Ophthalmology for NEET-PG
Cataract for NEET-PG
Cataract is opacification of the crystalline lens that scatters light and reduces vision, and it is the leading cause of reversible blindness worldwide and in India. For NEET-PG, the high-yield material is the types of cataract, the causes, the clinical features, and the principles of surgical management. Age-related senile cataract is the most common, presenting with painless progressive blurring, glare, and sometimes second sight from lens-induced myopia in nuclear cataract. Cataracts are classified by location as nuclear, cortical, and posterior subcapsular, the last causing early visual disturbance and glare, especially in bright light, and being associated with steroids and diabetes. Congenital cataract may follow intrauterine rubella, galactosaemia, or genetic causes and needs early surgery to prevent amblyopia, with an absent red reflex or leukocoria as the sign. Complicated cataract arises from ocular disease such as uveitis, and traumatic cataract from injury. Examination shows lens opacity on slit lamp and a diminished or absent red reflex. Modern treatment is phacoemulsification with intraocular lens implantation, which has replaced older extracapsular and intracapsular techniques, and biometry calculates the lens power. Complications include posterior capsular opacification treated by laser capsulotomy, and rarely endophthalmitis. Knowing the cataract types, posterior subcapsular associations, leukocoria in children, and phacoemulsification are consistent exam anchors.
MedNext Academy | 3 min read
Cataract for NEET-PG
Cataract is opacification of the crystalline lens that scatters light and reduces vision, and it is the leading cause of reversible blindness worldwide and in India. For NEET-PG, the high-yield material is the types of cataract, the causes, the clinical features, and the principles of surgical management. Age-related senile cataract is the most common, presenting with painless progressive blurring, glare, and sometimes second sight from lens-induced myopia in nuclear cataract. Cataracts are classified by location as nuclear, cortical, and posterior subcapsular, the last causing early visual disturbance and glare, especially in bright light, and being associated with steroids and diabetes. Congenital cataract may follow intrauterine rubella, galactosaemia, or genetic causes and needs early surgery to prevent amblyopia, with an absent red reflex or leukocoria as the sign. Complicated cataract arises from ocular disease such as uveitis, and traumatic cataract from injury. Examination shows lens opacity on slit lamp and a diminished or absent red reflex. Modern treatment is phacoemulsification with intraocular lens implantation, which has replaced older extracapsular and intracapsular techniques, and biometry calculates the lens power. Complications include posterior capsular opacification treated by laser capsulotomy, and rarely endophthalmitis. Knowing the cataract types, posterior subcapsular associations, leukocoria in children, and phacoemulsification are consistent exam anchors.
Cataract is opacification of the crystalline lens that scatters light and reduces vision, and it is the leading cause of reversible blindness worldwide and in India. For NEET-PG, the high-yield material is the types of cataract, the causes, the clinical features, and the principles of surgical management. Age-related senile cataract is the most common, presenting with painless progressive blurring, glare, and sometimes second sight from lens-induced myopia in nuclear cataract. Cataracts are classified by location as nuclear, cortical, and posterior subcapsular, the last causing early visual disturbance and glare, especially in bright light, and being associated with steroids and diabetes. Congenital cataract may follow intrauterine rubella, galactosaemia, or genetic causes and needs early surgery to prevent amblyopia, with an absent red reflex or leukocoria as the sign. Complicated cataract arises from ocular disease such as uveitis, and traumatic cataract from injury. Examination shows lens opacity on slit lamp and a diminished or absent red reflex. Modern treatment is phacoemulsification with intraocular lens implantation, which has replaced older extracapsular and intracapsular techniques, and biometry calculates the lens power. Complications include posterior capsular opacification treated by laser capsulotomy, and rarely endophthalmitis. Knowing the cataract types, posterior subcapsular associations, leukocoria in children, and phacoemulsification are consistent exam anchors.
Key points
- **Definition and burden:** Opacification of the crystalline lens. Cataract is the leading cause of reversible blindness worldwide and in India.
- **Senile cataract:** Age-related and the most common type, causing painless progressive blurring of vision, glare, and reduced contrast.
- **Second sight:** Nuclear cataract increases lens refractive index causing a myopic shift, so some patients read without glasses temporarily.
- **Morphological types:** Nuclear, cortical, and posterior subcapsular. Posterior subcapsular causes early glare and difficulty in bright light and near work.
- **Steroid and diabetes link:** Posterior subcapsular cataract is classically associated with corticosteroid use and diabetes mellitus.
- **Congenital cataract:** Follows intrauterine rubella, galactosaemia, or genetic causes. Needs early surgery to prevent stimulus deprivation amblyopia.
- **Leukocoria:** A white pupillary reflex or absent red reflex in an infant signals congenital cataract and must be evaluated urgently.
- **Complicated cataract:** Arises secondary to ocular disease such as chronic uveitis, and traumatic cataract follows penetrating or blunt injury.
- **Diagnosis:** Slit lamp shows the lens opacity and the red reflex is diminished or absent on distant direct ophthalmoscopy.
- **Surgical treatment:** Phacoemulsification with foldable intraocular lens implantation is the current standard, guided by biometry for lens power.
- **Complications:** Posterior capsular opacification is the commonest late complication, treated by Nd:YAG laser capsulotomy. Endophthalmitis is a rare but serious risk.
Frequently Asked Questions
What is the most common type of cataract?
Age-related senile cataract is the most common type, causing painless progressive blurring of vision and glare.
What is second sight in cataract?
Nuclear cataract raises the lens refractive index, producing a myopic shift that lets some older patients read without glasses for a while.
Which cataract type is linked to steroids and diabetes?
Posterior subcapsular cataract is classically associated with corticosteroid use and diabetes and causes early glare in bright light.
Why is congenital cataract a surgical emergency?
Untreated congenital cataract deprives the developing visual pathway and causes irreversible amblyopia, so early surgery is essential.
What is the current standard cataract surgery?
Phacoemulsification with foldable intraocular lens implantation is the standard, guided by biometry to select lens power.
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