INI-CET 2024 — Ophthalmology

Q: What term describes a condition where the axial length of the eye does not match its refractive power?

Axial Ametropia. ***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. [Practice more Ophthalmology PYQs on OnCourse]

Q: In a child presenting unilateral watering and photophobia which of the following is the least likely disorder?

Congenital NLDO. **Congenital NLDO** - **Congenital nasolacrimal duct obstruction (NLDO)** typically presents with **unilateral watering** (epiphora) due to blockage of tear drainage. - While it causes watering, **photophobia** is not a characteristic symptom of isolated NLDO, making it less likely given the combined presentation. *Congenital entropion* - **Congenital entropion** involves the inward turning of the eyelid margin, causing eyelashes to rub against the cornea. - This irritation can lead to **unilateral watering** and **photophobia** due to corneal abrasion and discomfort. *Congenital glaucoma* - **Congenital glaucoma** is characterized by elevated intraocular pressure, which can cause corneal edema and stretching. - These changes commonly result in **unilateral watering** (epiphora) and marked **photophobia**, often accompanied by **buphthalmos** (enlarged eye). *Congenital dacryocystitis* - **Congenital dacryocystitis** is an infection of the lacrimal sac, often secondary to NLDO. - It presents with **unilateral watering**, discharge, and inflammation of the lacrimal sac, and the associated irritation can induce **photophobia**. [Practice more Ophthalmology PYQs on OnCourse]

Q: A 40-year-old male experiences flashes of light. Which of the following can likely be the reason?

Retinal detachment. ***Retinal detachment*** - Flashes of light, or **photopsia**, are a classic symptom of **retinal detachment**, often caused by the retina pulling away from the underlying choroid. - This sensation occurs as the detached retina is mechanically stimulated, sending abnormal signals to the brain that are interpreted as light flashes. *CRAO* - **Central Retinal Artery Occlusion (CRAO)** typically presents with **sudden, painless, severe vision loss** in one eye, not flashes of light. - The primary pathology is a blockage of blood flow to the retina, leading to **ischemia** and vision impairment. *SAH* - **Subarachnoid Hemorrhage (SAH)** is a neurological emergency characterized by **sudden, severe headache** (thunderclap headache), stiff neck, and altered mental status. - While it can cause visual disturbances, these are usually **diplopia** or **visual field defects** due to cranial nerve involvement, not flashes of light related to retinal pathology. *Branch retinal artery occlusion* - **Branch Retinal Artery Occlusion** causes **sudden, painless vision loss** in a specific part of the visual field corresponding to the occluded branch. - Like CRAO, it is an ischemic event and does not typically present with flashes of light; instead, it results in a **scotoma** or partial vision loss. [Practice more Ophthalmology PYQs on OnCourse]

Q: An 80-year-old patient complains of pain, redness, and diminished vision in the left eye. On examination, the intraocular pressure (IOP) in the right eye is 16 mmHg, while the left eye shows 50 mmHg. The left eye also exhibits deep anterior chamber flare and a white cataract. What is the most likely diagnosis?

Phacolytic glaucoma. ***Phacolytic glaucoma*** - The combination of **extremely high intraocular pressure** (50 mmHg) in the left eye, along with a **mature (white) cataract** and **deep anterior chamber flare**, is highly suggestive of phacolytic glaucoma. - This condition occurs when **lens proteins leak** from a hypermature cataract, triggering a macrophagic inflammatory response that **clogs the trabecular meshwork**, leading to an acute rise in IOP. *Central retinal artery occlusion (CRAO)* - While CRAO causes acute, profound **vision loss** in one eye, it is generally associated with a **normal or low IOP**, not the extremely high pressure seen in the left eye. - Fundoscopic examination would typically reveal a **cherry-red spot** and **pale retina**, which are not described. *Fuchs' heterochromic iridocyclitis* - This condition is characterized by **chronic, low-grade anterior uveitis** and often leads to **heterochromia** (different colored irises) and **secondary glaucoma**. - However, it typically presents with **mild IOP elevation** (if at all) and not the acute, markedly high pressure and visible white cataract with flare described here. *Malignant glaucoma* - Malignant glaucoma (also known as aqueous misdirection) presents with an **elevated IOP** and is characterized by a **shallow or flat anterior chamber**, often in the presence of a pupillary block mechanism. - The patient's left eye is described as having a **deep anterior chamber** with flare, which contradicts the typical findings of malignant glaucoma. [Practice more Ophthalmology PYQs on OnCourse]

Q: A patient presents with superior quadrant vision loss since one week. Patient has Rheumatic Heart Disease (RHD) and is not taking medications. What is the most likely diagnosis?

