Page 21 of 23
OP9.1-5 | Retina, Optic Nerve and Visual Pathway — Graded Quiz
Click any question card to reveal the correct answer.
When performing indirect ophthalmoscopy with a 20-dioptre condensing lens, which of the following correctly describes the image seen by the examiner?
Correct. Indirect ophthalmoscopy gives a real, inverted image with approximately 3x magnification (20D lens) and a wide field of view. The image appears upside-down and laterally reversed.
Indirect ophthalmoscopy produces a real, inverted (upside-down and laterally reversed) aerial image between the condensing lens and the examiner. With a 20D lens, magnification is approximately 3x. Compare with direct ophthalmoscopy which gives a virtual, erect image with approximately 15x magnification but a very narrow field. The inverted image of indirect is a key practical point — the examiner must mentally reverse left/right and superior/inferior.
The virtual, erect, 15x magnified image describes direct ophthalmoscopy. Indirect ophthalmoscopy uses a condensing lens to form a real, inverted aerial image with lower magnification (approximately 3x with 20D) but a much wider field of view.
Click to reveal answer
A 52-year-old man with 18-year type 2 diabetes and poorly controlled hypertension is found on screening to have the following in his right eye: microaneurysms, hard exudates, venous beading in three quadrants, intraretinal microvascular abnormalities in four quadrants, and more than 20 dot-blot haemorrhages in each quadrant. No new vessels are seen. How should this eye be classified and managed?
Correct. This eye meets all three of the 4-2-1 criteria for severe NPDR. No new vessels means it is not yet PDR. Severe NPDR warrants close 3-monthly follow-up and consideration of early PRP given the high conversion risk.
The 4-2-1 rule defines severe NPDR: haemorrhages in all 4 quadrants, venous beading in 2 or more quadrants, or IRMA in 1 or more quadrants — any one criterion suffices. This patient meets all three. Without new vessels, classification is severe NPDR (not PDR). Severe NPDR has a 50% risk of converting to PDR within 1 year; early PRP may be considered. This is distinct from PDR where PRP is mandatory.
Venous beading in 3 quadrants, IRMA in 4 quadrants, and haemorrhages in all 4 quadrants all independently fulfil the 4-2-1 rule for severe NPDR. The absence of new vessels means this is not PDR. Severe NPDR (not mild or moderate) is the correct classification, and early PRP may be indicated given the high conversion risk to PDR.
Click to reveal answer
A 60-year-old man with treated diabetes is found to have new vessels on the optic disc (NVD) covering more than one-quarter of the disc area in his right eye, with a small pre-retinal haemorrhage. Visual acuity is 6/9. What is the most appropriate treatment?
Correct. NVD covering more than one-quarter disc area with a pre-retinal haemorrhage is high-risk PDR by DRS criteria. Urgent PRP is the standard treatment. Observation is never appropriate for high-risk PDR.
High-risk PDR characteristics include: NVD greater than one-quarter disc area, any NVD with vitreous haemorrhage, or NVE greater than one-half disc area with vitreous haemorrhage. This patient has high-risk PDR. Standard treatment is urgent panretinal photocoagulation (PRP), which reduces the risk of severe visual loss by 50%. Anti-VEGF may be used as an adjunct but PRP is the primary treatment. Vitrectomy is reserved for non-clearing haemorrhage or tractional retinal detachment.
This is high-risk PDR (NVD > 1/4 disc area + pre-retinal haemorrhage). Anti-VEGF treats macular oedema, not PDR as primary management. Vitrectomy is reserved for non-clearing vitreous haemorrhage or traction detachment, not initial PDR treatment. Preserved acuity does not justify observation in high-risk PDR — PRP halves the risk of severe visual loss.
Click to reveal answer
A 67-year-old woman with a history of hypertension presents with sudden painless visual loss in her left eye over a few hours. Fundoscopy shows a sectoral, wedge-shaped area of retinal whitening and oedema in the superior retina with a superior altitudinal visual field defect. The disc appears pale and swollen. What is the most likely diagnosis?
Correct. BRAO causes a wedge-shaped area of retinal whitening (ischaemic oedema) in the distribution of the occluded arteriole, producing a matching sectoral visual field defect.
Branch retinal artery occlusion (BRAO) produces a sectoral, wedge-shaped area of retinal whitening (ischaemic oedema) corresponding to the territory of the occluded arteriole, with a matching visual field defect. BRVO produces haemorrhages in the affected sector, not whitening. AION produces disc swelling with an altitudinal defect but the disc is the primary site and the retinal pallor is not sectoral in the same way. The distinction between BRAO and AION can be subtle but the wedge-shaped retinal whitening pointing to the disc is characteristic of BRAO.
BRVO produces flame haemorrhages in the affected sector, not whitening. Retinal detachment shows an elevated, corrugated retina. The wedge-shaped retinal whitening pointing toward the disc, corresponding exactly to an arteriolar territory, is the hallmark of BRAO.
Click to reveal answer
A premature neonate (28 weeks gestation, birth weight 900 g) is undergoing routine screening at 32 weeks post-menstrual age. The ophthalmologist finds zone II, stage 3 ROP with plus disease in both eyes. What is the most appropriate treatment?
Correct. Zone II, stage 3 ROP with plus disease meets Type 1 ROP criteria (threshold for treatment). Laser photocoagulation of the avascular retina or intravitreal anti-VEGF is indicated.
Type 1 ROP (the threshold for treatment) is defined as zone I any stage with plus disease, zone I stage 3 without plus disease, or zone II stage 2 or 3 with plus disease. This patient has zone II, stage 3 with plus disease — this meets Type 1 criteria and requires treatment. Treatment is laser photocoagulation to the avascular peripheral retina, or intravitreal anti-VEGF (particularly in zone I disease). Supplemental oxygen actually worsens ROP (hyperoxia promotes neovascularisation on re-exposure to normal oxygen after initial high O2).
