Ocular imaging and lasers

37 NEET-PG practice questions on Ocular imaging and lasers, part of Ophthalmology. The first 25 are below; the first 5 with answers and explanations (tap Show answer after you have chosen), the rest in Learn with a free account.

1. Question 1 · Hard

   Distortion of straight lines and a central smudge in the right eye have troubled a retired headmaster for 3 weeks; there is a grey-green lesion with subretinal fluid under the fovea and drusen in both eyes. He had anaphylaxis with hypotension during a fluorescein angiogram 2 years ago. Which investigation is most appropriate to confirm choroidal new vessels?

   1. AFull-field electroretinogram
   2. BRepeat FFA with antihistamine cover
   3. CIndocyanine green angiography
   4. DOCT angiography

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   Answer: D · OCT angiography

   The picture suggests neovascular (wet) age-related macular degeneration. After anaphylaxis to fluorescein, re-exposure is dangerous even with premedication, and ICG angiography is also an injected dye with its own allergy risk. OCT angiography detects flow in choroidal new vessels non-invasively by comparing repeated OCT scans, and structural OCT shows the fluid, so anti-VEGF can be started and monitored without any dye. Key point: When dye angiography is unsafe, OCT angiography can show choroidal new vessels without any injection.

   • A: The ERG measures diffuse retinal function and cannot show new vessels.
   • B: Premedication does not reliably prevent repeat anaphylaxis to fluorescein.
   • C: ICG is also an injected dye with a risk of allergy and is not needed here.

2. Question 2 · Easy

   After an intravitreal anti-VEGF injection, which complication is the most serious threat to sight?

   1. ASubconjunctival haemorrhage
   2. BInfective endophthalmitis
   3. CCorneal epithelial abrasion
   4. DTransient rise in IOP

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   Answer: B · Infective endophthalmitis

   Endophthalmitis after intravitreal injection is rare (about 1 in 2,000 to 3,000 injections) but can destroy the eye; povidone-iodine 5% to the conjunctiva, a lid speculum and a no-talk technique are used to prevent it. Patients are told to return at once with pain, redness or falling vision. Subconjunctival haemorrhage is the commonest complication but harmless. Key point: Endophthalmitis is the most serious complication of intravitreal injections; povidone-iodine antisepsis prevents it.

   • A: Subconjunctival haemorrhage is common and harmless.
   • C: An epithelial abrasion heals in a day or two without lasting harm.
   • D: The IOP rise after injection is short-lived and usually settles within an hour.

3. Question 3 · Medium

   A young farmer from Thanjavur has his third episode of floaters and blurred vision in the right eye. The fundus shows sheathing of peripheral retinal veins, and fluorescein angiography shows a wide area of peripheral capillary non-perfusion with leaking sea-fan new vessels at its edge. Blood sugar and haemoglobin electrophoresis are normal, and the Mantoux test is strongly positive. Chest X-ray is clear and he has no systemic complaints. Which treatment controls the new vessels?

   1. AOral steroids alone, without laser
   2. BFocal grid laser to the macula
   3. CNd:YAG laser vitreolysis
   4. DScatter laser to the non-perfused retina

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   Answer: D · Scatter laser to the non-perfused retina

   Recurrent vitreous haemorrhage with peripheral periphlebitis and non-perfusion in a young Indian man is Eales disease, thought to be a hypersensitivity to tuberculoprotein. The ischaemic peripheral retina drives new vessels, so scatter photocoagulation of the non-perfused area makes them regress; steroids are used in the active inflammatory phase and vitrectomy for non-clearing haemorrhage. Key point: Eales disease: peripheral periphlebitis and non-perfusion; new vessels are treated with scatter laser to the ischaemic retina.

   • A: Steroids help active vasculitis but do not make established new vessels regress.
   • B: Macular laser does not treat peripheral neovascularisation.
   • C: YAG vitreolysis is for floaters, not new vessels.

4. Question 4 · Medium

   B-scan ultrasonography in a high myope with a sudden shower of floaters and a dense vitreous haemorrhage: 1. A thick, bright membrane is attached at the optic disc. 2. The membrane forms a V or funnel shape towards the disc. 3. It shows little after-movement on eye movement. 4. It stays highly reflective at low gain. Which of these features favour a retinal detachment over a posterior vitreous detachment?