BRAO. ***BRAO*** - **Branch retinal artery occlusion** (BRAO) presents with **sudden, painless sectoral or quadrant visual field loss** corresponding to the distribution of the occluded arterial branch. - Superior quadrant vision loss indicates **inferior retinal involvement** (visual field is inverted on retina). - **Rheumatic heart disease** not on anticoagulation poses high risk for **cardiac emboli** from valvular vegetations or atrial fibrillation, which preferentially cause **arterial occlusions** (BRAO/CRAO). - Fundoscopy shows **retinal whitening** in the affected area with a clear demarcation line. *BRVO* - **Branch retinal vein occlusion** causes quadrant vision loss but is **NOT typically embolic** in nature. - BRVO is associated with systemic **vascular risk factors** (hypertension, diabetes, hyperlipidemia), not cardiac emboli. - Fundoscopy shows **flame-shaped hemorrhages** and cotton-wool spots in a wedge distribution. *CRAO* - **Central retinal artery occlusion** presents with **complete, sudden painless monocular vision loss** affecting the entire visual field. - Shows classic **"cherry-red spot"** at the fovea due to diffuse retinal ischemia. - Would not present with isolated quadrant vision loss. *CRVO* - **Central retinal vein occlusion** causes **complete monocular vision loss** with "blood and thunder" appearance on fundoscopy. - Presents with diffuse retinal hemorrhages throughout the retina, not isolated to one quadrant. [Practice more Ophthalmology PYQs on OnCourse]

6 Previous Year Questions with Answers & Explanations

Questions

What term describes a condition where the axial length of the eye does not match its refractive power?

In a child presenting unilateral watering and photophobia which of the following is the least likely disorder?

A 40-year-old male experiences flashes of light. Which of the following can likely be the reason?

An 80-year-old patient complains of pain, redness, and diminished vision in the left eye. On examination, the intraocular pressure (IOP) in the right eye is 16 mmHg, while the left eye shows 50 mmHg. The left eye also exhibits deep anterior chamber flare and a white cataract. What is the most likely diagnosis?

A patient presents with superior quadrant vision loss since one week. Patient has Rheumatic Heart Disease (RHD) and is not taking medications. What is the most likely diagnosis?

A-wave in Electroretinogram corresponds to the activity of

INI-CET 2024 - Ophthalmology INI-CET Practice Questions and MCQs

Question 1: 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 2: In a child presenting unilateral watering and photophobia which of the following is the least likely disorder?

A. Congenital entropion
B. Congenital glaucoma
C. Congenital NLDO (Correct Answer)
D. Congenital dacryocystitis

Explanation: **Congenital NLDO** - **Congenital nasolacrimal duct obstruction (NLDO)** typically presents with **unilateral watering** (epiphora) due to blockage of tear drainage. - While it causes watering, **photophobia** is not a characteristic symptom of isolated NLDO, making it less likely given the combined presentation. *Congenital entropion* - **Congenital entropion** involves the inward turning of the eyelid margin, causing eyelashes to rub against the cornea. - This irritation can lead to **unilateral watering** and **photophobia** due to corneal abrasion and discomfort. *Congenital glaucoma* - **Congenital glaucoma** is characterized by elevated intraocular pressure, which can cause corneal edema and stretching. - These changes commonly result in **unilateral watering** (epiphora) and marked **photophobia**, often accompanied by **buphthalmos** (enlarged eye). *Congenital dacryocystitis* - **Congenital dacryocystitis** is an infection of the lacrimal sac, often secondary to NLDO. - It presents with **unilateral watering**, discharge, and inflammation of the lacrimal sac, and the associated irritation can induce **photophobia**.

Question 3: A 40-year-old male experiences flashes of light. Which of the following can likely be the reason?

A. Retinal detachment (Correct Answer)
B. CRAO
C. SAH
D. Branch retinal artery occlusion

Explanation: ***Retinal detachment*** - Flashes of light, or **photopsia**, are a classic symptom of **retinal detachment**, often caused by the retina pulling away from the underlying choroid. - This sensation occurs as the detached retina is mechanically stimulated, sending abnormal signals to the brain that are interpreted as light flashes. *CRAO* - **Central Retinal Artery Occlusion (CRAO)** typically presents with **sudden, painless, severe vision loss** in one eye, not flashes of light. - The primary pathology is a blockage of blood flow to the retina, leading to **ischemia** and vision impairment. *SAH* - **Subarachnoid Hemorrhage (SAH)** is a neurological emergency characterized by **sudden, severe headache** (thunderclap headache), stiff neck, and altered mental status. - While it can cause visual disturbances, these are usually **diplopia** or **visual field defects** due to cranial nerve involvement, not flashes of light related to retinal pathology. *Branch retinal artery occlusion* - **Branch Retinal Artery Occlusion** causes **sudden, painless vision loss** in a specific part of the visual field corresponding to the occluded branch. - Like CRAO, it is an ischemic event and does not typically present with flashes of light; instead, it results in a **scotoma** or partial vision loss.

