Binocular Alignment

Binocular alignment is evaluated with a cover test. The examiner holds a point light source beneath his or her own eyes and observes the light reflections in the patient's corneas in the near field (40 cm) and at a distance (5 m). The reflections are normally in the center of each pupil. If the corneal reflection is not in the center of the pupil in one eye, then a tropia is present in that eye. Then the examiner covers one eye with a hand or an occluder (Fig. 1.6) and tests whether the...

Injuries to the Lacrimal System

Etiology Lacerations and tears in the medial canthus (such as dog bites or glass splinters) can divide the lacrimal duct. Obliteration of the punctum and lacrimal canaliculus is usually the result of a burn or chemical injury. Injury to the lacrimal sac or lacrimal gland usually occurs in conjunction with severe craniofacial trauma (such as a kick from a horse or a traffic accident). Dacryocystitis is a common sequela, which often can only be treated by surgery (dacryocystorhinostomy). Clinical...

Epikeratophakic Keratoplasty Epikeratophakia

Principle Severe myopia and hyperopia are corrected by suturing specially prepared hyperopic or myopic partial-thickness corneal grafts on to the recipient's cornea. This involves special trephination and preparation of the recipient's cornea. The donor graft is then fitted into the prepared cornea and sutured in place. The donor corneal button is prepared as a frozen section and shaped to the required refractive power these implants can be ordered from eye banks. Indications Any severity of...

Corneal Erosion

Etiology This disorder follows initial trauma to the surface cornea, such as the fingernail of a child carried in the parent's arms, a spiked-leaf palm tree, or a branch that snaps back on to the eye. Properly treated, this epithelial defect usually heals within a short time, i.e., 24 to 48 hours depending on the size of the defect. However, occasionally the epithelial cells do not properly adhere to Bowman's layer so that the epithelium repeatedly ruptures at the site of the initial injury....

Cavernous Sinus Thrombosis Definition

Rare but severe acute clinical syndrome in which the spaces of the cavernous sinus posterior to the orbital cavity become thrombosed, usually in the presence of adjacent purulent processes. This is not an orbital disorder in the strict sense. Etiology These are purulent inflammations that have spread from the middle ear, petrous bone, orbital cavities, or from the facial skin via the angular vein. Symptoms Patients present with an acute clinical picture with headache, stupor, fever, and...

Differential diagnosis

Gonococcal conjunctivitis and inclusion conjunctivitis (see Fig.4.3). Silver catarrh (harmless conjunctivitis with slimy mucosal secretion following Crede's method of prophylaxis with silver nitrate). Treatment During the first few weeks, the infant should be monitored for spontaneous opening of the stenosis. During this period, antibiotic and anti-inflammatory eyedrops and nose drops (such as erythromycin and xylo-metazoline 0.5 for infants) are administered. If symptoms persist, irrigation...

Curvature of Field

This means that the magnification of the image changes as one approaches the periphery. The result is a sharp image with peripheral curvature. Convex or plus lenses produce pincushion distortion concave or minus lenses produce barrel distortion (Fig. 16.23). Fig. 16.22 a Lenses may be regarded as composed of many prisms, which explains many of the optical phenomena of lenses such as dispersion. b A prism refracts a light ray toward its base twice (solid line). However, it appears to the...

Louse Infestation of the Eyelids

This refers to infestation of the margin of the eyelid with crab lice as a result of poor hygienic conditions. The small oval nits frequently hang from the eyelashes (Fig. 2.16), causing inflammation of the margin of the eyelid with severe itching. Mechanical removal with forceps is a time consuming but effective treatment. Application of a 2 mercury precipitate ointment over an extended period of time is also effective. Louse infestation of the eyelids. - Fig. 2.16 Under poor hygienic...

Cataract Definition

A cataract is present when the transparency of the lens is reduced to the point that the patient's vision is impaired. The term cataract comes from the Greek word katarraktes (downrushing waterfall) because earlier it was thought that the cataract was a congealed fluid from the brain that had flowed in front of the lens. General symptoms Development of the cataract and its symptoms is generally an occult process. Patients experience the various symptoms such as seeing only shades of gray,...

Determining Corneal Sensitivity

Non-ophthalmologists may perform a simple preliminary examination of corneal sensitivity with a distended cotton swab (see Fig. 1.11, p. 11). This examination also helps the ophthalmologist confirm the diagnosis in the presence of a suspected viral infection of the cornea or trigeminal or facial neuropathy as these disorders are associated with reduced corneal sensitivity. Ophthalmologists may use an automatic Drager esthesiometer for precise testing of corneal sensitivity and for follow-up...

Examination Methods

The incidence of ocular injuries remains high despite the increase in safety regulations in recent years, such as mandatory seat belts and protective eye-wear for persons operating high-speed rotary machinery. Therefore it is important that every general practitioner and health care staff member is able to recognize an ocular injury and provide initial treatment. The patient should then be referred to an ophthalmologist, who should be solely responsible for evaluation of the injury and...

