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OP9.4 | Posterior Segment Disorder Survey: Retinopathies, Detachment, Macular Disease, Dystrophy and Retinoblastoma — SDL Guide

Learning Objectives

Classify hypertensive retinopathy using the Keith-Wagener-Barker grading system and identify grade IV as a hypertensive emergency requiring immediate management
Describe the clinical features, classification, and management of retinopathy of prematurity (ROP) and Eales disease
Distinguish rhegmatogenous, tractional, and exudative retinal detachment by mechanism and fundoscopic appearance, and describe their management
Describe the clinical features and management of central serous retinopathy, cystoid macular oedema, and age-related macular degeneration (dry and wet types)
Describe the fundoscopic features, genetics, and management of retinitis pigmentosa and recognise retinoblastoma as a life-threatening emergency requiring urgent referral

INSTRUCTIONS

The posterior segment of the eye — retina, vitreous, optic nerve head — is the site of a remarkable diversity of disorders: from the commonplace (hypertensive retinopathy visible in any hypertensive patient's fundus) to the oncological emergency (retinoblastoma in a toddler with a white pupil). This survey module maps the key conditions across five disease categories, equipping you to recognise their characteristic presentations and act correctly — whether that means managing hypertension urgently, arranging neonatal ROP screening, or making an emergency retinoblastoma referral.

References

Khurana AK. Comprehensive Ophthalmology, 7th ed. Chapters on Retinal Disorders and Intraocular Tumours (textbook)
Parsons' Diseases of the Eye, 22nd ed. Chapters on Diseases of the Retina and Choroid (textbook)

Version 2.0 | NMC CBUC 2024

CLINICAL SCENARIO

A paediatrician receives a referral note about a 2-year-old girl whose parents noticed 'a white glow in her right eye in photographs.' The GP has reassured them it is 'probably just the camera.' The paediatrician examines the child and finds the right pupil does not show a red reflex — it shows a white reflex (leukocoria). This child has retinoblastoma until proven otherwise. Retinoblastoma is the most common intraocular malignancy of childhood and, if untreated, is life-threatening. The paediatrician makes an emergency ophthalmology referral. Two years later, the child is alive — her eye was enucleated, and the tumour had not spread beyond the globe. The GP who reassured the family almost cost the child her life. Know your leukocoria.

WHY THIS MATTERS

Every clinician who examines a fundus or a child's pupil may encounter the conditions in this module. Hypertensive retinopathy is present in a third of hypertensive patients and grades your antihypertensive treatment effectiveness. Retinopathy of prematurity (ROP) requires active screening of premature infants by the paediatrician who must know when to refer. Retinal detachment presents as an emergency with sudden visual symptoms and surgical urgency. Macular degeneration is the leading cause of blindness in the elderly in developed countries, and central serous retinopathy affects young men in stressful occupations. Retinoblastoma is a life-threatening malignancy of childhood where early recognition by a general physician — before the GP or paediatrician sees an ophthalmologist — can save both the eye and the life. Retinitis pigmentosa, while chronic and currently untreatable, requires counselling and genetic referral for affected families. Together, these conditions span the full range of clinical urgency from routine to emergency, and every physician needs to know where each falls.

RECALL

Recall from the ophthalmoscopy SDL: the retina is a layered neural tissue with the retinal pigment epithelium (RPE) lying between the photoreceptors and the choroid (the outer vascular layer). The RPE actively pumps subretinal fluid back into the choroid, keeping the retina attached. A break or failure of this pumping mechanism leads to retinal detachment. Also recall the vitreoretinal interface: the vitreous gel (composed of collagen and hyaluronic acid) is attached to the retina at the vitreous base anteriorly and at the disc and macula. As we age, the vitreous liquefies and separates from the retina (posterior vitreous detachment, PVD) — this is a critical event that can cause retinal tears. From pathology, recall that RB1 is the first identified tumour suppressor gene — its loss (both alleles) causes retinoblastoma. Knudson's two-hit hypothesis explains both heritable (germline mutation + somatic second hit) and sporadic (two somatic hits) forms.

Presenting Clues: When to Suspect Posterior Segment Disease

Recognising the clinical context in which posterior segment disease presents is the first step to timely diagnosis and referral. Each category of condition has a characteristic clinical setting that should trigger a targeted examination.

Hypertension: any hypertensive patient requires periodic fundoscopy to grade retinopathy severity and assess end-organ damage. The classic grade IV presentation — bilateral blurred disc margins with papilloedema in a patient with severely elevated BP — is a medical emergency (hypertensive encephalopathy).

Prematurity: a premature infant (<32 weeks gestation or <1500 g birth weight) must be screened for retinopathy of prematurity (ROP) — first examination at 4-6 weeks postnatal age or 31-32 weeks postmenstrual age (whichever is later), performed by an ophthalmologist. Early signs of ROP may be visible only with indirect ophthalmoscopy and scleral indentation.

Young Indian man with floaters and visual obscurations: Eales disease — idiopathic peripheral periphlebitis — should be considered, especially if the patient is a young adult male and the presentation includes recurrent vitreous haemorrhage.

New floaters and flashing lights, or a 'shadow/curtain' in peripheral vision: this classic triad suggests retinal detachment — always a surgical emergency. Flashing lights (photopsia) indicate vitreous traction on the retina; floaters indicate vitreous haemorrhage or pigment cells. A progressive curtain in the visual field suggests the detachment is expanding.

