Ophthalmology A Short Textbook - part 5 doc

227 Isocoria with constricted or dilated pupils is primarily of interest to the neu- rologist and less so the ophthalmologist. These disorders are therefore dis- cussed at the end of the section. 9.4.1 Isocoria with Normal Pupil Size Relative Afferent Pupillary Defect Causes: Unilateral sensory disorder such as retinal detachment, neuritis of the optic nerve, atrophy of the optic nerve, or retinal vascular occlusion. Diagnostic considerations: ❖ Direct light reflex is decreased or absent (relative afferent pupillary defect) in the affected eye. ❖ The consensual light reflex in the affected eye is weak or absent but normal in the unaffected eye. ❖ The swinging flashlight test reveals dilation in the affected eye when illuminated (Marcus Gunn pupil) or reduced constriction and earlier dila- tion in the presence of lesser lesions (afferent pupillary defect). ❖ Near reflex is normal. ❖ Unilaterally reduced visual acuity and/or field of vision. Unilateral blindness (afferent defect) does not produce anisocoria. Bilateral Afferent Pupillary Defect Causes: Bilateral sensory disorder such as maculopathy or atrophy of the optic nerve. Diagnostic considerations: ❖ Delayed direct and consensual light reflexes. ❖ The swinging flashlight test produces identical results in both eyes (where disorder affects both sides equally). ❖ Near reflex is normal. ❖ Bilaterally reduced visual acuity and/or field of vision. 9.4 Pupillary Motor Dysfunction Lang, Ophthalmology © 2000 Thieme All rights reserved. Usage subject to terms and conditions of license. 228 9.4.2 Anisocoria with Dilated Pupil in the Affected Eye Complete Oculomotor Palsy Causes: ❖ Processes in the base of the skull such as tumors, aneurysms, inflamma- tion, or bleeding. Diagnostic considerations: ❖ Direct and consensual light reflexes without constriction in the affected eye (fixed pupil). ❖ Near reflex miosis is absent. ❖ Impaired motility and double vision. Sudden complete oculomotor palsy (loss of motor and parasympa- thetic function) is a sign of a potentially life-threatening disorder. In unconscious patients, unilateral mydriasis is often the only clinical sign of this. Tonic Pupil Causes: Postganglionic damage to the parasympathetic pathway, pre- sumably in the ciliary ganglion, that frequently occurs with diabetes mellitus, alcoholism, viral infection, and trauma. Diagnostic considerations: ❖ Direct and consensual light reflexes show absent or delayed reaction, possibly with worm-like segmental muscular contractions. ❖ Dilation is also significantly delayed. ❖ Near reflex is slow but clearly present; accommodation with delayed relaxation is present. ❖ Motility is unimpaired. ❖ Pharmacologic testing with 0.1% pilocarpine. – Significant miosis in the affected eye (denervation hypersensitivity). – No change in the pupil of the unaffected eye (too weak). ❖ Adie’s tonic pupil syndrome: The tonic pupil is accompanied by absence of the Achilles and patellar tendon reflexes. Tonic pupil is a relatively frequent and completely harmless cause of unilateral mydriasis. 9 Pupil Lang, Ophthalmology © 2000 Thieme All rights reserved. Usage subject to terms and conditions of license. 229 Iris Defects Causes: ❖ Trauma (aniridia or sphincter tears). ❖ Secondary to acute angle closure glaucoma. ❖ Synechiae (post-iritis or postoperative). Diagnostic considerations: Patient history and slit-lamp examination. Following Eyedrop Application (Unilateral Administration of a Mydriatic) Simple anisocoria Causes: Presumably due to asymmetrical supranuclear inhibition of the Edinger-Westphal nucleus. Diagnostic considerations: ❖ Direct and consensual light reflexes and swinging flashlight test show con- stant difference in pupil size. ❖ Near reflex is normal. ❖ Pharmacologic testing: Cocaine test (4% cocaine eyedrops are applied to both eyes and pupil size is measured after one hour): bilateral pupil dila- tion indicates an intact neuron chain. 9.4.3 Anisocoria with a Constricted Pupil in the Affected Eye Horner’s Syndrome Causes: Damage to the sympathetic pathway. ❖ Central (first neuron): – Tumors. – Encephalitis. – Diffuse encephalitis. ❖ Peripheral (second neuron): – Syringomyelia. – Diffuse encephalitis. – Trauma. – Rhinopharyngeal tumors. – Goiter. 9.4 Pupillary Motor Dysfunction Lang, Ophthalmology © 2000 Thieme All rights reserved. Usage subject to terms and conditions of license. 