5- Opthalmic diseases

Question 1

diseases of the eyelids

Answer 1

Blepharitis: Inflammation of the eyelids, often causing redness and tenderness.

Hordeolum (Stye): An acute, inflammatory lesion of the eyelid. It can be:
Internal Hordeolum: Inflammation of the meibomian glands.
External Hordeolum: Folliculitis of the glands of Zeis.

Chalazion: A granulomatous inflammation around the meibomian glands or glands of Zeis, leading to a painless swelling.

Xanthelasma: Yellow plaques of lipid-containing macrophages, typically on the nasal aspect of the eyelids.

Question 2

trachoma

Answer 2

Cause: Chronic, contagious conjunctivitis caused by Chlamydia trachomatis.

Prevalence: Leading cause of blindness worldwide, especially in Asia, the Middle East, and Africa.
Transmission: Spread through fingers, fomites, and flies, often due to poor hygiene and overcrowding.

Pathogenesis
Immune Response: Inflammatory reaction to C. trachomatis.
Bilateral Involvement: Primarily affects the upper conjunctiva.
Cellular Infiltrate: Lymphocytic infiltration with conjunctival lymph follicles and necrotic germinal centers.

Complications: Scarring of the conjunctiva and eyelids, leading to eyelid distortion.

Microscopic Features
Leber Cells: Macrophages containing nuclear fragments.
Secondary Infections: Common bacterial infections.

Question 3

opthalma neonatum

Answer 3

Cause: Severe, acute conjunctivitis in newborns, often caused by Neisseria gonorrhoeae.

Transmission: Infection during birth from an infected mother.

Complications: Corneal ulceration, perforation, scarring, and panophthalmitis.

Other Causative Organisms
Chlamydia trachomatis and other pyogenic bacteria.

Question 4

pinguecula and pterygium

Answer 4

Pinguecula
Description: Yellowish conjunctival lump, usually nasal to the corneoscleral limbus.
Cause: Sun-damaged connective tissue (actinic elastosis).

Pterygium
Description: Vascularized conjunctival growth onto the cornea, often associated with pinguecula.
Recurrence: Frequently recurs after excision.

Question 5

cataract

Answer 5

Overview
Definition: Opacification of the crystalline lens.

Causes:
Age-related: Most common in the USA.

Other Causes: Diabetes, nutritional deficiencies, toxins, drugs, physical agents, and ocular diseases.

Associated Conditions: Congenital rubella, skin diseases, and systemic diseases.

Clinical Presentation
Mature Cataract: Complete opacification of the lens, leading to a white appearance of the pupil.

Question 6

pthisis bulbi

Answer 6

Definition: End-stage, atrophic, and disorganized eye, often due to trauma or inflammation.

Features:
Small, hard eye with intraocular ossification.
Flattened, opaque cornea.
Disorganized intraocular contents with retinal detachment.

Microscopic Findings
Intraocular bone formation derived from hyperplastic pigment epithelium.

Question 7

ocular neoplasms

Answer 7

Types: Benign and malignant neoplasms arising from various cell types in the eye and adjacent structures.

Common Malignancies:
Eyelid: Basal cell carcinoma.
Intraocular: Retinoblastoma (from retinal neurons) and uveal melanoma (from melanocytes).
Primary Intraocular Lymphoma: Typically diffuse large B-cell lymphoma in older individuals.
Metastatic Tumors: More common than primary eye cancers, often from leukemia, breast, lung, or neuroblastoma.

Question 8

malignant melanoma

Answer 8

Overview
Origin: Arises from uveal melanocytes, most commonly in the choroid.

Cell Types:
Spindle A cells (no nucleoli).
Spindle B cells (prominent nucleoli).
Epithelioid cells (distinct borders, prominent nucleoli).
Smaller epithelioid-like cells.

Spread and Prognosis
Spread: Hematogenous dissemination, direct extension to sclera and orbital tissues.

Prognostic Factors: Tumor size, location, cell type, and genetic markers.

Poor Prognosis Indicators: Epithelioid cell composition, high mitotic activity, and chromosome 3 monosomy.

Question 9

retinoblastoma

Answer 9

Overview
Definition: Most common intraocular malignant neoplasm in children.
Onset: Typically within the first 2 years of life, sometimes present at birth.
Inheritance: 6-8% are inherited; 25% of sporadic cases are bilateral.

Molecular Pathogenesis
Genetic Basis: Mutations or deletions in the Rb tumor suppressor gene on chromosome 13.
Associated Risks: Increased susceptibility to other malignancies like osteogenic sarcoma.

Clinical Features
Symptoms: White pupil (leukocoria), strabismus, poor vision, hyphema, or red, painful eye.
Spread: Extension into the optic nerve, intracranial spread, and hematogenous metastasis (commonly to bone marrow).

Microscopic Features
Undifferentiated Cells: Small, round cells with hyperchromatic nuclei.
Differentiated Elements: Flexner-Wintersteiner rosettes and fleurettes, indicating photoreceptor differentiation.
Calcification: Focal zones of dystrophic calcification are characteristic.