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Maharashtra HSC Ophthalmic Technician (Vocational) study materials
Maharashtra HSC Ophthalmic Technician (Vocational) study resources

Maharashtra HSC Ophthalmic Technician (Vocational) practice questions

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Question 1Basic Ocular Anatomy and Physiology

Which layer of the eyeball is the tough outer coat that includes the sclera and cornea?

  1. Vascular layer (uvea)
  2. Vitreous body
  3. Neural layer (retina)
  4. Fibrous layer (tunica fibrosa) Correct answer.

Explanation

The wall of the eye is arranged in three concentric coats. The outermost is the fibrous coat, made of the opaque sclera posteriorly and the transparent cornea anteriorly, and it gives shape and protection. The uvea and retina lie deeper, while the vitreous is a gel filling the cavity rather than a coat.

Question 2Basic Ocular Anatomy and Physiology

The cornea derives most of its oxygen supply in the open-eye state from which source?

  1. The central retinal artery
  2. The atmosphere, dissolved in the tear film Correct answer.
  3. The choroidal circulation
  4. The anterior ciliary arteries

Explanation

The cornea is avascular and therefore draws oxygen mainly from the air through the tear film when the lids are open. The choroid and retinal vessels supply the inner eye, and the anterior ciliary arteries supply the limbal region and conjunctiva rather than the corneal centre. This is why contact-lens wear and lid closure can stress corneal oxygenation.

Question 3Basic Ocular Anatomy and Physiology

Aqueous humour is produced mainly by which structure?

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

Explanation

Aqueous humour is secreted by the epithelium covering the ciliary processes of the ciliary body. It then flows through the pupil into the anterior chamber and drains at the angle. The corneal endothelium and trabecular meshwork participate in fluid handling but do not produce aqueous.

Question 4Basic Ocular Anatomy and Physiology

Which photoreceptor type is concentrated at the fovea centralis and supports high-acuity colour vision?

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

Explanation

The fovea is a small pit packed with cones and is responsible for sharp central vision and colour discrimination. Rods are sparse at the fovea and dominate the peripheral retina for dim-light vision. Bipolar and ganglion cells are relay neurons, not photoreceptors.

Question 5Basic Ocular Anatomy and Physiology

The optic nerve leaves the eye at a point where the retinal layers are interrupted, producing which clinical feature?

  1. The ora serrata
  2. A physiological blind spot Correct answer.
  3. The macula lutea
  4. The foveal reflex

Explanation

At the optic disc the axons gather to form the nerve and the photoreceptor layer is absent, so no light is detected there. This creates the physiological blind spot, which is filled in centrally by the brain. The macula and fovea are the high-acuity region, and the ora serrata is the peripheral retinal margin.

Question 6Basic Ocular Anatomy and Physiology

Which extraocular muscle is the primary elevator of the eye in the primary position?

  1. Medial rectus
  2. Inferior rectus
  3. Superior rectus Correct answer.
  4. Superior oblique

Explanation

The superior rectus runs from the apex to the upper surface of the globe and its main action is elevation. The inferior rectus depresses, the superior oblique intorts and depresses, and the medial rectus adducts. Elevation is therefore attributed to the superior rectus, assisted by the inferior oblique.

Question 7Basic Ocular Anatomy and Physiology

Tears drain from the eye into the nose through which sequence of structures?

  1. Canaliculus, punctum, nasolacrimal duct, lacrimal sac
  2. Punctum, lacrimal sac, canaliculus, nasolacrimal duct
  3. Lacrimal sac, punctum, canaliculus, nasolacrimal duct
  4. Punctum, canaliculus, lacrimal sac, nasolacrimal duct Correct answer.

Explanation

Tears enter the upper and lower puncta at the lid margins, pass along the canaliculi into the lacrimal sac, and then descend the nasolacrimal duct to open in the nasal cavity. The order matters clinically because obstruction at any step causes epiphora.

Question 8Basic Ocular Anatomy and Physiology

Aqueous humour leaves the anterior chamber mainly through which route?

  1. Trabecular meshwork into Schlemm canal Correct answer.
  2. Ciliary body into the posterior chamber
  3. Optic nerve sheath into the subarachnoid space
  4. Retinal pigment epithelium into the choroid

Explanation

The major outflow path is through the trabecular meshwork at the anterior chamber angle into Schlemm canal, then into episcleral veins. This pathway is the target of pressure-lowering treatment in glaucoma. The other options describe secretion or unrelated fluid spaces.

