
The most common cause of vitreous hemorrhage in adults is
Choroidal neovascularization is most commonly seen in which of the following refractive errors?
What is the condition characterized by a relative afferent pupillary defect?
NEET-PG 2013 - Ophthalmology NEET-PG Practice Questions and MCQs
Question 1061: What are the characteristic features of Posner-Schlossman syndrome?
- A. Ipsilateral optic atrophy with contralateral papilloedema
- B. Unilateral glaucomatous changes with mild anterior uveitis (Correct Answer)
- C. Granulomatous uveitis with iris heterochromia
- D. None of the options
Explanation: ***Unilateral glaucomatous changes with mild anterior uveitis*** - Posner-Schlossman syndrome, also known as **glaucomatocyclitic crisis**, is characterized by recurrent, acute attacks of **unilateral elevated intraocular pressure** (glaucomatous changes). - These attacks are accompanied by **mild anterior uveitis**, which typically presents with few or no precipitates and minimal redness. *Ipsilateral optic atrophy with contralateral papilloedema* - This constellation of symptoms, known as **Foster Kennedy syndrome**, is associated with intracranial masses, not Posner-Schlossman syndrome. - It involves **optic atrophy** in one eye due to direct pressure on the optic nerve and **papilledema** in the other eye due to increased intracranial pressure. *Granulomatous uveitis with iris heterochromia* - **Granulomatous uveitis** is characterized by large mutton-fat keratic precipitates and often seen in diseases like sarcoidosis or tuberculosis, which is not typical for Posner-Schlossman. - **Iris heterochromia** (different colored irises) is a characteristic feature of **Fuchs' heterochromic cyclitis**, another form of chronic anterior uveitis, but not Posner-Schlossman syndrome. *None of the options* - This option is incorrect as one of the provided choices accurately describes the characteristic features of Posner-Schlossman syndrome. - The other options describe different ophthalmological conditions.
Question 1062: Which of the following is not a cause of exudative retinal detachment?
- A. Scleritis
- B. Toxemia of pregnancy
- C. High myopia (Correct Answer)
- D. Central serous retinopathy
Explanation: ***High myopia*** - **High myopia** is a risk factor for **rhegmatogenous retinal detachment**, which is caused by a retinal break, not by fluid accumulation from a vascular or inflammatory process. - In rhegmatogenous detachment, vitreous fluid passes through the break into the subretinal space, separating the **neurosensory retina** from the **retinal pigment epithelium**. *Toxemia of pregnancy* - **Toxemia of pregnancy** (preeclampsia/eclampsia) can cause **exudative retinal detachment** due to choroidal ischemia and dysfunction of the retinal pigment epithelium, leading to fluid leakage. - The elevated **blood pressure** and systemic vascular changes impair choroidal perfusion, resulting in serous fluid accumulation beneath the retina. *Scleritis* - **Posterior scleritis** can lead to **exudative retinal detachment** by causing inflammation and edema of the choroid and sclera, which in turn compromises the integrity of the retinal pigment epithelium. - The inflammatory process increases vascular permeability, allowing fluid to leak into the subretinal space. *Central serous retinopathy* - **Central serous retinopathy** is a classic example of **exudative retinal detachment**, characterized by serous fluid accumulation under the macula. - This occurs due to dysfunction or a break in the **retinal pigment epithelium**, often associated with stress and corticosteroid use, leading to fluid leakage from the choroid.
Question 1063: Which of the following is NOT a feature of CMV retinitis?
- A. Perivasculitis
- B. Brush-fire appearance
- C. Immunosuppression
- D. Cracked mud appearance (Correct Answer)
Explanation: ***Cracked mud appearance*** - **"Cracked mud appearance"** is not a term used to describe CMV retinitis. The classic descriptions include **"pizza pie"**, **"cottage cheese and ketchup"**, and **"brush-fire"** appearances. - CMV retinitis presents with **necrotizing retinitis** with hemorrhages and granular opacification, not a cracked or atrophic pattern. - This option describes a **non-existent finding** in the context of CMV retinitis. *Immunosuppression* - **Immunosuppression**, especially due to **HIV/AIDS** (CD4 count <50 cells/μL), organ transplantation, or chemotherapy, is a **primary risk factor** for CMV retinitis. - It is crucial for the **reactivation** of latent CMV infection, leading to opportunistic disease. - While technically a predisposing condition rather than a "feature" of the disease itself, it is strongly associated with CMV retinitis. *Brush-fire appearance* - The **"brush-fire appearance"** is a classic description of CMV retinitis, referring to the **active leading edge** of the infection with confluent areas of necrosis and hemorrhage spreading across the retina. - This term captures the **fulminant necrotizing retinitis** with yellow-white retinal opacification and hemorrhages. *Perivasculitis* - **Perivasculitis**, or inflammation around the retinal blood vessels, is a **characteristic pathological feature** of CMV retinitis. - It often manifests as **frosted branch angiitis** (white sheathing around retinal vessels), which can be seen in severe cases.
