1. Cataracts & Glaucoma Flashcards
What is the definition of Cataract?
How does it affect men and women?
Opacification of the crystalline lens.
It is the most common cause of curable blindness.
Affect men and women equally.
Symptoms of cataracts? (5)
- Blurred vision- (Reduced VA and loss of contrast sensitivity).
- Change in refractive error- due to change in refractive index in lens nucleus.
- Glare (increased scatter).
- Change in colour vision (mixing of yellow- blue).
- Monocular diplopia (double vision in 1 eye).
Structure of lens?
Biconvex transparent structure
What are the the 4 layers of the lens?
- Capsule- outer most layer: control lens shape.
- Epithelium- contains epithelial cells
- Cortex- jelly like part of the crystalline lens.
- Nucleus- found at the centre- it is an optically defined zone.
Which layer in the lens becomes thicker and denser with age?
Nucleus
List the 5 types of cataracts
- Age- related
- Trauma
- Diabetic
- Secondary Cataract
- Congenital
Describe nuclear sclerosis cataract:
This is a type of age related cataract. It causes loss of transparency and yellowing of the lens nucleus. Additionally, Pseudo-myopic shift due to increased refractive index of the nucleus.
Describe Posterior Subcapsular cataract
Focal dot-like appearance. Associated with glare. It affects near vision more then distance vision.
Why does posterior subcapsular cataract occur?
Due to posterior migration of lens epithelial cells.
Location of posterior subcapsular cataract
Located in front of the posterior lens capsule.
Describe cortical cataract? - Appearance and it is associated with? As it advances describe the appearance?
Vacuoles or clefs between lens fibres in the cortex. Associated with glare. Later, radial spoke- like opacities.
Describe the advance stages of cataracts
Age related Cataracts are more likely to reach advance stages if they are mixed (2 types of cataracts that occur at the same time).
1. Intumescent: Swollen Lens
2. Mature: Entire lens opaque
3. Hyper- mature: Capsule permeability increases and leaks liquefied lens matter, leading to shrinkage of the cataract and wrinkling of anterior capsule.
4. Morganian: Total liquefaction of the cortex, inferior displacement of the nucleus.
Cataracts can be caused by trauma, explain how?
- Direct penetrating injury
- Blunt trauma (e.g, blow to the head)— this will cause rosette opacities.
- Very rarely but cataracts can be caused by infra-red exposure, X-rays, Electric shocks or lighting.
Explain how diabetic patients and cataracts are related? And the cause
Diabetes increases progression of cataracts. This is because the opacities progress very rapidly.
Cause: Osmotic stress leads to overhydration of the lens from fluctuating blood glucose leads to accumulation of lens protein.
How do diabetic cataracts look?
Bilateral white punctate or snowflakes
Ocular side effects of corticosteroids?
Induce cataracts
Pharmaceutically induced cataracts?
- Corticosteroids
- Chlorpromazine (anti-psychotic)
- Miotics
- Amiodarone
Describe the cataract caused by Corticosteroids
- Tropic and systemic
- Found initially in the posterior subcapsular, then anterior subcapsular.
Describe how the cataracts caused by Chlorpromazine (Anti-psychotics) look like?
Fine yellow/brown granules in the anterior capsule.
They can progress to star-shaped opacities
Long use of Miotics can cause?
Tiny anterior subcapsular vacuoles
Some cataracts can develop secondary to certain ocular conditions such as?
(4)
- Chronic anterior uveitis
- Acute angle- closure glaucoma
- High myopia
- Retinitis pigmentosa
Secondary cataracts cause what?
Posterior subcapsular opacities (star or flaked shaped opacities)
When are congenital cataracts detected?
Detected at birth
When do juvenile cataracts develop?
During childhood- upto age of 12
What is the most common type of congenital cataract? And where does it occur
Lamellar
Central opacities between nucleus and cortex
What is the treatment procedure for cataract?
It is surgically managed through PHACOEMULSIFICATION… this is the use of local anesthesia to remove most of the lens (liquefaction of the lens using ultrasound probe) and this lens is replaced by a plastic implant (IOL).
After Phaco surgery patients are given which 2 drops?
- Antibiotic.. to prevent infection
- Corticosteriods.. to prevent inflammation
One complication of Cataract is posterior capsular opacification. Why does this take place?
