FMGE 2025 - Ophthalmology Practice Questions

Q: The following light reflex is seen in a patient. How much is the deviation?

45 PD. ***45 PD*** - The image displays the **Hirschberg test** (corneal light reflex test), which estimates the angle of strabismus. The light reflex is displaced nasally in the left eye, indicating an outward deviation (**exotropia**). - A reflex located approximately midway between the pupil margin and the limbus corresponds to a deviation of about 22.5 degrees, which is equivalent to **45 prism diopters (PD)**. *30 PD* - A deviation of 30 PD corresponds to approximately 15 degrees, where the light reflex would be seen at the **pupillary margin**. - This represents a smaller deviation than what is depicted in the image. *90 PD* - This value corresponds to a large deviation of 45 degrees, where the light reflex would be located at the **limbus** (the junction of the cornea and sclera). - The light reflex in the image is positioned midway between the pupil and limbus, indicating a smaller deviation than what would be seen with a full 90 PD deviation. *90°* - This is an extremely large deviation and is also an incorrect unit of measurement for this test; **prism diopters (PD)** are the standard unit used to quantify strabismus. - One degree of deviation is roughly equal to two prism diopters, making a 90-degree deviation (180 PD) anatomically inconsistent with the image.

Q: A patient presents with a down and out right eye with ptosis since birth. What is the nerve palsy?

3rd nerve palsy. ***3rd nerve palsy (Correct Answer)*** - The **oculomotor nerve (CN III)** supplies the levator palpebrae superioris, leading to **ptosis**, and most extraocular muscles (superior rectus, medial rectus, inferior rectus, and inferior oblique) - When CN III is paralyzed, the unopposed actions of **CN IV (superior oblique)** and **CN VI (lateral rectus)** pull the eye into the characteristic **"down and out"** position - **Congenital 3rd nerve palsy** presents with ptosis and the down-and-out eye position from birth - This is the classic triad: **ptosis + down and out eye + dilated pupil** (if pupil-involving) *4th nerve palsy (Incorrect)* - Palsy of the **trochlear nerve (CN IV)** affects only the superior oblique muscle - Presents with impaired **downward and inward movement** and **intorsion** - Typically causes **vertical diplopia** (especially on downward gaze) and compensatory **head tilt** to the opposite side - Does **NOT** cause ptosis or the pronounced "down and out" position *6th nerve palsy (Incorrect)* - Palsy of the **abducens nerve (CN VI)** affects only the lateral rectus muscle - Causes failure of **abduction** (outward movement), resulting in the eye being pulled **inward** (esotropia) - Does **NOT** cause ptosis or downward deviation of the eye *7th nerve palsy (Incorrect)* - The **facial nerve (CN VII)** controls facial muscles, including orbicularis oculi - Causes **lagophthalmos** (inability to close the eyelid) and facial weakness, NOT ptosis - Does **NOT** affect extraocular movements or eye position

Q: A posterior staphyloma was observed on indirect ophthalmoscopy. What is the likely diagnosis?

High myopia. ***High myopia*** - A **posterior staphyloma** is an outpouching of the sclera at the posterior pole of the eye, which is a pathognomonic sign of **pathological** or **high myopia** due to excessive axial elongation. - Other associated fundus findings in high myopia include **chorioretinal atrophy**, **lacquer cracks** (breaks in Bruch's membrane), and an increased risk of **retinal detachment**. *Hypermetropia* - Hypermetropia (farsightedness) is characterized by a **shorter axial length**, which is the opposite of the anatomical changes seen in high myopia that lead to staphyloma formation. - Fundus examination in hypermetropia may reveal a small, crowded optic disc, sometimes referred to as **pseudopapilledema**, but not scleral ectasia. *Primary open-angle glaucoma* - The primary funduscopic sign of glaucoma is progressive damage to the **optic nerve head**, manifesting as an increased **cup-to-disc ratio** and thinning of the neuroretinal rim. - While a myopic optic disc can be difficult to assess for glaucoma, a staphyloma itself is a feature of the sclera and retina, not a primary sign of glaucoma. *Retinitis pigmentosa* - This is an inherited retinal dystrophy with characteristic fundus findings including **bone-spicule pigmentation** in the mid-periphery, **arteriolar attenuation**, and **waxy pallor of the optic disc**. - These changes result from photoreceptor and retinal pigment epithelium degeneration, and are not associated with the formation of a posterior staphyloma.

Question 1

The following light reflex is seen in a patient. How much is the deviation?

Accepted Answer

45 PD

Answer

90 PD

Answer

30 PD

Answer

90°

Question 2

A patient presents with a down and out right eye with ptosis since birth. What is the nerve palsy?

Accepted Answer

3rd nerve palsy

Answer

4th nerve palsy

Answer

6th nerve palsy

Answer

7th nerve palsy

Question 3

A posterior staphyloma was observed on indirect ophthalmoscopy. What is the likely diagnosis?

Accepted Answer

High myopia

Answer

Retinitis pigmentosa

Answer

Primary open-angle glaucoma

Answer

Hypermetropia

FMGE 2025 — Ophthalmology