NEET-PG 2015 - Ophthalmology Practice Questions

Q: In which of the following conditions does Berlin's edema occur?

After concussional trauma. ***After concussional trauma*** - **Berlin's edema**, also known as **commotio retinae**, is a form of **retinal edema** that occurs following **blunt trauma** to the eye. - It results from the disruption of the **photoreceptor outer segments** and retinal pigment epithelium, leading to a **dull, gray-white appearance** of the retina. *Open angle glaucoma* - Characterized by **progressive optic nerve damage** and visual field loss, typically due to elevated intraocular pressure, without retinal edema. - The primary pathology involves the **trabecular meshwork**, not direct retinal swelling. *After cataract surgery* - A common complication is **cystoid macular edema** (Irvine-Gass syndrome), which affects the macula and can cause blurred vision. - This is distinct from Berlin's edema, as it is a **post-surgical inflammatory response**, not a direct traumatic injury. *Diabetic retinopathy* - Involves various retinal changes due to diabetes, such as **microaneurysms**, hemorrhages, and **macular edema** from leaky vessels. - It is a **metabolic and vascular disease**, not a direct consequence of acute ocular trauma.

Q: All of the following are complications of traumatic hyphema except which of the following?

Corneal Ulcer. ***Corneal Ulcer*** - A **corneal ulcer** is typically caused by infection, trauma, or exposure keratitis and is not a direct complication of blood in the anterior chamber from a **traumatic hyphema**. - While prolonged elevation of **intraocular pressure** from hyphema could theoretically impair corneal health, a direct ulcer is not a typical or primary complication. *Rebleeding* - **Rebleeding** is a common and serious complication of hyphema, usually occurring 2-7 days after the initial injury. - It often results in a more significant bleed and carries a higher risk of complications such as **elevated intraocular pressure** and **blood staining of the cornea**. *Pupillary Block* - **Pupillary block** can occur if the amount of blood from the hyphema prevents the flow of aqueous humor from the posterior to the anterior chamber. - This blockage leads to a buildup of **aqueous humor** in the posterior chamber, causing the iris to bow forward and potentially precipitating **acute angle-closure glaucoma**. *Posterior synechiae* - **Posterior synechiae** can develop due to inflammation (uveitis) associated with the hyphema, where the iris adheres to the anterior lens capsule. - This complication can lead to **irregular pupil shape**, **pupillary block glaucoma**, or other visual disturbances.

Q: What is the most common eye lesion in HIV?

Cotton wool spots. ***Cotton wool spots*** - These are the most common ocular manifestation in HIV-positive individuals, resulting from **ischemic retinal nerve fiber layer damage**. - While not vision-threatening themselves, their presence indicates **microvascular damage** and can be a sign of systemic disease progression. *Kaposi Sarcoma of Lid* - While Kaposi sarcoma can affect the eyelids in HIV patients, it is **not the most common ocular lesion**. - It presents as a **reddish-purple nodule** or plaque and is an indicator of advanced immunosuppression. *CMV Retinitis* - Cytomegalovirus (CMV) retinitis is a significant and **vision-threatening opportunistic infection** in advanced HIV. - However, it occurs in patients with **severe immunosuppression** (low CD4 counts) and is less common overall than cotton wool spots. *Choroiditis* - Choroiditis, an inflammation of the choroid, can occur in HIV patients due to various opportunistic infections or directly from the virus. - It is **less prevalent** than cotton wool spots and typically requires specific etiologies beyond HIV itself.

Q: Which optical instrument utilizes the principle of total internal reflection?

Gonioscope. ***Gonioscope*** - A **gonioscope** uses mirrors or prisms to allow visualization of the **anterior chamber angle**, leveraging **total internal reflection** to bypass the normal optical limitations of the cornea. - The principle of total internal reflection occurs when light traveling from a denser medium (like the prism/mirror in the gonioscope) hits an interface with a less dense medium (like air or the aqueous humor) at an angle greater than the **critical angle**, causing all light to reflect back. *Pachymeter* - A **pachymeter** is used to measure the **thickness of the cornea**, typically employing ultrasound or optical methods. - It does not rely on total internal reflection but rather on the time-of-flight of sound waves or the reflection/scattering of light from corneal layers. *Ophthalmoscope* - An **ophthalmoscope** is used to examine the posterior segment of the eye, including the **fundus**, optic disc, and retina. - It works by directing a light source into the eye and viewing the reflected light, using lenses to focus the image, without utilizing total internal reflection. *Lensometer* - A **lensometer** (or focimeter) is an optician's instrument used to measure the prescription of eyeglasses or contact lenses, including **sphere, cylinder, and axis**. - Its operation is based on standard lens optics and does not involve the principle of total internal reflection.