Question 9Basic Ocular Anatomy and Physiology

Pupillary constriction in bright light is mediated by which pathway?

  1. Sympathetic fibres from the superior cervical ganglion
  2. The optic nerve fibres directly innervating the iris
  3. Parasympathetic fibres travelling with the oculomotor nerve Correct answer.
  4. The trigeminal nerve's ophthalmic branch

Explanation

Light signals travel in the optic nerve and pretectal area and reach the Edinger-Westphal nucleus, whose parasympathetic fibres run with the oculomotor nerve to the ciliary ganglion and then to the sphincter pupillae. Sympathetic fibres dilate the pupil instead. The optic nerve carries sensory input but does not directly innervate iris muscle.

Question 10Basic Ocular Anatomy and Physiology

A lesion compressing the optic chiasm would most characteristically produce which visual field defect?

  1. Central scotoma of one eye
  2. Bitemporal hemianopia Correct answer.
  3. Homonymous hemianopia
  4. Enlarged physiological blind spot

Explanation

The chiasm carries crossing fibres from the nasal hemiretinae, which subserve the temporal fields. Compression from below, as by a pituitary adenoma, damages these crossing fibres and causes loss of both temporal fields. Post-chiasmal lesions instead cause homonymous defects.

Question 11Basic Ocular Anatomy and Physiology

The anterior chamber is bounded anteriorly by the cornea and posteriorly by which structures?

  1. The sclera and the conjunctiva
  2. The iris and the lens Correct answer.
  3. The retina and the choroid
  4. The ciliary body and the vitreous

Explanation

The anterior chamber lies between the corneal endothelium in front and the iris and pupillary part of the lens behind. Its lateral boundary is the angle with the trabecular meshwork. The posterior chamber, in contrast, lies behind the iris and in front of the lens.

Question 12Basic Ocular Anatomy and Physiology

Vitamin A deficiency affects vision chiefly because of its role in which process?

  1. Synthesis of collagen in the sclera
  2. Maintenance of corneal endothelial pumping
  3. Production of aqueous humour by the ciliary body
  4. Formation of rhodopsin in the rod photoreceptors Correct answer.

Explanation

Retinal, a vitamin A derivative, is the chromophore of rhodopsin and other visual pigments. Deficiency impairs rod function first, giving night blindness, and later damages the ocular surface. The other options describe processes not dependent on the visual pigment cycle.

Question 13Basic Ocular Anatomy and Physiology

The ciliary muscle contracts to allow accommodation. What is the immediate effect on the lens?

  1. It moves anteriorly without changing curvature
  2. It becomes more convex and its refractive power increases Correct answer.
  3. It becomes flatter and its refractive power decreases
  4. It rotates within the pupil

Explanation

Contraction of the ciliary ring slackens the zonular fibres, letting the elastic lens capsule mould the lens into a rounder, thicker shape. The increased curvature raises dioptric power for near vision. Relaxation of the muscle reverses this for distance viewing.

Question 14Basic Ocular Anatomy and Physiology

Which statement correctly describes the blood supply of the outer retina?

  1. The outer retina is avascular and depends on the vitreous
  2. The outer retina is supplied by branches of the central retinal artery
  3. The outer retina receives blood only from the anterior ciliary arteries
  4. The outer retina is nourished by the choroidal capillaries Correct answer.

Explanation

The photoreceptors and outer nuclear layer lie beyond the reach of the retinal vessels and depend on diffusion from the choriocapillaris. The inner retina is supplied by branches of the central retinal artery. This division explains why choroidal disease and retinal vascular occlusion produce different patterns of damage.

Question 15Basic Ocular Anatomy and Physiology

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

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

Explanation

A complete oculomotor palsy leaves the eye turned down and out because only the lateral rectus and superior oblique remain active, and it also paralyses the sphincter pupillae, giving a fixed dilated pupil. Abducens palsy would cause failure of abduction but no pupillary change. Trochlear palsy affects depression in adduction, and optic nerve disease affects vision, not eye movement.

Question 16Basic Ocular Anatomy and Physiology

Why does a corneal abrasion heal without scarring in its epithelial layer, whereas a deep stromal injury may scar?

