Vitreous Hemorrhage Definition

Retrohyaloid Space

Bleeding into the vitreous chamber or a space created by vitreous detachment. Epidemiology The annual incidence of this disorder is seven cases per 100000. Etiology A vitreous hemorrhage may involve one of three possible pathogenetic mechanisms (Fig. 11.5) 1. Bleeding from normal retinal vessels as can occur as a result of mechanical vascular damage in acute vitreous detachment or retinal tear. 2. Bleeding from retinal vessels with abnormal changes as can occur as a result of retinal...

Retrochiasmal Lesions

Etiology Retrochiasmal lesions may result from a wide variety of neurologic disorders such as tumors, vascular insults, basal meningitis, aneurysms of the posterior communicating artery, abscesses, injuries (such as a contrecoup injury to the occipital lobe), and vasospasms (in an ocular migraine). Symptoms, diagnostic considerations, and clinical picture Visual field testing in particular will provide information on the location of the lesion. Perimetry is therefore a crucial diagnostic study....

Examination of the Conjunctiva

Inflammation The Eyeball Scleritis

The conjunctiva is examined by direct inspection. The bulbar conjunctiva is directly visible between the eyelids the palpebral conjunctiva can only be examined by everting the upper or lower eyelid. The normal conjunctiva is smooth, shiny, and moist. The examiner should be alert to any reddening, secretion, thickening, scars, or foreign bodies. Eversion of the lower eyelid. The patient looks up while the examiner pulls the eyelid downward close to the anterior margin (Fig. 1.7). This exposes...

The Fibres That Hold Lens In Position

Lens Position Eye

Function of the lens The lens is one of the essential refractive media of the eye and focuses incident rays of light on the retina. It adds a variable element to the eye's total refractive power (10-20 diopters, depending on individual accommodation) to the fixed refractive power of the cornea (approximately 43 diopters). Shape The fully developed lens is a biconvex, transparent structure. The curvature of the posterior surface, which has a radius of 6 mm, is greater than that of the anterior...

Concomitant Strabismus Definition

Concomitant strabismus differs from paralytic strabismus in that the angle of deviation remains the same in every direction of gaze. The deviating eye follows the normal fellow eye at a constant angle. Epidemiology Concomitant strabismus occurs almost exclusively in children. Approximately 5.3-7.4 of all children are affected. In 60-70 of all cases, the disorder initially manifests itself within the first two years of life. Etiology Vision at birth is neither focused nor binocular, and both...

Conjunctival Xerosis Definition

Conjunctival Xerosis

Desiccation of the conjunctiva due to a vitamin A deficiency. Conjunctival xerosis due to vitamin a deficiency. - Fig. 4.5 a Kerat-inization of the superficial epithelial cells causes the surface of the conjunctiva to lose its luster. Conjunctival xerosis due to vitamin a deficiency. - b The keratinized epithelial cells die and create characteristic Bitot's spots in the palpebral fissure. b The keratinized epithelial cells die and create characteristic Bitot's spots in the palpebral fissure....

Noninfectious Conjunctivitis

Conjunctival Chemosis

Table 4.4 provides an overview of pathogens, symptoms, and treatments of noninfectious conjunctivitis. Acute conjunctivitis is frequently attributable to a series of external irritants or to dry eyes conjunctivitis sicca . The disorder is unpleasant but benign. Primary symptoms include foreign-body sensation, reddening of the eyes of varying severity, and epiphora. Therapy should focus on eliminating the primary irritant and treating the symptoms. Acute conjunctivitis should be distinguished...

Frequent traumatic cataracts

Irreversible Amblyopia

Contusion cataract Contusion of the eyeball will produce a rosette-shaped subcapsular opacity on the anterior surface of the lens. It will normally remain unchanged but will migrate into the deeper cortex over time due to the apposition of new fibers Fig. 7.13 . Fig. 7.11 Typical symptoms include a crest-shaped whitish opacity beneath the anterior lens capsule along the visual axis. Fig. 7.11 Typical symptoms include a crest-shaped whitish opacity beneath the anterior lens capsule along the...

