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Terms in this set (1976)

Superior orbital fissure

The superior orbital fissure is a cleft between the lesser and greater wings of the sphenoid. Structures traveling through the superior orbital fissure include the oculomotor nerve (CN III), trochlear nerve (CN IV), abducens nerve (CN VI), lacrimal nerve, frontal nerve, nasociliary nerve, and the ophthalmic vein (superior and inferior divisions). These structures can be damaged when there is orbital trauma causing fractures through the floor of the orbit into the maxillary sinus. This leads to superficial orbital fissure syndrome (also known as Rochon-Duvigneaud's syndrome). Signs include paralysis of extraocular muscles, diplopia, ptosis, exophthalmia and decreased sensation of the upper eyelid and forehead. Vision loss or blindness implies a more serious injury involving the orbital apex (orbital apex syndrome).

Tolusa-Hunt syndrome (THS) is an inflammatory condition within the cavernous sinus or superior orbital fissure causing damage to the structures in those regions. Signs are usually acute and unilateral at onset in adults and the most common presenting signs are pain and ophthalmoparesis.

The internal auditory (or acoustic) meatus is a canal in the petrous portion of the temporal bone through which the facial (CN VII) and vestibulocochlear nerves (CN VIII) and the labyrinthine artery travel. Damage to these structures can result in deafness and facial muscle paralysis. Acoustic neuromas will commonly expand the internal auditory meatus and damage these structures. Other signs may include tinnitus or vertigo.

The stylomastoid foramen is the termination of the facial canal between the styloid and mastoid processes of the temporal bone. The facial nerve and stylomastoid artery travel through this area. Damage to this area can result in facial drooping and paralysis. Bell's palsy (idiopathic facial nerve paralysis) is an inflammatory condition that may lead to swelling of the facial nerve in this region.

The superficial temporal artery is a major artery arising from the bifurcation of the external carotid artery. The artery begins within the parotid salivary gland and passes over the zygomatic process of the temporal bone. It is often affected in cases of giant cell arteritis (which is also known as temporal arteritis for this reason). This condition is a vasculitis of the medium and large arteries of the head and is not necessarily restricted to the temporal artery. Temporal arteritis is seen predominantly in older patients and is characterized by fever, headache, sensitivity on the scalp, jaw pain, reduced visual acuity or vision loss, diplopia, and acute tinnitus. Due to potentially rapid progressive vision loss, this disease is a medical emergency. Treatment usually consists of high-dose corticosteroids.
Para-central scotoma

Characteristic defects in glaucoma consist of damage to the optic nerve head, resulting in a retinal nerve fiber bundle defect. The configuration of nerve fibers served by the damaged bundle will correspond to a specific defect in the visual field. The earliest visual field changes that may suggest glaucomatous damage commonly consist of an increased variability of responses in an area that will eventually develop a defect.

When a glaucomatous visual field defect does occur, it tends to initially present as a paracentral scotoma. Paracentral scotomas are typically small and relatively steep depressions that are most commonly observed just supero-nasal to the fovea. Approximately 70% of all early glaucomatous field defects can be characterized as a paracentral scotoma. This type of defect is due to damage of the papillomacular bundle which will respect the horizontal midline.

It is important to remember that a single visual field test cannot definitively prove that a visual field defect exists. For this reason, interpretation of visual fields should not be performed in isolation, but rather in conjunction with other clinical findings (IOP, appearance of optic nerve, RNFL). According to Kanski's Clinical Ophthalmology, there is a set of minimal criteria for determining glaucomatous damage (also known as Anderson's criteria), which is summarized below:

1. Glaucoma hemifield test that is "outside normal limits" on at least 2 consecutive occasions.
2. A cluster of 3 or more non-edge points in a location typical for glaucoma, all of which are depressed on pattern standard deviation (PSD) at a P < 5% level and one of which is depressed at a P <1% level, on 2 consecutive occasions.
3. Corrected pattern standard deviation (CPSD) that occurs in less than 5% of normal individuals on two consecutive fields.
A.Conductive keratoplasty

Explanation

In cases where the corneal curvature must be steepened in order to correct for refractive error (hyperopia or presbyopia), conductive keratoplasty (CK) is a viable surgical option. Although this surgical procedure was used more often in earlier years, it is not currently as widely used as laser-assisted in-situ keratomileusis (LASIK) and photorefractive keratectomy (PRK). In comparison to CK, LASIK and PRK tend to be safe, have long-standing results, and more predictable outcomes. The CK technique involves using a radiofrequency probe to create burns in either one or two concentric rings in the mid-peripheral region of the cornea. These thermal laser burns cause subsequent stromal shrinkage, which results in an increase in the curvature of the cornea. This change in curvature typically decays over time, but the procedure can be repeated.

