Anatomy
2 questionsThe zonules suspending the lens are attached to the?
Lens is attached to ciliary body via?
NEET-PG 2015 - Anatomy NEET-PG Practice Questions and MCQs
Question 861: The zonules suspending the lens are attached to the?
- A. Root of iris
- B. Ciliary body (Correct Answer)
- C. Anterior vitreous
- D. Limbus
Explanation: ***Ciliary body*** - The **suspensory ligaments of the lens**, also known as zonules of Zinn, connect the **lens capsule** to the **ciliary body**. - These zonules play a crucial role in **accommodation** by transmitting forces from the ciliary muscle to alter the shape of the lens. *Root of iris* - The **root of the iris** attaches the iris to the ciliary body but does not directly connect to the lens zonules. - The iris primarily controls the **pupil size** and light entry, while the zonules are involved in lens suspension and focusing. *Anterior vitreous* - The **anterior vitreous** is the part of the vitreous humor located in front of the lens. - While it is in close proximity to the lens, the zonules do not directly attach to the vitreous but rather to the ciliary body. *Limbus* - The **limbus** is the transitional zone between the cornea and the sclera, the white outer layer of the eye. - It is an important anatomical landmark for eye surgery and drainage of aqueous humor, but it has no direct role in suspending the lens.
Question 862: Lens is attached to ciliary body via?
- A. Limbus
- B. Vitreous Humour
- C. Root of iris
- D. Zonular fibers (Correct Answer)
Explanation: ***Zonular fibers*** - The **suspensory ligaments** of the lens, known as zonular fibers (or **Zonules of Zinn**), connect the lens capsule to the ciliary body. - These fibers play a crucial role in **accommodation** by transmitting the tension from the ciliary muscle to the lens, causing it to change shape [2]. *Limbus* - The **limbus** is the junction between the cornea and the sclera, serving as a transitional zone [3]. - It does not directly attach the lens to the ciliary body but is an important anatomical landmark for eye surgery. *Vitreous Humour* - The **vitreous humor** is the clear, gel-like substance that fills the space between the lens and the retina [4]. - It maintains the shape of the eye and holds the retina in place, but it does not provide structural attachment for the lens. *Root of iris* - The **root of the iris** is the outermost part of the iris where it attaches to the ciliary body. - While it is adjacent to the ciliary body, it is the iris structure itself and does not serve to attach the lens [1].
Ophthalmology
8 questionsAll of the following are true for sympathetic ophthalmitis except which of the following?
Where is the intraocular lens placed during cataract surgery?
Non foldable lens is made of?
Rigid gas permeable (RGP) lenses are made from which of the following combinations of materials?
Which mode of ultrasonography is used to measure the axial length of the eyeball?
What is the type of cataract associated with Galactosemia?
Rosette cataract is seen due to:
What is the most common etiopathogenetic cause of glaucoma?
NEET-PG 2015 - Ophthalmology NEET-PG Practice Questions and MCQs
Question 861: All of the following are true for sympathetic ophthalmitis except which of the following?
- A. Mostly results from a penetrating wound
- B. Autoimmune etiology
- C. Dalen-Fuchs nodules may be seen
- D. Affects the injured eye (Correct Answer)
Explanation: ***Affects the injured eye*** - Sympathetic ophthalmia is a **bilateral, granulomatous panuveitis** that characteristically affects the **fellow, uninjured eye** (sympathizing eye) following trauma or surgery to the other eye (exciting eye). - The disease involves an immune response directed against ocular antigens, typically from the uveal tissue, in the uninjured eye. *Mostly results from a penetrating wound* - This statement is true; **penetrating ocular trauma** (e.g., from surgery or injury) is the most common trigger for sympathetic ophthalmia. - The exposure of uveal antigens from the injured eye initiates an autoimmune response. *Autoimmune etiology* - This statement is true; sympathetic ophthalmia is an **autoimmune disease** mediated by T-lymphocytes against uveal antigens. - The condition is characterized by a delayed hypersensitivity reaction against exposed uveal proteins. *Dalen Fuch's nodules may be seen* - This statement is true; **Dalen-Fuchs nodules** are characteristic histopathological findings in sympathetic ophthalmia. - These are accumulations of epithelioid cells and lymphocytes located between the retinal pigment epithelium and Bruch's membrane.
Question 862: Where is the intraocular lens placed during cataract surgery?