Blunt Ocular Trauma Ocular Contusion

Epidemiology and etiology Ocular contusions resulting from blunt trauma such as a fist, ball, champagne cork, stone, falling on the eye, or a cow's horn are very common. Significant deformation of the globe can result where the diameter of the blunt object is less than that of the bony structures of the orbit. Clinical picture and diagnostic considerations Deformation exerts significant traction on intraocular structures and can cause them to tear. Often there will be blood in the anterior...

Hyperopia Farsightedness Definition

Manufacture Hypermetropia

In hyperopia, there is a discrepancy between the refractive power and axial length of the eye such that parallel incident light rays converge at a focal point posterior to the retina (Fig. 16.10a). Epidemiology Approximately 20 of persons between the ages of 20 and 30 have refraction exceeding +1 diopters. Most newborns exhibit slight hyperLang, Ophthalmology 2000 Thieme All rights reserved. Usage subject to terms and conditions of license. Fig. 16.10 a The focal point of parallel light rays...

Xanthelasma Definition

Milia Millium Testiculos

Local fat metabolism disorder that produces lipoprotein deposits. These are usually bilateral in the medial canthus. Fig. 2.20 The round cysts of the glands of Moll are usually located in the angle of the eye. The weight causes temporary ectropion. Fig. 2.20 The round cysts of the glands of Moll are usually located in the angle of the eye. The weight causes temporary ectropion. Epidemiology Postmenopausal women are most frequently affected. A higher incidence has also been observed in patients...

Surgical Treatment Vitrectomy Definition

Fundus Drawing

Surgical removal and replacement of the vitreous body with Ringer's solution, gas, or silicone oil. Indication The primary indications include Unabsorbed vitreous hemorrhage. Tractional retinal detachment. Proliferative vitreoretinopathy. Removal of intravitreal displaced lenses or foreign bodies. Severe postoperative or post-traumatic inflammatory vitreous changes. Procedure The vitreous body cannot simply be aspirated from the eye as the vitreoretinal attachments would also cause retinal...

Parasitic Retinal Disorders Definition

Leukocoria

Inflammation of the retina caused by infection with parasites such as Onchocerca volvulus (the pathogen that causes onchocerciasis), Toxocara canis or Toxocara cati (nematode larvae that are normally intestinal parasites of dogs and cats), Taenia solium, (pork tapeworm), and other parasites. Epidemiology Onchocerciasis, like trachoma and leprosy, is one of the most frequent causes of blindness worldwide. However, like the other parasitic diseases discussed here, it is rare in Europe and North...

Childhood Glaucomas Definition

Goniotomy And Trabeculotomy

Any abnormal increase in intraocular pressure during the first years of life will cause dilatation of the wall of the globe, and especially of the cornea. The result is a characteristic, abnormally large eye buphthalmos with a progressive increase in corneal diameter. This is also referred to as hydrophthalmos or hydrophthalmia. Epidemiology Glaucomas in children occur once every 12000-18000 births and account for about 1 of all glaucomas. Primary congenital glaucoma is an inherited autosomal...

Conjunctival Papilloma

Palpebral Conjunctival Lesions

Papillomas are of viral origin (human papillomavirus) and may develop from the bulbar or palpebral conjunctiva. They are benign and do not turn malignant. As in the skin, conjunctival papillomas can occur as branchingpediculate tumors or as broad-based lesions on the surface of the conjunctiva (Fig. 4.22). Papillomas produce a permanent foreign-body sensation that is annoying to the patient, and the entire lesion should be surgically removed. Fig. 4.22 Broad-based papilloma originating from the...

Conjunctival Deposits

These can occur in both the conjunctiva and cornea. Some, like some tumors, lead to pigmented changes in the conjunctiva. However, their typical appearance usually readily distinguishes them from tumors (Fig. 4.24). The following conjunctival and corneal deposits and discolorations may occur Adrenochrome deposit (Fig.4.24h). Prolonged use of epinephrine eyedrops (as in glaucoma therapy) produces brownish pigmented changes in the inferior conjunctival fornix and on the cornea as a result of...