   1. A1 and 2 only
   2. B1, 2 and 3 only
   3. C3 and 4 only
   4. D1, 2, 3 and 4

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   Answer: D · 1, 2, 3 and 4

   On B-scan a detached retina is a thick, highly reflective membrane that stays bright as gain is reduced, is tethered at the optic disc and ora serrata (often a V or funnel shape) and shows only slight after-movement. A posterior vitreous detachment is thinner, less reflective, fades at low gain, moves freely with marked after-movement and is usually not attached at the disc. With an attached retina hidden behind vitreous blood, early repeat B-scans are needed. Key point: B-scan retinal detachment: thick, bright at low gain, tethered to the disc, little after-movement; PVD is thin and mobile.

   • A: Statements 3 and 4 also favour a retinal detachment.
   • B: Statement 4 also favours a retinal detachment.
   • C: Statements 1 and 2 also favour a retinal detachment.

5. Question 5 · Medium

   Fundus of a bus driver with 15 years of type 2 diabetes (HbA1c 9.4%): new vessels on the disc covering about half a disc area with a small pre-retinal haemorrhage. OCT shows no macular oedema, and vision is 6/9 in that eye. He can attend the clinic regularly. Which treatment is most appropriate?

   1. APanretinal photocoagulation
   2. BObservation with review in 3 months
   3. CPars plana vitrectomy
   4. DFocal macular laser

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   Answer: A · Panretinal photocoagulation

   New vessels on the disc of a third of a disc area or more, or any disc new vessels with vitreous or pre-retinal haemorrhage, are high-risk characteristics of proliferative diabetic retinopathy. These eyes need prompt panretinal photocoagulation (or anti-VEGF with close follow-up), which reduces severe visual loss by about half. Focal laser is for macular oedema, and vitrectomy is for non-clearing haemorrhage or traction. Key point: High-risk PDR (NVD with haemorrhage): treat promptly with PRP.

   • B: Waiting 3 months risks vitreous haemorrhage and traction in high-risk PDR.
   • C: Vitrectomy is for non-clearing haemorrhage or tractional detachment.
   • D: Focal macular laser treats macular oedema, which is absent here.

6. Question 6 · Hard

   Perimetry of a woman with gradually failing vision in the right eye shows a central scotoma in the right eye and a superotemporal defect respecting the vertical meridian in the left eye. Her right colour vision is poor, there is a right RAPD, and the right disc is pale. Where is the lesion?

   1. AJunction of the right optic nerve and chiasm
   2. BLeft optic radiation in the temporal lobe
   3. CRight optic tract
   4. DMiddle of the optic chiasm

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7. Question 7 · Hard

   On the fourth day after an uneventful phacoemulsification at a district hospital, a 72-year-old retired farmer with type 2 diabetes (HbA1c 8.1%) returns with severe pain and redness of the operated right eye. Vision has fallen to perception of light with accurate projection, the cornea is hazy, there is a 3 mm hypopyon and there is no fundal glow. B-scan shows dense, diffuse vitreous echoes, a thickened choroid and an attached retina. The other eye is normal. An aqueous sample has been sent and hourly fortified topical antibiotics have been started. What is the most appropriate next step?

   1. ATopical antibiotics; review in 24 hours
   2. BOral moxifloxacin and topical steroids
   3. CEarly vitrectomy with intravitreal antibiotics
   4. DVitreous tap with intravitreal antibiotics

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8. Question 8 · Easy

   Dense vitreous haemorrhage hides the fundus of the right eye in a man with long-standing type 2 diabetes who noticed sudden painless loss of vision this morning. Vision is hand movements close to the face and the red reflex is absent. Before treatment is planned, the retina must be checked for detachment. Which investigation is most useful now?

   1. AB-scan ultrasonography
   2. BOptical coherence tomography
   3. CFundus fluorescein angiography
   4. DIndocyanine green angiography

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9. Question 9 · Easy

   Panretinal photocoagulation (PRP) for proliferative diabetic retinopathy: 1. Burns are placed in the peripheral retina, sparing the macula. 2. It reduces the ischaemic drive for VEGF production. 3. It can reduce night vision and the peripheral field. 4. It improves pre-existing diabetic macular oedema. Which are correct?

