Keratoconus and Ectatic Disorders — MCQs
Reis-Buckler dystrophy affects which layer of the cornea?
Which of the following is NOT a cause of crystal keratopathy?
Which of the following is not a feature of keratoconus?
A patient, three years post-surgery, presents with the condition shown in the image and complains of decreased vision. What is the most likely diagnosis?
A 15-year-old girl with myopic astigmatism does not want to wear glasses. What is the best alternative for her?
Which of the following is a feature of vernal keratoconjunctivitis?
Scissor reflex is seen in ?
Which is an emergency therapeutic indication of keratoplasty?
Identify the diagnosis based on the clinical image shown.
What is the gold standard method for visualizing the periphery of the retina?
Keratoconus and Ectatic Disorders Indian Medical PG Practice Questions and MCQs
Question 1: Reis-Buckler dystrophy affects which layer of the cornea?
- A. Stroma
- B. Bowman's membrane (Correct Answer)
- C. Endothelium
- D. Epithelium
Explanation: ***Bowman's membrane*** - **Reis-Buckler dystrophy** is a type of corneal dystrophy specifically characterized by the progressive destruction and irregular regeneration of **Bowman's membrane** and the superficial stroma. - This leads to the formation of an abnormal fibrous layer that causes recurrent corneal erosions and significant visual impairment due to corneal opacification. *Epithelium* - While patients often experience recurrent **corneal erosions** involving the epithelium, the primary pathology in Reis-Buckler dystrophy affects the underlying Bowman's membrane. - The epithelial damage is secondary to the irregular surface created by the diseased Bowman's layer. *Stroma* - The **stroma** can be secondarily affected with superficial scarring and opacification in Reis-Buckler dystrophy, but the initial and primary site of pathology is Bowman's membrane. - Other dystrophies, such as macular or granular dystrophies, primarily involve the corneal stroma. *Endothelium* - The **endothelium** is not directly affected in Reis-Buckler dystrophy. - Endothelial dystrophies, such as Fuchs' endothelial dystrophy, involve the innermost layer of the cornea and lead to corneal edema.
Question 2: Which of the following is NOT a cause of crystal keratopathy?
- A. Schnyder's Dystrophy
- B. Bietti's Dystrophy
- C. Diabetes (Correct Answer)
- D. Cystinosis
Explanation: ***Diabetes*** - While diabetes can cause various ocular complications, such as **diabetic retinopathy**, **neovascular glaucoma**, and **cataracts**, it is **not associated** with crystal keratopathy. - Corneal changes in diabetes might include epithelial defects or reduced corneal sensitivity, but **not the deposition of crystalline substances in the cornea**. - **This is the correct answer** as diabetes does NOT cause crystal keratopathy. *Cystinosis* - **Cystinosis** is a metabolic disorder characterized by the accumulation of **cystine crystals** throughout the body, including the **cornea**. - These crystals can lead to significant **photophobia**, **corneal erosions**, and visual impairment, making it a **classic cause of crystal keratopathy**. - Corneal involvement typically appears in childhood with diffuse crystalline deposits. *Schnyder's Dystrophy* - **Schnyder's corneal dystrophy** is an inherited corneal dystrophy characterized by the deposition of **cholesterol and lipid crystals** in the central and peripheral cornea. - This leads to **dense corneal opacification** and can significantly impair vision over time, representing a **classic cause of crystal keratopathy**. - The cornea shows characteristic subepithelial and stromal crystal deposits. *Bietti's Crystalline Dystrophy* - **Bietti's crystalline dystrophy** is a rare, inherited chorioretinal dystrophy characterized by **crystalline deposits primarily in the retina and choroid**. - While the name suggests crystalline involvement, these crystals are predominantly **intraretinal and do NOT typically cause corneal crystal deposits**. - Therefore, Bietti's is **NOT a typical cause of crystal keratopathy** (corneal disease), though minimal peripheral corneal crystals have been rarely reported in advanced cases. - The confusion arises from the word "crystalline" in its name, but the pathology is retinal, not corneal.
