Ligand-Gated Ion Channels Nicotinic Receptors and G-Protein Coupled Receptors

Clinical Notes: Eye, Ear, Skin, and Related Conditions 1. Open Angle Glaucoma (OAG) 1.1 Definition Open-angle glaucoma is a chronic optic neuropathy characterized by progressive loss of retinal ganglion cells and visual field defects, associated with elevated intraocular pressure (IOP). 1.2 Pathophysiology • Obstruction to aqueous humour outflow via trabecular meshwork → increased IOP • Elevated IOP damages optic nerve head → cupping → visual field loss 1.3 Normal IOP 10–21 mmHg 1.4 Symptoms • Gradual, painless peripheral vision loss (tunnel vision) • Blurred vision • Difficulty adjusting to low light 1.5 Red Flags • Noticeable peripheral vision loss • Sudden vision changes (rare) • Headaches, eye pain (suggest secondary glaucoma) 1.6 First-line Treatment • Prostaglandin analogues (e.g., Latanoprost) → increases uveoscleral outflow • Target IOP <21 mmHg or individualized 1.7 Alternative Treatment • Beta-blocker: Bexatolol (B1 selective) • MOA: Reduces aqueous humour formation by ciliary body 1.8 Monitoring & Advice • Regular IOP checks (3–6 months) • Educate on adherence and side effects • Monitor for peripheral vision changes 1 2. Dry Eye Syndrome 2.1 Causes • Increased tear evaporation • Decreased lacrimal gland production • Environmental factors (wind, screen use, low humidity) 2.2 Symptoms • Gritty/sandy sensation • Redness • Excessive tearing • Symptoms worsen throughout the day 2.3 Treatment • First-line: Carbomer-based artificial tears (transient blurred vision) • Non-pharmacological: blinking, breaks from screens, warm compresses 3. Conjunctivitis 3.1 Causes • Most common: Bacterial (Staphylococcus aureus) • Other: Viral (adenovirus), allergic, chemical 3.2 Symptoms • Redness, irritation, watery/purulent discharge • Sticky discharge starts in one eye and spreads (bacterial) • Mild photophobia (viral/allergic) 3.3 Treatment • Chloramphenicol drops/ointment • Drops: 1 drop every 2 hours for 3 days → 1 drop QDS for 3 days • Ointment: 1 drop QDS • Hygiene: avoid sharing towels, discard eye makeup, stop contact lens use 4. Motion Sickness 4.1 Symptoms • Nausea, pallor, fatigue • Abdominal discomfort • Vomiting 4.2 Treatment • First-generation antihistamines (cyclizine) • Anticholinergics (scopolamine patch) 2 • Non-pharma: sit facing forward, avoid reading, focus on horizon, hydration 5. Otitis Media 5.1 Causes • Bacterial infection (Streptococcus pneumoniae, Haemophilus influenzae) 5.2 Symptoms • Ear pain, fever, hearing loss • Purulent discharge if tympanic membrane perforates • Red flag: bleeding, severe systemic symptoms 5.3 Treatment • Oral antibiotics: Amoxicillin first-line • Topical: Gentamicin ear drops (if perforated/local) • Analgesia: paracetamol/NSAIDs 6. Herpes Simplex Virus Type 1 (HSV1) 6.1 Symptoms • Burning, tingling sensation before lesion • Cold sore formation within 7–10 days • Triggered by sunlight, stress 6.2 Treatment • Antiviral: Aciclovir (inhibits viral DNA polymerase) • Topical or systemic depending on severity 7. Eczema (Atopic Dermatitis) 7.1 Symptoms • Red, itchy, inflamed patches • Commonly in creases (elbows, knees) • Chronic scratching → lichenification 7.2 Treatment • Topical corticosteroids: Hydrocortisone, Beclomethasone • Emollients: maintain skin hydration • Avoid triggers: allergens, harsh soaps 8. Psoriasis 8.1 Symptoms • Pink-red plaques with silvery scales 3 • Common: elbows, knees, scalp • Eczema vs psoriasis: eczema in folds, less thick scaling 8.2 Management • Topical steroids, vitamin D analogues • Phototherapy for severe cases • Systemic agents for extensive disease 9. Pharmacological Notes 9.1 Prostaglandin Analogues • Latanoprost, Bimatoprost → increase uveoscleral outflow • Side effects: redness, eyelash growth, iris color change 9.2 Beta-blockers (Ocular) • Bexatolol: B1 selective, reduces aqueous production • Monitor contraindications: asthma, bradycardia, heart block 9.3 Antibiotics • Chloramphenicol: binds 50S ribosome → inhibits protein synthesis • Amoxicillin: inhibits bacterial cell wall synthesis 9.4 Antivirals • Aciclovir: nucleoside analog → inhibits viral DNA replication 9.5 Corticosteroids • Hydrocortisone: mild anti-inflammatory • Beclomethasone: moderate potency 9.6 Dry Eye Relief • Carbomer-based artificial tears 10. Patient Education • Eye hygiene for conjunctivitis • Correct drop/ointment use • Avoid eczema/psoriasis triggers • Adherence to glaucoma therapy • Recognize red flags: vision loss, persistent pain, systemic symptoms 4 11. Summary Table of Key Conditions Condition Key Symptoms First-line Treatment Notes / Red Flags Open-angle glaucoma Loss of peripheral vision Latanoprost Monitor IOP; Bexatolol if intolerant Dry eyes Gritty eyes, redness, tearing Carbomer tears Worsens throughout day Conjunctivitis Redness, discharge, sticky Chloramphenicol Hygiene advice, monitor spread Motion sickness Nausea, pallor, fatigue Cyclizine Avoid triggers, nonpharma measures Otitis media Ear pain, fever, hearing loss Amoxicillin, Gentamicin drops Red flag: bleeding HSV1 Cold sores, tingling Aciclovir Sunlight can trigger Eczema Red, itchy patches Hydrocortisone Avoid irritants Psoriasis Pink plaques, silver scales Topical steroids, phototherapy Chronic management 5