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Kuwait Board Ophthalmology study materials
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Kuwait Board Ophthalmology practice questions

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Question 1Basic Sciences and Ocular Anatomy/Physiology

During phacoemulsification, the surgeon asks which structure must remain intact to preserve the eye's main refractive interface after the natural lens is removed. Which structure is this?

  1. The anterior lens capsule
  2. The zonular fibers of Zinn
  3. The posterior lens capsule Correct answer.
  4. The ciliary body epithelium

Explanation

The posterior capsule is deliberately preserved during standard phacoemulsification because it supports the intraocular lens implant and separates the anterior from the posterior segment. The anterior capsule is opened by capsulorrhexis and largely removed, so it does not serve this role. Preserving the posterior capsule also reduces the risk of vitreous prolapse and retinal complications.

Question 2Basic Sciences and Ocular Anatomy/Physiology

Aqueous humor drains from the anterior chamber mainly through the trabecular meshwork into which venous structure?

  1. The pial veins via the perivascular spaces
  2. The vortex veins via the suprachoroidal space
  3. The retinal veins via the optic nerve sheath
  4. The episcleral veins via the canal of Schlemm Correct answer.

Explanation

The conventional outflow pathway passes through the trabecular meshwork into Schlemm's canal and then into collector channels and episcleral veins. This route accounts for most aqueous drainage in the normal eye. The uveoscleral pathway is a minor alternative that drains into the suprachoroidal space.

Question 3Basic Sciences and Ocular Anatomy/Physiology

Which corneal layer is primarily responsible for maintaining corneal deturgescence and transparency?

  1. Descemet membrane
  2. The endothelium Correct answer.
  3. The stroma
  4. The epithelium

Explanation

Corneal endothelial cells actively pump fluid out of the stroma, keeping the tissue relatively dehydrated and therefore transparent. Their barrier and pump functions compensate for the stroma's natural tendency to swell. Endothelial cell loss leads to corneal edema and haze.

Question 4Basic Sciences and Ocular Anatomy/Physiology

A patient cannot abduct the right eye, and the right pupil is dilated. Which cranial nerve is most likely affected?

  1. The right abducens nerve
  2. The right oculomotor nerve Correct answer.
  3. The right trochlear nerve
  4. The right optic nerve

Explanation

A dilated pupil with ophthalmoplegia points to a compressive oculomotor nerve lesion, which also causes failure of abduction because the medial rectus is unopposed. An isolated abducens palsy produces esotropia without pupillary dilation. Pupillary involvement is the key localizing feature here.

Question 5Basic Sciences and Ocular Anatomy/Physiology

Light shone into the left eye causes both pupils to constrict, but light shone into the right eye produces no response in either pupil. Where is the lesion?

  1. The right optic nerve Correct answer.
  2. The left oculomotor nerve
  3. The left optic nerve
  4. The right oculomotor nerve

Explanation

An afferent pupillary defect occurs when the sensory input from one eye fails, so neither pupil responds to light in that eye. Because the efferent limb is intact, the consensual response from the fellow eye still works. This pattern localizes to the right optic nerve or retina.

Question 6Basic Sciences and Ocular Anatomy/Physiology

Which retinal cells generate the action potentials that form the optic nerve fibers?

  1. Ganglion cells Correct answer.
  2. Bipolar cells
  3. Photoreceptors
  4. Horizontal cells

Explanation

Retinal ganglion cells are the only retinal neurons that fire conventional action potentials, and their axons converge to form the optic nerve. Photoreceptors and bipolar cells signal through graded potentials rather than spikes. Horizontal and amacrine cells modulate these graded signals locally.

Question 7Basic Sciences and Ocular Anatomy/Physiology

A lesion at the optic chiasm, such as a pituitary adenoma, classically produces which visual field defect?

