NEET-PG 2015 — Ophthalmology
59 Previous Year Questions with Answers & Explanations
Cataract is caused by all except:
What is a reverse hypopyon?
Large, white keratic precipitates (mutton-fat KPs) are characteristically seen in?
Which of the following methods is not used to measure refractive error?
Strabismic amblyopia is more common in patients with:
Astigmatism is defined as?
Which is the most powerful refractive surface of the eye?
What term describes a condition where the axial length of the eye does not match its refractive power?
In a case of myopia, LASIK can correct up to how many diopters?
What is regular astigmatism?
NEET-PG 2015 - Ophthalmology NEET-PG Practice Questions and MCQs
Question 1: Cataract is caused by all except:
- A. Ultraviolet radiation
- B. Infrared radiation
- C. Microwave radiation
- D. MRI (Correct Answer)
Explanation: ***MRI*** - Magnetic Resonance Imaging (MRI) uses powerful **magnetic fields** and radio waves to generate images, which are not known to cause cataracts. - The energy used in MRI is **non-ionizing** and does not directly damage lens proteins. *Ultraviolet radiation* - Prolonged exposure to **UV-B radiation** is a significant risk factor for the development of various types of cataracts, especially cortical and posterior subcapsular cataracts. - UV radiation can cause oxidative damage to lens proteins and lipids, leading to their aggregation and opacification. *Infrared radiation* - Chronic exposure to high levels of **infrared (IR) radiation**, such as that experienced by glassblowers or steelworkers, can lead to "glassblower's cataract" or "heat cataract." - IR radiation causes thermal damage to the lens, particularly the anterior capsule and subcapsular region. *Microwave radiation* - High-intensity **microwave radiation** has been implicated in the formation of cataracts, particularly in occupational exposure scenarios. - It causes thermal effects within the lens due to absorption of energy, leading to protein denaturation and opacification.
Question 2: What is a reverse hypopyon?
- A. Collection of pus in the vitreous
- B. Abscess in the orbit
- C. Seen in corneal ulcer close to being ruptured
- D. Collection of emulsified silicone oil in the anterior chamber (Correct Answer)
Explanation: ***Collection of emulsified silicone oil in the anterior chamber*** - A **reverse hypopyon** is characterized by the accumulation of **emulsified silicone oil droplets** in the anterior chamber, which float superiorly due to silicone oil's lower specific gravity than aqueous humor. - This condition is typically observed in patients who have undergone **vitrectomy with silicone oil tamponade** for retinal detachment, and it can indicate **silicone oil emulsification**. *Collection of pus in the vitreous* - A collection of pus in the vitreous is known as **vitreous abscess** or **endophthalmitis**, which is a severe infection causing inflammation within the eye. - This condition presents with significant pain, vision loss, and typically a **hypopyon** (pus in the anterior chamber) with a horizontal level, not a reverse hypopyon. *Abscess in the orbit* - An **orbital abscess** is a localized collection of pus within the orbit, typically caused by bacterial infection, leading to proptosis, pain, and ophthalmoplegia. - This condition affects the tissues surrounding the eye, not the anterior chamber contents, and does not involve the characteristic silicone oil droplets seen in a reverse hypopyon. *Seen in corneal ulcer close to being ruptured* - A **corneal ulcer** with impending rupture may present with a **hypopyon** (pus in the anterior chamber) due to severe inflammation and infection. - This hypopyon consists of inflammatory cells that settle inferiorly due to gravity, distinct from the floating silicone oil droplets of a reverse hypopyon.
Question 3: Large, white keratic precipitates (mutton-fat KPs) are characteristically seen in?
- A. Hemorrhagic uveitis
- B. Old healed uveitis
- C. Granulomatous uveitis (Correct Answer)
- D. Acute anterior uveitis
Explanation: ***Granulomatous uveitis*** - **Mutton-fat keratic precipitates (KPs)** are large, greasy-appearing white deposits on the corneal endothelium, characteristic of **granulomatous inflammation**. - These KPs are composed of macrophages and epithelioid cells, reflecting a **chronic, cell-mediated immune response** seen in granulomatous conditions. *Hemorrhagic uveitis* - This condition involves significant **intraocular bleeding**, which would manifest as hyphema or vitreous hemorrhage, not mutton-fat KPs. - While inflammation may be present, the defining feature is blood, which obscures vision differently than KPs. *Old healed uveitis* - After uveitis heals, KP morphology can change, often appearing smaller, more pigmented, or forming distinct patterns such as **Arlt's triangle**, but not typically actively large, white mutton-fat KPs. - Healed KPs often reflect a less active or resolved inflammatory process, unlike fresh mutton-fat KPs. *Acute anterior uveitis* - This typically presents with smaller, finer, and more numerous **non-granulomatous KPs** (sometimes called "stellate KPs"), in contrast to the large, greasy mutton-fat KPs. - The inflammation is usually acute and less focally organized compared to granulomatous forms.
Question 4: Which of the following methods is not used to measure refractive error?
- A. Keratometry
- B. Retinoscopy
- C. Refractometry
- D. Spectrometry (Correct Answer)
Explanation: ***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.
Question 5: Strabismic amblyopia is more common in patients with:
- A. Constant strabismus (Correct Answer)
- B. Alternating strabismus
- C. Latent strabismus
- D. Intermittent strabismus
Explanation: **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.
Question 6: Astigmatism is defined as?