  1. The epithelium has no nerve supply and therefore cannot scar
  2. The stroma is avascular and therefore cannot heal at all
  3. Epithelium regenerates from limbal stem cells, while stromal healing involves collagen remodelling Correct answer.
  4. The endothelium migrates over the wound to replace lost stroma

Explanation

Corneal epithelium is continually renewed from stem cells at the limbus and regrows smoothly over an intact basement membrane. Stromal wounds heal by keratocyte-mediated collagen deposition, which can leave opacity if the architecture is not restored. Endothelium does not regenerate stroma; it only maintains deturgescence.

Question 17Basic Ocular Anatomy and Physiology

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

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

Explanation

Meibomian glands secrete the oily superficial layer that retards evaporation and stabilises the tear film. The aqueous layer comes from the lacrimal gland, and mucin from conjunctival goblet cells. Loss of the lipid layer produces rapid tear break-up and evaporative dry eye.

Question 18Basic Ocular Anatomy and Physiology

During direct ophthalmoscopy, the examiner sees the optic disc. Which retinal landmark lies approximately 2.5 disc diameters temporal to it?

  1. The optic nerve head
  2. The vortex veins
  3. The macula Correct answer.
  4. The ora serrata

Explanation

The macula lies temporal to the optic disc, roughly two to three disc diameters away and slightly below the horizontal midline. It is the area of highest cone density and is identified by its darker colour and lack of large vessels. The ora serrata is far anteriorly and the vortex veins are peripheral.

Question 19Basic Ocular Anatomy and Physiology

Which change explains the reduced amplitude of accommodation typically seen after age 40?

  1. Loss of corneal sensitivity
  2. Progressive hardening of the lens nucleus and capsule Correct answer.
  3. Weakness of the medial rectus muscle
  4. Atrophy of the retinal pigment epithelium

Explanation

Presbyopia results from increasing rigidity of the crystalline lens, so the capsule cannot mould it despite normal ciliary muscle contraction. The near point recedes and reading glasses become necessary. Muscle weakness and retinal changes do not account for the age-related loss of accommodation.

Question 20Basic Ocular Anatomy and Physiology

Aqueous humour flows from the posterior chamber to the anterior chamber through which opening?

  1. The optic canal
  2. The pupil Correct answer.
  3. The suprachoroidal space
  4. The canal of Schlemm

Explanation

Aqueous secreted into the posterior chamber passes through the pupil into the anterior chamber before draining at the angle. If the pupil is blocked, as in pupillary block glaucoma, pressure rises in the posterior chamber and the iris bows forward. Schlemm canal is part of the outflow route and lies at the angle.

Question 21Basic Ocular Anatomy and Physiology

Interruption of the ophthalmic division of the trigeminal nerve affects the eye mainly by causing which change?

  1. Loss of corneal sensation with impaired blink and healing Correct answer.
  2. Complete loss of vision in the affected eye
  3. Paralysis of the levator palpebrae superioris
  4. Loss of parasympathetic pupil constriction

Explanation

The ophthalmic division carries sensory fibres from the cornea and conjunctiva, so its damage removes the protective reflex that triggers blinking and tearing. The anaesthetic cornea is prone to injury and poor epithelial healing. Vision, lid elevation and the light reflex depend on other pathways.

Question 22Basic Ocular Anatomy and Physiology

A lesion at the optic tract on the right side would produce which field defect?

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

Explanation

Each optic tract carries fibres from the temporal retina of the same side and the nasal retina of the opposite side, so it represents the opposite visual field. A right tract lesion therefore removes the left half of the visual field in both eyes. Chiasmal lesions give bitemporal defects, and lateral chiasmal compression can give binasal loss.

Question 23Basic Ocular Anatomy and Physiology

Why is the corneal stroma transparent despite containing collagen fibrils?

  1. The corneal epithelium absorbs all scattered light before it reaches the stroma
  2. The stroma contains no collagen and is purely water
  3. The fibrils are uniform in diameter and regularly spaced, limiting light scatter Correct answer.
  4. The stroma is heavily pigmented to absorb stray light

Explanation

Transparency depends on the lattice arrangement of collagen fibrils of near-uniform diameter and spacing, which keeps destructive interference and scatter low. Corneal dehydration maintained by the endothelial pump is also essential. Pigment and epithelial absorption do not explain stromal clarity.

Question 24Basic Ocular Anatomy and Physiology

A patient has a dilated pupil that reacts poorly to light but constricts briskly when a near object is viewed. This dissociation most suggests a lesion where?