Other examination methods

CT or MRI to diagnose causes. 14.2 Examination Methods 393 Goldmann hemispheric perimeter and visual field findings. - Humphrey field analyzer and visual field findings. - Fig. 14.3 a In static perimetry, the patient also focuses on a black dot in the middle of the hemisphere. As soon as the patient perceives a light marker, he or she presses a button that triggers an acoustic signal. The result is shown on the monitor on Fig. 14.3 a In static perimetry, the patient also focuses on a black dot...

Arcus Senilis

This is a grayish-white ring-shaped fatty deposit near the limbus that can occur at any age but usually appears in advanced age (Fig. 5.14). Arcus senilis is usually bilateral and is a frequently encountered phenomenon. It occurs as a result of lipid deposits from the vessels of the limbus along the entire periphery of the cornea, which normally increase with advanced age. A lipid-free clear zone along the limbus will be discernible. Patients younger than 50 years who develop arcus senilis...

Seborrheic Blepharitis Definition

This relatively frequent disorder is characterized by scaly inflammation of the margins of the eyelids. Usually both eyes are affected. Etiology There are often several contributing causes. The constitution of the skin, seborrhea, refractive anomalies, hypersecretion of the eyelid glands, and external stimuli such as dust, smoke, and dry air in air-conditioned rooms often contribute to persistent chronic inflammation. Symptoms and diagnostic considerations The margins of the eyelids usually...

Measuring the Diameter of the Cornea

An abnormally large or small cornea (megalocornea or microcornea) will be apparent from simple visual inspection. A suspected size anomaly can be easily verified by measuring the cornea with a ruler. Corneal diameter may be determined more accurately with calipers (usually done under general anesthesia, see Fig. 10.21) or with the Wessely keratometer. This is a type of tube with a condensing lens with millimeter graduations at one end. The examiner places this end on the patient's eye and looks...

Tilted Disk

An optic nerve that exits the eye superiorly (Fig. 13.5) is referred to as a tilted disk. The superior circumference of the margin of the optic disk will be obscured in a manner similar to oblique entry of the optic nerve. A number of other changes may also be observed, including an inferior crescent, situs inversus of the retinal vessels, ectasia of the fundus, myopia, and visual field defects. These findings may occur in various combinations and are referred to collectively as tilted-disk...

Scleritis Definition

Diffuse or localized inflammation of the sclera. Scleritis is classified according to location Anterior (inflammation anterior to the equator of the globe). Posterior (inflammation posterior to the equator of the globe). Anterior scleritis is further classified according to its nature Non-necrotizing anterior scleritis (nodular or diffuse). Necrotizing anterior scleritis (with or without inflammation). Epidemiology Scleritis is far less frequent than episcleritis. Patients are generally older,...

Exotropia

Exotropia (divergent strabismus) is less common than esotropia. As it is usually acquired, the disorder is encountered more often in adults than in children, who more frequently exhibit esotropia. Exotropia less frequently leads to amblyopia because the strabismus is often alternating. Occasionally what is known as panorama vision will occur, in which case the patient has an expanded binocular field of vision. The following forms are distinguished Intermittent exotropia. This is the most common...

The Intraorbital and Intracranial Portion of the Optic Nerve

The intraorbital portion begins after the nerve passes through a sieve-like plate of scleral connective tissue, the lamina cribrosa. Inside the orbit, the optic nerve describes an S-shaped course that allows extreme eye movements. After the optic nerve passes through the optic canal, the short intracranial portion begins and extends as far as the optic chiasm. Like the brain, the intraorbital and intracranial portions of the optic nerve are surrounded by sheaths of dura mater, pia, and...

Diagnosis of Unilateral and Alternating Strabismus Unilateral Cover Test

A unilateral cover test can distinguish between manifest unilateral strabismus and alternating strabismus. The patient is requested to fixate on a point. The examiner than covers one eye and observes the uncovered eye (Fig. 17.8a -c). In unilateral strabismus, the same eye always deviates. When the deviating eye is covered, the uncovered eye (the leading, nondeviating eye) remains focused on the point of fixation. When the nondeviating eye is covered, the uncovered deviating eye has to take the...

Basic Knowledge

The anatomy of the visual pathway may be divided into six separate parts (Fig. 14.1) 1. Optic nerve This includes all of the optic nerve fiber bundles of the eye. 2. Optic chiasm This is where the characteristic crossover of the nerve fibers of both optic nerves occurs. The central and peripheral fibers from the temporal halves of the retinas do not cross the midline but continue into the optic tract of the ipsilateral side. The fibers of the nasal halves cross the midline and there enter the...

Astrocytoma Definition

An astrocytoma or astrocytic hamartoma is a benign tumor that develops from the astrocytes of the neuroglial tissue. Epidemiology Astrocytomas are rare. Etiology Astrocytomas belong to the phakomatoses and are presumably congenital disorders that develop from the layer of optic nerve fibers. They may manifest themselves as purely ocular disorders or in association with tuberous sclerosis (Bourneville's disease). Symptoms Patients usually have no ocular symptoms. Calcifying astrocytic hamartomas...

