Anatomy
1 questionsWhat is the thinnest portion of the sclera?
NEET-PG 2013 - Anatomy NEET-PG Practice Questions and MCQs
Question 1041: What is the thinnest portion of the sclera?
- A. Anterior to the rectus muscle insertion
- B. At the posterior pole
- C. At the limbus
- D. Posterior to the rectus muscle insertion (Correct Answer)
Explanation: ***Posterior to the rectus muscle insertion*** - The sclera is thinnest immediately **posterior to the insertion of the rectus muscles**, where it is about 0.3 mm thick. - This area is clinically relevant as it is a common site for globe rupture during trauma. *Anterior to the rectus muscle insertion* - The sclera is relatively thick in this region, measuring around **0.6 mm thick**. - It provides robust support and attachment for the rectus muscles. *At the posterior pole* - At the posterior pole, the sclera is the **thickest**, reaching about 1.0 mm, especially around the optic nerve. - This thickness is necessary to protect the delicate neural structures exiting the eye. *At the limbus* - The sclera-corneal junction, or **limbus**, has an intermediate thickness, around **0.8 mm**. - This area is critical for surgical procedures but is not the thinnest point.
Ophthalmology
9 questionsReis-Buckler dystrophy affects which layer of the cornea?
Which of the following statements about Fuchs' corneal dystrophy is incorrect?
Corneal sensations are decreased in all of the following conditions except:
Interstitial keratitis is associated with all of the following except:
What is the drug of choice for treating intermediate uveitis?
Snow banking is seen in?
Panophthalmitis involves ?
Polyopia/diplopia is seen in which type of cataract?
In senile nuclear cataract what type of myopia is seen?
NEET-PG 2013 - Ophthalmology NEET-PG Practice Questions and MCQs
Question 1041: Reis-Buckler dystrophy affects which layer of the cornea?
- A. Stroma
- B. Bowman's membrane (Correct Answer)
- C. Endothelium
- D. Epithelium
Explanation: ***Bowman's membrane*** - **Reis-Buckler dystrophy** is a type of corneal dystrophy specifically characterized by the progressive destruction and irregular regeneration of **Bowman's membrane** and the superficial stroma. - This leads to the formation of an abnormal fibrous layer that causes recurrent corneal erosions and significant visual impairment due to corneal opacification. *Epithelium* - While patients often experience recurrent **corneal erosions** involving the epithelium, the primary pathology in Reis-Buckler dystrophy affects the underlying Bowman's membrane. - The epithelial damage is secondary to the irregular surface created by the diseased Bowman's layer. *Stroma* - The **stroma** can be secondarily affected with superficial scarring and opacification in Reis-Buckler dystrophy, but the initial and primary site of pathology is Bowman's membrane. - Other dystrophies, such as macular or granular dystrophies, primarily involve the corneal stroma. *Endothelium* - The **endothelium** is not directly affected in Reis-Buckler dystrophy. - Endothelial dystrophies, such as Fuchs' endothelial dystrophy, involve the innermost layer of the cornea and lead to corneal edema.
Question 1042: Which of the following statements about Fuchs' corneal dystrophy is incorrect?
- A. Endothelial dystrophy
- B. Occurs in old age
- C. Unilateral condition (Correct Answer)
- D. Posterior dystrophy
Explanation: ***Unilateral condition - INCORRECT STATEMENT*** - **Fuchs' corneal dystrophy** is typically a **bilateral condition**, although it can be asymmetric in its presentation. - The disease often affects both eyes, progressing from early morning blurriness to constant visual impairment. - This is the INCORRECT statement - Fuchs' is NOT unilateral. *Posterior dystrophy - Correct statement* - **Fuchs' corneal dystrophy** is classified as a posterior corneal dystrophy, meaning it primarily affects the **corneal endothelium** and Descemet's membrane. - This posterior involvement leads to the characteristic guttata and corneal edema. *Endothelial dystrophy - Correct statement* - It is fundamentally an **endothelial dystrophy**, resulting from primary dysfunction and loss of corneal endothelial cells. - The compromised endothelial pump function leads to **stromal edema** and reduced visual acuity. *Occurs in old age - Correct statement* - Fuchs' corneal dystrophy typically presents in **middle to old age**, with symptoms often becoming noticeable in individuals over 50. - While congenital forms of corneal dystrophy exist, Fuchs' is not usually one of them.