Question 4: An 80-year-old patient complains of pain, redness, and diminished vision in the left eye. On examination, the intraocular pressure (IOP) in the right eye is 16 mmHg, while the left eye shows 50 mmHg. The left eye also exhibits deep anterior chamber flare and a white cataract. What is the most likely diagnosis?

A. Central retinal artery occlusion (CRAO)
B. Fuchs' heterochromic iridocyclitis
C. Malignant glaucoma
D. Phacolytic glaucoma (Correct Answer)

Explanation: ***Phacolytic glaucoma*** - The combination of **extremely high intraocular pressure** (50 mmHg) in the left eye, along with a **mature (white) cataract** and **deep anterior chamber flare**, is highly suggestive of phacolytic glaucoma. - This condition occurs when **lens proteins leak** from a hypermature cataract, triggering a macrophagic inflammatory response that **clogs the trabecular meshwork**, leading to an acute rise in IOP. *Central retinal artery occlusion (CRAO)* - While CRAO causes acute, profound **vision loss** in one eye, it is generally associated with a **normal or low IOP**, not the extremely high pressure seen in the left eye. - Fundoscopic examination would typically reveal a **cherry-red spot** and **pale retina**, which are not described. *Fuchs' heterochromic iridocyclitis* - This condition is characterized by **chronic, low-grade anterior uveitis** and often leads to **heterochromia** (different colored irises) and **secondary glaucoma**. - However, it typically presents with **mild IOP elevation** (if at all) and not the acute, markedly high pressure and visible white cataract with flare described here. *Malignant glaucoma* - Malignant glaucoma (also known as aqueous misdirection) presents with an **elevated IOP** and is characterized by a **shallow or flat anterior chamber**, often in the presence of a pupillary block mechanism. - The patient's left eye is described as having a **deep anterior chamber** with flare, which contradicts the typical findings of malignant glaucoma.

Question 5: A patient presents with superior quadrant vision loss since one week. Patient has Rheumatic Heart Disease (RHD) and is not taking medications. What is the most likely diagnosis?

A. CRAO
B. CRVO
C. BRAO (Correct Answer)
D. BRVO

Explanation: ***BRAO*** - **Branch retinal artery occlusion** (BRAO) presents with **sudden, painless sectoral or quadrant visual field loss** corresponding to the distribution of the occluded arterial branch. - Superior quadrant vision loss indicates **inferior retinal involvement** (visual field is inverted on retina). - **Rheumatic heart disease** not on anticoagulation poses high risk for **cardiac emboli** from valvular vegetations or atrial fibrillation, which preferentially cause **arterial occlusions** (BRAO/CRAO). - Fundoscopy shows **retinal whitening** in the affected area with a clear demarcation line. *BRVO* - **Branch retinal vein occlusion** causes quadrant vision loss but is **NOT typically embolic** in nature. - BRVO is associated with systemic **vascular risk factors** (hypertension, diabetes, hyperlipidemia), not cardiac emboli. - Fundoscopy shows **flame-shaped hemorrhages** and cotton-wool spots in a wedge distribution. *CRAO* - **Central retinal artery occlusion** presents with **complete, sudden painless monocular vision loss** affecting the entire visual field. - Shows classic **"cherry-red spot"** at the fovea due to diffuse retinal ischemia. - Would not present with isolated quadrant vision loss. *CRVO* - **Central retinal vein occlusion** causes **complete monocular vision loss** with "blood and thunder" appearance on fundoscopy. - Presents with diffuse retinal hemorrhages throughout the retina, not isolated to one quadrant.

Question 6: A-wave in Electroretinogram corresponds to the activity of

A. Pigment epithelium
B. Rods and cones (Correct Answer)
C. Nerve fibre layer
D. Ganglion cell layer

Explanation: ***Rods and cones*** - The **'a' wave** of the Electroretinogram (ERG) represents the **initial negative deflection**, primarily generated by the activity of the **photoreceptors** (rods and cones) in response to light stimulation. - This wave reflects the **hyperpolarization** of the photoreceptor cells as they absorb light and initiate the visual transduction cascade. *Pigment epithelium* - The **retinal pigment epithelium (RPE)** plays a crucial role in supporting photoreceptor function and has a slower, sustained electrical response, which contributes more to the **c-wave** of the ERG. - While the RPE is vital for retinal function, its primary electrical contribution is not represented by the initial negative a-wave. *Nerve fibre layer* - The **nerve fiber layer** consists of the axons of ganglion cells and does not directly contribute to the primary a-wave or b-wave of the ERG as it is involved in transmitting signals to the brain. - Damage to this layer may affect overall visual function but is not the source of the initial photoreceptor-driven electrical response. *Ganglion cell layer* - The **ganglion cell layer** is responsible for sending visual information to the brain, and its activity is typically reflected in later, more complex components of the ERG or in other electrophysiological tests like pattern ERG. - The initial photoreceptor response (a-wave) occurs upstream of the ganglion cell activity.