Developmental Anomalies

5.3.1 Protrusion Anomalies 5.3.1.1 Keratoconus Definition Conical, usually bilateral central deformation of the cornea with parenchymal opacification and thinning of the cornea. Epidemiology Keratoconus is the most frequently encountered deformation of the cornea. Occurrence is familial, although women are more likely to be affected than men. Etiology Keratoconus is probably a genetic disorder. It can occur in families with varying paths of hereditary transmission. Occasionally keratoconus is...

Orbital Hematoma

Orbital bleeding is usually post-traumatic but may occur less frequently due to coagulopathy resulting from vitamin C deficiency, anticoagulants, or leukemia. Retrobulbar injections prior to eye surgery and acute venous stasis such as may occur in coughing fits, asphyxia, or childbirth can also cause orbital hematomas. Exophthalmos may be accompanied by monocle or eyeglass hematoma, eyelid swelling, and subconjunctival hemorrhage limited motility is rare. Surgical decompression of the orbital...

AIDSRelated Retinal Disorders Definition

Retinal disorders in AIDS involve either AIDS-associated microangiopathy or infection. Epidemiology Up to 80 of all AIDS patients have retinal disorders as a result of the disease. Other ocular involvement is rare. Pathogenesis The pathogenesis of microangiopathy is still unclear. Opportunistic infections are frequently caused by viruses. Symptoms Microangiopathy is usually asymptomatic. Patients with infectious retinal disorders report loss of visual acuity and visual field defects. Diagnostic...

Electrophysiologic Examination Methods

(electroretinogram, electro-oculogram, and visual evoked potentials see Fig. 12.2a) Electroretinogram (ERG) This examination method uses electrodes to record the electrical response of the retina to flashes of light (Fig. 12.12 a). Photopic (light-adapted) and scotopic (dark-adapted) electroretinograms are obtained. The electroretinogram (ERG) consists of a negative A wave indicating the response of the photoreceptors and a positive B wave primarily indicating the response of the bipolar cells...

Impaired Accommodation 1641 Accommodation Spasm Definition

An accommodation spasm is defined as inadequate protracted contraction of the ciliary muscle. Etiology Accommodation spasms are rare. They may occur as functional impairment or they may occur iatrogenically when treating young patients with parasympathomimetic agents (miotic agents). The functional impairments are frequently attributable to heightened sensitivity of the accommodation center, which especially in children (often girls) can be psychogenic. Rarely the spasm is due to organic...

Trochlear nerve palsy

Causes The commonest cause is trauma less common causes include vascular disease (diabetes mellitus, hypertension, and arteriosclerosis). Trochlear nerve palsy is a relatively common phenomenon. Effects The superior oblique is primarily an intorter and a depressor in adduction. This results in upward vertical deviation of the paralyzed eye in adduction and vertical strabismus (see Fig. 17.16). Patients experience vertical diplopia the images are farthest apart in depression and intorsion....

Radiation Injuries Ionizing Radiation

Etiology Ionizing radiation (neutron, or gamma x-ray radiation) have high energy that can cause ionization and formation of radicals in cellular tissue. Penetration depth in the eye varies with the type of radiation, i.e., the wavelength, resulting in characteristic types of tissue damage (Fig. 18.13). This tissue damage always manifests itself after a latency period, often only after a period of years (see also Symptoms and clinical picture). Common sites include the lens (radiation cataract)...

Treatment

U An acute glaucoma attack is an emergency, and the patient requires immediate treatment by an ophthalmologist. The underlying causes of the disorder require surgical treatment, although initial therapy is conservative. Medical therapy. Goals ofconservative therapy Decrease intraocular pressure. Allow the cornea to clear (important for subsequent surgery). Time factor in reducing intraocular pressure Principles of medical therapy in primary angle closure glaucoma (see Fig. 10.3) Osmotic...

Tumors of the Lacrimal

Epidemiology Tumors of the lacrimal sac are rare but are primarily malignant when they do occur. They include papillomas, carcinomas, and sarcomas. Symptoms and diagnostic considerations Usually the tumors cause unilateral painless swelling followed by dacryostenosis. Diagnostic considerations The irregular and occasionally bizarre form of the structure in radiographic contrast studies is typical. Ultrasound, CT, MRI, and biopsy all contribute to confirming the diagnosis. Differential diagnosis...

Subjective Refraction Testing for Eyeglasses

While the patient looks at vision charts, the examiner places various combinations of lenses in front of the patient's eye. The patient reports which of two lenses produces the sharper image. The better of the two is then compared with the next lens. This incremental method identifies the optimal correction. It is expedient to use the patient's objective refraction as the starting point for subjective testing. Refraction testing is performed either with a series of test lenses from a case or...

Conjunctival Nevus

Birthmarks can occur on the conjunctiva as on the skin. They are usually located near the limbus in the temporal portion of the palpebral fissure, less frequently on the lacrimal caruncle. These benign, slightly raised epithelial or subepithelial tumors are congenital. Fifty percent of nevi contain hollow cystic spaces (pseudocysts) consisting of conjunctival epithelium and goblet cells. Conjunctival nevi may be pigmented (Fig.4.24a) or unpigmented (Fig. 4.24b), and they may increase in size as...

