MBBS Year
1st Year
Subject
What Is Usually Asked
Development and structure of the lens
ReferenceAll Years (1st-Final)All UniversitiesCataract:
Cataract: Notes, PPT and PYQs for MBBS
A cataract is any opacity of the crystalline lens or its capsule that reduces its transparency. It is the leading cause of blindness in India and one of the most important topics in 3rd Year MBBS Ophthalmology, with links to Anatomy and Physiology in 1st Year and to Community Medicine and Paediatrics.
SME-reviewed. Updated 2026.
Open in GeckoMed for PPT slides and offline notesQuick Summary: What You Need to Know for University Exams
- Cataract is classified as congenital or developmental and acquired; age-related (senile) cataract is the most common type.
- Senile cataract has cortical, nuclear and posterior subcapsular forms.
- The main symptom is gradual, painless, progressive loss of vision.
- Iris shadow is present in immature cataract and absent in mature cataract.
- Treatment is surgical: phacoemulsification or manual small incision cataract surgery (SICS) with a posterior chamber intraocular lens (IOL).
- Posterior capsular opacification is the most common late complication, treated with Nd:YAG laser capsulotomy.
- Endophthalmitis is the most serious early complication.
Cataract Across MBBS Subjects
| MBBS Year | Subject | What Is Usually Asked |
|---|---|---|
| 1st Year | Anatomy | Development and structure of the lens |
| 1st Year | Physiology | Accommodation, refraction |
| 1st Year | Biochemistry | Sorbitol pathway in diabetic cataract, galactosaemia |
| 3rd Year | Ophthalmology | Classification, clinical features, surgery, complications |
| 3rd Year | Community Medicine | Blindness control programme in India |
| Final Year | Paediatrics | Congenital cataract, TORCH infections |
MBBS Year
1st Year
Subject
What Is Usually Asked
Accommodation, refraction
MBBS Year
1st Year
Subject
What Is Usually Asked
Sorbitol pathway in diabetic cataract, galactosaemia
MBBS Year
3rd Year
Subject
What Is Usually Asked
Classification, clinical features, surgery, complications
MBBS Year
3rd Year
Subject
What Is Usually Asked
Blindness control programme in India
MBBS Year
Final Year
Subject
What Is Usually Asked
Congenital cataract, TORCH infections
Definition and Classification
Definition: Cataract is an opacity of the crystalline lens or its capsule, whether developmental or acquired, that may reduce vision.
Classification by Aetiology
| Type | Examples |
|---|---|
| Congenital and developmental | Idiopathic, hereditary, maternal infection (for example rubella), metabolic (galactosaemia), chromosomal disorders |
| Age-related (senile) | Cortical, nuclear, posterior subcapsular |
| Traumatic | Blunt injury (rosette-shaped cataract), penetrating injury |
| Metabolic | Diabetes (snowflake cataract in young people with poorly controlled diabetes), galactosaemia (oil-droplet cataract), hypocalcaemia |
| Complicated (secondary) | Chronic uveitis, glaucoma, retinal detachment, retinitis pigmentosa |
| Drug-induced | Corticosteroids (posterior subcapsular cataract) |
| Radiation and other physical causes | Infrared, ionising radiation, electric shock |
Type
Congenital and developmental
Examples
Idiopathic, hereditary, maternal infection (for example rubella), metabolic (galactosaemia), chromosomal disorders
Type
Age-related (senile)
Examples
Cortical, nuclear, posterior subcapsular
Type
Traumatic
Examples
Blunt injury (rosette-shaped cataract), penetrating injury
Type
Metabolic
Examples
Diabetes (snowflake cataract in young people with poorly controlled diabetes), galactosaemia (oil-droplet cataract), hypocalcaemia
Type
Complicated (secondary)
Examples
Chronic uveitis, glaucoma, retinal detachment, retinitis pigmentosa
Type
Drug-induced
Examples
Corticosteroids (posterior subcapsular cataract)
Type
Radiation and other physical causes
Examples
Infrared, ionising radiation, electric shock
Classification by Morphology
| Type | Description |
|---|---|
| Capsular | Involves the capsule |
| Subcapsular | Anterior or posterior subcapsular |
| Cortical | Involves the cortex |
| Nuclear | Involves the nucleus |
| Zonular (lamellar) | Opacity of a particular layer; a common visually significant congenital cataract |
Type
Capsular
Description
Involves the capsule
Type
Subcapsular
Description
Anterior or posterior subcapsular
Type
Cortical
Description
Involves the cortex
Type
Nuclear
Description
Involves the nucleus
Type
Zonular (lamellar)
Description
Opacity of a particular layer; a common visually significant congenital cataract
Stages of Senile Cortical Cataract
- Lamellar separation: Fluid clefts between lens fibres
- Incipient: Wedge-shaped (cuneiform) opacities with clear areas between them
- Immature: Opacity is incomplete; iris shadow present; the lens may swell (intumescent)
- Mature: Entire cortex is opaque; iris shadow absent
- Hypermature: Either Morgagnian (liquefied cortex with the nucleus sinking inferiorly) or sclerotic (shrunken lens)
Nuclear cataract hardens and changes colour over time, from yellow to brown (cataracta brunescens) and, rarely, black (cataracta nigra).