230 – Aneurysm. – Processes in the tip of the lung. ❖ Peripheral in the strict sense (third neuron): – Vascular processes. – Internal carotid aneurysm. Clinical Picture: ❖ Miosis (approximately 1 –2 mm difference) due to failure of the dilator pupillae muscle. ❖ Ptosis (approximately 1– 2 mm difference) due to failure of the muscle of Müller. ❖ Enophthalmos due to failure of the rudimentary lower eyelid retractors. This makes the lower eyelid project so that the eye appears smaller. This condition only represents a type of pseudoenophthalmos. ❖ Decreased sweat gland secretion (only present in preganglionic disorders as the sweat glands receive their neural supply via the eternal carotid). Diagnostic considerations: ❖ Direct and consensual light reflexes are intact, which distinguishes this disorder from a parasympathetic lesion); the pupil dilates more slowly (dilation deficit). ❖ Near reflex is intact. ❖ Pharmacologic testing with cocaine eyedrops: – Peripheral Horner’s syndrome: On the affected side, there is slight mydriasis (decrease in norepinephrine due to nerve lesion). On the unaffected side, there is significant mydriasis. – Central Horner’s syndrome: On the affected side, the pupil is dilated. On the unaffected side, the pupil is also dilated (the norepinephrine in the synapses is not inhibited). Following Eyedrop Application (Unilateral Administration of a Miotic as in Glaucoma Therapy) 9.4.4 Isocoria with Constricted Pupils Argyll-Robertson Pupil Causes: The precise location of the lesion is not known; presumably the dis- order is due to a lesion is in the pretectal region and the Edinger-Westphal nucleus such as tabes dorsalis (Argyll-Robertson phenomenon), encephalitis, 9 Pupil Lang, Ophthalmology © 2000 Thieme All rights reserved. Usage subject to terms and conditions of license. 231 diffuse encephalitis, syringomyelia, trauma, bleeding, tumors, and alco- holism. Diagnostic considerations: ❖ Direct and consensual light reflexes are absent. ❖ Near reflex is intact or there is overcompensation (the Edinger-Westphal nucleus is being controlled via the convergence center). ❖ The pupil is not round, and constriction is not always symmetrical. ❖ There is no reaction to darkness or pharmacologic stimuli. Bilateral Pupillary Constriction due to Pharmacologic Agents Causes: ❖ Morphine. ❖ Deep general anesthesia. ❖ Pilocarpine eyedrops. Toxic Bilateral Pupillary Constriction Causes: Mushroom poisoning. Inflammator y Bilateral Pupillary Constriction Causes: ❖ Encephalitis. ❖ Meningitis. 9.3.5 Isocoria with Dilated Pupils Parinaud’s Oculoglandular Syndrome Causes: Tumors such as pineal gland tumors that selectively damage fibers between the pretectal nuclei and the Edinger-Westphal nucleus. Diagnostic considerations: ❖ Fixed dilated pupils that do not respond to light. ❖ Normal near reflex. ❖ Limited upward gaze (due to damage to the vertical gaze center) and retraction nystagmus. 9.4 Pupillary Motor Dysfunction Lang, Ophthalmology © 2000 Thieme All rights reserved. Usage subject to terms and conditions of license. 232 Intoxication Causes: Atropine, spasmolytic agents, anti-parkinson agents, antidepres- sants, botulism (very rare but important), carbon monoxide, cocaine. Disorders ❖ Migraine. ❖ Schizophrenia. ❖ Hyperthyreosis. ❖ Hysteria. ❖ Epileptic seizure. ❖ Increased sympathetic tone (Bumke’s anxiety pupils). ❖ Coma. ❖ Agony. 9 Pupil Lang, Ophthalmology © 2000 Thieme All rights reserved. Usage subject to terms and conditions of license. 233 10 Glauc oma Gerhard K. Lang 10.1 Basic Knowledge Definition Glaucoma is a disorder in which increased intraocular pressure damages the optic nerve. This eventually leads to blindness in the affected eye. ❖ Primary glaucoma refers to glaucoma that is not caused by other ocular disorders. ❖ Secondary glaucoma may occur as the result of another ocular disorder or an undesired side effect of medication or other therapy. Epidemiology: Glaucoma is the second most frequent cause of blindness in developing countries after diabetes mellitus. Fifteen to twenty per cent of all blind persons lost their eyesight as a result of glaucoma. In Germany, approxi- mately 10% of the population over 40 has increased intraocular pressure. Approximately 10% of patients seen by ophthalmologists suffer from glau- coma. Of the German population, 8 million persons are at risk of developing glaucoma, 800 000 have already developed the disease (i.e., they have glau- coma that has been diagnosed by an ophthalmologist), and 80 000 face the risk of going blind if the glaucoma is not diagnosed and treated in time. Early detection of glaucoma is one of the highest priorities for the pub- lic health system. Physiology and pathophysiology of aqueous humor circulation (Fig. 10.1): The average normal intraocular pressure of 15 mm Hg in adults is significantly higher than the average tissue pressure in almost every other organ in the body. Such a high pressure is important for the optical imaging and helps to ensure several things: ❖ Uniformly smooth curvature of the surface of the cornea. ❖ Constant distance between the cornea, lens, and retina. ❖ Uniform alignment of the photoreceptors of the retina and the pigmented epithelium on Bruch’s membrane, which is normally taut and smooth. The aqueous humor is formed by the ciliary processes and secreted into the posterior chamber of the eye (Fig. 10. 