Ophthalmology
10 questionsStrabismic amblyopia is more common in patients with:
Astigmatism is defined as?
What is regular astigmatism?
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?
Which of the following statements about pterygium is false?
Silk retina is seen in ?
Pseudopapilledema with tigroid fundus appearance is seen in?
1mm change in axial length of the eyeball would change the refracting power of the eye by?
A 30 year old man presents to the clinic with pain in the eye, watering, redness, and photophobia. Examination of his eyes shows circumcorneal congestion and keratic precipitates. Assertion: Keratic precipitates (KPs) are proteinaceous deposits that can occur in various patterns on the corneal endothelium. Reason: Mutton fat KPs are seen in granulomatous iridocyclitis and are composed of epithelioid cells and macrophages.
NEET-PG 2015 - Ophthalmology NEET-PG Practice Questions and MCQs
Question 581: 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 582: 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 583: 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.
Question 584: 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 585: 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 586: Which of the following statements about pterygium is false?
- A. Arise from any part of conjunctiva (Correct Answer)
- B. Can cause astigmatism
- C. Surgery is treatment of choice
- D. UV exposure is risk factor
Explanation: ***Arise from any part of conjunctiva*** **(FALSE - Correct Answer)** - This statement is **FALSE** and thus the correct answer. - Pterygium characteristically arises from the **nasal (interpalpebral) bulbar conjunctiva** in 90-95% of cases. - It does NOT arise from "any part" - it has a specific predilection for the medial (nasal) limbus in the palpebral fissure zone. - Temporal pterygium is much less common (~10% of cases). *Can cause astigmatism* **(TRUE)** - This statement is TRUE. - As a pterygium grows across the cornea, it can induce **corneal astigmatism** by altering the curvature of the cornea. - This irregular corneal surface can blur vision, especially as the pterygium progresses towards the central visual axis. *Surgery is treatment of choice* **(TRUE)** - This statement is TRUE. - **Surgical excision** is the primary treatment for pterygium when it is symptomatic, threatens vision, or causes significant cosmetic concerns. - Indications for surgery include: growth towards the visual axis, inducing high astigmatism, significant discomfort, or cosmetic desire. - Adjunctive measures (mitomycin C, conjunctival autograft) help reduce recurrence. *UV exposure is risk factor* **(TRUE)** - This statement is TRUE. - **Ultraviolet (UV) radiation exposure** is a well-established and significant risk factor for the development and progression of pterygium. - This explains its higher prevalence in individuals living in sunny climates (between 37° N and 37° S latitude - "pterygium belt") and those with outdoor occupations.
Question 587: Silk retina is seen in ?
- A. Retinal detachment (Correct Answer)
- B. Diabetic retinopathy
- C. Macular degeneration
- D. Hypertensive retinopathy
Explanation: ***Retinal detachment*** - **"Silk retina" or "silky sheen"** is a classic ophthalmoscopic finding in retinal detachment, describing the **smooth, glistening appearance** of the detached sensory retina. - The detached retina appears **elevated, gray, and translucent** with characteristic folds or undulations, exhibiting a **satiny or silky luster** when examined. - Patients typically present with **photopsias (flashes of light)**, **floaters**, and progressive **visual field defect** described as a "curtain" or "shadow." - This is a true **ophthalmic emergency** requiring urgent surgical intervention. *Diabetic retinopathy* - Characterized by **microaneurysms, dot-blot hemorrhages, hard exudates**, and **cotton-wool spots** in non-proliferative stages. - Proliferative diabetic retinopathy shows **neovascularization** and vitreous hemorrhage. - Does not produce the "silk retina" appearance. *Macular degeneration* - Age-related macular degeneration presents with **drusen, pigmentary changes**, and in advanced stages, **geographic atrophy** or **choroidal neovascularization**. - May show a **"beaten-bronze" appearance** in certain macular dystrophies (Best's disease), but not "silk retina." - Central vision loss is the predominant symptom. *Hypertensive retinopathy* - Features include **generalized arteriolar narrowing, AV nicking, flame-shaped hemorrhages**, and **cotton-wool spots**. - In severe cases (Grade IV), **optic disc edema** and macular star exudates may occur. - Vascular changes dominate the clinical picture, not a silky retinal appearance.
Question 588: Pseudopapilledema with tigroid fundus appearance is seen in?
