Palpebral conjunctiva

Fig. 7.2 Horizontal section of the eyeball via the fovea centralis (Some extraocular structures are mentioned). 1, Levator muscle 2, Orbicularis oculi muscle 5, Eyelid skin 4, Palpebral conjunctiva 5, Bulbar conjunctiva 6, Superior tarsal plate 7, Upper eyelid margin 8, Cornea 9, Conjunctival sac 10, Sclera...

The preferred site for the instillation of eyedrops is the lower conjunctival sac (cul-de-sac). The anterior wall of this sac is the conjunctiva of the lower eyelid (palpebral conjunctiva), whereas the conjunctiva that covers the eyeball (bulbar conjunctiva) forms the posterior border, and the forniceal conjunctiva (the conjunctival bridge between bulbar and palpebral parts) lines the crater and the lateral borders of this space (Figure 24.1). 

FIGURE 24.1 Ocular and periocular tissues. EL, eyelid DD, drug droplet COR, cornea AC, anterior chamber PC, posterior chamber AOF, aqueous outflow tract (trabeculum meshwork and Schlemm canal) BCNJ, bulbar conjunctiva PCNJ, palpebral conjunctiva FCNJ, fornical conjunctiva FNX, fornix (conjunctival sac/cul-de-sac) SC, sclera IR, iris CB, ciliary body CHOR, choroid RET, retina ONH, optic nerve head V, vitreous L, lens Z, lens zonulae ORF, orbital fat. 

The palpebral conjunctiva begins at the posterior eyelid margin and extends posteriorly toward the fornix. 

The keratinized epithelium of the eyelids gradually transforms into the moist mucous membrane of the conjunctiva. The palpebral conjunctiva adheres tightly to the tarsus over the entire superior eyelid, as compared with the loosely adherent inferior palpebral conjunctiva. Clinically, this anatomic variation contributes to the different appearance of papillary hypertrophy occurring in the superior versus inferior palpebral conjunctiva. 

The palpebral conjunctiva is composed of nonkera-tinized stratified epithelium that decreases in thickness as it proceeds from the eyelid margin. Many mucin-secreting goblet cells are located near the fornix. The epithelium overlies the substantia propria, which consists of delicate connective tissue and blood vessels. Most of the immune system cellular components reside in the substantia propria.The stroma contains lymphocytes, lymphoid follicles, neutrophils, plasma cells, and mast cells, all of which proliferate extensively in conjunctival inflammatory disease. This proliferation leads to the formation of papillae and follicles. 

Figure 25-37 Foreign body (arroiv) on upper palpebral conjunctiva. (Courtesy of Larry J. Alexander, O.D.)...

Conjimctival phlyctenules appear on the limbus or bulbar conjimctiva. Lesions are usually close to the limbus near the free lid margin but can present anywhere on the bulbar conjimctiva. They rarely affect the palpebral conjunctiva. They often are surrounded by hyperemia. Corneal phlyctenules typically start at the limbus and are accompanied by a leash of conjunctival vessels (Figure 26-41). Initially, the overlying epithelium is intact... 

Examination typically reveals a marked conjunctivitis with a primarily follicular and papillary response of the palpebral conjunctiva.The follicles typically are worse in the inferior palpebral conjunctiva, with papillae more common in the superior. Preauricular lymphadenopathy is present in about 64% of patients at presentation and lasts approximately 1 week. Small subconjunctival hemorrhages are not an uncommon characteristic. 

In patients with AKC there is conjunctival hyperemia, erythema, injection, and chemosis (Figure 27-8). Papillary changes, diffuse in presentation, affect the inferior palpebral conjunctiva more commonly than the superior. Less frequently, giant papillae and follicles may be found. Conjunctival fibrosis and scarring may occur, along with symblepharon formation. 

Eyelid inflammation is a common result of exposure to allergens. The thin tissue of the eyelids and its highly vascularized nature make it a common site for allergic response. The eyelids share many common features with the conjunctiva, and because the bulbar and palpebral conjunctivas are continuous, there is a predisposition to inflammation from an immunologic hypersensitivity reaction. Consequently, the clinical features of the allergic response of the conjunctiva and lids often overlap. In addition, the eyelid skin is a frequent site for microbial colonization, in particular by Staphylococcus, which makes it susceptible to a variety of combination reactions. 

To evaluate the distribution and metabolism of [3H] tafluprost in ocular tissues and to study the IOP-lowering effects of the major metabolites of tafluprost, single ocular doses of [3H]tafluprost were administered to male/female cynomolgus monkeys (1 pg/eye for tissue distribution studies and 10 pg/eye for metabolic studies) [46]. Tafluprost was rapidly absorbed into ocular tissues and subsequently entered the systemic circulation. The highest concentrations of radioactivity were observed in the bulbar conjunctiva and the palpebral conjunctiva (323 and 180ng-eq/g, respectively) at 0.083 h after administration, and in the cornea (784ng-eq/g) at 0.25 h after administration. Nonvolatile radioactivity in plasma peaked (0.907 ng-eq/g) at 0.083 h after administration and then declined steadily. Three major metabolites shown in Figure 2.7, a carboxylic acid of tafluprost (AFP-172), 1,2-... 

In humans, the adult eyeball measures approximately one inch (2.5 centimeters) in diameter, and of its total surface area, only the anterior one-sixth is exposed to the external environment. This exposed area is protected by accessory structures of the eye, including the eyelids, eyelashes, eyebrows, lacrimal (tearing) apparatus, and extrinsic eye muscles. Each eyelid possesses a conjunctiva, which is a thin, transparent, and protective mucus membrane. The conjunctiva lines the inner aspect of the eyelids as the palpebral conjunctiva and folds back (reflects) over the eyelids onto the anterior exposed surface of the eyeball as the bulbar (ocular) conjunctiva. The bulbar conjunctiva covers only the white of tlae eye (not the cornea that covers over the iris and pupil). Because tlie bulbar conjunctiva is quite thin, blood vessels are clearly visible beneath it. When these blood vessels are dilated and congested from local irritation or infection (conjunctivitis, or inflammation of the conjunctiva), the result is the appearance of reddened and irritated bloodshot eyes. 

A) Redness (Refers to Palpebral Conjunctivae Only). Vessels definitely injected above normal —1... 

Most innovations in oxygen measurement have been in the engineering of sensors rather than in the electrochemistry. They nearly all rely on amperometric detection following the application of a suitable reducing potential. Innovations in design include miniaturisation for insertion into blood vessels [12,13], the inclusion of heaters for the transcutaneous measurement of blood gas [14,15] and shaping for mounting on the eye for measurement via the palpebral conjunctiva [16,17]. 

Topically applied drugs are potentially available for absorption by the scleral and palpebral conjunctiva (Cf. pathway 2, Fig. 2). Such routes of loss are referred to as "non productive absorption, since it is well documented that drugs which penetrate the conjunctiva are rapidly removed for the eye by local circulation, and undergo systemic absorption. A direct transscleral access to some intraocular tissues, however, cannot be excluded. 

Marked dilation of vessels running toward palpebral conjunctiva or marked congestion... 

Keratopathy has been reported in a few cases after prolonged topical use of epinephrine. Topical use of epinephrine normally causes a burning sensation, tear formation and ocular discomfort. On rare occasions a local conjunctival allergy can occur with hyperaemia, appearance of foUicles on the palpebral conjunctiva and occurrence of eosinophils. 

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