Q: Which is the most powerful refractive surface of the eye?

Cornea. ***Cornea*** - The **cornea** is the eye's outermost, transparent layer, responsible for approximately **two-thirds of the total refractive power** of the eye due to its highly curved anterior surface and the significant change in refractive index from air to corneal tissue. - Its fixed curvature and consistent refractive index make it the primary and most powerful component in bending light rays to focus them on the retina. *Conjunctiva* - The **conjunctiva** is a thin, translucent mucous membrane that lines the inner surface of the eyelids and covers the anterior sclera (white part of the eye). - Its primary function is protection and lubrication, producing mucus and tears, but it plays **no significant role in light refraction**. *Vitreous* - The **vitreous humor** is a transparent, gel-like substance that fills the space between the lens and the retina, maintaining the eye's shape. - It has a refractive index very similar to water (approximately 1.334) and contributes **minimally to the eye's total refractive power** because light has already been significantly refracted by the cornea and lens before reaching it. *Lens* - The **lens** is a transparent, biconvex structure located behind the iris, providing the remaining **one-third of the eye's refractive power**. - While crucial for **accommodation** (changing focal length to see objects at different distances), its refractive power is less than the cornea's, and its ability to change shape is what makes it unique, not its absolute power.

Q: Strabismic amblyopia is more common in patients with:

Constant strabismus. **Constant Strabismus** - In **constant strabismus**, one eye is always deviated, leading to **continuous suppression** of the image from the deviated eye by the brain. - This consistent suppression prevents proper visual development in the deviated eye, resulting in **amblyopia**. *Alternating strabismus* - In **alternating strabismus**, the deviation switches between the two eyes, allowing each eye to take turns fixing. - This alternation helps maintain relatively good visual acuity in both eyes, making **amblyopia less common** or severe. *Latent strabismus* - **Latent strabismus** (phoria) is a deviation that is only present when binocular fusion is disrupted (e.g., when one eye is covered). - Since fusion is typically maintained in daily vision, there is **no constant suppression** of one eye, and amblyopia is rare. *Intermittent strabismus* - **Intermittent strabismus** involves periods of deviation alternating with periods of straight eye alignment, often varying with fatigue or visual tasks. - While it can lead to amblyopia, it is **less common and severe** than with constant strabismus because there are periods when the visual input from both eyes is utilized.

Q: What is the average axial length of the human eyeball?

24 mm. ***24 mm*** - The **average axial length** of the human eyeball is approximately **24 mm**. - This length is crucial for **emmetropia**, where parallel light rays focus precisely on the retina. *16 mm* - An axial length of **16 mm** would indicate extreme **hyperopia** (farsightedness), as the eyeball would be significantly too short [1]. - This would result in light focusing behind the retina, leading to blurry vision. *20 mm* - An axial length of **20 mm** is still considerably shorter than average, suggesting **significant hyperopia**. - This deviation from the norm would impair visual acuity without corrective lenses. *28 mm* - An axial length of **28 mm** would classify the eye as significantly **myopic** (nearsighted), as the eyeball would be too long [1]. - In this case, light would focus in front of the retina, causing distant objects to appear blurry [1].

Q: Which of the following methods is not used to measure refractive error?