Pathophysiology
Flowchart
- The lens is avascular and relies on the aqueous humour for nutrition
- With age, antioxidant defences decline and oxidative damage increases
- Lens proteins (crystallins) denature and aggregate
- Changes in hydration and ion balance occur in the cortex
- The nucleus becomes compressed, hardened and pigmented
- Light scatters instead of passing through, producing opacity and reduced vision
Diabetic cataract: High glucose is converted to sorbitol by aldose reductase. Sorbitol accumulates in the lens, draws in water osmotically and causes swelling and opacity.
Galactosaemia: Galactose is converted to galactitol, which accumulates in the lens in a similar way.
(Examiner may ask you to draw the stages of cortical cataract or the sorbitol pathway.)
Clinical Features
Symptoms:
- Gradual, painless, progressive blurring of vision
- Glare, especially while driving at night
- Reduced contrast and faded colours
- Uniocular polyopia (multiple images in one eye) in early cortical cataract
- Coloured halos around lights
- "Second sight": improved near vision in early nuclear cataract because of a myopic shift
- Frequent change of spectacle power
Signs:
| Examination | Finding |
|---|---|
| Visual acuity | Reduced, depending on stage and location |
| Oblique illumination | Greyish-white opacity; iris shadow present in immature, absent in mature cataract |
| Distant direct ophthalmoscopy | Dark opacities against the red fundal glow |
| Slit-lamp examination | Type, location and density of the opacity |
| Pupil reactions | Normal, since cataract alone does not cause a relative afferent pupillary defect |
Examination
Visual acuity
Finding
Reduced, depending on stage and location
Examination
Oblique illumination
Finding
Greyish-white opacity; iris shadow present in immature, absent in mature cataract
Examination
Distant direct ophthalmoscopy
Finding
Dark opacities against the red fundal glow
Examination
Slit-lamp examination
Finding
Type, location and density of the opacity
Examination
Pupil reactions
Finding
Normal, since cataract alone does not cause a relative afferent pupillary defect
Senile Cataract Versus Other Causes of Gradual Painless Vision Loss
| Feature | Cataract | Chronic Open-Angle Glaucoma |
|---|---|---|
| Vision loss | Central blurring, glare | Peripheral field loss first |
| Lens | Opaque | Clear or age-appropriate |
| Optic disc | Normal | Cupping |
| Intraocular pressure | Normal | Often raised |
Feature
Vision loss
Cataract
Central blurring, glare
Chronic Open-Angle Glaucoma
Peripheral field loss first
Feature
Lens
Cataract
Opaque
Chronic Open-Angle Glaucoma
Clear or age-appropriate
Feature
Optic disc
Cataract
Normal
Chronic Open-Angle Glaucoma
Cupping
Feature
Intraocular pressure
Cataract
Normal
Chronic Open-Angle Glaucoma
Often raised
Diagnosis and Preoperative Evaluation
| Assessment | Purpose |
|---|---|
| Visual acuity and refraction | Degree of visual loss |
| Slit-lamp examination | Type and grading of cataract |
| Intraocular pressure | Rule out glaucoma |
| Fundus examination | Rule out retinal disease; B-scan ultrasound when the fundus cannot be seen |
| Sac syringing (lacrimal patency) | Detect chronic dacryocystitis, a source of infection |
| Keratometry and axial length (biometry) | Calculate intraocular lens power |
| Systemic evaluation | Blood pressure, blood sugar, and fitness for surgery |
Assessment
Visual acuity and refraction
Purpose
Degree of visual loss
Assessment
Slit-lamp examination
Purpose
Type and grading of cataract
Assessment
Intraocular pressure
Purpose
Rule out glaucoma
Assessment
Fundus examination
Purpose
Rule out retinal disease; B-scan ultrasound when the fundus cannot be seen
Assessment
Sac syringing (lacrimal patency)
Purpose
Detect chronic dacryocystitis, a source of infection
Assessment
Keratometry and axial length (biometry)
Purpose
Calculate intraocular lens power
Assessment
Systemic evaluation
Purpose
Blood pressure, blood sugar, and fitness for surgery
IOL power (SRK formula): P = A − 2.5L − 0.9K, where P is the lens power, A is the lens-specific constant, L is the axial length and K is the average keratometry reading.
Management
There is no proven medical treatment that reverses cataract. Spectacle correction can help in early stages; definitive treatment is surgery when the cataract affects daily activities.