- A. Refractive error due to long AP length of eyeball
- B. Varying refractive error in both eyes
- C. Varying shape perception by both eyes
- D. Refractive error wherein refraction varies along different meridians (Correct Answer)
Explanation: ***Refractive error wherein refraction varies along different meridians*** - **Astigmatism** is a type of **refractive error** where the eye’s cornea or lens has a different curvature in different directions (meridians). - This irregular curvature causes light rays to focus at multiple points on or in front of the retina, leading to **blurred or distorted vision**. *Refractive error due to long AP length of eyeball* - A long axial length of the eyeball is characteristic of **myopia** (nearsightedness), where light focuses in front of the retina. - This definition does not describe **astigmatism**, which is primarily about irregular curvature rather than overall length. *Varying refractive error in both eyes* - This describes **anisometropia**, a condition where the two eyes have significantly different refractive powers. - While anisometropia can coexist with astigmatism, it is not the definition of **astigmatism** itself. *Varying shape perception by both eyes* - This could imply conditions like **aniseikonia**, where the perceived size and shape of images differ between the two eyes. - It does not directly define **astigmatism**, which is a primary refractive error related to the focusing of light.
Question 7: Which is the most powerful refractive surface of the eye?
- A. Conjunctiva
- B. Cornea (Correct Answer)
- C. Vitreous
- D. Lens
Explanation: ***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.
Question 8: What term describes a condition where the axial length of the eye does not match its refractive power?
- A. Anisokonia
- B. Axial Ametropia (Correct Answer)
- C. Emmetropia
- D. Curvature ametropia
Explanation: ***Axial Ametropia*** - This term precisely describes a refractive error where the **axial length** of the eye is either too long or too short relative to its **optical power**, leading to images focusing in front of or behind the retina. - Examples include **myopia** (eye too long) and **hyperopia** (eye too short), which are fundamentally caused by a mismatch in axial length. *Anisokonia* - This condition refers to a significant difference in the **perceived size of images** between the two eyes, often due to unequal refractive errors between the eyes. - It does not directly describe the mismatch between axial length and refractive power itself, but rather a perceptual consequence that can result from asymmetric refractive errors. *Curvature ametropia* - This type of ametropia occurs when the **curvature** of the cornea or lens is abnormal, causing light rays to converge incorrectly. - While it's a form of refractive error, it specifically relates to the curvature of refractive surfaces, not the overall **axial length** of the eyeball. *Emmetropia* - This is the state of having **perfect vision**, where the refractive power of the eye correctly matches its axial length, allowing light to focus precisely on the retina without accommodation. - It describes the absence of refractive error, which is the opposite of the condition described in the question.
Question 9: In a case of myopia, LASIK can correct up to how many diopters?
- A. -4D
- B. -12D (Correct Answer)
- C. -20D
- D. -6D
Explanation: ***-12D*** - LASIK can effectively correct myopia up to approximately **-12 diopters** in suitable candidates, though this can vary slightly based on individual corneal thickness and health. - The excimer laser reshapes the **cornea** to reduce its curvature, thereby decreasing the focusing power of the eye and correcting the myopic error. *-20D* - While some highly myopic individuals might desire such a correction, LASIK is generally not recommended or effective for myopia higher than **-12 to -14 diopters** due to limitations in corneal tissue removal and potential for complications. - Correcting very high myopia with LASIK would require removing too much corneal tissue, potentially leading to **corneal instability** or vision-threatening complications like **ectasia**. *-6D* - This is a common and highly successful range for LASIK correction, but it represents only a **moderate level of myopia** and not the maximum correctable range. - Patients with myopia of -6D typically achieve excellent visual outcomes with very low complication rates after LASIK. *-4D* - This is a relatively low level of myopia, and LASIK is very effective for this amount of correction, but it is far from the **upper limit** of what LASIK can achieve. - This level of correction requires minimal corneal reshaping and typically results in a very high success rate and predictable outcomes.
Question 10: What is regular astigmatism?
- A. Astigmatism in which the principal meridians are parallel
- B. Asymptomatic astigmatism
- C. Astigmatism as a result of cataract surgery
- D. Astigmatism where the principal meridians are at a 90-degree angle to each other (Correct Answer)
Explanation: ***Astigmatism where the principal meridians are at a 90-degree angle to each other.*** - In **regular astigmatism**, the two principal meridians of the eye's refractive power are **perpendicular** (90 degrees apart), meaning they are not random. - This perpendicularity allows for correction with **sphero-cylindrical lenses**, as the different focal powers are along well-defined axes. *Astigmatism in which the principal meridians are parallel* - This statement is incorrect as it describes a non-existent or mischaracterized form of astigmatism; for astigmatism to occur, there must be a **difference in curvature** and thus power between two meridians, which cannot be parallel and distinct. - While meridians are typically measured, the concept of **parallel principal meridians** does not align with the definition of astigmatism. *Asymptomatic astigmatism* - This describes the **presence of astigmatism without noticeable symptoms**, not the type of astigmatism itself. - Astigmatism can be asymptomatic, particularly if it is of a **low magnitude**, but this term does not define its optical characteristics. *Astigmatism as a result of cataract surgery* - This refers to **induced astigmatism**, often post-surgical, which can be regular or irregular. - **Surgically induced astigmatism** is a cause, not a classification of astigmatism based on the orientation of its principal meridians.