  1. In the optic nerve
  2. In the dorsal midbrain (Parinaud syndrome) Correct answer.
  3. In the ciliary ganglion
  4. In the oculomotor nerve

Explanation

Light and near reflexes use separate pathways; the near response fibres bypass the dorsal midbrain lesion that interrupts the light reflex arc. The result is light-near dissociation with a dilated pupil. Optic nerve disease causes an afferent defect, and oculomotor or ciliary ganglion lesions impair the near response as well.

Question 25Optics, Refraction and Corrective Lenses

A spectacle lens is marked +2.00 DS. What does the 'D' in this prescription indicate?

  1. Distance between the lens centres
  2. Degree of astigmatism present
  3. Dioptre, the unit of refractive power Correct answer.
  4. Diameter of the finished lens blank

Explanation

The dioptre is the unit of refractive power and equals the reciprocal of the focal length in metres, so +2.00 D corresponds to a focal length of 0.50 m. It describes vergence change produced by the lens, not a physical measurement of the frame or blank.

Question 26Optics, Refraction and Corrective Lenses

Which type of lens is prescribed for a patient with uncorrected hypermetropia?

  1. A convex, converging lens Correct answer.
  2. A concave, diverging lens
  3. A prism with no refractive power
  4. A plano lens with no power

Explanation

A hypermetropic eye has insufficient converging power for its axial length, so the image would fall behind the retina. A convex converging plus lens adds convergence and brings the image forward onto the retina.

Question 27Optics, Refraction and Corrective Lenses

In a prescription written as -1.50 / -0.75 x 180, what does the value 180 represent?

  1. The axis of the correcting cylinder in degrees Correct answer.
  2. The reading addition in dioptres
  3. The base curve of the lens in dioptres
  4. The back vertex distance in millimetres

Explanation

The number after the multiplication sign is the cylinder axis, expressed in degrees from 1 to 180 on the protractor scale. It states the meridian in which the cylindrical power has no effect.

Question 28Optics, Refraction and Corrective Lenses

Which instrument is used to measure the back vertex power of a finished spectacle lens?

  1. Keratometer
  2. Lensmeter (focimeter) Correct answer.
  3. Retinoscope
  4. Slit lamp

Explanation

A lensmeter, also called a focimeter, neutralises the lens and reads its back vertex power, axis and prism directly. It is the standard instrument for verifying a dispensed prescription.

Question 29Optics, Refraction and Corrective Lenses

What is the far point of a myopic eye with a refractive error of -4.00 D?

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

Explanation

The far point distance equals the reciprocal of the refractive error in metres, so 1/4.00 gives 0.25 m, or 25 cm. Because the eye is myopic, this point lies in front of the eye.

Question 30Optics, Refraction and Corrective Lenses

Which surface curvature produces a converging effect in a spectacle lens?

  1. A surface with a toroidal axis only
  2. A surface that is concave towards the incoming light
  3. A surface that is perfectly flat
  4. A surface that is convex towards the incoming light Correct answer.

Explanation

A convex surface bulges towards the incoming light and converges parallel rays, giving positive power. Concave surfaces diverge rays and give negative power.

Question 31Optics, Refraction and Corrective Lenses

What is the main purpose of an anti-reflection coating on a spectacle lens?

  1. To increase the refractive index of the lens material
  2. To reduce surface reflections and improve light transmission Correct answer.
  3. To convert a spherical lens into a cylindrical lens
  4. To increase the thickness at the lens centre

Explanation

Anti-reflection coatings use thin-film interference to cancel reflected light at the lens surfaces. This raises light transmission and reduces glare and ghost images for the wearer.

Question 32Optics, Refraction and Corrective Lenses

A patient's prescription reads +3.00 / -1.00 x 90. What is the power in the vertical meridian (90 degrees)?

  1. +2.00 D Correct answer.
  2. -1.00 D
  3. +4.00 D
  4. +3.00 D

Explanation

In this notation the sphere acts along the axis meridian and the sphere plus cylinder acts at right angles to it. At 90 degrees the power is +3.00 added to -1.00, giving +2.00 D.

Question 33Optics, Refraction and Corrective Lenses

Convert -2.00 / +1.00 x 60 into cross-cylinder (alternate) form.

  1. -2.00 / -1.00 x 150
  2. -1.00 / +1.00 x 60
  3. -1.00 / -1.00 x 150 Correct answer.
  4. -3.00 / +1.00 x 60

Explanation

To transpose, add the cylinder to the sphere to get the new sphere (-1.00), reverse the sign of the cylinder (-1.00), and change the axis by 90 degrees (60 becomes 150). The resulting cross-cylinder form is -1.00 / -1.00 x 150.