Question 1043: Corneal sensations are decreased in all of the following conditions except:
- A. Neuroparalytic keratitis
- B. Leprosy
- C. Herpetic keratitis
- D. Recurrent corneal erosion syndrome (Correct Answer)
Explanation: ***Recurrent corneal erosion syndrome*** - This condition involves **defective adhesion** of the corneal epithelium to the underlying Bowman's layer and basement membrane, leading to sudden, severe pain upon waking. - While it causes **pain** and **epithelial defects**, it does not primarily involve nerve damage or decreased corneal sensation; rather, episodes are often very painful due to exposed nerve endings. *Herpetic keratitis* - Caused by the **herpes simplex virus (HSV)**, which can infect the trigeminal nerve and lead to **trophic changes** in the cornea. - This viral infection often results in **significant reduction** or loss of corneal sensation, making the eye more vulnerable to trauma and delayed healing. *Neuroparalytic keratitis* - This condition is also known as **neurotrophic keratitis** and results from damage to the **trigeminal nerve**, which supplies sensation to the cornea. - Loss of corneal sensation leads to impaired reflex tearing and blinking, making the cornea susceptible to epithelial breakdown and ulceration due to lack of protective mechanisms. *Leprosy* - In ocular leprosy, the **Mycobacterium leprae** directly invades the ciliary nerves, significantly impairing corneal sensation. - This reduced sensation in leprosy patients increases the risk of **corneal ulcers** and opacification due to undetected foreign bodies and trauma.
Question 1044: Interstitial keratitis is associated with all of the following except:
- A. Syphilis
- B. Acanthamoeba (Correct Answer)
- C. Chlamydia Trachomatis
- D. Herpes Zoster Virus (HZV)
Explanation: ***Acanthamoeba*** - **Acanthamoeba keratitis** is a **suppurative keratitis** characterized by a painful, ring-shaped infiltrate with epithelial ulceration, typically associated with contact lens use and contaminated water exposure. - It causes **ulcerative stromal inflammation**, not the **non-ulcerative deep stromal inflammation** that characterizes classic interstitial keratitis. - **This is NOT a cause of interstitial keratitis.** *Syphilis* - **Congenital syphilis** is the **CLASSIC cause** of bilateral **interstitial keratitis**, often presenting in late childhood with "salmon patch" appearance, photophobia, lacrimation, and eventual ghost vessels. - The inflammation is **non-ulcerative and chronic**, affecting the **deep corneal stroma** with preservation of epithelium. - This is the most important association with interstitial keratitis to remember. *Chlamydia Trachomatis* - **Chlamydia trachomatis** causes **trachoma**, a chronic keratoconjunctivitis leading to **superficial keratitis with pannus formation** (superficial vascularization from the limbus). - The corneal involvement in trachoma is **superficial**, not the deep stromal inflammation seen in classic interstitial keratitis. - While listed in some references, **Chlamydia is NOT a standard cause of interstitial keratitis** in major ophthalmology textbooks. - **Note:** This option is potentially debatable, but Acanthamoeba is the more definitively incorrect answer. *Herpes Zoster Virus (HZV)* - **Herpes zoster ophthalmicus** can lead to **interstitial keratitis** and **disciform keratitis** (immune-mediated stromal inflammation with disc-shaped corneal edema). - Similarly, **HSV (Herpes Simplex Virus)** causes stromal keratitis, a form of interstitial keratitis. - The corneal involvement includes **deep stromal inflammation, scarring**, and potential neurotrophic changes leading to vision impairment.
Question 1045: What is the drug of choice for treating intermediate uveitis?
- A. Atropine
- B. Antibiotics
- C. Topical steroids
- D. Systemic steroids (Correct Answer)
Explanation: ***Systemic steroids*** - **Systemic steroids** are the **drug of choice** for treating intermediate uveitis, especially when inflammation is significant or vision is threatened. - They effectively suppress the expansive **intraocular inflammation** typical of intermediate uveitis, which often involves the **vitreous** and **peripheral retina**. *Atropine* - **Atropine** is a **cycloplegic agent** primarily used to relieve ciliary spasm and prevent synechiae formation in anterior uveitis. - It does not address the underlying **inflammation** of intermediate uveitis, which is located more posteriorly. *Antibiotics* - **Antibiotics** are used to treat bacterial infections and are not indicated for **intermediate uveitis**, which is typically an **inflammatory** or **autoimmune disorder**. - They would be appropriate only if the uveitis were secondary to an **infectious cause**, which is not the primary characteristic of intermediate uveitis. *Topical steroids* - **Topical steroids** are effective for **anterior uveitis** but often fail to reach sufficient concentrations in the **vitreous** and **peripheral retina** to control the inflammation of intermediate uveitis. - **Intermediate uveitis** primarily affects the ciliary body, vitreous, and peripheral retina, requiring **systemic agents** for adequate therapeutic effect.
Question 1046: Snow banking is seen in?