Arteritic Anterior Ischemic Optic Neuropathy Definition

An acute disruption of the blood supply to the optic disk due to inflammation of medium-sized and small arterial branches. Epidemiology The annual incidence is approximately three cases per 100000.The disorder occurs almost exclusively after the age of 60. Women are affected slightly more often than men, accounting for 55 of all cases. Fifty per cent of all patients suffer from ocular involvement within a few days up to approximately three months of the onset of the disorder. Etiology Giant...

Superficial Punctate Keratitis Definition

Superficial punctate corneal lesions due to lacrimal system dysfunction from a number causes (see etiology). Epidemiology and etiology Superficial punctate keratoconjunctivitis is a very frequent finding as it can be caused by a wide variety of exogenous factors such as foreign bodies beneath the upper eyelid, contact lenses, smog, etc. It may also appear as a secondary symptom of many other forms of keratitis (see the forms of keratitis discussed in the following section). It can also occur in...

Position structure and nerve supply of the lacrimal gland The lacrimal

Krause Gland

Gland is about the size of a walnut it lies beneath the superior temporal margin of the orbital bone in the lacrimal fossa of the frontal bone and is neither visible nor palpable. A palpable lacrimal gland is usually a sign of a pathologic change such as dacryoadenitis. The tendon of the levator palpebrae muscle divides the lacrimal gland into a larger orbital part (two-thirds) and a smaller palpebral part (one-third). Several tiny accessory lacrimal glands (glands of Krause and Wolfring)...

Problems with Contact Lenses

Etiology These problems occur either with poorly seated rigid contact lenses that rub on the surface of the cornea or from overwearing soft contact lenses. Giant papillae from contact lens incompatibility. Giant papillae from contact lens incompatibility. Fig. 5.12 Wartlike protrusions of connective tissue on the pal-pebral conjunctiva due to contact lens or preservative incompatibility (with simple eversion of the upper eyelid). Fig. 5.12 Wartlike protrusions of connective tissue on the...

Corneal Dystrophies Definition

This term refers to a group of corneal metabolic dysfunctions that always lead to bilateral opacification of the various layers of the cornea (see Classification below). Epidemiology Corneal dystrophy tends to be rare. The most frequent form is Fuchs' endothelial dystrophy, followed by dystrophy in the corneal stroma. Etiology The various corneal dystrophies are genetic disorders. They usually manifest themselves in the first or second decade of life except for Fuchs' endothelial dystrophy,...

Posterior Uveitis Due to Toxoplasmosis Definition

Focal chorioretinal inflammation caused by infection. Epidemiology This clinical syndrome is encountered frequently. Pathogenesis The pathogen, Toxoplasma gondii, is transmitted by ingestion of tissue cysts in raw or undercooked meat or by oocysts from cat feces. In congenital toxoplasmosis, the child acquires the pathogen through transplacen-tal transmission. Symptoms and diagnostic considerations As a general rule, a negative complement-fixation test does not exclude Toxoplasma infection...

Blepharospasm Definition

This refers to an involuntary spasmodic contraction of the orbicularis oculi muscle supplied by the facial nerve. Etiology In addition to photosensitivity and increased tear production, blepharospasm will also accompany inflammation or irritation of the anterior chamber. (Photosensitivity, epiphora, and blepharospasm form a triad of reactive clinical symptoms.) Causes of the disorder include extrapyramidal disease such as encephalitis or multiple sclerosis. Trigeminal neuralgia or psy-chogenic...

Optic Neuritis Definition h

Optic neuritis is an inflammation of the optic nerve that may occur within the globe (papillitis) or posterior to it (retrobulbar optic neuritis). Epidemiology Optic neuritis occurs most frequently in adults between the ages of 20 and 45. Women are more frequently affected than men. Twenty to forty per cent of all patients with optic neuritis develop diffuse encephalitis (multiple sclerosis). Fig. 13.10 c Functional findings. The enlarged blind spot (indicated by hatching) is an early...

Neonatal Dacryocystitis

Etiology Approximately 6 of newborns have a stenosis of the mouth of the nasolacrimal duct due to a persistent mucosal fold (lacrimal fold or valve of Hasner). The resulting retention of tear fluid provides ideal growth conditions for bacteria, particularly staphylococci, streptococci, and pneumococci. Symptoms and diagnostic considerations Shortly after birth (usually within two to four weeks), pus is secreted from the puncta. The disease continues subcutaneously and pus collects in the...

Orbital Cavity 1551 Orbital Cellulitis Definition

Acute inflammation of the contents of the orbital cavity with the cardinal symptoms of limited motility and general malaise. H Orbital cellulitis is the most frequent cause of exophthalmos in children. Etiology Acute orbital inflammation posterior to the orbital septum is usually an inflammation that has spread from surrounding tissue. Over 60 of all cases (as high as 84 in children) may be classified as originating in the sinuses, especially the ethmoidal air cells and the frontal sinus. In...

Bacterial Keratitis

Epidemiology Over 90 of all corneal inflammations are caused by bacteria. Etiology The pathogens listed in Table 5.1 are among the most frequent causes of bacterial keratitis in the urban population in temperate climates. Table 5.1 The most common bacterial pathogens that cause keratitis Table 5.1 The most common bacterial pathogens that cause keratitis Typical characteristics of infection Infection progresses slowly with little pain. As in Staphylococcus aureus infection. Typical serpiginous...

