MRCSI (Ophth) Written common mistakes
MRCSI (Ophth) Written · Understand the traps and how to avoid them.
Committing to a single diagnosis for a unilateral red, painful eye before explicitly listing and excluding sight-threatening causes (acute angle-closure glaucoma, microbial keratitis, endophthalmitis, scleritis, anterior uveitis).
Candidates anchor on the most familiar presentation (e.g. conjunctivitis) and answer the first plausible option, because the stem feels like a classic vignette and time pressure rewards speed.
What to do instead
Before selecting, write a one-line rule-out for each sight-threatening cause and check which stem features (pain severity, photophobia, fixed mid-dilated pupil, contact lens use, hypopyon, reduced acuity) are present or absent. Only answer once each has been addressed.
Managing a red eye with topical steroid before fluorescein staining and exclusion of dendritic/herpetic ulceration.
The reflex is to treat inflammation, and the stem may emphasise discomfort and photophobia without flagging the corneal clue; steroid is a familiar 'anti-inflammatory' answer.
What to do instead
Treat 'steroid in a red eye' as a trigger to check for a corneal epithelial defect, contact lens history and vesicular rash. If any are present or unstated, choose the option that includes fluorescein assessment or antiviral therapy, not steroid alone.
Reading a visual field or OCT/imaging description and answering from the image's overall impression rather than naming the specific defect pattern and matching it to a lesion site.
Stems describe findings in prose; candidates pattern-match to a remembered disease name and skip the localisation step, which is where the discriminating options are set.
What to do instead
State the defect explicitly (e.g. bitemporal hemianopia, arcuate scotoma, altitudinal defect) and then state the anatomical site it localises to before looking at the options. Reject any option whose site does not match the stated defect.
Failing to stratify urgency: choosing a routine outpatient plan for a presentation that needs same-day or emergency referral (e.g. sudden painless vision loss, giant cell arteritis symptoms, chemical injury, retinal detachment, acute angle closure).
Candidates focus on diagnostic accuracy and treat the question as 'what is the diagnosis', overlooking that many items test the next management step and its timeframe.
What to do instead
For every item, answer two questions in order: (1) what is the diagnosis, (2) what is the timeframe? If any red-flag feature is present, the correct option will usually be the most urgent safe action, not the most elegant investigation.
Ignoring the systemic/medical context in an ophthalmic stem (e.g. diabetes, anticoagulation, immunosuppression, pregnancy, giant cell arteritis) and answering purely on ocular findings.
The ocular detail is vivid and draws attention; systemic modifiers are buried in the past medical history line and are easy to skim.
What to do instead
Re-read the history sentence by sentence and list every systemic condition and drug before answering. If a systemic condition is present, check whether it changes the diagnosis, the safety of a proposed treatment, or the urgency.
Confusing the investigation that confirms a diagnosis with the investigation that should be requested first or urgently in the acute setting (e.g. ordering imaging when an immediate clinical action or bedside test is required).
Candidates memorise 'gold standard' tests and select them regardless of the clinical scenario, missing that the question asks for the next step rather than the definitive test.
What to do instead
Read the question stem's final line carefully to identify whether it asks for next step, most likely diagnosis, best investigation or definitive management. Match the answer to that verb, not to the remembered gold standard.
In a general surgery item, choosing an operative option before completing resuscitation and assessment (ABC, fluids, analgesia, imaging/labs) in an acutely unwell patient.
The surgical diagnosis is often obvious (e.g. perforation, ischaemic bowel, obstructed hernia) and candidates jump to the definitive operation, forgetting that early management options are frequently the tested point.
What to do instead
For any acutely unwell surgical stem, order your answer as resuscitation and investigation first, then definitive treatment. If the option list contains both, choose the earliest appropriate step unless the stem states resuscitation is complete.
Applying a named scoring or severity system incorrectly, or using it at all where it is not validated (e.g. misapplying Alvarado, Glasgow, Child-Pugh, or trauma scores to the wrong population or with the wrong variables).
Scores are memorised as thresholds without the variable definitions, so a single misread value (e.g. wrong component, wrong unit, wrong age band) flips the answer.
What to do instead
Before using a score, write out its components and confirm each against the stem values. If a component is missing from the stem, the score is probably not the intended answer; look for a clinical-management option instead.
Confusing the indications, contraindications and timing of common general surgical procedures (e.g. when to operate versus observe in diverticulitis, appendicitis, gallstone disease, or when to use conservative versus surgical management of a hernia).
Guidelines have shifted toward conservative and minimally invasive pathways, but candidates rely on older teaching or a single memorable case, producing a confident but outdated answer.
What to do instead
Build a one-page table per common condition listing observation, antibiotics, and operative thresholds with the specific features that trigger each. Answer by matching the stem's features to the threshold, not to the remembered 'usual' operation.
Missing the perioperative and postoperative complication that the stem is describing, and attributing symptoms to the original disease or to a benign cause (e.g. post-op fever timing, anastomotic leak, wound infection, DVT, bile leak).
Candidates focus on the index operation and its expected recovery, and the stem's timeline clue (day of onset) is not used to discriminate between complications.
What to do instead
For any postoperative stem, note the postoperative day first, then list the complications expected at that time point. Choose the diagnosis consistent with both the day and the specific symptoms, and pair it with the confirmatory test or immediate action.