Question 1064: What condition is characterized by an "umbrella" configuration on fluorescein angiography?
- A. Retinitis pigmentosa
- B. Rhegmatogenous retinal detachment
- C. Central serous retinopathy (Correct Answer)
- D. Eale's disease
Explanation: ***Central serous retinopathy*** - The "umbrella" or "smokestack" configuration on **fluorescein angiography** is a classic finding in central serous retinopathy, indicating leakage of dye creating a mushroom-shaped plume. - This leakage originates from the **retinal pigment epithelium (RPE)** into the subretinal space, causing serous detachment of the neurosensory retina. *Retinitis pigmentosa* - Characterized by **progressive photoreceptor degeneration** and **pigmentary changes** in the retina, often described as "bone-spicule" pigmentation. - Fluorescein angiography in retinitis pigmentosa typically shows **atrophy** and **window defects**, not an umbrella pattern of leakage. *Rhegmatogenous retinal detachment* - Involves a **full-thickness break in the retina** that allows vitreous fluid to pass into the subretinal space, causing the retina to detach. - Fluorescein angiography is generally not used for primary diagnosis and would not show an umbrella pattern, but rather **non-perfusion** or vascular changes in the detached area. *Eale's disease* - A rare **idiopathic obliterative periphlebitis** primarily affecting the retinal veins, leading to recurrent vitreous hemorrhages and retinal neovascularization. - Fluorescein angiography would reveal **vascular sheathing**, **non-perfusion**, and **neovascularization**, which are distinct from the umbrella configuration.
Question 1065: Birdshot retinopathy is characterized by all except?
- A. Common in females
- B. Creamy yellow spots
- C. HLA-A29 positive
- D. Unilateral (Correct Answer)
Explanation: ***Unilateral*** - **Birdshot retinopathy** is characteristically a **bilateral** inflammatory condition affecting both eyes, even if the onset may be asymmetric. - The disease involves widespread inflammation of the **choroid** and **retina**, typically presenting in both eyes simultaneously or sequentially. - Unilateral presentation would be highly atypical and should prompt consideration of alternative diagnoses. *Common in females* - Birdshot retinopathy shows a **clear female predominance**, with approximately **2-3 times more females affected than males** (60-75% of cases). - This demographic trend is a well-established feature of the disease. - However, it does occur in both sexes and is still considered characteristic of the condition. *HLA-A29 positive* - A strong association with the **HLA-A29 allele** is a hallmark of birdshot retinopathy, found in **over 95% of affected individuals**. - This genetic marker is highly specific and often used to support the diagnosis. - HLA-A29 testing is considered part of the diagnostic workup. *Creamy yellow spots* - The presence of characteristic **creamy yellow-white choroidal lesions**, resembling birdshot scatter, is a defining clinical feature. - These lesions are typically located in the **mid-peripheral and posterior fundus**, distributed radially around the optic disc. - The "birdshot" appearance refers to the scattered pattern resembling shotgun pellet distribution.
Question 1066: The most common cause of vitreous hemorrhage in adults is
- A. Retinal hole
- B. Trauma
- C. Hypertension
- D. Diabetes (Correct Answer)
Explanation: ***Diabetes*** - **Proliferative diabetic retinopathy (PDR)** leads to the formation of new, fragile blood vessels (neovascularization) on the retinal surface or optic disc. - These new vessels are prone to bleeding into the **vitreous cavity**, making diabetes the most common cause of vitreous hemorrhage in adults. *Retinal hole* - A retinal hole or tear can lead to **rhegmatogenous retinal detachment** but does not commonly cause significant vitreous hemorrhage on its own. - While a tear can sometimes be associated with a small amount of hemorrhage, it is not the MOST common cause of widespread vitreous bleeding. *Trauma* - **Ocular trauma**, such as blunt or penetrating injuries, can certainly cause vitreous hemorrhage due to direct damage to retinal or choroidal blood vessels. - However, in the general adult population, **systemic diseases** like diabetes are statistically more frequent causes of spontaneous vitreous hemorrhage than acute trauma. *Hypertension* - Severe **hypertensive retinopathy** can cause retinal hemorrhages, microaneurysms, and cotton wool spots, but it typically does not lead to large-volume vitreous hemorrhage. - While hypertension can contribute to the severity of other retinal conditions, it is not the primary direct cause of vitreous hemorrhage itself.