Optic Disk Drusen

Drusen are yellowish lobular bodies in the tissue of the optic disk that are usually bilateral (in 70 of all cases). Ophthalmoscopy can reveal superficial drusen but not drusen located deep in the scleral canal. In the presence of optic disk drusen, the disk appears slightly elevated with blurred margins and without an optic cup (Fig. 13.9). Abnormal morphologic signs such as hyper-emia and nerve fiber edema will not be present. However, bleeding in lines along the disk margin or subretinal...

Oculomotor nerve palsy

Complete oculomotor nerve palsy Every intraocular and almost every extraocular muscle is affected, with loss of both accommodation and pupillary light reaction. The failure of the parasympathetic fibers in the oculomotor nerve produces mydriasis. Ptosis is present because the levator pal-pebrae is also paralyzed. The paralyzed eye deviates in extorsion and depression as the function of the lateral rectus and superior oblique is preserved. Patients do not experience diplopia because the ptotic...

Blepharophimosis

This refers to shortening of the horizontal palpebral fissure without pathologic changes in the eyelids. The palpebral fissure, normally 28-30 mm wide, may be reduced to half that width. Blepharophimosis is a rare disorder that is either congenital or acquired (for example, from scar contracture or aging). As long as the center of the pupil remains unobstructed despite the decreased size of the palpebral fissure, surgical enlargement of the palpebral fissure (by canthotomy or plastic surgery)...

Intraocular Portion of the Optic Nerve

The intraocular portion of the optic nerve is visible on ophthalmoscopy as the optic disk. All the retinal nerve fibers merge into the optic nerve here, and the central retinal vessels enter and leave the eye here. The complete absence of photoreceptors at this site creates a gap in the visual field known as the blind spot. Shape and size The optic disk (Fig. 13.2) is normally slightly vertically oval with an average area of approximately 2.7 mm2 and a horizontal diameter of approximately 1.8...

Herpes Zoster Keratitis Definition

Keratitis due to endogenous recurrence of chickenpox (caused by the varicella-zoster virus see herpes zoster ophthalmicus). Etiology Proceeding from the trigeminal ganglion, the virus reinfects the region supplied by the trigeminal nerve. The eye is only affected where the ophthalmic division of the trigeminal nerve is involved. In this case, the nasociliary nerve supplying the interior of the eye will also be affected. Hutchinson's sign, vesicular lesions on the tip of the nose, will be...

Chlamydial Conjunctivitis

Chlamydia are Gram-negative bacteria. 1 See Appendix for side effects of medications Lang, Ophthalmology 2000 Thieme All rights reserved. Usage subject to terms and conditions of license. Table 4.2 Overview of infectious conjunctivitis Table 4.2 Overview of infectious conjunctivitis Staphylococcal Subacute Purulent discharge, conjunctivitis blepharitis, superficial punctate keratitis, thickening of the conjunctivitis at the lim-bus Staphylococci Gram-posi-tive cluster form Streptococcal...

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....

Surgical Treatment Vitrectomy Definition

Retinal Detachment Treatment

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...

Asteroid Hyalosis

These usually unilateral opacities of the vitreous body (75 of all cases) are not all that infrequent. They are thought to be linked to diabetes mellitus and hypercholesterolemia. The disorder is characterized by white calcific deposits that are associated with the collagen fibers of the vitreous body and therefore are not very mobile. Most patients are not bothered by these opacities. However, the examiner's view of the fundus can be significantly obscured by snow flurries of white opacities....

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...

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...

Examination Methods Visual Acuity see Chapter 1 1221 Examination of the Fundus

Mirror Fundus

Direct ophthalmoscopy (Fig. 12.4a see also Fig. 1.13) A direct ophthalmoscope is positioned close to the patient's eye. The examiner sees a 16-power magnified image of the fundus. Advantages. The high magnification permits evaluation of small retinal findings such as diagnosing retinal microaneurysms. The dial of the ophthalmoscope contains various different plus and minus lenses and can be adjusted as necessary. These lenses compensate for refractive errors in both the patient a Direct...

Developmental Anomalies of the Lens

Anomalies of lens shape are very rare. Lenticonus is a circumscribed conical protrusion of the anterior pole (anterior lenticonus) or posterior pole (posterior lenticonus). A hemispherical protrusion is referred to as lentiglobus. Symptoms include myopia and reduced visual acuity. Some patients with Alport's syndrome (kidney disease accompanied by sensorineural hearing loss and anomalies of lens shape) have anterior lenticonus. Posterior lenticonus may be associated with a lens opacity (Fig....

Treatment and Avoidance of Strabismic Amblyopia

Strict occlusion therapy by eye patching or eyeglass occlusion is the most effective method of avoiding or treating strabismic amblyopia. Primarily the leading eye is patched. 478 17 Ocular Motility and Strabismus Occlusion therapy of amblyopia. - 478 17 Ocular Motility and Strabismus Occlusion therapy of amblyopia. - Fig. 17.11 The leading eye is patched for several hours or days at a time to improve visual acuity in the deviating amblyopic eye. Fig. 17.11 The leading eye is patched for...