Question 3: Which of the following is not a feature of keratoconus?
- A. Haab's striae (Correct Answer)
- B. Irregular astigmatism
- C. Scissoring reflex
- D. Munson's sign
Explanation: ***Haab's striae*** - **Haab's striae** are characteristic of congenital glaucoma, presenting as horizontal breaks in Descemet's membrane due to increased intraocular pressure and corneal stretching. - In contrast, keratoconus involves **vertical breaks in Descemet's membrane** (due to corneal thinning and protrusion), known as Vautin's striae or Vogt's striae, not Haab's striae. *Irregular astigmatism* - **Irregular astigmatism** is a hallmark of keratoconus, resulting from the asymmetric and non-uniform thinning and protrusion of the cornea. - This irregular corneal shape leads to a significant reduction in visual acuity that cannot be fully corrected with spherical or regular cylindrical lenses. *Scissoring reflex* - The **scissoring reflex** (or scissoring phenomena) is an objective finding observed during retinoscopy in patients with keratoconus, indicating significant irregular astigmatism. - It refers to the opposing movements of the retinoscopic reflex, resembling the opening and closing of scissors, as the light across the pupil is neutralized. *Munson's sign* - **Munson's sign** is a classic clinical finding in advanced keratoconus, where the lower eyelid protrudes in a V-shape when the patient looks downwards. - This protrusion is caused by the conical shape of the cornea pushing against the eyelid.
Question 4: A patient, three years post-surgery, presents with the condition shown in the image and complains of decreased vision. What is the most likely diagnosis?
- A. Corneal Dystrophy
- B. Posterior Subcapsular Cataract (PSC)
- C. Pseudophakic Bullous Keratopathy
- D. Posterior Capsular Opacification (Correct Answer)
Explanation: ***Posterior Capsular Opacification*** - The image (especially part B, the **red reflex view**) shows a cloudy membrane with **Elschnig pearls** and fibrous tissue behind the intraocular lens, which is characteristic of **PCO**. - PCO commonly occurs months to years after cataract surgery and causes **decreased vision** due to scattering of light. *Corneal Dystrophy* - Corneal dystrophies primarily affect the **cornea**, leading to various forms of corneal opacification, and would typically appear as cloudiness or irregularities within the corneal layers. - While it can cause decreased vision, the opacification seen in the image is clearly behind the iris plane and involves the posterior capsule, not the cornea. *Pseudophakic Bullous Keratopathy* - This condition involves **corneal edema** and **bullae formation** due to endothelial cell dysfunction, leading to a hazy cornea. - The image does not show corneal edema or bullae; instead, the primary pathology is located at the **posterior capsule** of the intraocular lens. *Posterior Subcapsular Cataract (PSC)* - A PSC is a type of cataract that forms **before cataract surgery** and affects the natural crystalline lens. - The patient is three years post-surgery, indicating that the natural lens has been replaced, making a PSC (of the natural lens) an impossible diagnosis in this context.
Question 5: A 15-year-old girl with myopic astigmatism does not want to wear glasses. What is the best alternative for her?
- A. LASIK
- B. Spherical Specs
- C. Contact lenses (Toric) (Correct Answer)
- D. FEMTO Lasik
Explanation: ***Contact lenses (Toric)*** - **Toric contact lenses** are specifically designed to correct **astigmatism**, along with myopia or hyperopia, by having different refractive powers in different meridians. - They offer a non-surgical alternative to glasses, addressing the patient's desire not to wear spectacles, and are generally safe and effective for teenagers. *LASIK* - **LASIK (Laser-Assisted In Situ Keratomileusis)** is a surgical procedure to correct refractive errors, but it is not typically recommended for individuals under **18-21 years of age** due to continued eye growth and refractive changes. - The patient's age of 15 makes her an unsuitable candidate for LASIK at this time. *Spherical Specs* - **Spherical spectacles** are designed to correct myopia or hyperopia but cannot adequately correct **astigmatism**, which is a significant component of this patient's refractive error. - The patient also explicitly states she does not want to wear glasses, making this option undesirable. *FEMTO Lasik* - **FEMTO LASIK** is an advanced form of LASIK that uses a femtosecond laser to create the corneal flap, offering higher precision and safety. - However, similar to traditional LASIK, it is a **refractive surgical procedure** and typically not performed on patients younger than **18 years old** due to ongoing eye development.