Question 1067: Choroidal neovascularization is most commonly seen in which of the following refractive errors?
- A. Myopia (Correct Answer)
- B. Hypermetropia
- C. Presbyopia
- D. Astigmatism
Explanation: ***Myopia*** - High myopia, particularly **pathologic myopia** (>6D or axial length >26mm), is a significant risk factor for **choroidal neovascularization (CNV)** among refractive errors due to the elongation of the eyeball stretching and thinning the choroid and Bruch's membrane. - The mechanical stress and associated **degenerative changes** in the posterior segment can lead to ruptures in Bruch's membrane, facilitating the growth of new, fragile blood vessels from the choroid into the subretinal space. - **Pathologic myopia** is the **second most common cause of CNV overall** (after age-related macular degeneration) and the **most common cause in patients under 50 years**. *Hypermetropia* - Hypermetropia (farsightedness) is associated with a **shorter axial length** of the eye, which generally reduces the risk of the structural changes that predispose to CNV. - While other conditions can cause CNV, hypermetropia itself is **not a risk factor** for its development. *Presbyopia* - Presbyopia is an **age-related loss of accommodation** due to hardening of the lens and weakening of the ciliary muscle, affecting near vision. - It is a refractive change related to the lens's flexibility and **not directly to the structural changes** in the choroid or retina that lead to CNV. *Astigmatism* - Astigmatism is a refractive error where the eye's cornea or lens has **irregular curvature**, causing blurred vision at all distances. - It is a **surface curvature issue** and does not typically involve the deep structural changes in the choroid or retina that are conducive to choroidal neovascularization.
Question 1068: What is the condition characterized by a relative afferent pupillary defect?
- A. Efferent pathway defect
- B. Cerebral lesion
- C. Total afferent pupillary defect
- D. Marcus Gunn pupil (Correct Answer)
Explanation: ***Marcus Gunn pupil, a defect in the afferent pathway of the eye*** - A **Marcus Gunn pupil**, also known as a **relative afferent pupillary defect (RAPD)**, occurs due to a lesion or dysfunction in the **afferent (sensory) pathway** of one eye. - This results in an asymmetric response to light, where the pupil of the affected eye appears to dilate paradoxically when light is swung from the unaffected to the affected eye during the **swinging flashlight test**. *Efferent pathway defect* - An **efferent pathway defect** (e.g., in the oculomotor nerve, CN III) would cause a **fixed, dilated pupil** with impaired direct and consensual light reflexes, rather than an RAPD. - Such a defect would typically affect the motor response of the pupil, causing it to be unable to constrict. *Cerebral lesion* - While certain cerebral lesions can affect pupillary responses, a **relative afferent pupillary defect** specifically points to an issue in the direct sensory input from the retina to the brainstem. - Large **cerebral lesions** are more likely to cause other neurological signs or abnormalities in the motor control of the eye. *Total afferent pupillary defect* - A **total afferent pupillary defect**, often seen in **amaurotic pupil** (blind eye without light perception), would result in no direct or consensual light response in the affected eye. - In a RAPD, there is still some, albeit reduced, response to light, making it a **relative** defect rather than a total absence of afferent signaling.
Pharmacology
1 questionsWhich of the following antiglaucoma medications can cause drowsiness?
NEET-PG 2013 - Pharmacology NEET-PG Practice Questions and MCQs
Question 1061: Which of the following antiglaucoma medications can cause drowsiness?
- A. Brimonidine (Correct Answer)
- B. Latanoprost
- C. Dorzolamide
- D. Timolol
Explanation: ***Brimonidine*** - **Brimonidine** is an **alpha-2 adrenergic agonist** [1] that can cause central nervous system depression, leading to side effects such as **drowsiness** and fatigue. - This systemic side effect is more common with the topical ophthalmic formulation due to systemic absorption. *Latanoprost* - **Latanoprost** is a **prostaglandin analog** that primarily works by increasing uveoscleral outflow, and its side effects are mainly localized to the eye (e.g., iris color change, eyelash growth). - It does not typically cause systemic side effects like drowsiness because its systemic absorption is minimal. *Dorzolamide* - **Dorzolamide** is a **topical carbonic anhydrase inhibitor** [1] that reduces aqueous humor production, and its most common side effects include local ocular irritation and a bitter taste. - While systemic carbonic anhydrase inhibitors can cause fatigue and drowsiness, the topical formulation has very limited systemic absorption, making drowsiness uncommon. *Timolol* - **Timolol** is a **non-selective beta-blocker** [1] that reduces aqueous humor production and can cause systemic side effects such as bradycardia, bronchospasm, and hypotension. - While some beta-blockers can cause fatigue, **drowsiness** as a prominent side effect is less common compared to alpha-2 agonists.