Types of Cataract Surgery
| Technique | Key Points |
|---|---|
| Intracapsular cataract extraction (ICCE) | Entire lens removed with its capsule; now largely obsolete |
| Extracapsular cataract extraction (ECCE) | Nucleus and cortex removed, posterior capsule preserved; larger incision |
| Manual small incision cataract surgery (SICS) | Sutureless scleral tunnel incision; low cost and widely used in India |
| Phacoemulsification | Nucleus broken up with ultrasound through a small incision; faster recovery |
| Femtosecond laser-assisted surgery | Laser performs some steps; available in selected centres |
Technique
Intracapsular cataract extraction (ICCE)
Key Points
Entire lens removed with its capsule; now largely obsolete
Technique
Extracapsular cataract extraction (ECCE)
Key Points
Nucleus and cortex removed, posterior capsule preserved; larger incision
Technique
Manual small incision cataract surgery (SICS)
Key Points
Sutureless scleral tunnel incision; low cost and widely used in India
Technique
Phacoemulsification
Key Points
Nucleus broken up with ultrasound through a small incision; faster recovery
Technique
Femtosecond laser-assisted surgery
Key Points
Laser performs some steps; available in selected centres
Intraocular lens: A posterior chamber IOL placed in the capsular bag is the standard. Aphakia (absence of the lens) without an IOL requires thick spectacles or contact lenses.
Congenital cataract: Visually significant congenital cataract needs early surgery to prevent stimulus deprivation amblyopia.
Complications
Complications of Untreated Cataract
| Complication | Mechanism |
|---|---|
| Phacomorphic glaucoma | Swollen (intumescent) lens causes secondary angle closure |
| Phacolytic glaucoma | Lens proteins leak from a hypermature cataract and block the trabecular meshwork |
| Phacoanaphylactic uveitis | Immune reaction to lens proteins |
| Lens subluxation or dislocation | Weakened zonules in hypermature cataract |
Complication
Phacomorphic glaucoma
Mechanism
Swollen (intumescent) lens causes secondary angle closure
Complication
Phacolytic glaucoma
Mechanism
Lens proteins leak from a hypermature cataract and block the trabecular meshwork
Complication
Phacoanaphylactic uveitis
Mechanism
Immune reaction to lens proteins
Complication
Lens subluxation or dislocation
Mechanism
Weakened zonules in hypermature cataract
Complications of Cataract Surgery
| Timing | Complications |
|---|---|
| During surgery | Posterior capsule rupture, vitreous loss, dropped nucleus, iris injury |
| Early after surgery | Endophthalmitis (most serious), corneal oedema, raised intraocular pressure, wound leak, anterior uveitis |
| Late after surgery | Posterior capsular opacification ("after-cataract", the most common), cystoid macular oedema (Irvine-Gass syndrome), retinal detachment, IOL decentration |
Timing
During surgery
Complications
Posterior capsule rupture, vitreous loss, dropped nucleus, iris injury
Timing
Early after surgery
Complications
Endophthalmitis (most serious), corneal oedema, raised intraocular pressure, wound leak, anterior uveitis
Timing
Late after surgery
Complications
Posterior capsular opacification ("after-cataract", the most common), cystoid macular oedema (Irvine-Gass syndrome), retinal detachment, IOL decentration
Prevention and Control (Community Medicine Angle)
- Cataract is the leading cause of blindness in India.
- The National Programme for Control of Blindness and Visual Impairment (NPCBVI) supports cataract surgery, especially through free or subsidised services for people in need.
- Measures include screening camps, outreach, trained eye care workers and improving surgical quality.
- Risk reduction includes UV protection with sunglasses, stopping smoking and good diabetes control.
Prognosis
Visual outcome after uncomplicated modern cataract surgery is usually excellent. Outcomes are poorer when there is coexisting disease such as glaucoma, diabetic retinopathy or amblyopia, or after surgical complications.
Quick Viva Questions
Q: What is second sight? A: Improved near vision in early nuclear cataract due to a myopic shift.
Q: Is the iris shadow present in mature cataract? A: No. It is present in immature cataract and absent in mature cataract.
Q: Which cataract is rosette-shaped? A: Traumatic cataract after blunt injury.
Q: Why is sac syringing done before cataract surgery? A: To detect chronic dacryocystitis, which increases the risk of endophthalmitis.
Q: How is posterior capsular opacification treated? A: With Nd:YAG laser capsulotomy.
How Cataract Appears in MBBS University Exams
Typical question styles (not attributed to specific papers or years):
- "Classify cataract. Describe the clinical features and management of senile cataract." (Long essay, Ophthalmology)
- "Describe the complications of cataract surgery and their management." (Long essay, Ophthalmology)
- "Write a short note on congenital cataract." (Short note, Ophthalmology or Paediatrics)
- "Write a short note on posterior capsular opacification." (Short note)
- "Write a short note on diabetic cataract." (Short note, Ophthalmology or Biochemistry)
- "Describe the National Programme for Control of Blindness and Visual Impairment." (Community Medicine)
Frequently Asked Questions
What is the most common type of cataract? ‘
Age-related (senile) cataract is the most common type. It occurs in cortical, nuclear and posterior subcapsular forms, often in combination.
What is the most common late complication of cataract surgery?
Posterior capsular opacification (after-cataract). It is treated with Nd:YAG laser capsulotomy.
Can I download the cataract PPT for my presentation?
Yes. Use the Download PPT button at the top of this page. The GeckoMed app also gives offline access to the slides and notes.
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