   1. A1, 2 and 3 only
   2. B1 and 2 only
   3. C2, 3 and 4 only
   4. D1, 2, 3 and 4

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10. Question 10 · Easy

    Eighteen months after an uneventful phacoemulsification, vision has slowly blurred again, and retroillumination shows Elschnig pearls behind the IOL. Which laser treats this?

    1. AExcimer laser (193 nm)
    2. BArgon laser (514 nm)
    3. CDiode laser (810 nm)
    4. DNd:YAG laser (1064 nm)

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11. Question 11 · Medium

    On the fifth day after trabeculectomy, IOP is 4 mmHg, the anterior chamber is shallow and fundoscopy shows smooth, brown, dome-shaped elevations in the periphery. B-scan shows thick, smooth, dome-shaped membranes that do not insert at the optic disc and almost touch each other in the centre of the vitreous cavity. Which complication do these findings show?

    1. APosterior vitreous detachment
    2. BSerous choroidal detachment
    3. CExudative retinal detachment
    4. DRhegmatogenous retinal detachment

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12. Question 12 · Medium

    B-scan of a myope with a sudden curtain over the upper field and a hazy view of the fundus: 1. A bright, thick membrane that stays attached at the optic disc. 2. A spike of 100% height on the A-scan. 3. A thin membrane that moves freely and fades when the gain is lowered. 4. The membrane inserts at the ora serrata. Which findings favour retinal detachment over posterior vitreous detachment?

    1. A1, 2 and 4 only
    2. B1 and 3 only
    3. C1, 2, 3 and 4
    4. D2 and 3 only

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13. Question 13 · Medium

    Two days after an intravitreal ranibizumab injection for wet AMD, given at a busy eye hospital in Madurai, a retired weaver returns with severe pain, vision reduced to hand movements, marked conjunctival congestion, a hazy cornea and a 2 mm hypopyon; the red reflex is poor. Which management is best now?

    1. ATopical steroids for sterile inflammation
    2. BHourly topical antibiotics, review tomorrow
    3. COral ciprofloxacin and cycloplegics
    4. DVitreous tap and intravitreal antibiotics

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14. Question 14 · Medium

    Recurrent subretinal haemorrhages and orange-red subretinal nodules next to the optic disc are seen in a woman of 62 from Chennai; OCT shows a sharply peaked pigment epithelial detachment. Three monthly ranibizumab injections at a private clinic have given a poor response, with vision still 6/36 and fresh blood at the last visit. Which investigation best confirms the suspected diagnosis?

    1. AFundus autofluorescence
    2. BFundus fluorescein angiography
    3. CIndocyanine green angiography
    4. DB-scan ultrasonography

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15. Question 15 · Medium

    Selective laser trabeculoplasty (SLT) for open-angle glaucoma: 1. It uses a Q-switched, frequency-doubled Nd:YAG laser at 532 nm. 2. It targets pigmented trabecular cells and spares the surrounding tissue. 3. It can be repeated. 4. It is the laser of choice in primary angle closure. Which statements are correct?

    1. A1, 2 and 3 only
    2. B1, 2, 3 and 4
    3. C2, 3 and 4 only
    4. D1 and 2 only

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16. Question 16 · Medium

    Six weeks after an Nd:YAG posterior capsulotomy, a pseudophakic engineer with high axial myopia (axial length 27.5 mm) notices many new floaters, flashes of light and a grey shadow rising from below in the same eye. The capsulotomy had cleared his vision to 6/6, and the IOP checked an hour after the laser was normal. Which complication of the laser is most likely?

    1. ARhegmatogenous retinal detachment
    2. BPitting and cracking of the IOL optic
    3. CCystoid macular oedema
    4. DPost-laser IOP spike

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17. Question 17 · Medium

    Ophthalmic lasers, statements: 1. The Nd:YAG laser (1064 nm) cuts tissue by photodisruption. 2. The excimer laser (193 nm) used in LASIK removes corneal stroma by photoablation. 3. The argon laser is the standard laser for posterior capsulotomy. 4. The diode laser (810 nm) is used for cyclophotocoagulation. Which of these are true?