Radial keratotomy is also an older surgical procedure in which a diamond blade is used to create several radial corneal incisions (the number and depth of the incisions depends on the refractive error) in order to flatten the corneal curvature in patients with myopic refractive errors. Limbal relaxation incisions are similar in that arcuate incisions are made on opposite sides of the corneal periphery in the meridian of the "plus" cylinder axis in order to create flattening of the steep corneal curvature (with some smaller steepening of the flat meridian) in an attempt to reduce the amount of corneal astigmatism.

Photorefractive keratotomy (PRK) and laser-assisted in-situ keratomileusis (LASIK) are refractive surgery techniques that use an excimer laser to ablate corneal tissue to a certain depth in either the central cornea (to correct myopia) or peripherally (to correct hyperopia)
A.Superior tarsal follicles

Explanation

Chlamydia causes two forms of conjunctivitis, trachoma and inclusion. Trachoma is more common in lesser-developed countries and can cause blindness if not treated appropriately. Trachoma presents in several stages, initially starting with mucopurulent discharge, lymphadenopathy, red eye, small superior tarsal follicles, and mild superior pannus. As the condition evolves, the formation of limbal follicles occurs and will eventually scar causing Hebert's pits, which are characteristic of this infection. This condition, if left untreated, ultimately progresses to horrible scarring of the eyelid (Arlt's line) and cornea, causing extremely poor visual acuity. Diagnosis is made with the observation of two or more of the following: follicles on the upper tarsus, pannus (particularly superiorly), limbal follicles or Herbert's pits and typical conjunctival scarring of the upper lid. Treatment includes oral doxycycline, tetracycline, or erythromycin along with topical tetracycline or erythromycin ointment. Azithromycin is also a good choice because it is given as 1000 mg PO which delivers exceptional compliance; however, this is not to be prescribed to those with liver disease or to young adults under the age of 16.

Inclusion conjunctivitis is linked to venereal disease and can present either unilaterally or bilaterally (which is more common) as follicles on the upper and lower tarsal plates (lower follicles will be larger and more prominent), lymphadenopathy, possible mucopurulent discharge, lid edema, micropannus, superior corneal sub-epithelial infiltrates, superficial punctate keratitis, and scarring of the upper eyelid (sometimes called Arlt's line or "basketweave" because of its appearance). This type of conjunctivitis is less severe than trachoma. Treatment is similar to that of trachoma.

Follicles are related to cellular immunity which serves to protect against viruses. Many types of viral infections can cause inferior palpebral follicles, such as EKC, Herpes simplex and molluscum contagiosum. Superior tarsal follicles are highly suggestive of a chlamydial infection. A superior papillary response is generally associated with an allergic response. Inferior tarsal papillae are frequently seen in bacterial infections and allergic responses as papillae act as the release sites for both eosinophils (associated with allergies) and polymorphonuclear leukocytes which destroy bacteria.
B.Keratoacanthoma

Explanation

Keratoacanthoma appears very much like squamous cell carcinoma (SCC) in that it tends to progress rapidly and appears to ulcerate. This condition typically occurs in middle-aged and elderly patients of Caucasian descent on areas of the skin that are exposed. The lesion appears elevated, and eventually the center will produce a scab-like plug of keratin. The margins surrounding the plug will be rolled. At some point the keratin plug will fall out, resulting in the formation of a pit, and the lesion will regress. Most patients and clinicians do not like to wait this condition out due to its similarities to SCC.

Actinic keratosis is a pre-cursor to squamous cell carcinoma and appears as scaly, dry skin that does not heal. People with skin that is of lighter pigmentation along with excessive exposure to ultraviolet light tend to be most at risk for development of this condition.

Squamous cell carcinoma (SSC) is thankfully one of the rarest malignancies but due to its ability to metastasize can be quite dangerous. This malignancy has the ability to progress rapidly and has a high affinity for people who spend a lot of time in the sun, especially those who are light-skinned. The only way to definitively diagnose SCC is to refer for a biopsy and ensuring the use of Mohs technique. This strategy takes more time but ensures that the lesion is removed. Essentially, Mohs procedure calls for removal of tissue and biopsy of the surrounding borders. If the borders prove to be malignant then more tissue is removed and biopsied. This continues until the borders prove to be free of any carcinoma.

Basal cell carcinoma (BCC) is the most common malignant lid lesion and mercifully tends to be very slow-growing. BCC generally appears as a waxy, translucent nodule. Eventually the nodule will ulcerate. Patients may bring these to your attention and tell you that they have "had it for years and it just does not seem to heal". Whenever you hear this it is best to send out for biopsy via Mohs technique. BCC very rarely metastasizes.