Anatomy and Disorders of the Eye

Study Notes

The eye has three layers: outer, middle, and inner.
The outer layer consists of the cornea and sclera.
The middle layer includes the choroid, ciliary body, and iris, providing blood supply.
The inner layer contains optically clear structures like the aqueous humor, lens, and vitreous body.
Eye preparations should be sterile.
Multiple-use eye drop containers should not be used for more than 4 weeks after opening.

Stye (Hordeolum):
- A local pyogenic infection of the eyelash follicle or sebaceous gland.
- Presents as a tender, palpable nodule on the eyelid.
Chalazion:
- A chronic inflammatory swelling resulting from blockage of a meibomian gland.
- More common in adults than children.
- May require surgical removal or local antibacterial preparations.
Blepharitis:
- Inflammation of the eyelid margins.
- Symptoms include inflammation, scaling, itching, edema, and yellow crusts on eyelashes.
- Causes may include allergy or seborrheic dermatitis.
- Managed by cleaning eyes with saline solution and applying local antibacterial preparations.

Entropion:
- Eyelid turns inward, causing eyelashes to rub against the cornea.
Ectropion:
- Eyelid turns outward, not touching the eye.
Both conditions are common in older adults and lead to discomfort and dryness.

Foreign Substance Contact:
- Remove foreign particles carefully.
- Refer cases involving metallic objects, chemical exposure, or thermal damage.
Conjunctivitis (Pink Eye):
- Inflammation of the conjunctiva.
- Presents with redness and swelling of the eyelids.
- Can be acute or chronic.
Causes and Symptoms:* - Allergic: Affects both eyes, watery discharge, itching, and rhinitis. - Viral: Affects both eyes, watery discharge, gritty feeling, often associated with colds. - Bacterial: Initially affects one eye, purulent discharge, gritty feeling, not usually linked to other symptoms.
Management:* - Allergic: Ocular decongestants, topical or systemic antihistamines. - Viral: Artificial tears, ocular decongestants. - Bacterial: Topical antibacterial preparations.
Dry Eye (Keratoconus):
- Mild red eye, gritty feeling, sensation of foreign body, excess tears.
- Management: Artificial tears, as needed.
Subconjunctival Haemorrhage:
- Can occur at any age after minor trauma, sneezing, or coughing.
- While alarming, the extravasated blood is gradually absorbed within two weeks.

Topical Antibacterial Preparations:
- Broad-spectrum: Chloramphenicol, ciprofloxacin, ofloxacin, gentamicin, framycetin.
- Anti-staphylococcal activity: Fusidic acid.
- Available as monotherapy or combined with corticosteroids.
- Dosing: Usually three to four times a day.
- Advise patients to continue treatment for 48 hours after healing.
- Emphasize careful handwashing and proper application to the lower conjunctival sac to avoid contamination.
Anti-inflammatory Preparations:
- Corticosteroids: Betamethasone, dexamethasone, etc.
- Important: Corticosteroid medications for the eyes may increase the risks of eye pressure or cataracts. Use only as directed by your doctor.