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OP2.1-8 | Lids, Adnexa and Orbit — PBL Case

CLINICAL SETTING

Dr Priya Menon, a junior resident in the ophthalmology department of a tertiary care hospital in South India, is on call when three members of the same extended family present on the same busy evening. The cases are unrelated but arrive within 2 hours of each other, testing the resident's ability to prioritise and reason through distinct clinical problems. Case 1 — Ravi, 8 years: Ravi's mother brings him with right eyelid swelling for 3 days following a right-sided maxillary tooth extraction done by a local dentist 6 days ago. He was given oral antibiotics by the dentist. Tonight, the right lid is so swollen Ravi cannot open the eye. His temperature is 38.9 °C. His mother says that when she tried to open the lid an hour ago, 'the eye looked pushed forward.' She is frightened. Case 2 — Meenakshi, 44 years: Meenakshi has known Graves' disease and was last seen by the endocrinologist 8 months ago. She is here because 'my eyes look bigger and redder every month.' She has also noticed that the colour red looks 'less bright' in her left eye compared to the right since last week. She has been using lubricating drops for dry eyes. Her last thyroid function test was normal on carbimazole. Case 3 — Grandfather Rajan, 72 years: Grandfather Rajan has a 4-month history of painless, slowly progressive swelling 'just below the right eyebrow' that the family noticed while looking at photographs. His right eye appears to have been pushed slightly downward. He has no pain, no fever, no change in vision, and no known history of cancer. His GP has been treating him for 'sinusitis' for 3 months without improvement.

Trigger 1: Ravi — The Hot, Swollen Eye That Cannot Open

Dr Priya assesses Ravi first as he has fever and a high-priority triage tag. She carefully opens Ravi's right eyelid. The globe appears proptosed — pushed forward — compared to the left. When she asks Ravi to look left, right, up, and down, he says it hurts to move the eye. His visual acuity in the right eye is 6/12 with the left eye covered. His temperature is 39.1 °C. He has right-sided nasal congestion. She is about to order an IV cannula and call the paediatric team, but the on-call registrar phones and says: 'It is probably preseptal cellulitis — just give oral antibiotics and send him home.' Dr Priya is unsure. She has just read that the three features distinguishing orbital from preseptal cellulitis are proptosis, restricted/painful EOM, and visual compromise — and Ravi has all three.

DISCUSSION POINTS

Is the registrar's assessment correct? Use the three clinical signs Ravi has to argue for or against a postseptal (orbital) diagnosis. What is the anatomical significance of the orbital septum in separating preseptal from orbital infections?
What is the most likely source of Ravi's orbital cellulitis given his dental history and age? Which wall of the orbit is most at risk from dental and sinus infections, and why?
What is Chandler's classification of orbital cellulitis? Which Chandler grade does Ravi most likely represent based on the available findings?
Dr Priya orders an urgent CT orbit. What specific findings would she expect on CT, and what CT finding would mandate immediate surgical referral regardless of antibiotic response?
How frequently should visual acuity and colour vision be monitored in an admitted patient with orbital cellulitis, and why is colour vision specifically important?

Click to reveal Trigger 2: Meenakshi — The Eyes That Grow Redder Each Month (discuss previous trigger first!)

Trigger 2: Meenakshi — The Eyes That Grow Redder Each Month

While Ravi is being assessed by the paediatric surgical team, Dr Priya sees Meenakshi. On examination: bilateral proptosis (right 21 mm, left 23 mm on Hertel exophthalmometry; normal for this population ≤18 mm), bilateral upper lid retraction (scleral show above iris on primary gaze), bilateral periorbital oedema, and chemosis. Ocular movements show bilateral inferior rectus restriction with limitation of upgaze. Intraocular pressures are elevated bilaterally (right 22 mmHg, left 26 mmHg). Meenakshi's symptom of reduced red colour brightness in the left eye concerns Dr Priya deeply. She tests colour vision with an Ishihara chart and finds the left eye scores 8/15 plates versus 15/15 in the right. Visual acuity is 6/6 right and 6/9 left. Dr Priya calculates the clinical activity score (CAS). She counts: spontaneous orbital pain (yes), pain on eye movement (yes), redness of conjunctiva (yes), redness of eyelids (yes), chemosis (yes), and worsening proptosis (yes). CAS = 6/7.

DISCUSSION POINTS

What is the pathophysiology of thyroid eye disease? Explain the role of TSH receptor antibodies (TRAb) in driving orbital fibroblast activation, glycosaminoglycan deposition, and extraocular muscle enlargement.
Explain why the IOP is elevated in this patient when gaze is in the primary position, and why it rises further on upgaze. Which extraocular muscle enlargement accounts for this pattern?
Meenakshi has colour desaturation in the left eye with near-normal visual acuity. What complication does this represent, and why does colour vision fall before Snellen acuity?
With a CAS of 6/7, what is the immediate treatment priority? Outline the EUGOGO management sequence — distinguishing between treatment for active versus inactive disease, and the correct order of rehabilitative surgeries.
Meenakshi mentions that her endocrinologist is considering radioiodine ablation for her Graves' disease. What advice would you give her ophthalmologist regarding the ophthalmological implications of radioiodine?

Click to reveal Trigger 3: Grandfather Rajan — The Painless Lump Below the Brow (discuss previous trigger first!)

Trigger 3: Grandfather Rajan — The Painless Lump Below the Brow

Finally, Dr Priya sees Grandfather Rajan. He is brought by his son, who shows her photos on his phone — in a photograph from 6 months ago, both eyes look symmetrical; in one from last month, the right eye appears to have been pushed slightly downward and outward. On examination: the right globe is displaced infero-laterally. There is a firm, non-tender, smooth, palpable mass in the superolateral aspect of the right orbit. The mass does not transilluminate. Visual acuity is 6/6 bilaterally. There is no redness, no pain, no warmth. Intraocular pressure is normal. Hertel exophthalmometry shows right 20 mm, left 18 mm. A CT orbit ordered at 10 pm shows a well-circumscribed, rounded, hypo-attenuating mass at the right zygomaticofrontal suture with smooth, non-destructive pressure erosion of the adjacent orbital wall. No intracranial extension. The radiologist's report suggests 'most likely a dermoid cyst, but a lacrimal gland tumour cannot be excluded given the superolateral location.' The son asks: 'Doctor, can we just do a small biopsy to confirm what it is?'

DISCUSSION POINTS

Using the direction of globe displacement, explain the anatomical principle for localising orbital masses. Where is Rajan's mass located, and why does it push the globe infero-laterally?
The CT shows a low-attenuation (fat-density) mass at the zygomaticofrontal suture. What is the embryological origin of dermoid cysts, why do they arise at bony suture lines, and what is the definitive management of a confirmed orbital dermoid?
The radiologist says a lacrimal gland tumour cannot be excluded. What is the classification of lacrimal gland tumours? If this were a lacrimal gland pleomorphic adenoma, what is the ONE rule about biopsy that must not be violated, and what is the clinical consequence of violating it?
How would the management differ if CT had shown bony destruction and irregular margins rather than smooth pressure erosion? What does bony destruction suggest, and what investigations are required?
Enumerate the indications for urgent referral of an orbital tumour to a specialist orbital/ocular oncology centre.

Learning Issues

Research these questions and bring your findings to the discussion.

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