Staphyloma and Ectasia

Staphyloma refers to a bulging of the sclera in which the underlying uveal tissue in the bulge is also thinned or degenerated. By far the most common form is posterior staphyloma in severe myopia, a bulging of the entire posterior pole of the eyeball (Fig. 6.1). Staphyloma can also occur secondary to scleritis (see Fig. 6.4). Ectasia is a thinning and bulging of the sclera without uveal involvement, as can occur secondary to inflammation. Both staphyloma and ectasia are secondary or incidental...

Epithelial Conjunctival Tumors 4531 Conjunctival Cysts

Conjunctival cysts are harmless and benign. Occurrence is most often postoperative (for example after surgery to correct strabismus), post-traumatic, or spontaneous. They usually take the form of small clear fluid-filled inclusions of conjunctival epithelium whose goblet cells secrete into the cyst and not on to the surface (Fig. 4.21 ). Cysts can lead to a foreign-body sensation and are removed surgically by marsupialization (removal of the upper half of the cyst). 106 4 Conjunctiva...

Disadvantages of Contact Lenses

Contact lenses exert mechanical and metabolic influences on the cornea. Therefore, they require the constant supervision of an ophthalmologist. Mechanical influences on the cornea can lead to transient changes in refraction. Spectacle blur can result when eyeglasses suddenly no longer provide the proper correction after removing the lens. Contact lenses require careful daily cleaning and disinfection. This is more difficult, time-consuming, and more expensive than eyeglass care and is...

Disorders of the Lower Lacrimal System 331 Dacryocystitis

Inflammation of the lacrimal sac is the most frequent disorder of the lower lacrimal system. It is usually the result of obstruction of the nasolacrimal duct and is unilateral in most cases. Epidemiology The disorder most frequently affects adults between the ages of 50 and 60. Etiology The cause is usually a stenosis within the lacrimal sac. The retention of tear fluid leads to infection from staphylococci, pneumococci, Pseudomonas, or other pathogens. Symptoms Clinical symptoms include highly...

Vitritis and Endophthalmitis Definition

This refers to acute or chronic intraocular inflammation due to microbial or immunologic causes. In the strict sense, any intraocular inflammation is endophthalmitis. However, in clinical usage and throughout this book, endophthalmitis refers only to inflammation caused by a microbial action that also involves the vitreous body (vitritis). On the other hand, isolated vitritis without involvement of the other intraocular structures is inconceivable due to the avascularity of the vitreous...

Retinal Arterial Occlusion Definition

Retinal infarction due to occlusion of an artery in the lamina cribrosa or a branch retinal artery occlusion. Epidemiology Retinal artery occlusions occur significantly less often than vein occlusions. Etiology Emboli (Table 12.2) are frequently the cause of retinal artery and branch retinal artery occlusions. Less frequent causes include inflammatory processes such as temporal arteritis (Horton's arteritis). 12.3 Vascular Disorders 321 Table 12.2 Causes of embolus in retinal artery occlusion...

Normal and Abnormal Fundus Findings in General

Normal fundus The retina is normally completely transparent without any intrinsic color. It receives its uniform bright red coloration from the vascula-ture of the choroid (Fig. 12.8). The vessels of the choroid themselves are obscured by the retinal pigment epithelium. Loss of transparency of the retina is a sign of an abnormal process (for example in retinal edemas, the retina appears whitish yellow). The optic disk is normally a sharply defined, yellowish orange structure (in teenagers it is...

Examination of the Cornea

The cornea is examined with a point light source and a loupe (Fig. 1.10). The cornea is smooth, clear, and reflective. The reflection is distorted in the presence of corneal disorders. Epithelial defects, which are also very painful, will take on an intense green color after application of fluorescein dye corneal infiltrates and scars are grayish white. Evaluating corneal sensitivity is also important. Sensitivity is evaluated bilaterally to detect possible differences in the reaction of both...

Other causes for exposure keratitis without facial nerve palsy include

Uncompensated exophthalmos in Graves' disease. Insufficient eyelid closure following eyelid surgery to correct ptosis. Insufficient eye care in patients receiving artificial respiration on the intensive care ward. Symptoms Similar to superficial punctate keratitis (although usually more severe) but unilateral. Diagnostic considerations Application of fluorescein dye will reveal a typical pattern of epithelial lesions (Fig. 5.11 i). Treatment Application of artificial tears is usually not...

Neonatal Conjunctivitis

Epidemiology Approximately 10 of the newborn contract conjunctivitis. Etiology (Table 4.3) The most frequent pathogens are Chlamydia, followed by gonococci. Neonatal conjunctivitis is less frequently attributable to other bacteria such as Pseudomonas aeruginosa, Haemophilus, Staphylococcus aureus and Streptococcus pneumoniae, or to herpes simplex. The infection occurs at birth. Chlamydia infections are particularly important because they are among the most common undetected maternal genital...

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....

Xanthelasma Definition

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...