Persistent Hyperplastic Primary Vitreous PHPV Definition

Persistence of the embryonic primary vitreous (hyaloid arterial system including the posterior tunica vasculosa lentis). Epidemiology This developmental anomaly is also very rare. Symptoms and findings Usually the disorder is unilateral. Anterior variant of PHPV. With this more frequent variant, a white pupil (leukocoria or amaurotic cat's eye) typically will be discovered shortly after birth. This is caused by the whitish plate of connective tissue posterior to the lens. Depending on the...

Tunica Vasculosa Lentis

Canal Cloquet

Importance of the vitreous body for the eye The vitreous body stabilizes the globe although the eye can remain intact without the vitreous body see vitrectomy . It also prevents retinal detachment. Embryology The development of the vitreous body can be divided into three phases First phase first month of pregnancy fetus measures 5-13 mm cranium to coccyx The primary vitreous forms during this period. This phase is characterized by the entry of mesenchyme into the optic cup through the embryonic...

Vitreous Detachment Definition

Martegiani Ring

Complete or partial detachment of the vitreous body from its underlying tissue. The most common form is posterior vitreous detachment see Fig. 11.3a anterior or basal vitreous detachment is much rarer. Epidemiology Six percent of patients between the ages of 54 and 65 and 65 of all patients between the ages of 65 and 85 have posterior vitreous detachment. Patients with axial myopia have a predisposition to early vitreous detachment. Presumably the vitreous body collapses earlier in these...

Examination Methods

Hertel Exophthalmometer

Cardinal symptoms Unilateral or bilateral enophthalmos recession of the eyeball within the orbital cavity or exophthalmos protrusion of the eyeball are characteristic of many orbital disorders Table 15.2 . These conditions should be distinguished from pseudoexophthalmos due to a long eyeball in severe myopia, and pseudoenophthalmos due to a small eyeball, such as in microphthalmos or phthisis bulbi. The following list of examination techniques begins with the simple standard techniques and...

Vascular Disorders 1231 Diabetic Retinopathy Definition

Exudates Eye

Diabetic retinopathy is an ocular microangiopathy. Epidemiology Diabetic retinopathy is one of the main causes of acquired blindness in the industrialized countries. Approximately 90 of all diabetic patients have retinopathy after twenty years. Pathogenesis and individual stages of diabetic retinopathy Diabetes mel-litus can lead to changes in almost every ocular tissue. These include symptoms of keratoconjunctivitis sicca, xanthelasma, mycotic orbital infections, transitory refractory changes,...

Astigmatism Definition

Irregular Distances Mesuring

Astigmatism is derived from the Greek word stigma point and literally means lack of a focal point. The disorder is characterized by a curvature anomaly of the refractive media such that parallel incident light rays do not converge at a point but are drawn apart to form a line. Epidemiology Forty-two per cent of all humans have astigmatism greater than or equal to 0.5 diopters. In approximately 20 , this astigmatism is greater than 1 diopter and requires optical correction. Pathophysiology The...

Etiology and corresponding visual field defects

Visual Fields Defects

Pituitary adenomas These are tumors that proceed from the hormone-secreting cells of the anterior lobe of the pituitary gland. As they increase in size superiorly, they reach the anterior margin of the chiasm where they compress the inferior and nasal fibers that cross there Fig. 14.5 . This leads to an initial visual field defect in the superior temporal quadrant that may later progress to complete bilateral temporal hemianopsia. The visual field defect usually spreads in an asymmetrical...

Secondary Angle Closure Glaucoma Definition

Rubeosis Iridis Causes

In secondary angle closure glaucoma as in primary angle closure glaucoma, the increase in intraocular pressure is due to blockage of the trabecular meshwork. However, the primary configuration of the anterior chamber is not the decisive factor. The most important causes Rubeosis iridis. Neovascularization draws the angle of the anterior chamber together like a zipper (neovascular glaucoma). Ischemic retinal disorders such as diabetic retinopathy and retinal vein occlusion can lead to rubeosis...

