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 781: 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 782: 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 questionsPosterior staphyloma is seen in which condition?
Unilateral frontal blisters with upper lid edema and conjunctivitis is seen in?
Which organism can penetrate corneal endothelium?
All of the following are true about Keratoconus, except:
All 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?
NEET-PG 2015 - Ophthalmology NEET-PG Practice Questions and MCQs
Question 781: Posterior staphyloma is seen in which condition?
- A. Myopia (Correct Answer)
- B. Hypermetropia
- C. Astigmatism
- D. Presbyopia
Explanation: ***Myopia*** - A **posterior staphyloma** is an outward bulging of the posterior sclera and choroid, which is a common complication of **high myopia**. - It occurs due to the excessive elongation of the eyeball in myopic eyes, leading to thinning and weakening of the posterior sclera. *Hypermetropia* - This condition involves the eye being too short or the cornea being too flat, causing light to focus behind the retina, and is not associated with posterior staphyloma. - Hypermetropia is typically associated with **smaller axial length** and doesn't lead to the structural changes that cause staphyloma. *Astigmatism* - Astigmatism results from an **irregular curvature of the cornea or lens**, causing light to focus at multiple points on the retina, leading to blurred vision. - It describes a refractive error related to the shape of the optical surfaces, not an outward bulging of the posterior eye wall. *Presbyopia* - This is an **age-related decline in the eye's ability to focus on near objects** due to hardening of the crystalline lens and weakening of the ciliary muscles. - Presbyopia is a normal aging process of the lens and has no association with the structural changes of the posterior sclera seen in staphyloma.
Question 782: Unilateral frontal blisters with upper lid edema and conjunctivitis is seen in?
- A. Herpes Simplex
- B. Herpes Zoster Ophthalmicus (Correct Answer)
- C. Neuroparalytic Keratitis
- D. Acanthamoeba Keratitis
Explanation: ***Herpes Zoster Ophthalmicus*** - This condition is characterized by a **unilateral vesicular rash** (blisters) in the **trigeminal dermatome (V1)**, which includes the forehead and upper eyelid, along with significant **lid edema** and **conjunctivitis**. - **Hutchinson's sign** (lesions on the tip, side, or root of the nose) indicates a high risk of ocular involvement due to the nasociliary nerve innervation. *Acanthamoeba Keratitis* - This is an **amoebic infection** of the cornea typically associated with **contact lens wear** and often presents with severe pain and a **ring infiltrate** in the cornea. - It does not typically present with unilateral frontal blisters or significant lid edema. *Herpes Simplex* - Herpes simplex typically causes **recurrent corneal ulcers** (dendritic or geographic) and sometimes blepharitis, but not the widespread **unilateral frontal blisters** seen in the trigeminal distribution. - While it can cause conjunctivitis and lid edema, the pattern of skin lesions is the key differentiator. *Neuroparalytic Keratitis* - This condition results from **trigeminal nerve damage**, leading to corneal anesthesia and subsequent **trophic corneal ulceration**. - It presents primarily with **corneal findings** (epithelial defects, ulcers) due to impaired sensation and tear film stability, not initial vesicular skin lesions or prominent lid edema.
Question 783: Which organism can penetrate corneal endothelium?
- A. Staphylococcus Aureus
- B. Haemophilus influenzae (Correct Answer)
- C. Aspergillus fumigatus
- D. Neisseria gonorrhoeae
Explanation: ***Haemophilus influenzae*** - *Haemophilus influenzae* is unique in its ability to penetrate the **intact corneal endothelium** through its specific virulence factors and enzymatic mechanisms. - Along with *Neisseria meningitidis*, it can breach the **Descemet's membrane and endothelial barrier** without requiring prior epithelial damage. - This property makes it particularly dangerous as it can cause **endophthalmitis** by directly accessing the anterior chamber. *Neisseria gonorrhoeae* - While highly virulent, *N. gonorrhoeae* penetrates the **corneal epithelium** (outer layer) through its proteases, not the endothelium (inner layer). - It causes severe **hyperacute conjunctivitis** and can lead to **corneal perforation**, but via epithelial destruction and stromal infiltration. *Staphylococcus aureus* - A common cause of **bacterial keratitis** following epithelial defects or trauma. - Causes stromal infiltration and abscess formation but **cannot penetrate intact endothelium**. *Aspergillus fumigatus* - This fungus causes **fungal keratitis** typically after trauma with vegetative matter. - Invades through **epithelial breaches** and stromal infiltration, not through intact endothelial penetration.
Question 784: All of the following are true about Keratoconus, except:
- A. Astigmatism
- B. Increased curvature of cornea and Astigmatism
- C. Thick cornea (Correct Answer)
- D. Fleischer's ring
Explanation: ***Thick cornea*** - Keratoconus is characterized by **progressive corneal thinning** and weakening, not thickening. - This corneal thinning leads to a conical protrusion, causing significant visual distortion and irregular astigmatism. *Increased curvature of cornea and Astigmatism* - Keratoconus features **increased corneal curvature** with progressive steepening into a cone-shaped configuration. - This results in **irregular astigmatism**, a hallmark feature causing distorted vision at all distances. *Astigmatism* - **Irregular astigmatism** is a cardinal feature of keratoconus due to the asymmetric corneal shape. - Causes blurred and distorted vision that is difficult to correct with spectacles alone. *Fleischer's ring* - **Fleischer's ring** is an iron deposit ring at the base of the cone in keratoconus, visible on slit-lamp examination. - It represents hemosiderin deposition in the basal epithelial cells and is a characteristic clinical sign of keratoconus.
Question 785: 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 786: 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 787: 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 788: 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.