Introduction and Objective Refraction
OPHTHALMOSCOPY
Learning Objectives
● Understand and perform direct and indirect ophthalmoscopy.
● Know when to use each technique.
● Recognise key signs of ocular health and disease.
Comparing Techniques
Aspect Direct Ophthalmoscopy Indirect Ophthalmoscopy
Magnification High (~15x) Lower (~3x)
Field of View Small Wide
Image Upright Inverted & reversed
Portability Handheld Requires headset/lens
Use Routine exams Detecting peripheral pathology,
media opacities
Clinical Use
, Direct is best for optic disc assessment, C:D ratio, and macula.
Indirect is preferred for retinal periphery and detached retina assessment.
Recording Findings
C:D Ratio (Cup-to-Disc Ratio)
● Expressed as cup diameter ÷ disc diameter.
- How many cups can fit into the disc / 10
● Example: 0.3 = 30% of disc is cup.
● Assess vertically.
● Normal - 0..4
For example, in this image 5 of these cups can fit into the disc
10/5 = 2
Cm - mm = 0.2
Abnormal Signs:
● Eccentric cup - displaced
● Rim notching - dip in the shape
● Inter-eye asymmetry (>0.2 difference)
● Pale disc colour
Choroidal Crescent
● Benign variant where choroidal pigment visible (usually temporal).
- Dark ring of pigment seen around the optic disc
- More common in myopia
● Caused by incomplete retinal tissue abutment around the disc.
OPHTHALMOSCOPY
Learning Objectives
● Understand and perform direct and indirect ophthalmoscopy.
● Know when to use each technique.
● Recognise key signs of ocular health and disease.
Comparing Techniques
Aspect Direct Ophthalmoscopy Indirect Ophthalmoscopy
Magnification High (~15x) Lower (~3x)
Field of View Small Wide
Image Upright Inverted & reversed
Portability Handheld Requires headset/lens
Use Routine exams Detecting peripheral pathology,
media opacities
Clinical Use
, Direct is best for optic disc assessment, C:D ratio, and macula.
Indirect is preferred for retinal periphery and detached retina assessment.
Recording Findings
C:D Ratio (Cup-to-Disc Ratio)
● Expressed as cup diameter ÷ disc diameter.
- How many cups can fit into the disc / 10
● Example: 0.3 = 30% of disc is cup.
● Assess vertically.
● Normal - 0..4
For example, in this image 5 of these cups can fit into the disc
10/5 = 2
Cm - mm = 0.2
Abnormal Signs:
● Eccentric cup - displaced
● Rim notching - dip in the shape
● Inter-eye asymmetry (>0.2 difference)
● Pale disc colour
Choroidal Crescent
● Benign variant where choroidal pigment visible (usually temporal).
- Dark ring of pigment seen around the optic disc
- More common in myopia
● Caused by incomplete retinal tissue abutment around the disc.