Hypertensive Retinopathy and Sclerotic Changes Definition

Fundo Olho Com Toxoplasmose

Arterial changes in hypertension are primarily caused byvasospasm in arteriosclerosis they are the result of thickening of the wall of the arteriole. Epidemiology Arterial hypertension in particular figures prominently in clinical settings. Vascular changes due to arterial hypertension are the most frequent cause of retinal vein occlusion. Pathogenesis High blood pressure can cause breakdown of the blood-retina barrier or obliteration of capillaries. This results in intraretinal bleeding,...

Vascular pigmented layer

Diabetic Rubeosis Chinese Patient

Lang Structure The uveal tract also known as the vascular pigmented layer, vascular tunic, and uvea takes its name from the Latin uva grape because the dark pigmentation and shape of the structure are reminiscent of a grape. The uveal tract consists of the following structures Position The uveal tract lies between the sclera and retina. Neurovascular supply Arterial supply to the uveal tract is provided by the ophthalmic artery. The short posterior ciliary...

Disorders of the Skin and Margin of the Eyelid 35 255 Herpes Zoster Ophthalmicus Definition

Herpes Eyelid Children

Facial rash caused by the varicella-zoster virus. Epidemiology The disorder usually affects immunocompromised persons between the ages of 40 and 60 who have underlying disorders. Etiology The disorder is caused by the varicella-zoster virus, which initially manifests itself as chickenpox. If activation or reinfection occurs, the latent neurotropic viruses present in the body can lead to the clinical syndrome of herpes zoster ophthalmicus Fig. 2.14 . Symptoms The incubation period is 7-18 days,...

Herpes Simplex of the Eyelids Definition

Herpes The Eyelid

Acute, usually unilateral eyelid disorder accompanied by skin and mucous membrane vesicles. Etiology Infection of the skin of the eyelids results when latent herpes simplex viruses present in the tissue are activated by ultraviolet radiation. The virus spreads along sensory nerve fibers from the trigeminal ganglion to the surface of the skin. Symptoms Typical clustered eruptions of painful vesicles filled with serous fluid frequently occur at the junction of mucous membranes and skin (Fig....

Disorders of the Lacrimal Gland 351 Acute Dacryoadenitis Definition

Lacrimal Gland Infection

Acute inflammation of the lacrimal gland is a rare disorder characterized by intense inflammation and extreme tenderness to palpation. Etiology The disorder is often attributable to pneumococci and staphylo-cocci, and less frequently to streptococci. There may be a relationship between the disorder and infectious diseases such as mumps, measles, scarlet fever, diphtheria, and influenza. Symptoms and diagnostic considerations Acute dacryoadenitis usually occurs unilaterally. The inflamed swollen...

Anisometropia Definition

In anisometropia, there is a difference in refractive power between the two eyes. Epidemiology Anisometropia of at least 4 diopters is present in less than 1 of the population. Etiology The reason for the varying development of the two eyes is not clear. This primarily congenital disease is known to exhibit a familial pattern of increased incidence. Pathophysiology In anisometropia, there is a difference in refractive power between the two eyes. This refractive difference can be corrected...

Bests Vitelliform Dystrophy

Epidemiology The disorder is rare, with an incidence similar to Stargardt's disease. Inheritance The disorder is inherited as an autosomal dominant trait with variable penetrance and expressivity. The gene locus is on chromosome 11 Symptoms Clinical manifestation occurs between the ages of 5 and 15 years. Initially there is a subjectively slight decrease in visual acuity. In the later stages of the disorder, vision is reduced to about 20 200. Findings and diagnostic considerations A typical...

Degenerative Retinoschisis Definition

Afrequently bilateral split in an inner and outer layer of the retina. The split is usually at the level of the outer plexiform layer (Fig. 12.25). Epidemiology About 25 of all people have retinoschisis. The tendency increases with age. Pathogenesis Idiopathic retinal splitting occurs, usually in the outer plexi-form layer. Symptoms Retinoschisis is primarily asymptomatic. The patient will usually notice a reduction of visual acuity and see shadows only when the retinal split is severe and...