    1. A1, 3 and 4 only
    2. B2, 3 and 4 only
    3. C1, 2 and 4 only
    4. D1 and 2 only

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18. Question 18 · Medium

    In the casualty at night, a welder struck by a flying metal fragment has a full-thickness corneoscleral laceration with uveal tissue at the wound and a dense hyphaema hiding the fundus. The duty resident needs to know whether a foreign body is inside the eye before the repair is planned. Which is the best investigation now?

    1. AMRI of the orbits
    2. BB-scan through the closed lids
    3. CPlain orbital X-ray in two views
    4. DNon-contrast CT of the orbits

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19. Question 19 · Hard

    An orange-red, dome-shaped choroidal lesion about 6 disc diameters across lies next to the macula of a 45-year-old man, with overlying subretinal fluid that has reduced vision to 6/24. B-scan shows an acoustically solid mass without choroidal excavation or orbital shadowing, and the A-scan shows high, regular internal reflectivity. ICG angiography shows early intense hyperfluorescence with late 'wash-out'. Systemic examination and liver ultrasound are normal. Which treatment is preferred to resolve the subretinal fluid?

    1. APhotodynamic therapy with verteporfin
    2. BPlaque brachytherapy at tumour doses
    3. CIntravitreal anti-VEGF alone
    4. DEnucleation

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20. Question 20 · Medium

    A primigravida at 22 weeks with type 1 diabetes has blurred vision in the right eye; OCT shows centre-involving macular oedema (thickness 430 um) and vision is 6/18. Retinopathy is moderate non-proliferative in both eyes, her HbA1c is 7.2% and blood pressure is 118/76 mmHg. Which treatment is preferred during pregnancy?

    1. AFocal or grid macular laser
    2. BIntravitreal aflibercept
    3. CIntravitreal bevacizumab
    4. DOral acetazolamide

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21. Question 21 · Medium

    OCT of the left macula of a woman who sees a central gap and distorted lines shows a full-thickness defect through all retinal layers at the fovea, 350 µm wide, with cuffs of intraretinal fluid at its edges and a separated posterior hyaloid. Acuity is 6/36. What is the best management?

    1. AMonthly intravitreal anti-VEGF
    2. BFocal laser to the edges of the hole
    3. CObservation, as holes this size close
    4. DVitrectomy, ILM peel and gas tamponade

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22. Question 22 · Medium

    Faricimab, used for wet AMD and diabetic macular oedema, differs from ranibizumab because it also blocks which molecule?

    1. ATumour necrosis factor-alpha
    2. BPlatelet-derived growth factor
    3. CAngiopoietin-2
    4. DPlacental growth factor

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23. Question 23 · Easy

    Optical coherence tomography forms cross-sectional images of the retina using which principle?

    1. AReflection of high-frequency ultrasound
    2. BFluorescence of an injected dye
    3. CMagnetic resonance of protons
    4. DLow-coherence interferometry of near-infrared light

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24. Question 24 · Medium

    Centre-involving diabetic macular oedema with vision of 6/36 and a central subfield thickness of 520 um on OCT is found in a schoolteacher with well-controlled type 2 diabetes. There is no proliferative disease, the IOP is 15 mmHg and her blood pressure is 130/80 mmHg. She has had no stroke or heart attack. What should be started?

    1. AIntravitreal anti-VEGF injections
    2. BPanretinal photocoagulation
    3. CModified grid macular laser
    4. DPars plana vitrectomy with ILM peel

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25. Question 25 · Hard

    As the ophthalmologist at a district hospital serving a tribal block of Jharkhand, you see a 38-year-old daily-wage labourer with type 2 diabetes. Both eyes have proliferative diabetic retinopathy with new vessels elsewhere and small pre-retinal haemorrhages; OCT shows no macular oedema and vision is 6/9 in each eye. He travels 6 hours by bus to reach the hospital and says he cannot come every month because he would lose his wages. Intravitreal anti-VEGF and laser are both available free under the state scheme. Which treatment is the better choice for him?

    1. AFocal macular laser
    2. BObservation until haemorrhage occurs
    3. CPanretinal photocoagulation
    4. DMonthly intravitreal anti-VEGF alone

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