Question 6: Which of the following is a feature of vernal keratoconjunctivitis?
- A. Follicular hypertrophy
- B. Papillary hypertrophy (Correct Answer)
- C. Pseudomembrane formation
- D. Membrane formation
Explanation: ***Papillary hypertrophy*** - This is a hallmark feature of **vernal keratoconjunctivitis (VKC)**, particularly the presence of large, **cobblestone papillae** on the upper tarsal conjunctiva. - The papillary reaction is due to inflammation and infiltration of the conjunctival stroma with lymphocytes, plasma cells, and eosinophils, leading to raised bumps. - VKC is a chronic, bilateral allergic condition typically affecting children and young adults, with seasonal exacerbations. *Follicular hypertrophy* - **Follicular hypertrophy** is characterized by dome-shaped, avascular elevations formed by hyperplasia of lymphoid tissue, commonly seen in **viral conjunctivitis** and **chlamydial conjunctivitis**. - It is not typically seen in VKC, which is an allergic condition with a papillary rather than follicular response. *Pseudomembrane formation* - **Pseudomembrane formation** is a coagulum of inflammatory exudates and necrotic epithelial cells that loosely adheres to the conjunctiva and can be peeled off without bleeding, often seen in severe **adenoviral conjunctivitis**. - This feature is not characteristic of vernal keratoconjunctivitis. *Membrane formation* - **True membrane formation** involves a fibrinous exudate that is firmly adherent to the conjunctiva, and removal causes bleeding. It is seen in **bacterial conjunctivitis** (particularly diphtheria) and **Stevens-Johnson syndrome**. - Unlike papillary hypertrophy in VKC, membrane formation represents severe inflammatory or infectious processes.
Question 7: Scissor reflex is seen in ?
- A. Open angle glaucoma
- B. Phlyctenular conjunctivitis
- C. Keratoconus (Correct Answer)
- D. Interstitial keratitis
Explanation: ***Keratoconus*** - The **scissor reflex**, or **scissoring reflex**, is a characteristic finding during **retinoscopy** in patients with **keratoconus**. - It is caused by the irregular and variable refractive power across the cornea, leading to a distorted red reflex that appears to split into two bands moving in opposite directions. *Open angle glaucoma* - **Open-angle glaucoma** is characterized by progressive damage to the **optic nerve** and visual field loss, typically with a normal open anterior chamber angle. - It does not involve abnormalities in corneal shape or light refraction that would produce a scissor reflex during retinoscopy. *Phlyctenular conjunctivitis* - **Phlyctenular conjunctivitis** is an inflammatory condition characterized by small nodular lesions (phlyctenules) on the conjunctiva or cornea, often associated with a hypersensitivity reaction to microbial antigens. - This condition primarily affects the surface of the eye and does not cause the corneal ectasia or irregular astigmatism seen in keratoconus. *Interstitial keratitis* - **Interstitial keratitis** is an inflammation of the corneal stroma without significant involvement of the epithelium or endothelium, often associated with systemic infections like syphilis or Lyme disease. - While it can cause corneal opacification and vision loss, it typically does not lead to the conical shape or irregular astigmatism characteristic of keratoconus, which produces the scissor reflex.
Question 8: Which is an emergency therapeutic indication of keratoplasty?