- A. Surface of iris
- B. Capsular bag (Correct Answer)
- C. Around the limbus
- D. Over the face of vitreous
Explanation: ***Capsular bag*** - The **capsular bag** is the natural anatomical space where the human crystalline lens resides and is the ideal location for an intraocular lens (IOL) to mimic the natural lens's position and function. - Placing the IOL in the capsular bag provides **optimal stability**, centration, and reduces the risk of complications such as glare or secondary glaucoma. *Surface of iris* - Placing an IOL on the surface of the iris (**iris-fixated IOL**) is a less common surgical approach, typically reserved for cases where capsular support is absent or insufficient. - This position can lead to potential complications including **iris chafing**, pigment dispersion, and increased risk of uveitis or secondary glaucoma. *Over the face of vitreous* - Placing an IOL over the face of the vitreous typically occurs in cases of **capsular rupture** with inadequate posterior capsule support, requiring anterior vitrectomy and alternative IOL fixation. - This position is less stable and carries a higher risk of **vitreous prolapse**, retinal detachment, and cystoid macular edema compared to capsular bag placement. *Around the limbus* - The limbus is the **junction between the cornea and sclera** and is an entirely incorrect location for an intraocular lens implant. - An IOL around the limbus would be outside the globe and would serve no optical purpose within the eye, leading to **severe visual impairment** and potentially structural damage.
Question 863: Non foldable lens is made of?
- A. Acrylic
- B. PMMA (Correct Answer)
- C. Hydrogel
- D. Silicone
Explanation: ***PMMA*** - **Polymethylmethacrylate (PMMA)** is a rigid, non-foldable material historically used for **intraocular lenses (IOLs)**. - Due to its rigidity, PMMA IOLs require a **larger incision** for implantation, which can lead to astigmatism and slower recovery. *Silicone* - **Silicone** is a flexible, foldable material commonly used for modern IOLs, allowing for **smaller incisions**. - It has excellent **elastic properties** but may be associated with certain risks in eyes with silicone oil. *Acrylic* - **Acrylic** (both hydrophobic and hydrophilic) is a popular material for foldable IOLs, known for its **biocompatibility** and ability to be inserted through small incisions. - It is currently the most widely used material due to its **foldable nature** and good optical qualities. *Hydrogel* - **Hydrogel** is a type of hydrophilic acrylic material, characterized by its **high water content** and flexibility. - While foldable, hydrogel IOLs are less commonly used than other acrylic types, partly due to some concerns about long-term clarity or calcification in certain formulations.
Question 864: Rigid gas permeable (RGP) lenses are made from which of the following combinations of materials?
- A. Hydroxymethylmethacrylate
- B. Cellulose acetate Butyrate
- C. Polymethylmethacrylate
- D. Copolymer of PMMA, Silicon containing monomer & cellulose acetyl butyrate (Correct Answer)
Explanation: ***Copolymer of PMMA, Silicon containing monomer & cellulose acetyl butyrate*** - **Rigid gas permeable (RGP) lenses** are designed to be permeable to oxygen, which is achieved through the incorporation of **silicon-containing monomers**. - The combination of **PMMA** (for rigidity), **silicon** (for oxygen permeability), and **cellulose acetyl butyrate** (for improved wettability and flexibility) provides the desired mechanical and optical properties. *Polymethylmethacrylate* - **PMMA** was the primary material for the earliest **hard contact lenses** but offered virtually no oxygen permeability. - This lack of oxygen permeability led to significant corneal hypoxia issues and limited wear time. *Hydroxymethylmethacrylate* - **Hydroxymethylmethacrylate (HEMA)** is a key material in **hydrogel soft contact lenses**, known for its ability to absorb water. - HEMA is not used in RGP lenses because it would make the lens soft and flexible, contrary to the "rigid" characteristic. *Cellulose acetate Butyrate* - **Cellulose acetate butyrate (CAB)** was an early material used for **gas permeable lenses**, offering some oxygen permeability. - While it was an improvement over PMMA, it did not achieve the high level of oxygen permeability seen with newer silicon-containing materials.
Question 865: Which mode of ultrasonography is used to measure the axial length of the eyeball?
