20 Viva Questions That Trip Up Candidates — and How to Answer Them

Do not memorise twenty speeches

An examiner asks, “Why can’t you see the angle directly?” A candidate who knows the fact may still lose control: they start with three glaucoma diagnoses, add a laser procedure, then cannot say the optical principle. The question was short. The answer should be short, ordered and capable of surviving the next question.

Use this four-part frame for most practical viva prompts:

1. First sentence: identify or define the item in one line.
2. Principle: give one anatomy, optics, pharmacology or design reason.
3. Discriminator: state the distinction the examiner is likely testing.
4. Stop line: close after the relevant point instead of volunteering management.

The twenty prompts below are rehearsal patterns, not leaked questions and not a claim about any university’s blueprint. Local formats, tray contents and examiner emphasis vary. They are written for postgraduate ophthalmology exam education, not for patient-specific assessment or treatment.

Optics and anterior-segment questions

1. “Why is the anterior chamber angle not directly visible?”

First sentence: “At the cornea–air interface, light from the angle undergoes total internal reflection, so the angle cannot be viewed directly.”

Discriminator: “Gonioscopy changes the optical situation with a contact lens and mirrors/prisms, allowing the angle to be assessed.” Do not say that the angle is hidden merely because it lies “behind the cornea.” The key is optics. If asked for order of structures, give them anterior to posterior: Schwalbe’s line, trabecular meshwork, scleral spur, ciliary body band and iris root, while acknowledging that visibility varies with configuration. This terminology and the role of indentation are cross-checked in AAO EyeWiki’s gonioscopy reference and the NCBI clinical overview.

Stop line: “I would report the visible structures and configuration by quadrant rather than infer a diagnosis from one feature.”

2. “Direct versus indirect ophthalmoscopy?”

First sentence: “Direct ophthalmoscopy gives an upright virtual image with higher magnification but a smaller field; indirect ophthalmoscopy gives a wider, inverted real image with stereopsis.”

Discriminator: State the consequence, not just the image orientation: indirect viewing is better suited to a broad peripheral fundus view, while direct viewing is a hand-held direct system. Do not claim a single magnification figure unless the device and lens are specified. “Indirect” does not mean that every indirect system uses the same lens or working distance.

Stop line: “The method selected depends on the part of the fundus and the examination context.”

3. “What is an optical section?”

First sentence: “An optical section is a narrow slit beam used to localise a finding within a transparent ocular structure by depth.”

Discriminator: The answer needs beam geometry: a broad diffuse beam shows surface overview; a narrow beam creates a sectional view through cornea or lens. Do not call every thin beam an optical section if the station has not narrowed it. In a demonstration station, say which interface or layer you are trying to localise, rather than naming a disease from a reflection. AAO EyeWiki’s slit-lamp examination guide uses this illumination vocabulary.

Stop line: “I would describe the plane and observed finding before interpreting it.”

4. “Why use fluorescein with cobalt-blue illumination?”

First sentence: “Fluorescein supports ocular-surface examination because it fluoresces under cobalt-blue illumination.”

Discriminator: The station is usually testing the relationship between dye and filter/illumination, not a treatment plan. A surface-staining pattern is a description, not automatically a diagnosis. If the examiner changes the filter, say what you see under the stated illumination rather than reciting a memorised label.

Stop line: “I would record the pattern and correlate it with the rest of the examination.”

5. “What is Van Herick assessment?”

First sentence: “Van Herick assessment estimates peripheral anterior chamber depth by comparing the dark chamber gap with corneal optical-section thickness at the limbus.”

Discriminator: It is a screening estimate, not a replacement for gonioscopy. This distinction earns more marks than a ratio quoted without a beam position. If a candidate says “it diagnoses angle closure,” the examiner can immediately challenge them. Answer with what it estimates and its limitation.

Stop line: “It raises or lowers concern about peripheral chamber depth; angle assessment requires the appropriate method.”

Motility, pupil and posterior-segment questions

6. “What does the cover test show?”

First sentence: “The cover test detects ocular misalignment by observing refixation movements under specified viewing conditions.”

Discriminator: Cover–uncover identifies a manifest deviation (tropia); alternate cover dissociates fusion and reveals total deviation, including a latent component. Do not say “cover test shows squint” and stop. Describe which eye moves, when, and under which test. That is a reproducible observation, whereas an unqualified label is not.

Stop line: “I would record laterality, direction, fixation preference and the condition of the test before assigning a measurement.”