- A. Astigmatism
- B. Presbyopia
- C. Hypermetropia
- D. Myopia (Correct Answer)
Explanation: ***Myopia*** - **Pseudopapilledema** with a **tigroid fundus** (tessellated or salt-and-pepper appearance) is characteristically observed in high myopia due to the oblique entry of the **optic nerve** into the globe and thinning of the choroid and retinal pigment epithelium. - The pseudopapilledema is caused by the crowding of axons and glial tissue within the optic disc, giving a raised appearance, and is distinct from true papilledema which involves **optic disc edema** due to increased **intracranial pressure**. - The tigroid fundus results from the visibility of underlying **choroidal vessels** through the attenuated retinal pigment epithelium in the stretched, elongated myopic eye. *Hypermetropia* - **Hypermetropia** (farsightedness) typically presents with a small, compact optic disc, but does not exhibit the specific findings of **pseudopapilledema** or tigroid fundus. - This condition is characterized by the eye being too short or the lens having insufficient power, causing light to focus behind the retina. *Astigmatism* - **Astigmatism** is characterized by an **irregularly shaped cornea** or lens, leading to blurred vision at all distances. - While it can cause some distortion, it is not associated with the specific optic disc appearance of **pseudopapilledema** or the fundus changes seen in high myopia. *Presbyopia* - **Presbyopia** is an age-related condition where the eye's natural lens loses its flexibility, making it difficult to focus on **near objects**. - It affects the **accommodative ability** of the eye and does not manifest with any characteristic changes in the optic disc morphology such as **pseudopapilledema** or retinal/choroidal changes.
Question 589: 1mm change in axial length of the eyeball would change the refracting power of the eye by?
- A. 1D
- B. 2D
- C. 3D (Correct Answer)
- D. 4D
Explanation: ***3D*** - A 1mm change in the **axial length** of the eyeball leads to an approximate **3 diopter (D) change** in the refractive power of the eye. - This relationship is crucial for understanding **refractive errors** like myopia (if the eyeball is too long) or hyperopia (if it's too short). *1D* - A 1D change in refractive power corresponds to a much larger change in the **focal length** of the eye, not typically 1mm in axial length. - This value is too small to reflect the significant impact of a 1mm axial length alteration on the eye's focusing ability. *2D* - While a direct relationship exists, 2D is an **underestimation** of the actual refractive change caused by a 1mm alteration in axial length. - This value would imply a less sensitive optical system than the human eye. *4D* - A 4D change would represent an **overestimation** of the refractive power change for a 1mm alteration in axial length. - Such a high value is generally seen with more substantial anatomical variations or surgical interventions.
Question 590: A 30 year old man presents to the clinic with pain in the eye, watering, redness, and photophobia. Examination of his eyes shows circumcorneal congestion and keratic precipitates. Assertion: Keratic precipitates (KPs) are proteinaceous deposits that can occur in various patterns on the corneal endothelium. Reason: Mutton fat KPs are seen in granulomatous iridocyclitis and are composed of epithelioid cells and macrophages.
- A. Both Assertion and Reason are true, and Reason is the correct explanation for Assertion
- B. Both Assertion and Reason are true, and Reason is not the correct explanation for Assertion (Correct Answer)
- C. Assertion is true, but Reason is false
- D. Assertion is false but reason is true
Explanation: ***Both Assertion and Reason are true, and Reason is not the correct explanation for Assertion*** **Why both statements are true:** - The **Assertion** is correct: Keratic precipitates (KPs) are inflammatory cell and protein deposits that adhere to the **corneal endothelium** and can present in various patterns including fine dusty KPs, medium-sized KPs, and large mutton fat KPs. - The **Reason** is also correct: **Mutton fat KPs** are characteristic of **granulomatous anterior uveitis** (granulomatous iridocyclitis) and consist of aggregations of **epithelioid cells and macrophages**, appearing as large, greasy, white deposits. **Why Reason does NOT explain Assertion:** - The Reason describes a **specific type** of KP (mutton fat) and its cellular composition in one particular form of inflammation (granulomatous). - The Assertion makes a **general statement** about KPs occurring in various patterns. - The Reason does not explain **why** KPs can occur in various patterns or what determines these different patterns - it only describes one specific pattern. *Incorrect: Both true with Reason explaining Assertion* - The Reason is too specific and only describes one type of KP, not the general mechanism of pattern variation. *Incorrect: Assertion true, Reason false* - Both statements are medically accurate and well-established in ophthalmology literature. *Incorrect: Assertion false, Reason true* - KPs are well-documented deposits on the corneal endothelium in various forms of uveitis, making the Assertion true.