Question 34Optics, Refraction and Corrective Lenses

Two thin lenses of +5.00 D and -2.00 D are placed in contact. What is the equivalent power of the combination?

  1. +7.00 D
  2. +2.50 D
  3. -10.00 D
  4. +3.00 D Correct answer.

Explanation

For thin lenses in contact the powers add algebraically, so +5.00 plus -2.00 gives +3.00 D. The combination behaves as a single converging lens of that power.

Question 35Optics, Refraction and Corrective Lenses

Why is back vertex distance important when prescribing a high-power spectacle lens?

  1. It changes the effective power reaching the eye as the lens moves away from the cornea Correct answer.
  2. It fixes the pantoscopic tilt of the frame
  3. It determines the colour of the tint applied to the lens
  4. It sets the minimum edge thickness of the lens

Explanation

The effective power at the eye depends on the distance between the back surface of the lens and the cornea. For strong plus or minus lenses, a change in this distance alters the vergence reaching the eye, so the prescription must be compensated.

Question 36Optics, Refraction and Corrective Lenses

A patient reports that straight lines appear tilted and objects look distorted after being fitted with new high-minus lenses. Which optical effect best explains this?

  1. Prismatic effect from the lens periphery Correct answer.
  2. Chromatic aberration from dispersion
  3. Spherical aberration from the lens centre
  4. Reduced light transmission from the coating

Explanation

High-minus lenses are thick at the edge and act like prisms away from the optical centre, so the eye sees objects displaced and lines bent. This prismatic effect causes the reported spatial distortion, which reduces as the eye adapts or with better centration.

Question 37Optics, Refraction and Corrective Lenses

What is the purpose of a prism in a spectacle prescription for a patient with a tropia?

  1. To flatten the corneal curvature
  2. To displace the image so both eyes can align comfortably Correct answer.
  3. To increase the reading addition
  4. To change the refractive index of the lens

Explanation

A prism deviates light so the image of an object falls on the fovea of the deviating eye. This relieves diplopia and allows binocular single vision without excessive effort.

Question 38Optics, Refraction and Corrective Lenses

Which lens material property most directly reduces the edge thickness of a high-minus prescription?

  1. A higher Abbe number
  2. A higher refractive index Correct answer.
  3. A lower refractive index
  4. A thinner anti-reflection coating

Explanation

A higher refractive index bends light more per unit of surface curvature, so less curvature and thinner edges are needed for the same power. This is why high-index materials are chosen for strong minus prescriptions.

Question 39Optics, Refraction and Corrective Lenses

A patient with presbyopia needs a near addition. Which parameter in the prescription provides this?

  1. The sphere value only
  2. The 'Add' value Correct answer.
  3. The cylinder axis
  4. The pupillary distance

Explanation

The near addition is written separately as 'Add' and is added to the distance sphere to give the near power. It compensates for the reduced amplitude of accommodation in presbyopia.

Question 40Optics, Refraction and Corrective Lenses

What does an Abbe number of about 30 in a lens material indicate?

  1. High impact resistance
  2. Low dispersion and minimal colour fringing
  3. High refractive index alone
  4. High dispersion and greater colour fringing Correct answer.

Explanation

The Abbe number is inversely related to dispersion, so a value near 30 means relatively high dispersion. Such materials produce more chromatic aberration and visible colour fringes, especially in high powers.

Question 41Optics, Refraction and Corrective Lenses

A keratometry reading of 7.80 mm is obtained. What does this value represent?

  1. The axial length of the eye
  2. The radius of curvature of the anterior cornea Correct answer.
  3. The thickness of the corneal centre
  4. The power of the crystalline lens

Explanation

A keratometer measures the radius of curvature of the anterior corneal surface in millimetres, which can then be converted to dioptric power. A reading of 7.80 mm is a typical corneal radius.

Question 42Optics, Refraction and Corrective Lenses

A patient is prescribed a +10.00 D lens at a vertex distance of 12 mm. If the lens is moved to 15 mm from the cornea, what happens to the effective power at the eye?

  1. It decreases Correct answer.
  2. It stays exactly the same
  3. It becomes a cylindrical power
  4. It increases

Explanation

For a plus lens, moving it further from the eye reduces the vergence arriving at the cornea, so the effective power falls. This is why high plus prescriptions must be compensated when vertex distance changes.

Question 43Optics, Refraction and Corrective Lenses

What is the centration distance measured for when fitting a pair of single-vision spectacles?