Spectrometry. ***Spectrometry*** - **Spectrometry** measures the absorption or emission of light by a substance at different wavelengths, primarily used for chemical analysis and material science. - It does not directly assess the **focal power** of the eye or its refractive state. *Keratometry* - **Keratometry** measures the curvature of the anterior surface of the cornea, which is essential for determining astigmatism and fitting contact lenses. - While it doesn't measure the entire refractive error, it provides crucial data used in **refractive error assessment**. *Retinoscopy* - **Retinoscopy** is an objective method for determining the eye's refractive error by observing the movement of reflected light in the patient's pupil as a light source is swept across the eye. - It helps determine the approximate sphere and cylinder power needed for proper vision correction, especially useful in **uncooperative patients** or children. *Refractometry* - **Refractometry** (often performed with an autorefractor) is an automated method that uses light reflections from the retina to estimate the eye's refractive error. - It provides an objective measurement of the **spherical, cylindrical, and axial components** of refractive error, serving as a starting point for subjective refraction.

Q: Pilocarpine is used in all of the following except:

Malignant Glaucoma. ***Malignant Glaucoma*** - **Pilocarpine** is contraindicated in **malignant glaucoma** because it can worsen the condition by causing **ciliary body edema** and anterior displacement of the lens-iris diaphragm. - This form of glaucoma requires treatment aimed at posterior displacement of the lens-iris diaphragm, often involving **cycloplegics**, **hyperosmotic agents**, or surgical interventions. *Primary, Open Angle Glaucoma* - **Pilocarpine** is an effective **miotic agent** that increases aqueous humor outflow through the **trabecular meshwork**, thereby lowering intraocular pressure. - It can be used as a treatment for **primary open-angle glaucoma**, although it is less commonly used due to its side effects and the availability of better-tolerated medications. *Acute Angle Closure Glaucoma* - **Pilocarpine** is typically used in the management of **acute angle-closure glaucoma** after the intraocular pressure has been acutely lowered by other agents. - It works by inducing **miosis**, which pulls the iris away from the **trabecular meshwork**, opening the angle and facilitating aqueous outflow. *Chronic Synechial Angle Closure Glaucoma* - In **chronic synechial angle-closure glaucoma**, **pilocarpine** can be used to break or prevent the formation of new **peripheral anterior synechiae** by constricting the pupil. - However, its effectiveness is limited if extensive synechiae have already formed, as these physically block the outflow pathway.

Question 1

In which of the following conditions does Berlin's edema occur?

Accepted Answer

After concussional trauma

Answer

Open angle glaucoma

Answer

After cataract surgery

Answer

Diabetic retinopathy

Question 2

All of the following are complications of traumatic hyphema except which of the following?

Accepted Answer

Corneal Ulcer

Answer

Pupillary Block

Answer

Posterior synechiae

Answer

Rebleeding

Question 3

What is the most common eye lesion in HIV?

Accepted Answer

Cotton wool spots

Answer

Kaposi Sarcoma of Lid

Answer

CMV Retinitis

Answer

Choroiditis

Question 4

Which optical instrument utilizes the principle of total internal reflection?

Accepted Answer

Gonioscope

Answer

Pachymeter

Answer

Ophthalmoscope

Answer

Lensometer

Question 5

Which is the most powerful refractive surface of the eye?

Accepted Answer

Cornea

Answer

Conjunctiva

Answer

Vitreous

Answer

Lens

Question 6

Strabismic amblyopia is more common in patients with:

Accepted Answer

Constant strabismus

Answer

Alternating strabismus

Answer

Latent strabismus

Answer

Intermittent strabismus

Question 7

Aniseikonia is ?

Accepted Answer

Projection of different sized images into visual cortex of two retinae

Answer

Projection of different colored images into the visual cortex of one eye

Answer

Change in the perception of object size due to distance

Answer

Temporary visual disturbances affecting one eye

Question 8

What is the average axial length of the human eyeball?

Accepted Answer

24 mm

Answer

16 mm

Answer

20 mm

Answer

28 mm

Question 9

Which of the following methods is not used to measure refractive error?

Accepted Answer

Spectrometry

Answer

Keratometry

Answer

Retinoscopy

Answer

Refractometry

Question 10

Pilocarpine is used in all of the following except:

Accepted Answer

Malignant Glaucoma

Answer

Primary, Open Angle Glaucoma

Answer

Acute Angle Closure Glaucoma

Answer

Chronic Synechial Angle Closure Glaucoma

NEET-PG 2015 — Ophthalmology