  1. Binasal hemianopia
  2. Homonymous hemianopia
  3. Bitemporal hemianopia Correct answer.
  4. Central scotoma

Explanation

Fibers from the nasal retina, which subserve the temporal visual fields, decussate at the chiasm. A chiasmal lesion therefore interrupts both nasal retinas and produces loss of both temporal fields. This is the classic bitemporal hemianopia of pituitary compression.

Question 8Basic Sciences and Ocular Anatomy/Physiology

Tear film stability depends most directly on which component produced by the meibomian glands?

  1. The inner mucin layer
  2. The middle aqueous layer
  3. The corneal glycocalyx
  4. The superficial lipid layer Correct answer.

Explanation

Meibomian glands secrete the outer lipid layer that retards evaporation and stabilizes the tear film. Loss of this layer causes evaporative dry eye with rapid tear break-up. The aqueous and mucin layers originate from the lacrimal gland and conjunctival goblet cells respectively.

Question 9Basic Sciences and Ocular Anatomy/Physiology

Which extraocular muscle has its origin at the orbital apex via the annulus of Zinn and is the only muscle innervated by the trochlear nerve?

  1. The superior rectus muscle
  2. The lateral rectus muscle
  3. The inferior oblique muscle
  4. The superior oblique muscle Correct answer.

Explanation

The superior oblique arises near the orbital apex and is supplied by the fourth cranial nerve. The inferior oblique arises from the orbital floor and is supplied by the oculomotor nerve. This distinction matters when interpreting vertical motility deficits.

Question 10Basic Sciences and Ocular Anatomy/Physiology

In a patient with a third nerve palsy, which movement remains preserved if the lesion is complete?

  1. Adduction of the eye
  2. Abduction of the eye Correct answer.
  3. Depression of the eye
  4. Elevation of the eye

Explanation

A complete oculomotor palsy paralyzes the medial, superior, and inferior recti and the inferior oblique, leaving abduction to the lateral rectus intact. The eye rests in a down-and-out position. Elevation, adduction, and depression are all impaired.

Question 11Basic Sciences and Ocular Anatomy/Physiology

Which structure forms the main barrier preventing the spread of infection from the conjunctiva into the orbital tissues?

  1. The levator aponeurosis
  2. The tarsal plate
  3. The orbital septum Correct answer.
  4. The conjunctival fornix

Explanation

The orbital septum is a fibrous sheet that separates the superficial eyelids from the orbital contents. It limits the spread of preseptal inflammation into the orbit. Once infection breaches it, orbital cellulitis with risk to vision develops.

Question 12Basic Sciences and Ocular Anatomy/Physiology

Intraocular pressure measured by applanation tonometry depends on which physical principle?

  1. Rebound velocity of a probe striking the cornea
  2. Doppler shift of ultrasound reflected from the cornea
  3. Force per unit area required to flatten a fixed corneal area Correct answer.
  4. Resistance to indentation of the cornea by a known weight

Explanation

Goldmann applanation tonometry applies the Imbert-Fick principle, relating the force needed to flatten a standard area of cornea to intraocular pressure. Corneal thickness and curvature influence the reading. Other devices such as rebound tonometers use different physical principles.

Question 13Basic Sciences and Ocular Anatomy/Physiology

A patient reports a curtain over the superior visual field of the right eye. Which retinal region is most likely detached?

  1. The nasal retina of the right eye
  2. The temporal retina of the right eye
  3. The superior retina of the right eye
  4. The inferior retina of the right eye Correct answer.

Explanation

The retinal image is inverted, so inferior retinal detachment produces a visual field defect in the superior field. The defect appears in the eye whose retina is affected. Localizing the field defect helps identify the retinal break before surgery.

Question 14Basic Sciences and Ocular Anatomy/Physiology

Which type of photoreceptor predominates in the foveal center and underlies high-acuity photopic vision?

  1. Bipolar cells
  2. Amacrine cells
  3. Rods
  4. Cones Correct answer.

Explanation

The foveola contains a dense array of cones with minimal convergence onto ganglion cells, which supports high spatial resolution. Rods are absent from the foveal center and dominate the periphery. This arrangement explains the fovea's role in color and detail vision.

