Ophthalmology · MU Sofia

77. Clinical findings in primary open angle glaucoma - aetiology, risk factors, clinical findings, treatment and prophylaxis

Explains primary open angle glaucoma as a chronic, raised-pressure condition, covering predisposing factors, the proposed mechanism of reduced aqueous outflow, and symptoms. It then sets out investigations such as tonometry, diurnal variation, gonioscopy and the provocative water test, followed by early, advanced and atrophic optic disc changes and the visual field pattern. It closes with medical, laser and surgical treatment and a brief note on normal tension glaucoma.

Inside: 3 sections · 5 labelled pictures · 16 flashcards · 6 min

Topic 77 of 91 in the MU Sofia syllabus for Ophthalmology (Medicine, Year 4). The free AceMed note covers it in 3 sections, about 829 words (6 min of reading), with 16 flashcards.

In this note

  1. Open angle Glaucoma Topic 52
  2. Therapeutic choices ; Medical, laser, filtration surgery
  3. Normal tension glaucoma

Open angle Glaucoma Topic 52

A. primary angle glaucoma

A type of primary glaucoma with eyes that have an open angle of anterior chamber also known as chronic simple glaucoma of adult onset and is characterised by slowly pressure raised IOP (>21mmHg) with optic disc cupping and specific visual field defects

Etiopathogenesis ( not known exactly)

a) Predisposing factors: Heredity , age (more in 50-70), race (more in black people) , myopes, diabetic, cigarette smokers

B)Pathogenesis :the cause is unknown but the mechanism is

→Rise in IOP due to decrease in aqueous outflow due to increased resistance by age related thickening /sclerosis of trabecules and malfunction of canal of Schlemm

Clinical features

Symptoms

progressive and usually asymptomatic until significant visual field is lost

Delayed dark adaptation

Reading/close work → due to pressure on ciliary muscles& its nerve supply

Mild head and ear ache

Investigations required

  1. 1. Tonometry
  2. 2. Diurnal variation test → early case detection
  3. 3. Gonioscopy → rule out other forms of glaucoma
  4. 4. Slit lamp examination → rule out causes of secondary open glaucoma
  5. 5. Perimeter → detect visual field defect
  6. 6. Nerve fibre layer analyser→detect retinal nerve damage before changes occur
  7. 7. Provocative water test → if mm Hg rise is >8 after drinking of 1 L after 8 hours fast = diagnostic of POAG

Signs of Primary glaucoma

1. Anterior segment signs such as sluggish pupil reflect and haze cornea

2. Diurnal variation test → in early stages Diurnal variation may be exaggerated → repeated IOP observations within 24 hrs , usually it falls in the evening but it rises in early glaucomatic patients , Variations in IOP of >5 are suspicious and above 8 conclusive

3.Optic disc changes

→ as the changes are progressive and may take years recording of the appearance and a track record of changes on the nerve image is vital in the diagnosis

-Examination techniques includes, Direct ophthalmoscopy, slit-lamp biomicroscopy and Goldmann contact lens and indirect ophthalmoscopy

-optical coherence tomography can be used or scanning laser polarimetry aka nerve fibre analyser to take images

The changes can be divided into

A) Early Glaucomatous B) Advanced glaucomatous c) Glaucomatous optic atrophy

A) Early Glaucomatous

Normally cup to disc ration is 0.3-0.4 but in early

  • It can be 0.6 or more
  • Show vertical oval cupping or asymmetry in other eye
  • Pallor areas on the disc
  • Splinter haemorrhages present on or near the
  • optic disc margin.

B) Advanced glaucomatous

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