Forms of retinitis pigmentosa

Rod-cone dystrophy (classic retinitis pigmentosa, by far the most frequent form). 2. Cone-rod dystrophy (inverse retinitis pigmentosa). 3. Sectoral retinitis pigmentosa. 4. Retinitis pigmentosa sine pigmento (form without pigment). 5. Unilateral retinitis pigmentosa. 6. Leber's amaurosis (form occurring in early childhood). 7. Retinopathy punctata albescens (punctate retinitis). 8. In combination with other disorders in syndromes and metabolic disorders such as mucopolysaccharidoses, Fanconi's...

Stargardts Disease Definition

This is a macular dystrophy that proceeds from the retinal pigment epithelium. Inheritance Autosomal recessive disorder. Epidemiology Stargardt's disease is rare. Symptoms Progressive loss of visual acuity occurs between the ages of 10 and 20 years. Findings and diagnostic considerations Initial findings are slight with white fleck lesions in the macular region (Fig. 12.29), which may occur in combination with lesions in the entire fundus (fundus flavimaculatus). The electroretinogram and...

Evaluation of Tear Drainage

Tear Lacrimal Drainage System

Conjunctival fluorescein dye test Normal tear drainage can be demonstrated by having the patient blow his or her nose into a facial tissue following application of a 2 fluorescein sodium solution to the inferior fornix. Probing and irrigation These examination methods are used to locate stenoses. After application of a topical anesthetic, a conical probe is used to dilate the punctum. Then the lower lacrimal system is flushed with a physiologic saline solution introduced through a blunt cannula...

Conjunctiva Inclusion Conjunctivitis

Epidemiology Inclusion conjunctivitis is very frequent in temperate countries. The incidence in western industrialized countries ranges between 1.7 and 24 of all sexually active adults depending on the specific population studied. Etiology Oculogenital infection (Chlamydia trachomatis serotype D-K) is also caused by direct contact. In the newborn (see neonatal conjunctivitis), this occurs at birth through the cervical secretion. In adults, it is primarily transmitted during sexual intercourse,...

Eye 63 Diopters

16.1.1 Uncorrected and Corrected Visual Acuity Uncorrected visual acuity This refers to the resolving power of the eye without corrective lenses. Corrected visual acuity This refers to the resolving power of the eye with an optimal correction provided by corrective lenses (determined by visual acuity testing). Both uncorrected visual acuity and corrected visual acuity provide information on how far apart two objects must be for the eye to perceive them as distinct objects (minimum threshold...

Measuring the Density of the Corneal Epithelium

Placido Disc Keratoconus

A sufficiently high density of endothelial cells is very important for the transparency of the cornea (see Transparency). Gross estimation of the endothelial cell density is possible for a circumscribed area of the cornea using a slit lamp and indirect illumination. Both the viewing axis and illumination axis are offset from the visual axis. Precise quantification and morphologic evaluation of endothelial cells over large areas is only possible by means of specular microscopy, a technique...

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...

Corneal and Conjunctival Foreign Bodies

Epidemiology Foreign bodies on the cornea and conjunctiva are the commonest ocular emergency encountered by general practitioners and ophthalmologists. Etiology Airborne foreign bodies and metal splinters from grinding or cutting disks in particular often become lodged in the conjunctiva or cornea or burn their way into the tissue. Symptoms and diagnostic considerations The patient experiences a foreign-body sensation with every blink of the eye. This is accompanied by epiphora (tearing) and...

Metabolism and aging of the lens The lens is nourished by diffusion from

Nucleus Lens

In this respect it resembles a tissue culture, with the aqueous humor as its substrate and the eyeball as the container that provides a constant temperature. The metabolism and detailed biochemical processes involved in aging are complex and not completely understood. Because of this, it has not been possible to influence cataract development (see Cataract, p. 170) with medications. The metabolism and growth of the lens cells are self-regulating. Metabolic activity is...

Secondary Angle Closure Glaucoma Definition

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...

Schizo Tonometry

Indentation Tonometry

Function The pupil refers to the central opening in the iris. It acts as an aperture to improve the quality of the resulting image by controlling the amount of light that enters the eye. Pupillary light reflex This reflex arc consists of an afferent path that detects and transmits the light stimulus and an efferent path that supplies the muscles of the iris (Fig. 9.1). Parasympathetic pupillary reflex pathway. Parasympathetic pupillary reflex pathway. Afferent path. This path begins at the...

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...

Conjunctival Degeneration and Aging Changes 431 Pingueculum Definition

Palpebral Fold Defined

Harmless grayish yellowthickening of the conjunctival epithelium in the palpebral fissure. Epidemiology Pinguecula are the most frequently observed conjunctival changes. Etiology The harmless thickening of the conjunctiva is due to hyaline degeneration of the subepithelial collagen tissue. Advanced age and exposure to sun, wind, and dust foster the occurrence of the disorder. Symptoms Pingueculum does not cause any symptoms. Diagnostic considerations Inspection will reveal grayish yellow...

Degenerative Myopia Definition

The fundus in degenerative myopia is characterized by abnormal chorioretinal atrophy. Epidemiology Chorioretinal atrophy due to myopia is rare. Pathogenesis The atrophy usually occurs in the presence of severe myopia exceeding minus 6 diopters. The causes include stretching changes in the retina, choroid, and Bruch's membrane due to the elongated globe in axial myopia. Symptoms Loss of visual acuity occurs where there is macular involvement. Findings and diagnostic considerations Typical signs...

