Important One-Liners in Ophthalmology

Nov 26, 2024

Embryology of Eye Structures

Surface Ectoderm

Lens
Conjunctival, Corneal epithelium
Lacrimal glands

Mesoderm

Extraocular muscles
Sclera
Iris
Choroid

Neural Ectoderm

Smooth muscles of iris
Iris epithelium & Ciliary epithelium
Retina
Optic nerve

Neural Crest

Corneal stroma, keratocytes, Corneal endothelium
Trabecular meshwork endothelium
Melanocytes
Ciliary muscles
Lenticular opacity, which diminishes the vision most, is 'Posterior subcapsular cataract because it is near the nodal point of the eye.
Drugs causing posterior subcapsular cataract
- Busulphan
- Steroids
- Chloroquine
Named cataracts: conditions
- Oil drop cataract—galactosemia
- Sunflower cataract - Wilson's disease
- Christmas tree cataract - myotonic dystrophy
- Snowflake cataract: diabetes mellitus
- Rosette cataract—trauma
Normal IOP = 10-21 mmHg; Peaks in the early morning Because steroid level is higher in the morning
- Normal diurnal variation of IOP is equal to or less than 5 mmHg.
Layers of retina
- Retinal pigment epithelium
- Layers of rods and cones
- External limiting membrane
- Outer nuclear layer
- Outer plexiform layer
- Inner nuclear layer
- Inner plexiform layer
- Ganglion cell layer
- Nerve fibre layer
- Internal limiting membrane

Also read: Pathology One-Liners for Medical Students

Extraocular Muscles

Muscle	Primary action	2° action	Nerve supply
Medial rectus	Adduction		Oculomotor Nerve (III)
Lateral nerve	Abduction		Abducens' Nerve (IV)
Superior rectus	Elevation	Intorsion and adduction	Oculomotor Nerve
Inferior rectus	Depression	Extortion and Adduction	Oculomotor Nerve
Superior Oblique	Intorsion	Depression and Abduction	Trochlear Nerve
Inferior oblique	Extorsion	Elevation and Abduction	Oculomotor Nerve

The angle subtended by any letter on the Snellen's chart at the nodal point of the patient is 5 min
M/c etiological factor for acute and chronic dacryocystitis → Staphylococcus aureus
Sequale of acute dacryocystitis treated by DCR → Lacrimal fistula
Reflex tear production starts around 6 weeks
Chalazion is a chronic lipogeanulomatous inflammation of the meibomian gland.
M/c cause of recurrent chalazion → Uncorrected mild refractive error.
Treatment of chalazion is Incision & Curettage
Causes of Acute Red eye
- Acute conjunctivitis
- Acute iridocyclitis
- Acute Angle-closure Glaucoma
- Corneal abrasion/infection
Treatment and prevention of trachoma
- Treat with a single oral dose of Azithromycin (or) Tetracycline eye ointment for 6 weeks
- SAFE strategy by WHO for controlling Trachoma
  - S – Surgery for trichiasis
  - A – Antibiotics
  - F – Facial hygiene
  - E – Environmental hygiene
Signs of Graft rejection in patients for keratoplasty

Krachmer spots: Subepithelial Graft rejection
Khodadoust line: Endothelial Graft rejection
Kaye's dot: Epithelial Graft rejection

The minimum number of endothelial cells in a corneal graft should be at least 2000 cells/mm²
P.E.R.F.E.C.T surgery is related to pterygium; it stands for pterygium Extended Removal followed by extended conjunctival transplant
Pterygium
- Connective tissue disorder
- Etiology: UV-B
- M/c located nasally

Also read: Important One-Liners in Public Health & Community Medicine (PSM)

Glass Rod is Used to Differentiate between Pterygium and Pseudopterygium

If glass rod passes through → pseudo pterygium
If it does not pass through → Pterygium
Hypopyon
- Inverse hypopyon/hyperleon is a complication of RD surgery
- Silicon gel which is a vitreous substrate, leaks into the anterior chamber during RD surgery
- Recurrent Hypopyon → Behcet's disease
- Pseudohypopyon → Retinoblastoma
M/c cause of Bacterial keratitis (Worldwide) → Staphylococcus Aureus
- India → Staphylococcus epidermidis
Keyhole shaped scotoma is a feature of lateral geniculate body lesion
Keyhole vision is a feature of occipital lobe lesion
Weber's syndrome is 3rd nerve palsy with C/L hemiplegia
Benedicts syndrome is 3rd nerve palsy with C/L hemiataxia and tremors.
Millard Gubler syndrome is 6th nerve palsy with C/L hemiplegia
Foster – Kennedy syndrome is I/L optic atrophy + c/L papilla
- Seen in
  - Frontal lobe tumors
  - Olfactory lobe tumor
Oil droplet cataract - Galactosemia
Oil droplet reflex - Keratoconus
Oil globular reflex - Anterior lenticonus
“A” wave in ERG is due to activity of Rods
“B” wave in ERG is due to Bipolar cells and muller cells
“C” wave in ERG is due to RPE
Ocular features of Rubella
- Microphthalmos
- Rubella keratitis
- Angle anomaly
- Cataract (m/c)
- Salt and pepper fundus
Salt & Pepper fundus is seen in
- Rubella
- Syphilis
- Myotonic dystrophy
Direction of subluxation in Marfan's syndrome → Superotemporal
Direction of subluxation in Homocystinuria → inferonasal
Causes of pulsating proptosis
- M/c
  - Carotico - cavernous fistula
  - NF – 1
  - Fracture of roof of orbita
Intraocular lenses
- Non-foldable IOL (Rigid): Made of PMMA
- Foldable IOL:
  - Silicone IOL
  - Acrylic IOL
  - Hydrophobic
  - Hydrophilic
  - Hydrogel IoL
- Multifocal IOLs
  - Allows clear vision for both distance and near
1st order neurons: bipolar cells
2nd order neurons - Ganglion cells/ optic nerve
3rd order neurons - Lateral geniculate body
M/c presentation of retinoblastoma is leukocoria
2nd m/c presentation is strabismus
M/c made of spread is through optic nerve
Wave length of Femto laser is 1054 nm
Wave length of Excimer laser is 193 nm
Wave length of NDYAG laser is 1064 mm
Wave length Argon is 514 nm
Most important factor to keep the cornea in dehydrated state is endothelial pump dysfunction
Vitamin deficiencies and ocular findings
- Vit A deficiency → Xerophthalmia
- Vit B₂ deficiency → circumcorneal neovascularisation
- Vit B₆ deficiency → Gyrate atrophy
- Vit B₁₂ deficiency → Optic neuritis
Features of Blunt trauma
- Rosette shaped cataract
- Vossious Ring
- Berlin's edema
Headlight in fog is a feature of Toxoplasmas

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