- A. White coat syndrome
- B. Eales syndrome
- C. Diabetic kidney disease
- D. Intermediate uveitis (Correct Answer)
Explanation: ***Intermediate uveitis*** - **Snow banking** refers to the accumulation of inflammatory exudates on the surface of the **pars plana** and **ora serrata**, a characteristic sign of intermediate uveitis. - This condition primarily affects the **vitreous** and peripheral retina, often leading to symptoms like **floaters** and **decreased vision**. *White coat syndrome* - This refers to a phenomenon where a patient's **blood pressure is elevated** in a clinical setting due to anxiety, but is normal outside of the medical environment. - It has no ophthalmic manifestations or association with "snow banking." *Eales syndrome* - This is an idiopathic inflammatory condition primarily affecting the **peripheral retinal vasculature**, leading to **vasculitis**, occlusion, and neovascularization. - While it can cause vitreous hemorrhage, it does not typically present with "snow banking" as a primary feature. *Diabetic kidney disease* - This is a complication of **diabetes mellitus** characterized by damage to the small blood vessels in the kidneys, leading to impaired kidney function. - It is a systemic condition with no direct relationship to ocular "snow banking" or uveitis.
Question 1047: Panophthalmitis involves ?
- A. Inner coat of eyeball
- B. Inner and outer coat but sparing tenon's capsule
- C. All structures of the eyeball including Tenon's capsule (Correct Answer)
- D. None of the options
Explanation: ***All structures of the eyeball including Tenon's capsule*** - **Panophthalmitis** is a severe inflammation or infection that affects **all coats of the eyeball** (sclera, choroid, retina). - Crucially, it also extends to the **intraocular contents** and the **Tenon's capsule**, leading to potential destruction of the entire eye. *Inner coat of eyeball* - This description is characteristic of **uveitis** (inflammation of the uvea: iris, ciliary body, choroid) or **endophthalmitis** if it extends to the vitreous and retina. - However, **panophthalmitis** is a more extensive condition, involving more than just the inner coats. *Inner and outer coat but sparing tenon's capsule* - This scenario describes **endophthalmitis**, which involves inflammation of the internal structures of the eye (vitreous, retina, choroid) and potentially the sclera. - However, the sparing of Tenon's capsule differentiates it from **panophthalmitis**, which expressly includes involvement of this fibrous sheath. *None of the options* - This option is incorrect because Option C accurately describes the comprehensive nature of **panophthalmitis**, which is an inflammation of all ocular structures, including Tenon's capsule. - The definition of panophthalmitis is critical in distinguishing it from less severe inflammatory conditions of the eye.
Question 1048: Polyopia/diplopia is seen in which type of cataract?
- A. Nuclear cataract
- B. Posterior subcapsular cataract
- C. Anterior polar cataract
- D. Cortical cataract (Correct Answer)
Explanation: ***Cortical cataract*** - **Cortical cataracts** cause spokes or vacuoles that refract light in multiple directions, leading to **polyopia** or **diplopia**. - The irregular opacities disrupt the light path, causing the brain to perceive **multiple images**. *Nuclear cataract* - **Nuclear cataracts** primarily affect central vision and cause **myopic shift**, not typically polyopia or diplopia. - They cause **blurry vision** and difficulty seeing in dim light as the lens nucleus hardens and yellows. *Posterior subcapsular cataract* - **Posterior subcapsular cataracts** are characterized by glare and difficulty with reading, mainly affecting near vision. - They form at the back of the lens, close to the nodal point, causing earlier onset of **visual symptoms** with less impact on polyopia. *Anterior polar cataract* - **Anterior polar cataracts** are usually small, well-demarcated opacities at the front of the lens that typically do not cause significant visual impairment. - They rarely cause **polyopia** unless they are very large or dense, which is uncommon.
Question 1049: In senile nuclear cataract what type of myopia is seen?
- A. Curvature myopia
- B. Axial myopia
- C. Index myopia (Correct Answer)
- D. Lenticular myopia
Explanation: **Index myopia** - **Senile nuclear cataract** involves opacification and hardening of the lens nucleus, which increases the **refractive index** of the lens. - This results in a stronger refractive power of the eye, causing light to focus in front of the retina, characteristic of **myopia**. *Curvature myopia* - Occurs when there is an increase in the **curvature of the cornea** or lens, leading to increased refractive power. - While lens curvature can change, the primary mechanism in nuclear cataracts is refractive index change, not solely curvature. *Axial myopia* - Arises from an **elongation of the eyeball**, making the axial length too long relative to the refractive power. - This is a structural change in the eye's shape, not directly caused by changes within the lens itself due to cataract. *Lenticular myopia* - This term is a broader category that refers to myopia caused by changes in the lens, which **index myopia** falls under. - However, "index myopia" is more specific and accurately describes the underlying mechanism in senile nuclear cataracts.