Zone II stage 3 with plus disease meets Type 1 ROP treatment criteria. Observation is appropriate only for Type 2 ROP. Scleral buckle is used for stage 4 ROP (partial retinal detachment), not for stage 3. High supplemental oxygen was the original cause of ROP in premature neonates; it does not reverse neovascularisation.
Click to reveal answer
A 55-year-old man presents with a 3-day history of flashing lights (photopsia) and a shadow moving in from the periphery of his right eye. On fundoscopy, an elevated, corrugated retina is seen in the superior temporal quadrant with a small break visible at the 12 o'clock position. What type of retinal detachment is this and what is the recommended management?
Correct. Photopsia, a progressing visual field shadow, corrugated retina, and a visible retinal break = rhegmatogenous retinal detachment. Surgical repair is indicated, urgently if the macula is threatened.
Rhegmatogenous retinal detachment (RRD) is the most common type. It is caused by a full-thickness retinal break (rhegma = rent) that allows liquefied vitreous to pass beneath the retina, separating it from the RPE. Photopsia (flashing lights due to vitreoretinal traction) and a shadow advancing from the periphery (corresponding to the detachment) are classic symptoms. An identifiable retinal break on fundoscopy confirms the diagnosis. Treatment is surgical: scleral buckle, pars plana vitrectomy, or pneumatic retinopexy.
Exudative detachment has no retinal break and a smooth convex retina (from choroidal disease). Tractional detachment is fibrovascular, concave toward the disc, and occurs in PDR or sickle cell disease. Retinoschisis is a splitting of retinal layers without a full-thickness break. The visible break with corrugated elevated retina and classic symptoms confirms rhegmatogenous RD, requiring surgery.
Click to reveal answer
A patient with a known pituitary macroadenoma is found on visual field testing to have loss of the temporal field in both eyes (bitemporal hemianopia). Which fibres are compressed at the chiasm to produce this field defect?
Correct. Nasal retinal fibres carry temporal visual field information and cross at the chiasm. Central compression (pituitary adenoma) selectively damages these crossing fibres, producing bitemporal hemianopia.
At the optic chiasm, nasal retinal fibres from each eye cross to the opposite optic tract. Nasal retinal fibres subserve the temporal visual field. A central compressive lesion at the chiasm (e.g., pituitary adenoma) damages these crossing nasal fibres from both eyes, knocking out the temporal field bilaterally — bitemporal hemianopia. Uncrossed temporal fibres (subserving the nasal field) are in the lateral chiasm and are spared by a central compression.
Temporal retinal fibres (uncrossed) carry the nasal visual field and run on the lateral sides of the chiasm — they are spared by a central pituitary tumour. The nasal retinal fibres, which carry the temporal visual field, cross at the chiasm and are compressed by a centrally expanding lesion, producing the classic bitemporal hemianopia of pituitary adenoma.
Click to reveal answer
A 72-year-old woman with no history of diabetes or hypertension presents with gradual bilateral loss of central vision over 3 years. Fundoscopy shows bilateral drusen at the macula and a patch of pigment epithelial atrophy at the fovea. Visual acuity is 6/24 in both eyes. She denies metamorphopsia. What is the most appropriate management?
Correct. Dry AMD (drusen + geographic atrophy, no metamorphopsia or neovascularisation) is managed with AREDS2 supplements to slow progression, plus low-vision rehabilitation and smoking cessation.
This patient has dry AMD (geographic atrophy). There is no metamorphopsia, no subretinal fluid, and no haemorrhage to suggest wet (neovascular) AMD. Dry AMD management includes AREDS2 supplements (vitamins C and E, beta-carotene or lutein/zeaxanthin, zinc, copper) which reduce the risk of progression to advanced AMD in patients with intermediate or advanced AMD in one eye. Anti-VEGF and PDT are for wet AMD. Low-vision aids and smoking cessation are also important.
Anti-VEGF and PDT are treatments for wet (neovascular) AMD with active choroidal neovascularisation. The absence of metamorphopsia, haemorrhage, and subretinal fluid indicates dry AMD. Focal laser to the macula would cause permanent scotoma. AREDS2 supplementation is the evidence-based intervention to reduce progression risk in dry AMD.
Click to reveal answer
A 40-year-old otherwise healthy man presents with bilateral gradual visual field constriction since his teenage years. He reports night blindness (nyctalopia) from childhood. Fundoscopy shows bilateral bone-spicule pigmentation in the mid-periphery, attenuated arterioles, and a waxy pale disc. ERG is extinguished. What is the most likely diagnosis?
Correct. The triad of bone-spicule pigmentation, attenuated arterioles, and waxy disc pallor with childhood nyctalopia and extinguished ERG is diagnostic of retinitis pigmentosa.
The classic triad of retinitis pigmentosa (RP) is: bone-spicule pigmentation in the mid-periphery, arteriolar attenuation, and waxy disc pallor. Nyctalopia from childhood due to rod photoreceptor loss and progressive concentric visual field constriction leading to tunnel vision are the hallmark symptoms. ERG shows markedly reduced or extinguished rod responses. RP is inherited (autosomal recessive most common), and there is currently no curative treatment.
Stargardt disease causes macular (central) dystrophy, not peripheral. Choroideremia is X-linked and shows diffuse choroidal atrophy. Gyrate atrophy is caused by ornithine aminotransferase deficiency and shows scalloped areas of chorioretinal atrophy. The peripheral bone-spicule pigmentation triad with childhood nyctalopia and extinguished ERG is the hallmark of retinitis pigmentosa.
Click to reveal answer