1 [A]). At a rate of about 2 –6 µl per Lang, Ophthalmology © 2000 Thieme All rights reserved. Usage subject to terms and conditions of license. 234 Physiology of aqueous humor circulation. A E D C B Ciliary body Lens Iris CorneaCanal of Schlemm Trabecular meshwork Collecting channel Conjunctiva Episcleral venous plexus Fig. 10.1 As it flows from the nonpigmented cells of the ciliary epithelia A to beneath the conjunctiva D , the aqueous humor overcomes physiologic resistance from two sources: the resistance of the pupil B and the resistance of the trabecular meshwork C . minute and a total anterior and posterior chamber volume of about 0.2– 0.4 ml, about 1– 2% of the aqueous humor is replaced each minute. The aqueous humor passes through the pupil into the anterior chamber. As the iris lies flat along the anterior surface of the lens, the aqueous humor can- not overcome this pupillary resistance ( first physiologic resistance; Fig. 10.1 [B]) until sufficient pressure has built up to lift the iris off the surface of the lens. Therefore, the flow of the aqueous humor from the posterior chamber into the anterior chamber is not continuous but pulsatile. Any increase in the resistance to pupillary outflow (pupillary block) leads to an increase in the pressure in the posterior chamber; the iris inflates anteri- orly on its root like a sail and presses against the trabecular meshwork (Table 10. 2). This is the pathogenesis of angle closure glaucoma. Various factors can increase the resistance to pupillary outflow (Table 10. 1). The aqueous humor flows out of the angle of the anterior chamber through two channels: ❖ The trabecular meshwork (Fig. 10.1 [C]) receives about 85% of the out- flow, which then drains into the canal of Schlemm. From here it is con- 10 Glaucoma Lang, Ophthalmology © 2000 Thieme All rights reserved. Usage subject to terms and conditions of license. 235 Table 10.1 Factors that increase resistance to pupillary outflow and predispose to angle closure glaucoma Increased contact between the margin of the pupil and lens with: ❖ Small eyes ❖ Large lens (increased lens volume) due to: – Age (lens volume increases with age by a factor of six) – Diabetes mellitus (osmotic swelling of the lens) ❖ Miosis – Age (atrophy of the sphincter and dilator muscles) – Medications (miotic agents in glaucoma therapy) – Iritis (reactive miosis) – Diabetic iridopathy (thickening of the iris) ❖ Posterior synechiae (adhesions between lens and iris) Increased viscosity of the aqueous humor with: ❖ Inflammation (protein, cells, or fibrin in the aqueous humor) ❖ Bleeding (erythrocytes in the aqueous humor) ducted by 20 –30 radial collecting channels into the episcleral venous plexus (D). ❖ A uveoscleral vascular system receives about 15% of the outflow, which joins the venous blood (E). The trabecular meshwork (C) is the second source of physiologic resistance. The trabecular meshwork is a body of loose sponge-like avascular tissue between the scleral spur and Schwalbe’s line. Increased resistance in present in open angle glaucoma. Classification: Glaucoma can be classified according to the specific pathophysiology (Table 10. 2). The many various types of glaucoma are nearly all attributable to increased resistance to outflow and not to heightened secretion of aqueous humor. 10.1 Basic Knowledge Lang, Ophthalmology © 2000 Thieme All rights reserved. Usage subject to terms and conditions of license. 236 Table 10.2 Classification of glaucoma Form of glaucoma Incidence Open angle glaucoma Primary Over 90% of all glaucomas Secondary 2– 4% of all glaucomas Angle closure glaucoma Primary (pupillary block glaucoma) About 5% of all glaucomas Secondary 2– 4% of all glaucomas Juvenile glaucoma 1% of all glaucomas Absolute glaucoma This is not a separate form of glaucoma, rather it describes an often painful eye blinded by glaucoma Linse Linse Linse Linse Linse 10 Glaucoma Lang, Ophthalmology © 2000 Thieme All rights reserved. Usage subject to terms and conditions of license. [...]