Gradual central vision loss with metamorphopsia (distortion of straight lines) in an older patient: consider AMD, particularly wet AMD if the onset is subacute and progressive.

White pupil (leukocoria) in a child under 5: retinoblastoma is the most important and life-threatening diagnosis. Other causes include dense cataract, retinal detachment, retinopathy of prematurity (stage 5), and Coats disease — but retinoblastoma must be excluded urgently in every child with leukocoria.

Night blindness (nyctalopia) and progressive tunnel vision in a young adult: retinitis pigmentosa. Ask about family history (autosomal dominant, AR, or X-linked recessive inheritance).

Anatomy and Pathophysiology: Why the Posterior Segment Fails

The posterior segment disorders, despite their clinical diversity, arise from a small number of pathophysiological mechanisms. Understanding these mechanisms organises the clinical findings logically.

Vascular endothelial injury and leakage underlie hypertensive retinopathy, Eales disease, and CMO. In hypertensive retinopathy, the elevated pressure damages the arterial wall through hyaline arteriosclerosis, leading to arteriolar narrowing, haemorrhages, and — at the most severe stage — disc ischaemia (papilloedema). In Eales disease, an inflammatory (possibly tuberculin hypersensitivity-mediated) periphlebitis of peripheral retinal veins leads to venous occlusion, ischaemia, neovascularisation, and recurrent vitreous haemorrhage.

Retinal separation from the RPE is the mechanism of retinal detachment and central serous retinopathy. The RPE actively maintains retinal attachment by pumping subretinal fluid into the choroid. In rhegmatogenous RD, a break in the retina (tear from vitreous traction, or hole from atrophic degeneration) allows fluid to pass from the vitreous through the break and accumulate beneath the retina — lifting it off. In tractional RD, fibrovascular membranes (from PDR, ROP, or penetrating trauma) physically pull the retina off the RPE without a break. In exudative (serous) RD, exudate from underlying choroidal tumours, severe hypertension, or inflammation collects beneath the retina passively. In CSR, a localised defect in the RPE barrier allows fluid from the choroidal circulation to accumulate beneath the neurosensory retina, producing a dome-shaped neurosensory detachment.

Drusen and choroidal neovascularisation (CNV) characterise AMD. Drusen are deposits of extracellular material under the RPE; their accumulation impairs RPE function in dry AMD, leading to geographic atrophy. In wet AMD, rupture of Bruch's membrane allows vessels from the choriocapillaris to grow through into the sub-RPE and subretinal space — CNV — which leaks, bleeds, and scars, causing rapid central vision loss.

Photoreceptor dystrophy from genetic RPE-photoreceptor dysfunction underlies retinitis pigmentosa. The primary defect involves rod photoreceptors (and later cones); over decades, progressive rod death leads to night blindness followed by tunnel vision. Bone-spicule pigmentation represents migration of RPE cells into the degenerating outer retina.

RB1 tumour suppressor loss causes retinoblastoma. Both copies of RB1 must be inactivated (Knudson's two-hit hypothesis) — in heritable form, the first hit is germline (inherited) and the second is somatic; in sporadic, both hits are somatic. The resulting tumour grows as a white, chalky retinal mass with calcium deposits, which can seed the vitreous (vitreous seeds) and spread via the optic nerve to the CNS.

Ocular Examination and Investigations for Posterior Segment Disorders

The investigation of posterior segment disorders uses a core set of tools — many already described in the ophthalmoscopy SDL — with specific additions for particular conditions.

Dilated fundoscopy and slit-lamp biomicroscopy: the foundation for all posterior segment assessment. Indirect ophthalmoscopy with scleral indentation is essential for peripheral retinal examination (RD, ROP, peripheral changes in Eales/RP).

Optical Coherence Tomography (OCT): provides cross-sectional retinal layer imaging. Essential for: CSR (neurosensory detachment — subretinal fluid dome), CMO (cystoid spaces in the inner nuclear layer — the characteristic pattern), AMD (drusen under RPE in dry; subretinal/sub-RPE fluid in wet AMD), macular oedema, and monitoring treatment responses.

Fundus Fluorescein Angiography (FFA): delineates areas of non-perfusion (ischaemia), leakage, and neovascularisation. Used in hypertensive retinopathy (grade), ROP assessment, Eales (non-perfusion and NV mapping), AMD (to detect CNV subtype — classic vs occult), and CSR (pinpoint leakage at the RPE defect site — 'smokestack' or 'inkblot' pattern).

B-scan ultrasonography: essential when the fundal view is obscured by vitreous haemorrhage, dense cataract, or opaque media. Used to detect retinal detachment (acoustically dense membrane on B-scan) and to image retinoblastoma (high internal reflectivity + calcification = echogenic mass with acoustic shadowing — helps distinguish from Coats disease).

Electroretinogram (ERG): records the mass electrical response of the retina to light stimuli; extinguished (flat) ERG is pathognomonic of advanced retinitis pigmentosa (widespread rod loss). Also used in ROP assessment.

Examination Under Anaesthesia (EUA): for retinoblastoma — allows full fundal examination, measurement of tumour size, and planning of treatment under general anaesthetic. Never perform a fine needle biopsy of suspected retinoblastoma (risk of seeding).