Takes place due to the migration of epithelial cells and leads to reduced vision after surgery. However, this is a low risk complication.
One complication of cataract is Cystoid Macular Oedema. What is observed? And what does this lead to?
Fluid filled cysts, swelling, oedema at the macula that leads to blurred vision
What are the high risk complication of cataract surgeries?
- Vitreous loss
- Iris prolapse.. This is the distortion of the pupil
- Endophthalmitis.. This is a serious eye infection
How is IOP regulated in the eye?
Production and drainage of the aqueous humour
What controls the production of aqueous humour in the eye?
Ciliary processes via ciliary body
Which nervous system regulates IOP in the eye
SYMPATHETIC NERVOUS SYSTEM
-Alpha receptors… stimulation reduce aqueous production
-Beta receptors.. stimulation increases aqueous production
Aqueous humour is drained through what site and into what?
Drained through pupil into Canal of Schlemm via anterior chamber angle and trabecular meshwork, additionally uveo-scleral outflow route (accounting for 20% of the outflow).
Define glaucoma
It is an optic neuropathy which causes characteristic optic nerve cupping and visual field loss.
What is the aim of treatment for glaucoma?
Aimed to reduce IOP
In primary open angle glaucoma what is the 1st line of treatment?
Eyedrops
Types of glaucoma (5)
1.Primary open angle
2. Normal tension
3. Angle-closure
4.Ocular hypertension
5. Secondary and congenital
What is the most common type of glaucoma?
Primary open angle glaucoma (POAG)
Characteristic of POAG-5
- Adult onset
- Raised IOP (greater then 21mmHg)
- Open anterior chamber angle
- Optic nerve head damage
- Visual field loss
Risk factors of POAG
- Raised IOP
- Older age
- Black population
- Family history of glaucoma
- Myopia
- Type II diabetes
- Thinner central cornea
Describe NTG
Sub-type of POAG, with a normal mean IOP of less then 21mmHg. Optic disc hemorrhages may be observed. Visual field defects tend to be more focal, deeper and closer to fixation than in POAG.
Risk factors of NTG (normal tension glsucoma)
- older age
- Females
- Japanese race
- People with less central corneal thickness
- People with thinner corneas
Angle closure glaucoma elevates IOP due to?
Obstruction of aqueous outflow by closure of the angle by the peripheral iris
Sub- types of ACG
Acute and Chronic
What is acute angle closure glaucoma?
Sudden total closure of the angle
symptoms of Acute angle closure glaucoma
- Rapid loss of vision
- Periocular pain
- Nausea and vomiting
- Transient blur
- Seeing haloes around light
Signs of angle closure glaucoma (ACG)
- Ciliary flush (Redness around the limbus)
- Elevated IOP (50-100mmHg)
- Corneal oedema
- Shallow anterior chamber
- Aqueous flare
- Vertical oval, fixed semi-dilated pupil
Risk factors of Angle Closure Glaucoma (ACG)
- Older age
- Females
- Asian
- Short axial length
- Family history
- Short hyperopic eyes
What is ocular hypertension?
Raised IOP, without signs of glaucomatous damage
Risk factors of Ocular Hypertension?
- IOP
- Age
- Central corneal thickness
- African- American race
- Males
- Myopia
- Family history
Optic nerve head damage is characterized by?
Pathological cupping
What happens to the nucleus in the lens with ageing?
The nucleus becomes thicker and bigger with age
3 age related cataracts?
- Nuclear Sclerosis
- Posterior Subcapsular
- Cortical
2 types of secondary cataract?
- Pharmaceutic- induced
- Related to other ocular disease
Symptoms of cataracts vary depending on?
Depending on type of cataract
Pseudo-myopic shift is caused in which type of cataract?
Nuclear Sclerosis
This is when ciliary muscles prevent the eye from focusing in the distance and sometimes intermittently.
Cataracts are more likely to reach advance stages if?
If they are mixed- 2 types occurring at the same time.
What is the risk of morganian stage of cataract?
Risk of leaked liquifies lens matter that can block TB meshwork , increasing blood pressure.
Appearance of hyper mature cataract?
Wrinkles on lens surface
IOP Levels depend upon?
Depends upon the balance between aqueous production and drainage
Aqueous production is formed by and related to which system?
Formed by ciliary processes regulated by sympathetic nervous system