- A. A-mode Ultrasonography (Correct Answer)
- B. B-mode Ultrasonography
- C. M-mode Ultrasonography
- D. None of the options
Explanation: ***A-mode Ultrasonography*** - **A-mode** (amplitude modulation) ultrasonography is a **one-dimensional** display that measures the distance between structures based on the time it takes for sound waves to reflect. - It is specifically used for **biometry**, such as measuring the axial length of the eyeball for **intraocular lens (IOL) power calculation** prior to cataract surgery. *B-mode Ultrasonography* - **B-mode** (brightness modulation) ultrasonography provides a **two-dimensional** image, displaying the cross-sectional anatomy of organs. - While useful for visualizing ocular structures, it is not primarily used for precise **axial length measurements**. *M-mode Ultrasonography* - **M-mode** (motion mode) ultrasonography displays the **movement** of structures over time in a one-dimensional format. - This mode is typically used in **cardiac imaging** to assess heart valve motion and chamber dimensions, not for static length measurements of the eye. *None of the options* - This option is incorrect because **A-mode ultrasonography** is indeed the gold standard for measuring the axial length of the eyeball. - The other modes (B-mode and M-mode) serve different diagnostic purposes in ultrasonography.
Question 866: What is the type of cataract associated with Galactosemia?
- A. Oil drop (Correct Answer)
- B. Snowflake cataract
- C. Blue dot cataract
- D. Polychromatic lustre cataract
Explanation: ***Oil drop*** - This characteristic appearance is caused by the accumulation of **galactitol** in the lens, leading to changes in refractive index. - The "oil drop" cataract is a classic sign of **galactosemia**, often appearing as an early manifestation of the disease. *Snowflake cataract* - This type of cataract is more commonly associated with **diabetes mellitus** rather than galactosemia. - It presents as **fluffy white opacities** that can lead to rapid vision loss. *Blue dot cataract* - This is typically a **congenital stationary cataract** with small, bluish opacities in the peripheral lens. - It is usually **benign** and non-progressive, and not specifically linked to metabolic disorders like galactosemia. *Polychromatic lustre cataract* - This describes the varied, iridescent colors seen in certain types of cataracts, often associated with **complicated cataracts** or those near the lens sutures. - It does not specifically refer to the unique "oil drop" appearance of galactosemic cataracts.
Question 867: Rosette cataract is seen due to:
- A. Hyperparathyroidism
- B. Copper foreign body
- C. Trauma (Correct Answer)
- D. Diabetes
Explanation: ***Trauma*** - A **rosette cataract** is a classic sign of **blunt or penetrating ocular trauma**, where the force disrupts the lens fibers, leading to a characteristic star-shaped opacity. - The trauma causes a rapid swelling and opacification of the lens, often in the anterior or posterior subcapsular regions in a flower-petal or stellar pattern. *Copper foreign body* - A **copper foreign body** typically causes a **chalcosis lentis**, characterized by a **sunflower cataract** (deposits in the anterior capsule) due to copper deposition. - This is distinct from a rosette cataract, which forms due to the mechanical disruption of lens integrity rather than elemental deposition. *Diabetes* - **Diabetic cataracts** are typically either **"snowflake" cataracts** (rapidly progressive in younger patients with uncontrolled diabetes) or more commonly **age-related cataracts** that progress faster in diabetic patients. - These are metabolically induced cataracts, not presenting with the characteristic rosette or star-shaped pattern associated with trauma. *Hyperparathyroidism* - **Hyperparathyroidism** can lead to **metabolic cataracts** due to chronic hypercalcemia, which can cause calcium deposition within the lens. - These cataracts are typically described as **punctate cortical or subcapsular opacities**, rather than the distinct rosette shape seen after trauma.
Question 868: What is the most common etiopathogenetic cause of glaucoma?
- A. Raised pressure in episcleral veins
- B. Decreased outflow (Correct Answer)
- C. Increased formation of aqueous humour
- D. Increased scleral outflow
Explanation: ***Decreased outflow*** - The most common cause of glaucoma is an **obstruction** or inefficiency in the drainage of **aqueous humor** from the eye, leading to its accumulation. - This reduced outflow results in an increase in **intraocular pressure (IOP)**, which damages the optic nerve. *Raised pressure in episcleral veins* - While elevated episcleral venous pressure can contribute to increased IOP and glaucoma, it is a **less common primary etiopathogenetic mechanism** compared to impaired outflow facility. - Conditions like **Sturge-Weber syndrome** or an **arteriovenous fistula** can cause this, but they are not the typical presentation of primary open-angle glaucoma. *Increased formation of aqueous humour* - An increase in the production of **aqueous humor** is rarely the primary cause of glaucoma. - The eye's regulatory mechanisms usually compensate, or if overproduction occurs, it is an **anatomical issue**, not an outflow issue. *Increased scleral outflow* - Increased **scleral outflow** (also known as uveoscleral outflow, which is a non-conventional drainage pathway) would actually lead to a **decrease** in intraocular pressure, not an increase. - This mechanism is often targeted by certain glaucoma medications (e.g., **prostaglandin analogues**) to lower IOP by facilitating drainage.