Progressive optic neuropathy characterized by acquired loss of retinal ganglion cells and atrophy of the optic nerve.
Etiology
Major risk factors:
- Elevated intraocular pressure (IOP)
- Relatively thin central cornea
- Insults to the eye: Trauma, uveitis, and steroid therapy.
Other risk factors:
- Old age
- Black race
- Positive first-degree family history
- Diabetes mellitus
- Elevated systolic blood pressure
- Migraine
Pathophysiology

Optic nerve atrophy:

Presentation
- Progressive loss of peripheral vision (typical visual field changes) followed by central visual field loss (blindness) (due to retinal ganglion cell loss)
- Frequent changes in presbyopic glasses (d/t increasing accommodative failure as a result of constant pressure on ciliary muscle & nerve supply)
Diagnosis
Direct ophthalmoscopy:
Loss of optic nerve tissue results in excavation or “cupping” of the optic nerve head, which is best viewed by direct ophthalmoscopy.
- ↑ Cup-to-disc ratio (vertical ratio ≥ 0.6)
- Substantial cup-to-disc asymmetry between both eyes (≥ 0.2)
- Thinning & notching of neuroretinal rim
- Flame-shaped disc haemorrhages
- Peripapillary atrophy
- Laminar dot sign: Pores in lamina cribrosa are slit shaped n visible upto margin of disc.
- Marked cupping “Beanpot cupping”
Schematic drawing of normal optic disc | Epomedicine. (2014, May 3). Glaucomatous Optic Disc Changes Made Simple. Epomedicine. https://epomedicine.com/medical-students/glaucomatous-optic-disc-changes-made-simple/ Schematic diagram of early optic disc changes in glaucoma | Epomedicine. (2014, May 3). Glaucomatous Optic Disc Changes Made Simple. Epomedicine. https://epomedicine.com/medical-students/glaucomatous-optic-disc-changes-made-simple/ Schematic diagram of Advanced glaucomatous changes in optic disc | Epomedicine. (2014, May 3). Glaucomatous Optic Disc Changes Made Simple. Epomedicine. https://epomedicine.com/medical-students/glaucomatous-optic-disc-changes-made-simple/
Perimetry:
Computer-based test that provides a printout of the visual fields, is a mainstay of glaucoma diagnosis and management
- Pattern of visual field loss:
- Isopter contraction
- Barring of blindspot
- Relative paracentral scotoma
- Siedel scotoma
- Arcuate scotoma “Bjerrum’s scotoma”
- Double arcuate or ring scotoma
- Tubular/tunnel vision and temporal island of vision
- Temporal island of vision
- Loss of perception of light


Optical coherence tomography (OCT):

Shaffer system:
Describes the degree to which the anterior chamber angle (ACA) is open


Management
Slowing disease progression and preservation of quality of life are the main goals for glaucoma treatment.
Non-pharmacological managemnet:
- Regular aerobic exercise (help lower intraocular pressure)
Pharmacological management:
Reduction of intraocular pressure (IOP)
- β-Adrenergic blockers: Timolol, levobunolol, carteolol, metipranolol, betaxolol
- Reduction of aqueous humor production
- Prostaglandin analogues (prostamide): Latanoprost, travoprost, tafluprost, unoprostone, bimatoprost
- Increase in uveoscleral outflow of aqueous humor
- α-Adrenergic agonists: Brimonidine, apraclonidine
- Initial reduction of aqueous humor production with subsequent effect of increase in outflow
- Carbonic anhydrase inhibitors: Dorzolamide, brinzolamide, acetazolamide (oral)
- Reduction of aqueous humor production
- Cholinergic agonists: Pilocarpine, carbachol
- Increase in aqueous humor outflow
Surgical management
Indicated when target intraocular pressure cannot be reached medically, when optic nerve damage progresses despite achieving intraocular pressure goals with maximal medical therapy, or when patient is unable to comply with or tolerate medical therapy
- Laser trabeculoplasty
- Surgical trabeculectomy
Triple surgery procedure:
- Trabeculotomy
- Extracapsular cataract extraction (ECCE)
- Posterior chamber intraocular lens (PC-IOL) implantation
Glaucoma drainage devices (GDDs):
Create alternate aqueous pathways by channeling aqueous from anterior chamber through a long tube to an equatorial plate that promotes bleb formation
- Indications:
- Glaucoma not responding to medications or trabeculectomy operations
- Neovascular glaucoma
- Iridio-corneal syndrome
- Penetrating keratoplasty with glaucoma
- Glaucoma following retinal detachment surgery