... filtration bleb is a sign of sufficient drainage of aqueous humor O Technique (Fig 10.16 a – c): First a conjunctival flap is raised, which may be either fornix-based or limbal-based Then a partial-thickness scleral flap is raised Access to the anterior chamber is gained via a goniotomy performed with a 1 .5 mm trephine at the sclerocorneal junction or via a rectangular trabeculectomy performed with a. .. The patient may also perceive rings of color around light sources at night, which has traditionally been regarded as a symptom of angle closure glaucoma Primary open angle glaucoma often does not exhibit typical symptoms for years Regular examination by an ophthalmologist is crucial for early diagnosis Primary open angle glaucoma can be far advanced before the patient notices an extensive visual field... pressure Elevated intraocular pressure in a routine ophthalmic examination is an alarming sign Twenty-four-hour pressure curve Fluctuations in intraocular pressure of over 5 – 6 mm Hg may occur over a 24-hour period Gonioscopy The angle of the anterior chamber is open and appears as normal as the angle in patients without glaucoma Ophthalmoscopy Examination of the optic nerve reveals whether glaucomatous... ingredients and preparations (examples) Parasympathomimetic agents O Direct parasympathomimetic agents: Cholinergic agents – Pilocarpine – Carbachol – Aceclidine Mode of action Indications Side effects O Primary O Younger paImprove drainage of open angle tients frequentaqueous humor glaucoma ly do not O Acute angle in primary tolerate the open angle temporary closure glaucoma The myopia due to glaucoma effect... with an automatic perimeter as studies of early glaucoma have shown that the initial defects occur in this area (see Fig 10.11 a – d) The figure shows the visual field defect in the early stages of glaucoma The blind spot is slightly enlarged (arrow), and an arc-shaped paracentral Bjerrum’s scotoma is present (arrowhead) The standardized examination conditions in automatic perimetry not only permit early... crucial to diagnose the disorder as early as possible because the prognosis for glaucoma detected in its early stages is far better than for advanced glaucoma Where increased intraocular pressure remains undiagnosed or untreated for years, glaucomatous optic nerve damage and the associated visual field defect will increase to the point of blindness Diagnostic considerations: Measurement of intraocular... significantly increases beyond the age of 40, reaching a peak between the ages of 60 and 70 Its prevalence among 40-year-olds is 0.9% as compared to 4.7% among patients over the age of 50 Lang, Ophthalmology © 2000 Thieme All rights reserved Usage subject to terms and conditions of license  252 10 Glaucoma There appears to be a genetic predisposition for primary open angle glaucoma Over one- third of glaucoma... insular paracentral scotomas converge and extend to the blind spot Further loss of superior nasal visual field Circumscribed horizontal penetration of the Bjerrum's scotoma into the nasal half of the field of vision A new inferior nasal scotoma is a sign of a superior temporal nerve fiber lesion A small central and peripheral residual field of vision remains The arc-shaped scotoma has expanded into a. .. with a shallow anterior chamber and an angle that is partially or completely closed, the iris protrudes anteriorly and is not uniformly illuminated (see Fig 1.12) 10.2.2 Slit-Lamp Examination The central and peripheral depth of the anterior chamber should be evaluated on the basis of the thickness of the cornea An anterior chamber that is less than three times as deep as the thickness of the cornea in... supplanted by applanation tonometry Applanation tonometry: This method is the most common method of measuring intraocular pressure It permits the examiner to obtain a measurement on a sitting patient within a few seconds (Goldmann’s method, see Fig 10 .5 a – c) or on a supine patient (Draeger’s method) A flat tonometer tip has a diameter of 3.06 mm for applanation of the cornea over a corresponding area . angle glaucoma Primary Over 90% of all glaucomas Secondary 2– 4% of all glaucomas Angle closure glaucoma Primary (pupillary block glaucoma) About 5% of all glaucomas Secondary 2– 4% of all glaucomas Juvenile glaucoma 1%. Intraocular Pressure Palpation (Fig. 1. 15, p. 15) : Comparative palpation of both eyeballs is a pre- liminary examination that can detect increased intraocular pressure. ❖ If the examiner can indent. all glaucomas Juvenile glaucoma 1% of all glaucomas Absolute glaucoma This is not a separate form of glaucoma, rather it describes an often painful eye blinded by glaucoma Linse Linse Linse Linse Linse 10 Glaucoma Lang,