Question 15Basic Sciences and Ocular Anatomy/Physiology

Which statement best explains why the cornea is avascular yet remains viable?

  1. It derives nutrition from the vitreous body
  2. It is supplied entirely by branches of the central retinal artery
  3. It receives oxygen and nutrients by diffusion from tears, aqueous humor, and limbal vessels Correct answer.
  4. It stores glycogen that sustains all its layers without external supply

Explanation

Corneal avascularity supports optical clarity, and metabolic needs are met by diffusion from the tear film, aqueous humor, and limbal capillary arcades. This is why extended contact lens wear can cause hypoxic corneal changes. The absence of vessels also limits immune access and affects graft survival.

Question 16Basic Sciences and Ocular Anatomy/Physiology

A lesion of the right optic tract typically produces which visual field defect?

  1. Binasal hemianopia
  2. Bitemporal hemianopia
  3. Left homonymous hemianopia Correct answer.
  4. Right homonymous hemianopia

Explanation

The right optic tract carries fibers from the right temporal retina and left nasal retina, which subserve the left visual field. A lesion therefore causes a left homonymous hemianopia. Retrochiasmal lesions always produce contralateral homonymous defects.

Question 17Basic Sciences and Ocular Anatomy/Physiology

Accommodation for near vision involves which combination of changes?

  1. Ciliary muscle relaxation, zonular relaxation, and decreased lens curvature
  2. Ciliary muscle contraction, zonular tension, and decreased lens curvature
  3. Ciliary muscle contraction, zonular relaxation, and increased lens curvature Correct answer.
  4. Ciliary muscle relaxation, zonular tension, and increased lens curvature

Explanation

During near vision the ciliary muscle contracts, reducing zonular tension and allowing the elastic lens to assume a more spherical, higher-power shape. This increases refractive power for near objects. Relaxation of the ciliary muscle reverses the process for distance.

Question 18Basic Sciences and Ocular Anatomy/Physiology

Which structure produces the aqueous humor that fills the anterior chamber?

  1. The trabecular meshwork
  2. The ciliary epithelium covering the ciliary processes Correct answer.
  3. The corneal endothelium
  4. The iris pigment epithelium

Explanation

Aqueous humor is actively secreted by the bilayered ciliary epithelium overlying the ciliary processes. Secretion involves active transport and is independent of intraocular pressure. The trabecular meshwork and iris epithelium are not secretory tissues.

Question 19Basic Sciences and Ocular Anatomy/Physiology

Which feature distinguishes the macula from the rest of the retina?

  1. It is supplied solely by the choroidal circulation with no retinal vessels nearby
  2. It contains a high density of cones and the foveal avascular zone Correct answer.
  3. It lacks a photoreceptor layer
  4. It is the only region containing retinal ganglion cells

Explanation

The macula is specialized for central vision with a cone-rich photoreceptor population, and its center lacks retinal capillaries to preserve optical clarity. Ganglion cells exist throughout the retina. This specialization makes macular disease disproportionately affect visual acuity.

Question 20Basic Sciences and Ocular Anatomy/Physiology

A patient develops ptosis and a small pupil on the same side after a neck injury. Which pathway is interrupted?

  1. The oculomotor nerve to the levator palpebrae
  2. The parasympathetic pathway to the sphincter pupillae
  3. The sympathetic pathway to the dilator pupillae and Muller muscle Correct answer.
  4. The optic nerve afferent fibers

Explanation

Horner syndrome results from interruption of the sympathetic supply to the iris dilator and the superior tarsal muscle, producing miosis and mild ptosis. The parasympathetic pathway constricts the pupil, so its loss would cause mydriasis. Localizing the lesion along the sympathetic chain guides further investigation.

