Case 3 summary
General ILOs:
- To demonstrate basic knowledge of abnormalities of the eye associated with this
case scenario: strabismus, errors in refraction, visual reflexes, visual fields
Refractive errors
Caused by light entering the eye whilst not being properly brought into focus on the retina:
Myopia – Caused by overly curved corneal surface or the eyeball being too long
(focus in front of retina). Treated with concave lens.
Hyperopia – Eyeball is too short or refracting system is too weak (focus behind
retina). Treated with convex lens.
Presbyopia – Normal ageing of the lens leading to refractive change. Older lenses are
less able to alter their curvature, causing difficulty with near vision.
Myopia
The result of a refractive power that is too great in relation to the axial length of the eye
(focus is in front of the retina):
Physiologic myopia – mismatch between refracting power and axial length of the
globe.
o Onset begins in the 20s and progresses through the 30s.
o Treated with spectacles or soft contact lens correction (concave, negative
dioptres).
o Laser in situ keratomileusis (LASI) may be used for mild to moderate
hyperopia.
Pathologic myopia – heritable condition where the eyeball is abnormally long.
Typically greater that 8.0 dioptre.
1
MBChB Y2 – Guillaume Antem
, o Dilated fundus exam should be performed for these individuals regularly to
assess for retinal detachment.
o Managed with spectacles or contact lenses
o Surgical and laser procedures may be needed to treat retinal and choroidal
lesions.
Hyperopia
The refracting power of the eye is insufficient to bring the focused image of an object onto
the retina (image lies posterior to the retinal plane):
Normal in infants and young children
Usually requires correcting in the 60s
May cause headaches
Managed with periodic cycloplegic refraction and spectacle or contact lens correction
o LASIK may be used for up to 5.0 dioptre of hyperopia.
2
MBChB Y2 – Guillaume Antem
, Astigmatism
The corneal surface is asymmetric, causing light to be refracted differently in different
planes:
Regular astigmatism – corrected with cylindrical and spherical spectacle lenses or
rigid contact lenses.
Irregular astigmatism – correctable with rigid contact lenses.
Amblyopia
Reduction in visual acuity caused by disuse during visual development. Blindness can occur
if amblyopia is not corrected before 8yrs. Amblyopia develops before 2yrs:
Development of the visual system mainly occurs in the first 3yrs of life and completes
at 8yrs.
3
MBChB Y2 – Guillaume Antem
General ILOs:
- To demonstrate basic knowledge of abnormalities of the eye associated with this
case scenario: strabismus, errors in refraction, visual reflexes, visual fields
Refractive errors
Caused by light entering the eye whilst not being properly brought into focus on the retina:
Myopia – Caused by overly curved corneal surface or the eyeball being too long
(focus in front of retina). Treated with concave lens.
Hyperopia – Eyeball is too short or refracting system is too weak (focus behind
retina). Treated with convex lens.
Presbyopia – Normal ageing of the lens leading to refractive change. Older lenses are
less able to alter their curvature, causing difficulty with near vision.
Myopia
The result of a refractive power that is too great in relation to the axial length of the eye
(focus is in front of the retina):
Physiologic myopia – mismatch between refracting power and axial length of the
globe.
o Onset begins in the 20s and progresses through the 30s.
o Treated with spectacles or soft contact lens correction (concave, negative
dioptres).
o Laser in situ keratomileusis (LASI) may be used for mild to moderate
hyperopia.
Pathologic myopia – heritable condition where the eyeball is abnormally long.
Typically greater that 8.0 dioptre.
1
MBChB Y2 – Guillaume Antem
, o Dilated fundus exam should be performed for these individuals regularly to
assess for retinal detachment.
o Managed with spectacles or contact lenses
o Surgical and laser procedures may be needed to treat retinal and choroidal
lesions.
Hyperopia
The refracting power of the eye is insufficient to bring the focused image of an object onto
the retina (image lies posterior to the retinal plane):
Normal in infants and young children
Usually requires correcting in the 60s
May cause headaches
Managed with periodic cycloplegic refraction and spectacle or contact lens correction
o LASIK may be used for up to 5.0 dioptre of hyperopia.
2
MBChB Y2 – Guillaume Antem
, Astigmatism
The corneal surface is asymmetric, causing light to be refracted differently in different
planes:
Regular astigmatism – corrected with cylindrical and spherical spectacle lenses or
rigid contact lenses.
Irregular astigmatism – correctable with rigid contact lenses.
Amblyopia
Reduction in visual acuity caused by disuse during visual development. Blindness can occur
if amblyopia is not corrected before 8yrs. Amblyopia develops before 2yrs:
Development of the visual system mainly occurs in the first 3yrs of life and completes
at 8yrs.
3
MBChB Y2 – Guillaume Antem