  1. The diameter of the lens blank before edging
  2. The thickness of the lens at its edge
  3. The distance from the frame bridge to the temple
  4. The distance between the optical centres of the two lenses Correct answer.

Explanation

Centration distance is the separation between the optical centres of the two lenses, matched to the patient's interpupillary distance. Correct centration prevents unwanted prism and maintains the intended optical performance.

Question 44Optics, Refraction and Corrective Lenses

A prescription is written +1.50 / -0.50 x 45. Which meridian carries the cylinder power?

  1. Neither meridian
  2. Both meridians equally
  3. The 45 degree meridian Correct answer.
  4. The 135 degree meridian

Explanation

The axis meridian, here 45 degrees, is the direction in which the cylinder has no effect, so the cylinder power acts at right angles to it. The meridian carrying the cylinder power is therefore 135 degrees, not 45 degrees.

Question 45Optics, Refraction and Corrective Lenses

Why does a high-minus spectacle lens show a 'ring' of magnification or minification at its edge when viewed by an observer?

  1. Because the edge acts as a strong prism and the lens is thick there Correct answer.
  2. Because the anti-reflection coating reflects more light at the edge
  3. Because the lens material changes refractive index at the edge
  4. Because the lens has a toroidal surface throughout

Explanation

The thick edge of a high-minus lens forms a prism-like zone that deviates light strongly, producing apparent displacement and a visible ring effect. This is a geometric consequence of thickness and curvature, not a coating or material change.

Question 46Optics, Refraction and Corrective Lenses

A patient with anisometropia of 4.00 D between the two eyes is prescribed spectacles. Which problem is most likely?

  1. Equal image sizes in both eyes
  2. Increased corneal curvature
  3. Complete loss of accommodation
  4. Unequal retinal image sizes causing intolerance Correct answer.

Explanation

A large difference in spectacle power between the two eyes produces unequal retinal image magnification, called aniseikonia. This can cause headache, diplopia and poor tolerance, so contact lenses or other options may be considered.

Question 47Optics, Refraction and Corrective Lenses

A lens has a front surface power of +6.00 D and a back surface power of -8.00 D. What is its approximate thin-lens power?

  1. -2.00 D Correct answer.
  2. +2.00 D
  3. +14.00 D
  4. -14.00 D

Explanation

For a thin lens in air the total power is the sum of the front and back surface powers, so +6.00 plus -8.00 gives -2.00 D. The lens is therefore a diverging minus lens.

Question 48Optics, Refraction and Corrective Lenses

A patient wearing a +8.00 D spectacle lens reports that objects appear larger than with the previous +4.00 D lens. Which optical principle explains this?

  1. Plus lenses magnify and the effect increases with power Correct answer.
  2. Magnification depends only on the lens tint
  3. Magnification depends only on the frame size
  4. Minus lenses magnify and the effect increases with power

Explanation

A plus lens acts as a magnifier, and spectacle magnification increases as the lens power rises. Moving from +4.00 D to +8.00 D therefore increases the apparent size of objects, which the patient notices.

Question 49Ophthalmic Instruments and Equipment Handling

Before a slit-lamp examination, the joystick and elevation controls of the instrument are stiff and the base slides unevenly. What is the most appropriate first action by the ophthalmic technician?

  1. Ask the patient to hold the table steady during the examination
  2. Dismantle the joystick assembly and lubricate the internal gears
  3. Clean the table surface and check that the base locking screw and joystick are correctly seated Correct answer.
  4. Force the joystick gently to loosen the mechanism during the examination

Explanation

A stiff joystick or sliding base is usually caused by a dirty or uneven table surface, an unlocked base screw, or a joystick that is not properly seated. The technician should first check these simple mechanical points before any examination use. Forcing the controls or dismantling the instrument risks damage and is outside the technician's role.

Question 50Ophthalmic Instruments and Equipment Handling

Which routine step best protects a direct ophthalmoscope from damage and keeps its optics clean between patients?

  1. Wipe the lens aperture with a dry tissue after every use
  2. Store it with the battery left inside and the switch on
  3. Immerse the head in disinfectant solution overnight
  4. Switch it off, remove the battery if stored long-term, and clean the aperture with a soft lens brush or blower Correct answer.

Explanation

The ophthalmoscope head should be switched off after use, and for long-term storage the batteries are removed to prevent leakage and corrosion. Dust on the aperture is removed with a soft brush or blower rather than abrasive wiping. Immersing the head in liquid damages the optics and electronics.