Question 21Optics, Refraction and Contact Lenses

A patient's manifest refraction is -4.00 DS in the right eye. At what distance from the eye is the far point located?

  1. 250 cm in front of the eye
  2. 40 cm in front of the eye
  3. 25 cm in front of the eye Correct answer.
  4. 4 cm in front of the eye

Explanation

The far point distance equals the reciprocal of the dioptric error, so 1/4.00 D equals 0.25 m, which is 25 cm. A myope of -4.00 DS therefore has a far point 25 cm in front of the principal plane.

Question 22Optics, Refraction and Contact Lenses

Which spectacle lens material property is quantified by the Abbe number?

  1. Impact resistance
  2. Surface scratch resistance
  3. Chromatic aberration Correct answer.
  4. Ultraviolet blocking

Explanation

The Abbe number (V value) expresses how little a material disperses light; a high Abbe number means low chromatic aberration. Low-Abbe high-index materials produce more colour fringing, especially in strong prescriptions.

Question 23Optics, Refraction and Contact Lenses

A soft contact lens has a back vertex power of -3.00 D and is worn on an eye with a vertex distance of 12 mm. What is the approximate power at the corneal plane?

  1. -3.12 D
  2. -3.00 D
  3. -2.50 D
  4. -2.89 D Correct answer.

Explanation

The effective power is F/(1 - dF), where d is the vertex distance in metres. For F = -3.00 D and d = 0.012 m, this gives -3.00/(1 + 0.036) = approximately -2.89 D. Minus lenses lose minus power as they move closer to the eye.

Question 24Optics, Refraction and Contact Lenses

A 6-year-old child has a cycloplegic retinoscopy of +6.00 DS in both eyes and a visual acuity of 6/12 that improves to 6/6 with the full correction. What is the most appropriate management?

  1. Prescribe a partial correction of +2.00 DS
  2. Prescribe a bifocal add of +2.50 DS
  3. Prescribe no glasses and review in one year
  4. Prescribe the full hyperopic correction and monitor Correct answer.

Explanation

Significant hyperopia with reduced acuity that normalises on correction indicates refractive amblyopia risk, so the full cycloplegic correction is prescribed to clear the retinal image. Bilateral high hyperopia in a young child is usually fully corrected rather than partially undercorrected.

Question 25Optics, Refraction and Contact Lenses

Which keratometric finding is classically associated with keratoconus?

  1. Superior corneal flattening with regular with-the-rule astigmatism
  2. Central corneal flattening with a low surface asymmetry index
  3. Horizontal steepening with a normal posterior float
  4. Inferior corneal steepening with irregular astigmatism Correct answer.

Explanation

Keratoconus produces inferior or inferotemporal steepening, irregular astigmatism, and abnormal topography patterns such as asymmetric bow-tie with inferior displacement. These topographic clues guide referral for corneal cross-linking assessment.

Question 26Optics, Refraction and Contact Lenses

A rigid gas-permeable lens is fitted on a cornea with 2.50 D of with-the-rule corneal toricity. Which fluorescein pattern indicates an acceptable spherical rigid lens fit?

  1. Inferior pooling with superior edge lift
  2. Uniform central clearance with even mid-peripheral bearing
  3. Central bearing with peripheral pooling in all quadrants
  4. Vertical band of central pooling with horizontal mid-peripheral bearing Correct answer.

Explanation

On a with-the-rule toric cornea the steepest meridian is vertical, so a spherical rigid lens aligns along the flat horizontal meridian and pools vertically. A vertical band of pooling with horizontal mid-peripheral touch is the expected toric alignment pattern.

Question 27Optics, Refraction and Contact Lenses

What is the primary optical purpose of an aspheric front surface on a spectacle lens?

  1. To reduce oblique astigmatism and marginal distortion Correct answer.
  2. To increase the Abbe number of the lens
  3. To increase the refractive index of the material
  4. To eliminate the need for a distance prescription

Explanation

An aspheric front surface progressively flattens toward the edge, reducing off-axis aberrations such as oblique astigmatism and power error. It also produces a flatter, thinner lens with a more natural appearance.

