1. What is the eye?
The sensory organ of vision that receives light, focuses it onto the retina, and converts it into neural signals.
2. Where is the eyeball located?
Within the bony orbit, surrounded by orbital fat, extraocular muscles, connective tissues, and protective structures.
3. What is the approximate anteroposterior diameter of the adult eyeball?
Approximately 24 mm.
4. What are the three principal coats of the eyeball?
The outer fibrous coat, middle vascular coat, and inner neural coat.
5. Which structures form the fibrous coat of the eyeball?
The sclera and cornea.
6. What is the sclera?
The opaque, dense connective tissue forming the posterior five-sixths of the outer coat of the eyeball.
7. What are the principal functions of the sclera?
To maintain the shape of the eyeball, protect its internal structures, and provide attachment for extraocular muscles.
8. What is the cornea?
The transparent, avascular anterior portion of the fibrous coat that provides most of the eye's refractive power.
9. What are the five classical layers of the cornea from anterior to posterior?
Corneal epithelium, Bowman's layer, stroma, Descemet's membrane, and corneal endothelium.
10. Which nerve provides sensory innervation to the cornea?
The ophthalmic division of the trigeminal nerve (cranial nerve V1), primarily through the nasociliary and long ciliary nerves.
11. What are the three principal components of the vascular coat, or uvea?
The choroid, ciliary body, and iris.
12. What is the choroid?
A highly vascular, pigmented layer between the sclera and retina that nourishes the outer retina and absorbs scattered light.
13. What are the major anatomical components of the ciliary body?
The ciliary muscle and ciliary processes, together with their supporting connective tissues and epithelium.
14. What is the function of the ciliary muscle?
It changes tension on the zonular fibers, allowing the lens to change shape during accommodation.
15. What is the iris?
The pigmented, contractile diaphragm anterior to the lens that regulates the amount of light entering the eye through the pupil.
16. Which two muscles control pupil diameter?
The sphincter pupillae constricts the pupil, while the dilator pupillae enlarges it.
17. What is the autonomic innervation of the sphincter pupillae?
Postganglionic parasympathetic fibers from the ciliary ganglion, carried through the short ciliary nerves.
18. What is the autonomic innervation of the dilator pupillae?
Postganglionic sympathetic fibers originating from the superior cervical ganglion.
19. What is the lens of the eye?
A transparent, biconvex, avascular structure situated behind the iris that fine-tunes the focusing of light onto the retina.
20. Which structures suspend the lens from the ciliary body?
The zonular fibers, also called suspensory ligaments of the lens.
21. What is the retina?
The innermost coat of the eyeball, containing photoreceptors and neural circuits that convert light into visual signals.
22. What are the two principal types of retinal photoreceptors?
Rods, specialized for low-light vision, and cones, specialized for color vision and high visual acuity.
23. What is the macula lutea?
A specialized region of the central retina responsible for detailed central vision.
24. What is the fovea centralis?
A small depression near the center of the macula with a high density of cone photoreceptors, providing maximum visual acuity.
25. What is the optic disc?
The region where retinal ganglion cell axons leave the eyeball to form the optic nerve and where the central retinal vessels enter or exit.
26. Why is the optic disc called the physiological blind spot?
It contains no rods or cones and therefore cannot detect light.
27. What are the anterior and posterior chambers of the eye?
The anterior chamber lies between the cornea and iris, while the posterior chamber lies between the iris and lens-ciliary body region.
28. Where is aqueous humor produced, and how does it normally drain?
It is produced by the ciliary processes, flows from the posterior chamber through the pupil into the anterior chamber, and drains mainly through the trabecular meshwork into Schlemm's canal.
29. What is the vitreous body?
A transparent, gel-like structure filling the vitreous chamber behind the lens and helping maintain the shape of the eyeball.
30. Which artery supplies the inner retina, and which cranial nerve carries visual signals to the brain?
The central retinal artery, a branch of the ophthalmic artery, supplies most of the inner retina; visual signals travel through the optic nerve (cranial nerve II).
