Gradual Loss of Vision

Differential Diagnosis

Common Diagnoses

Occasional Diagnoses

Rare Diagnoses

  • Syphilis
  • Cerebromacular Degeneration
  • Toxic Amblyopia (Tobacco, Methanol, Arsenic, Quinine, Carbon Bisulphide)
  • Choroidal Melanoma
  • Leber’s Hereditary Optic Atrophy

Ready Reckoner

Key distinguishing features of the most common diagnoses

CataractGlaucomaRetinopathyMacular DegenerationRetinal Detachment
Unilateral Visual LossPossiblePossiblePossiblePossibleYes
Pigment at MaculaNoNoNoYesNo
Exudate + HaemorrhageNoNoYesYesNo
Fundus ObscuredYesNoPossibleNoNo
Disc Cupped >50%NoYesNoNoNo

Possible Investigations

  • The only investigation the GP is likely to perform is a urinalysis and/or blood sugar or HbA1c for suspected diabetes. If glaucoma is a possibility, and the patient has not already seen the optician, then optician referral will provide information about fields and pressures. More obscure tests – such as posterior pole ultrasound and CT scan for retinal, or other, tumours; syphilis serology; skull X-ray for Paget’s disease; and neurological investigations for MS – are rarely required and are inevitably arranged in secondary care.

Top Tips

  • Opticians will tend to report cataracts in the elderly routinely. Referral for surgery is only required if the problem is significantly impairing the individual’s normal activities.
  • The presence of a cataract in relatively young patients is unusual and should prompt referral regardless of visual impairment – there may be a rare underlying metabolic cause.
  • Remember that significant glaucoma or other causes of visual loss may render the individual unfit to drive.
  • The elderly patient with a cataract whose vision is not improved considerably with the pinhole test probably has macular degeneration too, and so is unlikely to benefit much from cataract extraction.

Red Flags

  • It can be very difficult to establish in an elderly person whether the problem really has been gradual in onset or whether the history is more sudden; if in doubt, refer urgently as the cause may be acute and remediable.
  • Progressive early morning headache or proptosis with gradual loss of vision suggests a tumour. Refer urgently.
  • Gradual or recurrent visual loss or blurring with other intermittent neurological symptoms, especially in younger patients, suggests the possibility of MS.
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