Question 28Optics, Refraction and Contact Lenses

A pseudophakic patient reports glare and haloes at night after implantation of a multifocal intraocular lens. Which optical principle best explains this symptom?

  1. Increased spherical aberration from a low-power implant
  2. Chromatic aberration from a high-Abbe implant material
  3. Total internal reflection at the corneal endothelium
  4. Superposition of multiple diffractive orders at the retina Correct answer.

Explanation

Diffractive multifocal designs split incoming light into several orders, so focused and defocused images overlap on the retina. This superposition produces haloes and reduced contrast sensitivity, particularly with large pupils at night.

Question 29Optics, Refraction and Contact Lenses

A +10.00 DS spectacle lens is dispensed with its optical centre 4 mm nasal to the pupil centre in the right eye. What prismatic effect is induced at the pupil?

  1. 2.5 prism dioptres base-out
  2. 4 prism dioptres base-out Correct answer.
  3. 0.4 prism dioptres base-in
  4. 4 prism dioptres base-in

Explanation

Prentice's rule gives prism in dioptres as decentration in centimetres multiplied by lens power, so 0.4 cm times 10.00 D equals 4 prism dioptres. A plus lens decentred nasally acts as base-out prism, which the patient may tolerate or which may cause symptoms.

Question 30Optics, Refraction and Contact Lenses

Which statement correctly describes the optics of a pinhole aperture in refraction?

  1. It reduces the blur circle by limiting the effective pupil size Correct answer.
  2. It increases retinal illumination to improve acuity
  3. It eliminates diffraction effects at the pupil margin
  4. It corrects spherical refractive error directly

Explanation

A pinhole restricts the bundle of rays reaching the retina, shrinking the blur circle from defocus and thereby improving acuity in uncorrected refractive error. It does not change the eye's refractive power, only the effective aperture.

Question 31Optics, Refraction and Contact Lenses

A patient achieves 6/6 with a -6.00 DS spectacle correction but reports that objects appear smaller than with contact lenses. Which phenomenon explains this?

  1. Accommodative convergence excess
  2. Aniseikonia from corneal curvature change
  3. Minification from spectacle magnification Correct answer.
  4. Increased chromatic aberration with contact lenses

Explanation

Minus spectacle lenses are positioned some distance in front of the eye and minify the retinal image, an effect that increases with lens power. A contact lens sits on the cornea, so magnification is closer to unity and the image appears relatively larger.

Question 32Optics, Refraction and Contact Lenses

Which contact lens parameter is most important to verify before dispensing a rigid gas-permeable lens to correct high astigmatism?

  1. Water content
  2. Base curve and optic zone diameter Correct answer.
  3. Oxygen permeability
  4. Tint

Explanation

In rigid lens fitting for astigmatism, the base curve and optic zone diameter determine how the lens aligns with the toric cornea and whether the astigmatic error is masked. These parameters govern the fluorescein pattern and centration.

Question 33Optics, Refraction and Contact Lenses

A hyperopic patient wearing a +8.00 DS spectacle correction is converted to contact lenses. How does the required contact lens power compare with the spectacle power?

  1. It is identical to the spectacle power
  2. It becomes a minus lens
  3. It is more plus than the spectacle power Correct answer.
  4. It is less plus than the spectacle power

Explanation

For plus lenses, moving the correction closer to the eye increases its effective power, so the contact lens must be more plus than the spectacle prescription. The effect grows with lens power and vertex distance.

Question 34Optics, Refraction and Contact Lenses

A patient has a spherical equivalent of -2.00 D and 1.50 D of regular astigmatism. Which crossed-cylinder representation describes the principal meridians?

