Pharmacology
Lecture 1
Cataract:
• Definition of cataract
• Symptoms & signs of cataract
• Structure of the lens
• Ocular examination
• Types of cataract
• Treatment & complications
Definition: opacification of the crystalline lens.
Most common cause of curable blindness worldwide. Affects genders equally. Part of aging
process, can be in one or two eyes. Each decade numbers double.
Symptoms:
o Glare: increased scatter, haloes, night driving problems
o Blurred vision: reduced VA, loss of contrast sensitivity
o Change in refractive error: myopic shift, irregular astigmatism
o Monocular diplopia: double vision in one eye
o Change in color vision: blue and green absorbed, things look yellowish
Lens structure: biconvex. Capsule around, epithelial cells, cortex and nucleus.
Ocular examination: slit lamp optic section. Identify layers and observe opacities.
Risk factors: age, smoking, heavy alcohol use, diabetes, poor nutrition, medicines such as
corticosteroids, trauma, and prolonged exposure to sunlight.
Types of cataracts:
• Age-related
• Nuclear Sclerosis
, • Posterior Subcapsular
• Cortical
• Trauma
• Diabetic
• Secondary cataract
• Pharmaceutic-induced
• Related to other ocular disease
• Congenital and juvenile
Age-related
Nuclear sclerosis: loss of transparency – yellowing of nucleus. Pseudo-myopic shift due to
increase in refractive index of the nucleus (dense).
Posterior Subcapsular: focal dot-like appearance, located in front of the posterior lens
capsule. Due to a posterior migration of lens epithelial cells. Is associated with glare. NV
more affected than DV.
Cortical: characterised by vacuoles or clefts between lens fibres in the cortex. Can become
elongated, radial spoke-like opacities. If minimal – not seen until dilated as they start around
the edge. Associated with glare.
,Age-related can be mixed, e.g. cortical and nuclear sclerosis together. Mixed more likely
causes advanced stages.
Advanced stages of cataract:
• Intumescent: swollen lens
• Mature: entire lens opaque
• Hyper-mature: capsule permeability increases and leaks liquefied lens matter,
leading to shrinkage of the cataract and wrinkling of the anterior capsule
• Morganian: total liquefaction of the cortex, inferior displacement (sinking) of
the nucleus. Lens matter can leak out blocking trabecular meshwork, leading
to phacolytic glaucoma
Intumescent
mature
hypermature
morganian
Usually treated before advances in developed countries.
Trauma
, • Less common
• Direct penetrating injury
• Blunt trauma
• Stellate- or rossette-shaped opacities
• Rare causes:
• infra-red exposure (glass-blower’s cataract)
• Ionizing radiation (X-rays) – usually radiotherapy for ocular tumour
• Electric shock, lightning
Furnice workers (IR radiation) from working extreme heat sources -> exfoliation of lens
capsule.
Diabetic cataract
• The incidence and progression of cataract is elevated in patients with diabetes
• In some cases, opacities can progress very rapidly
• Osmotic overhydration of the lens
• Due to fluctuations in the blood sugar level
• Leads to bilateral white punctate or snowflake opacities and cortical opacities
So, reason: diabetes causes osmotic stress due to fluctuations in blood-sugar level. Increased
glucose in aqueous humor causes glycation of lens. As osmotic overhydration of lens occurs,
bilateral white punctate or snowflake opacities and cortical opacities start to appear.
type I diabetes, early snowflake
Secondary cataract
Pharmaceutic-induced.
Lecture 1
Cataract:
• Definition of cataract
• Symptoms & signs of cataract
• Structure of the lens
• Ocular examination
• Types of cataract
• Treatment & complications
Definition: opacification of the crystalline lens.
Most common cause of curable blindness worldwide. Affects genders equally. Part of aging
process, can be in one or two eyes. Each decade numbers double.
Symptoms:
o Glare: increased scatter, haloes, night driving problems
o Blurred vision: reduced VA, loss of contrast sensitivity
o Change in refractive error: myopic shift, irregular astigmatism
o Monocular diplopia: double vision in one eye
o Change in color vision: blue and green absorbed, things look yellowish
Lens structure: biconvex. Capsule around, epithelial cells, cortex and nucleus.
Ocular examination: slit lamp optic section. Identify layers and observe opacities.
Risk factors: age, smoking, heavy alcohol use, diabetes, poor nutrition, medicines such as
corticosteroids, trauma, and prolonged exposure to sunlight.
Types of cataracts:
• Age-related
• Nuclear Sclerosis
, • Posterior Subcapsular
• Cortical
• Trauma
• Diabetic
• Secondary cataract
• Pharmaceutic-induced
• Related to other ocular disease
• Congenital and juvenile
Age-related
Nuclear sclerosis: loss of transparency – yellowing of nucleus. Pseudo-myopic shift due to
increase in refractive index of the nucleus (dense).
Posterior Subcapsular: focal dot-like appearance, located in front of the posterior lens
capsule. Due to a posterior migration of lens epithelial cells. Is associated with glare. NV
more affected than DV.
Cortical: characterised by vacuoles or clefts between lens fibres in the cortex. Can become
elongated, radial spoke-like opacities. If minimal – not seen until dilated as they start around
the edge. Associated with glare.
,Age-related can be mixed, e.g. cortical and nuclear sclerosis together. Mixed more likely
causes advanced stages.
Advanced stages of cataract:
• Intumescent: swollen lens
• Mature: entire lens opaque
• Hyper-mature: capsule permeability increases and leaks liquefied lens matter,
leading to shrinkage of the cataract and wrinkling of the anterior capsule
• Morganian: total liquefaction of the cortex, inferior displacement (sinking) of
the nucleus. Lens matter can leak out blocking trabecular meshwork, leading
to phacolytic glaucoma
Intumescent
mature
hypermature
morganian
Usually treated before advances in developed countries.
Trauma
, • Less common
• Direct penetrating injury
• Blunt trauma
• Stellate- or rossette-shaped opacities
• Rare causes:
• infra-red exposure (glass-blower’s cataract)
• Ionizing radiation (X-rays) – usually radiotherapy for ocular tumour
• Electric shock, lightning
Furnice workers (IR radiation) from working extreme heat sources -> exfoliation of lens
capsule.
Diabetic cataract
• The incidence and progression of cataract is elevated in patients with diabetes
• In some cases, opacities can progress very rapidly
• Osmotic overhydration of the lens
• Due to fluctuations in the blood sugar level
• Leads to bilateral white punctate or snowflake opacities and cortical opacities
So, reason: diabetes causes osmotic stress due to fluctuations in blood-sugar level. Increased
glucose in aqueous humor causes glycation of lens. As osmotic overhydration of lens occurs,
bilateral white punctate or snowflake opacities and cortical opacities start to appear.
type I diabetes, early snowflake
Secondary cataract
Pharmaceutic-induced.