7. “What is a RAPD?”

First sentence: “A relative afferent pupillary defect is an asymmetry in afferent pupillary input, elicited clinically with the swinging-flashlight test.”

Discriminator: It is a sign of relative afferent dysfunction, not the name of a disease and not synonymous with an anisocoria. In the viva, describe the observed relative dilation when the light is moved to the affected side, then stop before offering a differential unless asked. The AAO EyeWiki RAPD reference supports this terminology.

Stop line: “I would correlate the sign with visual function, colour vision, fundus and the rest of the examination.”

8. “What is the red reflex?”

First sentence: “The red reflex is fundus light returning through the ocular media when the eye is viewed with an ophthalmoscope.”

Discriminator: Compare the two eyes and note symmetry, brightness and any opacity interrupting the reflex. Do not make the question patient-facing by launching into screening advice. In a station, a reduced or asymmetric reflex is an observation requiring correlation, not a final diagnosis from a single look.

Stop line: “I would compare both eyes and describe any interruption of the reflex objectively.”

9. “How do you present a fundus finding?”

First sentence: “I first state the adequacy of the view, then describe disc, macula, vessels and periphery in a fixed order.”

Discriminator: Begin with media and view limitation. A beautiful description of the disc loses value if the image is blurred or peripheral retina is not visible. Give laterality and objective features—colour, margins, cup/disc estimate where appropriate, haemorrhage location—before a diagnostic label.

Stop line: “My conclusion would be bounded by the quality and extent of the view.”

10. “How do you describe proptosis?”

First sentence: “I describe proptosis by laterality, axiality, direction, severity and associated ocular signs.”

Discriminator: Add visual function, pupils, motility, exposure signs and orbital signs as the station permits. “The eye is protruding” is not a presentation. Equally, do not name a cause before you have described whether displacement is axial, non-axial, unilateral or bilateral.

Stop line: “I would state the examination findings and the limitations of this station before discussing causes.”

Fields, lenses and interpretation questions

11. “How do you read a visual-field printout?”

First sentence: “I check patient and eye identity, test strategy and reliability information before I interpret the plots.”

Discriminator: Then progress from greyscale to total and pattern deviation, noting the pattern, hemifield relationship and any relevant structural correlation. “Glaucoma field” is not a description. A better statement is: “There is a superior arcuate pattern respecting the horizontal meridian, subject to the displayed reliability indices.” Do not attach a diagnosis without context.

Stop line: “I would interpret the defect with optic-disc, OCT and repeat-test context where relevant.”

12. “What makes a visual field unreliable?”

First sentence: “Reliability is judged from the printout’s test-quality information together with the pattern of performance and the clinical context.”

Discriminator: Do not recite one universal percentage cutoff as if every perimeter, strategy and laboratory uses the same rule. False positives, false negatives, fixation-related metrics and artefactual patterns must be read in the displayed report. If the test looks inconsistent, say it needs cautious interpretation or repeat correlation, not that it is automatically useless.

Stop line: “I would identify the specific reliability concern shown on this printout.”

13. “What is a 90 D lens used for?”

First sentence: “A 90 D lens is a high-plus non-contact lens used with the slit lamp for posterior-segment viewing.”

Discriminator: It is not a gonioscopy lens. The examiner often wants you to separate posterior-segment viewing from angle viewing, not to calculate lens optics. Describe the lens and the viewing system shown in the station.

Stop line: “The lens selection determines the field, magnification and context of the view.”

14. “What is indentation gonioscopy for?”

First sentence: “Indentation gonioscopy is dynamic angle assessment using gentle central corneal pressure with an appropriate lens.”

Discriminator: Its conceptual value is distinguishing appositional angle contact from peripheral anterior synechiae and assessing configuration. Do not demonstrate a manoeuvre on a patient or turn this into laser advice in a viva. The AAO gonioscopy reference describes the static and dynamic distinction.

Stop line: “I would report the dynamic observation in context rather than equate one finding with a diagnosis.”

Drugs, sutures and instruments questions

15. “Why does a mydriatic not always cycloplege?”

First sentence: “Mydriasis and cycloplegia are related but distinct pharmacological effects: pupil dilatation does not by itself establish loss of accommodation.”

Discriminator: Identify the class and formulation before making a stronger statement. A bottle colour, a brand name or an assumed local protocol is not enough evidence. In a drug station, the answer should remain at class, intended examination effect and major caution requested by the examiner; do not volunteer doses.