  1. -1.25 D and -2.75 D
  2. -0.50 D and -3.50 D Correct answer.
  3. -3.50 D and +1.50 D
  4. -2.00 D in both meridians

Explanation

The spherical equivalent is the mean of the two principal meridian powers, so the meridians differ by the cylinder and average to -2.00 D. With 1.50 D of cylinder, the powers are -2.00 plus and minus 0.75 D, giving -0.50 D and -3.50 D.

Question 35Optics, Refraction and Contact Lenses

Which factor most strongly increases the risk of corneal hypoxia with extended-wear soft contact lenses?

  1. High refractive index of the lens material
  2. High water content of the lens material
  3. Large optic zone diameter
  4. Low oxygen transmissibility of the lens material Correct answer.

Explanation

Corneal hypoxia during extended wear is driven mainly by low oxygen transmissibility (Dk/t) of the lens, which limits oxygen reaching the avascular cornea. Lens thickness and material permeability together determine Dk/t and thus the hypoxic risk.

Question 36Optics, Refraction and Contact Lenses

A patient with a -12.00 DS spectacle prescription is fitted with soft contact lenses. Which additional consideration is most relevant when finalising the contact lens power?

  1. Increasing the cylinder to match the spectacles
  2. Reducing the base curve to increase minus power
  3. Selecting a higher water content to reduce power
  4. Compensating for the vertex distance change Correct answer.

Explanation

At high minus powers, moving the correction from the spectacle plane to the cornea changes the effective power substantially, so the contact lens power must be recalculated from the vertex distance. Ignoring this leads to significant overcorrection.

Question 37Cornea and External Eye Disease

A 24-year-old contact lens wearer presents with a 6 mm corneal epithelial defect, a ring-shaped stromal infiltrate, and severe pain out of proportion to the examination. What is the most appropriate immediate management step?

  1. Start intensive topical fortified antibiotics and urgently arrange corneal scraping for culture Correct answer.
  2. Reassure and prescribe artificial tears four times daily
  3. Apply a bandage contact lens and prescribe topical steroid alone
  4. Prescribe topical antibiotic drops and review in one week

Explanation

This presentation suggests bacterial keratitis, possibly Pseudomonas, in a contact lens wearer, and a ring infiltrate with disproportionate pain raises concern for a severe or sight-threatening process. Corneal scraping for staining and culture with immediate intensive fortified topical antibiotics is the standard of care, and contact lens wear must stop. Delay in treatment risks corneal melting and perforation.

Question 38Cornea and External Eye Disease

Which organism is the most common cause of contact lens-associated microbial keratitis, particularly with overnight hydrogel wear?

  1. Moraxella lacunata
  2. Streptococcus pneumoniae
  3. Pseudomonas aeruginosa Correct answer.
  4. Herpes simplex virus type 1

Explanation

Pseudomonas aeruginosa is the classic and most frequent pathogen in contact lens-related keratitis, especially with extended or overnight wear and hydrogel lenses. It produces proteases and exotoxins that drive rapid stromal melting. Gram-positive organisms such as Streptococcus and Moraxella are more typical of post-traumatic or compromised ocular surface settings.

Question 39Cornea and External Eye Disease

A patient has a dendritic corneal ulcer with terminal bulbs that stains with fluorescein. Which topical agent is the first-line antiviral for this epithelial disease?

  1. Oral valacyclovir alone
  2. Topical trifluridine
  3. Topical ganciclovir gel
  4. Topical acyclovir ointment Correct answer.

Explanation

Topical acyclovir ointment five times daily is an effective first-line treatment for herpes simplex epithelial keratitis and is better tolerated than older agents. Ganciclovir gel is an alternative, and oral antivirals are useful adjuncts but not usually monotherapy for active epithelial disease. Trifluridine is effective but more toxic to the ocular surface.

Question 40Cornea and External Eye Disease

Which clinical finding most strongly suggests Acanthamoeba keratitis rather than herpes simplex keratitis in a contact lens wearer?