Coats Disease Definition

Coats Disease Retina Changes

Congenital retinal telangiectasia with vascular anomalies that nearly always presents unilaterally and can lead to exudation and eventually to exudative retinal detachment. Epidemiology This rare disorder manifests itself in young children and teenagers. Boys are usually affected (in about 90 of all cases). H Coats' disease usually occurs in young and teenage boys. It is nearly always unilateral. Pathogenesis Telangiectasia and aneurysms lead to exudation and eventually to retinal detachment....

Forms of cataracts in systemic disease

The typical diabetic cataract is rare in young diabetic patients. Transient metabolic decompensation promotes the occurrence of a typical radial snowflake pattern of cortical opacities (snowflake cataract). Transient hyperopia and myopia can occur. H Diabetic cataract progresses rapidly. Senile cataracts are observed about five times as often in older diabetics as in patients the same age with normal metabolism. These cataracts usually also occur two to three years earlier....

Pseudopterygium

A pseudopterygium due to conjunctival scarring differs from a pterygium in that there are adhesions between the scarred conjunctiva and the cornea and sclera. Causes include corneal injuries and or chemical injuries and burns. Pseudopterygia cause pain and double vision. Treatment consists of lysis of the adhesions, excision of the scarred conjunctival tissue, and coverage of the defect (this may be achieved with a free conjunctival graft harvested from the temporal aspect). Fig. 4.4 Extensive...

Curative Corneal Procedures 5711 Penetrating Keratoplasty Fig 518a

Principle This involves replacement of diseased corneal tissue with a full-thickness donor graft of corneal tissue of varying diameter. A clear, regularly refracting button of donor cornea is placed in an opacified or irregularly refracting cornea. The corneal button is sutured with a continuous single or double suture (Fig. 5.19) or with interrupted sutures. (For special considerations in corneal transplants, see also Morphology and healing.) Penetrating keratoplasty can be performed as an...

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...

Examination of the Conjunctiva

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...

Endothelial dystrophy such as

- Fuchs' endothelial dystrophy (the most frequently encountered form of corneal dystrophy). Symptoms and diagnostic considerations All patients suffer from a steadily increasing loss of visual acuity due to the generally gradual opacification of the cornea. This loss of visual acuity may progress to the point where a corneal transplant becomes necessary. Macular dystrophy is the most rapidly debilitating form of the stromal dystrophies, resulting in a severe loss of visual acuity in the second...

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...

Primary Glaucoma 265 1032 Primary Angle Closure Glaucoma Definition

Acute episodic increase in intraocular pressure to several times the normal value (10-20 mm Hg) due to sudden blockage of drainage. Production of aqueous humor and trabecular resistance are normal. Epidemiology The incidence among persons over the age of 60 is one per thousand. Women are three times as likely to be affected as men. Inuit are more frequently affected than other ethnic groups, whereas the disorder is rare in blacks. Etiology (See also physiology and pathophysiology of aqueous...

Viral Keratitis

Viral keratitis is frequently caused by Other rare causes include cytomegalovirus, measles virus, or rubella virus. 5.4.5.1 Herpes Simplex Keratitis Epidemiology and pathogenesis Herpes simplex keratitis is among the more common causes of corneal ulcer. About 90 of the population are carriers of the herpes simplex virus. A typical feature of the ubiquitous herpes simplex virus is an unnoticed primary infection that often heals spontaneously. Many people then remain carriers of the neurotropic...

Conjunctival Papilloma

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...

Developmental Anomalies 231 Coloboma Definition

Congenital Coloboma

A normally unilateral triangular eyelid defect with its base at the margin of the eyelid occurring most often in the upper eyelid (Fig. 2.3). Epidemiology and etiology. Colobomas are rare defects resulting from a reduction malformation (defective closure of the optic cup). They are only rarely the result of an injury. Diagnostic considerations The disorder is often accompanied by additional deformities such as dermoid cysts or a microphthalmos. Congenital defects of the first embryonic...

Abnormal Changes in the Vitreous Body

11.4.1 Persistent Fetal Vasculature (Developmental Anomalies) The embryonic vascular system in the vitreous body and lens normally disappears completely, leaving only the hyaloid canal. Persistence of the vascular system is referred to as persistent fetal vasculature. The following section describes the varying degrees of severity of this syndrome as they relate to the vitreous body. Persistence of the anterior tunica vasculosa lentis leads to a persistent pupillary membrane. Mittendorf's dot...

The water content of the corneal stroma remains constant at 70

Combined action of the epithelium and endothelium maintains a constant water content the epithelium seals the stroma off from the outside, while the endothelium acts as an ion pump to remove water from the stroma. This requires a sufficiently high density of endothelial cells. Endothelial cell density is age-dependent normally it is approximately 2500 cells per mm2. At cell densities below 300 endothelial cells per mm2, the endothelium is no longer able to pump water out of the cornea,...

Vascular Disorders 1231 Diabetic Retinopathy Definition

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,...