Stop line: “I would verify the labelled agent and concentration before discussing its specific effects.”

16. “Monofilament versus braided suture?”

First sentence: “Monofilament suture is a single strand; braided suture consists of multiple filaments.”

Discriminator: From that construction flow handling and tissue-interaction differences, but exact selection depends on material, tissue and procedure. Do not reduce the answer to “one is better.” The viva mark is in naming the physical distinction and then qualifying the choice.

Stop line: “I would identify the actual material and local surgical context before claiming an indication.”

17. “What is a spatulated needle?”

First sentence: “A spatulated needle has a flattened, cutting profile designed for lamellar passage in delicate ocular tissue.”

Discriminator: Compare shape, not merely size: a spatulated needle is different from a conventional round-bodied needle because its profile is designed to separate lamellae. Avoid demonstrating needle passage or describing a surgical sequence.

Stop line: “I would name the profile and its tissue-plane rationale; needle choice remains procedure-specific.”

18. “What is a chalazion clamp used for?”

First sentence: “A chalazion clamp has a ring plate opposite a solid plate and stabilises a segment of eyelid while providing compression.”

Discriminator: The ring-and-plate design is the identifying feature. It is not ordinary tissue forceps, and a request to identify it is not an invitation to perform the procedure verbally. State the broad function and its visible mechanism.

Stop line: “I would confirm the local tray and supervised procedure protocol for real use.”

19. “What is the first step with an unfamiliar instrument?”

First sentence: “I inspect the working end and classify it before naming it.”

Discriminator: Look for a blade, teeth, smooth jaws, a lock, a lumen, a scale or a viewing element. Say what that feature permits: cutting, grasping, holding, irrigation/aspiration, measuring or viewing. A morphology-based answer is safer than guessing an eponym.

Stop line: “I would confirm the exact local pattern rather than fabricate certainty.”

20. “What do you do when you do not know?”

First sentence: “I would describe the item or sign objectively, state the feature I need to check, and avoid inventing a label.”

Discriminator: This is not evasive language. “This appears to be a fine toothed tissue forceps because of the opposing tips; I would confirm the exact pattern from the tray” is a clinically mature answer. Similarly, for an image: “The view is limited, but I can describe the visible disc margin and haemorrhage location.”

Stop line: “I would seek the next relevant examination or source of confirmation under the station’s instructions.”

Five phrases that repair an answer under pressure

Use these only when they are true; they are not filler.

• “I will describe the finding before interpreting it.”
• “The key distinction here is ___ versus ___.”
• “That sign is consistent with relative afferent dysfunction; it is not a diagnosis on its own.”
• “This is a screening estimate; the definitive assessment in this context is ___.”
• “I would confirm the exact instrument/drug/printout setting rather than assume it.”

These phrases convert an overconfident answer into a defensible one. They also protect you from a common practical-exam error: using management language when the station is testing observation, terminology or mechanism.

Turn the list into a 25-minute viva circuit

Do not read all twenty repeatedly. Rehearse them in four rounds of five.

1. Thirty seconds per card: say the first sentence and discriminator aloud.
2. Fifteen-second interruption: ask yourself the likely follow-up—“How is it different?”, “What is the limitation?”, or “Show me the feature.”
3. Score only four fields: definition/identification, principle, discriminator and stop line.
4. Repair the missing field: write one replacement sentence, then repeat the same card at the end of the round.

After night duty, this is more useful than trying to memorise a ten-line model answer. If reports are the weak area, use How to Read Ophthalmology Reports/Tests. For mixed instrument or bottle stations, use Instruments & Drugs for Practical Exams/Viva. Build full timed stations around the OSCE, Practical & Viva Voce Ready bundle, and use the ophthalmology glossary to repair imprecise terms. These are revision routes, not official examination material or a substitute for supervised clinical training.

The RCOphth OST curriculum update gateway is a useful professional-college reference for broader training context. It does not prescribe an Indian university’s viva questions or marking scheme.

Sources

• AAO EyeWiki: Gonioscopy (accessed 18 August 2026).
• NCBI Bookshelf: Gonioscopy (accessed 18 August 2026).
• AAO EyeWiki: Slit Lamp Examination (accessed 18 August 2026).
• AAO EyeWiki: Relative Afferent Pupillary Defect (accessed 18 August 2026).
• Royal College of Ophthalmologists: OST curriculum updates (accessed 18 August 2026).