  1. A dendritic epithelial lesion with terminal bulbs
  2. Pain that is severe relative to the examination findings, with radial perineural infiltrates Correct answer.
  3. A central disciform stromal edema without epithelial defect
  4. A superior pannus with punctate epithelial erosions

Explanation

Acanthamoeba keratitis classically causes pain out of proportion to signs, radial keratoneuritis (perineural infiltrates), and a ring infiltrate later in the course, typically in contact lens wearers using tap water. Dendrites with terminal bulbs indicate herpes simplex, and disciform edema is more typical of herpetic stromal disease. Distinguishing these is critical because steroids worsen Acanthamoeba.

Question 41Cornea and External Eye Disease

A patient with rheumatoid arthritis develops peripheral corneal thinning with an epithelial defect and adjacent scleral inflammation. What is the most appropriate initial management?

  1. Topical steroid alone
  2. Topical antibiotic monotherapy
  3. Aggressive systemic immunosuppression with topical lubrication and protective measures Correct answer.
  4. Observation with artificial tears only

Explanation

Peripheral ulcerative keratitis in rheumatoid arthritis is an immune-mediated destructive process that requires prompt systemic immunosuppression, often with high-dose corticosteroids and steroid-sparing agents, in collaboration with rheumatology. Topical lubrication and protection, sometimes with tissue adhesive or tarsorrhaphy, support the ocular surface. Topical steroids alone risk worsening melting and perforation.

Question 42Cornea and External Eye Disease

A 35-year-old presents with a painful red eye, photophobia, and a dendritic epithelial lesion after starting topical steroid for presumed conjunctivitis. What is the most likely explanation for the worsening?

  1. Allergic reaction to the steroid vehicle
  2. Steroid enhancement of herpes simplex viral replication Correct answer.
  3. Steroid-induced ocular hypertension
  4. Steroid-induced ptosis

Explanation

Topical corticosteroids suppress local immune defenses and enhance herpes simplex virus replication, converting a limited epithelial infection into a more extensive or geographic ulcer. This is why steroids are contraindicated in undiagnosed epithelial keratitis. The correct approach is stopping the steroid and starting antiviral therapy.

Question 43Cornea and External Eye Disease

Which corneal dystrophy is characterized by bilateral, symmetric, central granular deposits that stain with Masson trichrome and are separated by clear intervening stroma?

  1. Macular corneal dystrophy
  2. Fuchs endothelial corneal dystrophy
  3. Granular corneal dystrophy type 1 Correct answer.
  4. Lattice corneal dystrophy type 1

Explanation

Granular corneal dystrophy type 1 shows discrete, sharply demarcated hyaline deposits in the anterior stroma with clear stroma between lesions, and the deposits stain with Masson trichrome. Macular dystrophy has ill-defined deposits involving the full stroma with diffuse haze, and lattice shows amyloid lines. Fuchs disease is an endothelial disorder with guttae and edema.

Question 44Cornea and External Eye Disease

A 55-year-old with long-standing keratoconus presents with sudden pain, decreased vision, and a localized protrusion of Descemet membrane with stromal edema. What is the diagnosis?

  1. Acute corneal hydrops Correct answer.
  2. Posterior polymorphous dystrophy
  3. Pellucid marginal degeneration
  4. Terrien marginal degeneration

Explanation

Acute corneal hydrops results from a rupture in Descemet membrane in advanced keratoconus, allowing aqueous to enter the stroma and produce sudden focal edema, pain, and marked visual loss. Management is usually conservative with hypertonic saline and topical steroids, and most resolve over weeks to months. Pellucid and Terrien are different ectatic or thinning disorders without acute Descemet rupture.

Question 45Cornea and External Eye Disease

Which finding on slit-lamp examination is most consistent with early keratoconus?

