Full-field ERG tests the entire retinaβs electrical response to light. You get electrodes on the cornea or skin, dark-adapt for ~20 mins, then flashes of light stimulate rods and cones. It records a-waves (photoreceptor activity) and b-waves (inner retinal response). Used to diagnose widespread retinal diseases like retinitis pigmentosa or Leber congenital amaurosis. Results show overall retinal function, not localized areas.
CORNEA DECOMPENSATION
ποΈ Corneal decompensation happens when the endothelium (the inner layer of the cornea) fails to pump out fluid, causing corneal swelling (edema), cloudiness, and blurry vision.
- Causes:
- Fuchsβ endothelial dystrophy (most common)
- Trauma (surgical or accidental)
- Long-term contact lens wear
- Glaucoma or high eye pressure
- Inflammation or infection
- Symptoms:
- Hazy or blurry vision (often worse in the morning)
- Glare and light sensitivity
- Eye discomfort or pain in advanced cases
- Halos around lights
- Stages:
- Early: Mild swelling, subtle visual changes
- Moderate: Noticeable edema, thickened cornea
- Advanced: Bullae formation (epithelial blisters), pain, and risk of infection
- Treatment:
- Mild: Hypertonic saline drops/ointment to draw out fluid
- Moderate: Reducing contributing factors (e.g., pressure control in glaucoma)
- Severe: Endothelial keratoplasty (DSEK, DSAEK, or DMEK) β partial corneal transplant replacing only the damaged endothelial layer
20D LENS
π Here’s more on a 20D lens:
- Magnification: A +20D lens provides approximately 20x magnification.
- Field of view: Offers a relatively wide field, useful for examining the retina.
- Use: Commonly used in ophthalmology for:
- Indirect ophthalmoscopy (with a slit lamp or head-mounted scope).
- Examining the posterior segment (retina, macula, etc.).
- Type: Typically a handheld, convex lens made of glass or acrylic.
- Working distance: Around 5 cm (2 inches) from the patient’s eye.
CONTACT LENS APPLICATOR
A contact lens applicator π is a handy tool that helps you put in (and sometimes take out) contact lenses, especially if you’re a newbie or have dexterity issues. Types include:
- Sucker/plucker: A small tool with a suction cup that grips the lens.
- Finger-tip applicator: A guide that fits on your finger to help position the lens.
They’re super useful if:
- You’re struggling to handle tiny lenses
- You have arthritis or finger issues
- You’re helping someone else with lenses (like kids)
DIAMOX
π¨ββοΈ Diamox (Acetazolamide) is a carbonic anhydrase inhibitor.
Uses:
- Glaucoma: Reduces intraocular pressure
- Edema: Treats fluid retention
- Altitude sickness: Prevents and treats symptoms
- Epilepsy: Adjunct therapy
Eye-related uses:
- Iocular pressure reduction: Glaucoma treatment
- Cystoid macular edema: Treats fluid buildup
Side effects:
- Numbness/tingling: Hands, feet, or face
- Dizziness: May affect daily activities
- Increased urination: Monitor hydration
LISAMINE GREEN STAINING
π¨ββοΈ Lissamine Green staining test assesses ocular surface damage, particularly conjunctival epithelial damage.
Procedure:
- Apply anesthetic drops (optional)
- Place Lissamine Green drops in eye
- Examine under white or blue light
Interpretation:
- Staining pattern: Indicates damage location/severity
- Scoring systems: Grade staining (e.g., Oxford scale)
Uses:
- Dry eye disease: Evaluates conjunctival staining
- Ocular surface disorders: Identifies damaged areas
- Conjunctival disorders: Assesses inflammation
FLOURESCEIN ANGIOGRAPHY
π¨ββοΈ Fluorescein angiography is a diagnostic test that uses fluorescein dye and a specialized camera to visualize the retinal blood vessels.
Key uses:
- Diabetic retinopathy: Detects leakage, neovascularization
- Macular degeneration: Identifies abnormal blood vessels
- Retinal vascular occlusions: Diagnoses blockages
- Tumors: Highlights abnormal vessels
Procedure:
- Inject fluorescein dye into arm vein
- Take photographs as dye circulates
- Capture early and late-phase images
Findings:
- Leakage: Dye escape from vessels
- Blockage: Dark areas (hypofluorescence)
- Neovascularization: Abnormal vessels
Precautions:
- Nausea, yellow skin discoloration (temporary)
- Allergic reactions (rare)
- Pregnancy/breastfeeding: Use cautiously
REFRACTION
π Refraction is the bending of light as it passes through different mediums (e.g., air, lens, cornea). In the eye, it focuses light onto the retina.
Types:
- Emmetropia: Normal vision.
- Myopia (nearsightedness): Blurred distance vision.
- Hyperopia (farsightedness): Blurred near vision.
- Astigmatism: Distorted vision.
- Presbyopia: Age-related near vision loss.
Tests:
- Visual acuity: Snellen chart.
- Autorefraction: Objective measurement.
- Subjective tests: Lens power adjustment.
Corrections:
- Glasses/contact lenses: Adjust refractive power.
- Surgery: LASIK, PRK, etc.
MYDRIATIC DRUGS
ποΈ Mydriatic drugs dilate the pupil (mydriasis) by relaxing the iris sphincter muscle. Used for exams, surgery, or treating inflammation.
Common examples:
- Phenylephrine (Ξ±-1 agonist)
- Effect: Fast (30β60 min), short (3β6h).
- Use: Diagnostic exams.
- Risk: Hypertension, arrhythmia.
- Tropicamide (anticholinergic)
- Effect: 30β45 min, lasts 4β6h.
- Use: Routine dilation.
- Risk: Blurred vision, photophobia.
- Atropine (strong, long-acting)
- Effect: 1β2 weeks.
- Use: Uveitis, amblyopia.
- Risk: Prolonged blur, dry mouth.
- Cyclopentolate
- Effect: 24β48h.
- Use: Pediatric exams.
- Risk: Behavioral changes in kids.
Precautions:
- Avoid driving until pupils return to normal.
- Glaucoma risk: Check IOP.
- Monitor elderly/kids.
- Side effects: Headache, stinging, dry eyes.