- A. Keratoconus
- B. Perforated corneal ulcer (Correct Answer)
- C. Myopia
- D. Hypermetropia
Explanation: ***Perforated corneal ulcer*** - A **perforated corneal ulcer** is an ocular emergency requiring urgent intervention to restore the integrity of the globe and prevent severe vision loss or endophthalmitis. Keratoplasty, in this context, acts as a tectonic graft to seal the perforation. - The emergent nature stems from the high risk of **intraocular infection** and **collapse of the anterior chamber**, which can lead to permanent damage and vision impairment. *Keratoconus* - While severe **keratoconus** can eventually lead to keratoplasty, it is typically an elective procedure performed to improve vision after other treatments like contact lenses are no longer effective. - It is a **slowly progressive condition** that does not usually pose an immediate threat to ocular integrity unless acute hydrops occurs, which itself may require different acute management. *Myopia* - **Myopia**, or nearsightedness, is a refractive error typically corrected with glasses, contact lenses, or elective refractive surgery (e.g., LASIK). - It is not a condition that warrants a **therapeutic or emergency keratoplasty**, as it does not involve structural compromise or disease of the cornea that would necessitate transplantation. *Hypermetropia* - **Hypermetropia**, or farsightedness, is also a refractive error, managed with corrective lenses or elective refractive surgery. - Similar to myopia, it does not involve a corneal disease process that would necessitate a **keratoplasty**, especially not on an emergency basis.
Question 9: Identify the diagnosis based on the clinical image shown.
- A. Horner-Trantas spots
- B. Herbert's pits (Correct Answer)
- C. Pannus
- D. Corneal dystrophy
Explanation: ***Herbert's pits*** - The image displays characteristic **pits at the limbus**, which are a hallmark of healed follicular conjunctivitis, specifically **Herbert's pits**. - These pits are pathognomonic for **trachoma**, a chronic keratoconjunctivitis caused by *Chlamydia trachomatis*. *Horner-Trantas spots* - These are small, raised, gelatinous white dots found at the limbus, typically containing **eosinophils**. - They are characteristic of **vernal keratoconjunctivitis**, an allergic inflammatory condition, and not seen in the provided image. *Pannus* - **Pannus** refers to the growth of **vascularized connective tissue** onto the cornea. - While pannus is also a feature of trachoma, the image specifically shows distinct limbal pits, rather than diffuse vascularization. *Corneal dystrophy* - **Corneal dystrophies** are a group of inherited, bilateral, and progressive corneal disorders that manifest as opacities or structural changes in the cornea. - The findings in the image, such as pits, are inflammatory in origin and distinct from the typically stromal or epithelial changes seen in corneal dystrophies.
Question 10: What is the gold standard method for visualizing the periphery of the retina?
- A. Direct ophthalmoscopy
- B. Indirect ophthalmoscopy (Correct Answer)
- C. Retinoscopy
- D. USG
Explanation: ***Correct: Indirect ophthalmoscopy*** - This method uses a **condensing lens** and a bright light source to provide a **wide-field, stereoscopic view** of the retina, making it ideal for visualizing the periphery. - It allows for examination even through some media opacities and is particularly useful for detecting peripheral retinal tears or detachments. - Provides a **field of view of 25-40 degrees** compared to only 5-10 degrees with direct ophthalmoscopy. *Incorrect: Direct ophthalmoscopy* - Provides a **highly magnified but narrow field of view**, making it difficult to systematically scan and visualize the entire peripheral retina. - It offers an **upright, monocular image** with limited depth perception, which is not optimal for assessing the three-dimensional structures of the retinal periphery. *Incorrect: Retinoscopy* - This is an objective method used to **determine the refractive error** of an eye, not for direct visualization of the retinal structures. - It involves observing the reflection of light from the retina as the examiner moves a light source across the eye. *Incorrect: USG* - **Ultrasound (USG)** is primarily used to visualize ocular structures when direct visualization is obscured by dense media opacities (e.g., severe cataracts, vitreous hemorrhage). - It provides 2D images and is not the gold standard for **routine, high-resolution visualization** of the retinal periphery when a clear view is obtainable.
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