  1. Central crystalline deposits in the stroma
  2. Superior corneal pannus with punctate erosions
  3. Inferior steepening with a scissoring reflex on retinoscopy Correct answer.
  4. Diffuse microcystic edema with guttae

Explanation

Early keratoconus produces inferior corneal steepening, irregular astigmatism, and a scissoring retinoscopic reflex, often before slit-lamp signs such as Fleischer ring or Vogt striae appear. Corneal topography confirms the diagnosis. The other findings describe inflammatory, endothelial, or metabolic disease rather than ectasia.

Question 46Cornea and External Eye Disease

Which topical medication is most appropriate for the treatment of vernal keratoconjunctivitis with giant papillae and corneal shield ulcers?

  1. Topical antiviral therapy
  2. Topical mast cell stabilizer or antihistamine with a short course of topical steroid Correct answer.
  3. Topical hypertonic saline
  4. Topical antibiotic alone

Explanation

Vernal keratoconjunctivitis is an IgE-mediated allergic disease, and first-line therapy includes mast cell stabilizers or combined antihistamine-mast cell agents, with short courses of topical steroids for severe inflammation and shield ulcers. Antibiotics, antivirals, and hypertonic saline do not address the allergic mechanism. Steroid use must be monitored for glaucoma and infection.

Question 47Cornea and External Eye Disease

A patient with severe dry eye has rose bengal staining of the conjunctiva and cornea, reduced tear break-up time, and a Schirmer test of 3 mm in five minutes. Which diagnosis is most likely?

  1. Ocular cicatricial pemphigoid
  2. Keratoconjunctivitis sicca Correct answer.
  3. Trachoma
  4. Atopic keratoconjunctivitis

Explanation

Keratoconjunctivitis sicca is characterized by reduced tear production (Schirmer less than 5 mm), rapid tear break-up, and ocular surface staining with rose bengal or lissamine green. Symptoms include burning and foreign body sensation. Atopic disease, trachoma, and cicatricial pemphigoid have different clinical features such as papillae, follicles, or symblepharon.

Question 48Cornea and External Eye Disease

Which systemic medication is a well-recognized cause of corneal verticillata (whorl-like epithelial deposits)?

  1. Atorvastatin
  2. Amiodarone Correct answer.
  3. Metformin
  4. Amoxicillin

Explanation

Amiodarone, chloroquine, hydroxychloroquine, and some other cationic amphiphilic drugs cause intracellular lipid accumulation in the corneal epithelium, producing whorl-like verticillata. These deposits usually spare vision and resolve after stopping the drug. Antibiotics, metformin, and statins are not classic causes of corneal verticillata.

Question 49Cornea and External Eye Disease

A 70-year-old presents with bilateral progressive visual loss, glare, and slit-lamp examination showing central corneal guttae and stromal edema. What is the most appropriate surgical management for visually significant disease?

  1. Phototherapeutic keratectomy
  2. Radial keratotomy
  3. Penetrating keratoplasty
  4. Descemet membrane endothelial keratoplasty Correct answer.

Explanation

Fuchs endothelial corneal dystrophy is an endothelial disease, and endothelial keratoplasty such as DMEK or DSAEK selectively replaces the diseased endothelium with faster recovery and better outcomes than full-thickness grafting. Penetrating keratoplasty is reserved for cases with extensive stromal scarring. Phototherapeutic keratectomy and radial keratotomy do not address endothelial failure.

Question 50Cornea and External Eye Disease

Which of the following is the most common cause of infectious keratitis in a patient with a history of corneal trauma from vegetative matter?

  1. Fusarium species Correct answer.
  2. Herpes simplex virus
  3. Adenovirus
  4. Neisseria gonorrhoeae

Explanation

Filamentous fungi such as Fusarium and Aspergillus are classic causes of keratitis after corneal injury with plant material, and they may present with feathery infiltrates, satellite lesions, and endothelial plaques. Treatment requires topical natamycin or amphotericin B and sometimes systemic antifungals. Gonococcus causes hyperacute purulent conjunctivitis, and herpes and adenovirus have different presentations.