OutlineTopographic Precorneal TearfilmParts of the EYE:

CorneaScleraLimbusAnterior chamberTrabecular

meshworkUveal tract

Iris Ciliary Body ChoroidLensRetinaMaculaOra SerrataVitreous

Orbit and Adnexa

Topographic features of the globe

23-25 mm

3 mm

24 mm

16 mm

250 µL 60 µL

5-6 mL

3 chambers

3 concentric layers

Precorneal tearfilm

Importance: Lubricates the surface of the cornea and

conjunctiva (vital for normal corneal function)

Produce a smooth optical surface

Provide O2 and other nutrients

Contain immunoglobulins, lysozyme and lactoferrin

Cornea

• Main refractive element of the eye

Sclera

Limbus

Surgical Limbus divided into 2 equal zones;

Anterior bluish gray zone overlying clear cornea and extending from Bowman’s layer to Schwalbe’s line

Posterior white zone overlying the trabecular meshwork and extending from Schwalbe’s line to the scleral spur or iris root

*** Essential in cataract surgery/glaucoma-filtering procedure

Anterior Chamber

Trabecular meshwork

Trabeculocytes -have

contractile properties = influence outflow resistance

- have phagocytic properties

3 layers:

• uveal portion•Corneoscleral meshwork•Juxtacanalicular tissue (adjacent to Schlemm’s canal

GonioscopyShows the anatomical structures of a normal anterior chamber angle: ciliary body (A), scleral spur (B), trabecular meshwork (C), and Schwalbe’s line (D).

Uveal tract

Attachment to sclera:

Scleral spurExit points of vortex veinsOptic nerve

Iris

Dilator M. – contracts w/ sympathetic α1 adrenergic stimulation

- inhibited by cholinergic parasympathetic stimulation

- via ophthalmic div. of CN V

Sphincter M. – inhibited by sympathetic innervation, relax in darkness

- parasympathetic via CN III (3%), constrict

Ciliary Body

Epithelium & stroma: 2 parts:

Pars plana – avascular, from ora serrata to ciliary process

- safest surgical approach to the vitreous cavity

Pars plicata – richly vascularized, consists of ciliary processes

Layers:longitudinalRadialCircular

Change with ageInnervation:

parasympathetic CN III (97%), constrict

Choroid

3 layers of vessels:Choriocapillaries

(innermost)Small vessels (middle)Large vessels

(outermost)

From long and short posterior A. and anterior ciliary A.

Drains to vortex system

Stroma – melanocytes

Degree of pigmentation – depends on the No. of pigmented melanocytes

Considered in photocoagulation

Lens

3 mm

6.5 mm

Lacks innervation

Avascular

Nourishment from aqueous and vitreous

Ant. Capsule = thicker than Post capsule

Human lens, cell division continues throughout life

Distant focus zonule is tensed lens flattened

Accommodation ciliary contracts zonule forward & inward lens globular

Retina

INNER

OUTER

FXNS:• Vit A met’m•Maintenance of outer blood-retina barrier•Absorption of light•Heat exchange

Macula

1.5 mm

Ora Serrata

20 mm

Vitreous• route for metabolites

•Vol = 4 mL

•Gel-like , 99% H2O

•More fluid= inc. age