Ординатура / Офтальмология / Английские материалы / Surgical Atlas of Orbital Diseases_Mallajosyula_2009

of patients with severe myopathy, or with a narrow boney orbital apex, or with tight lids limiting anterior displacement of tissues, compression of the optic nerve may ensue (Figure 6.5A).

TAO is an immune-mediated disease which is strongly associated with thyroid immune disorders such as Graves' disease or Hashimoto's thyroiditis. 90% of patients with orbitopathy have a current or past history of abnormal systemic thyroid hormone levels, while others may develop abnormal levels in the future. It is important to explain to patients that the orbitopathy is associated with, but not caused by, abnormal thyroid hormone levels, since patients often believe that the orbital disease should resolve once a euthyroid state is reached.

Thyroid gland epithelial cells have surface receptors which bind thyroid stimulating hormone (TSH, thyrotropin), a hormone secreted in pulses by the pituitary to control the release of thyroid hormone. In both Graves’ disease and Hashimoto's thyroiditis, circulating thyrotropin-receptor antibodies (TSH-R Antibodies, TRAb) are present which can bind to these same receptor sites, and initiate and perpetuate the disease.2 At least three subtypes of TRAb have been identified, presumed to arise from a small population of abnormal B-lymphocytes: (1) TSI (thyroid stimulating immunoglobulin), which causes hyperthyroidism;

(2) blocking TRAb, which prevents TSH from binding to thyroid cells and results in hypothyroidism;

Thyroid-Associated Orbitopathy 113

Figure 6.5A: Coronal CT scan near apex showing bilateral optic nerve crowding. This patient had impaired central vision (20/70, 20/

40), bilateral reduced color vision, and a right afferent pupil defect. VISA Score: V = 1/1 (optic neuropathy present)

Figure 6.4: Patient with TAO myopathy attempting to look up-wards.

She had bilateral upgaze limitation, the right reaching 30° and the left reaching 10°, based on the light reflexes on her cornea (VISA strabismus score = 3/3)

Figure 6.5B: Axial CT scan of same patient showing adequate medial wall decompression into ethmoid sinuses and resolution of optic neuropathy (V = 0/1; central vision 20/20 both eyes)

(3) binding TRAb, which binds onto TSH receptors transiently, and has little effect on overall thyroid hormone levels.

These circulating antibodies are thought to be mediators in orbitopathy as well, with the likely target being the orbital fibroblast.2 Orbital fibroblasts are present in extraocular muscle and in orbital fat. Orbital fibroblasts from patients with TAO have increased numbers of TSH-Receptors, which are thought to bind to circulating autoantibodies (TRAb), stimulating adipogenesis and deposition of hyaluronic acid within orbital muscle and fat, the histologic hallmark of TAO.

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Orbital fibroblasts in patients with TAO have also recently been shown to have an increased number of receptors to “insulin-like growth factor-1” (IGF-1 R), and serum from patients with TAO has been found to have circulating antibodies directed against IGF-1 receptors.15 Binding of IGF-1 receptors has been shown to attract and activate T- lymphocytes and macrophages through inflammatory mediators, which may be the mechanism of initiating and propagating the inflammatory and immune cascade in TAO.16

Course of Disease

As with other immune disorders such as rheumatoid arthritis or Sjogren’s disease, TAO typically has a progressive (active) inflammatory phase followed by a stable (inactive) postinflammatory phase. This pattern of the disease was first described by Rundle, and the plot of orbital disease severity against time has been called Rundle's curve.17,18 The steepness of the graph in the active phase reflects the acuity of progression, with a steeper slope often leading to more serious sequellae.11

The duration of the active phase may last from 6-18 months, during which the patient may experience inflammatory symptoms of orbital discomfort, periocular and conjunctival edema and redness, and progression in proptosis, strabismus or optic neuropathy. Management during this phase is aimed at modulating the immune response and reducing the inflammation, usually with the use of steroids, radiotherapy, or other immunosuppressive agents, and hopefully limiting the destructive consequences of the active phase.

A useful analogy for patients is that the inflammatory phase is like a house on fire. While ignited, efforts are made to staunch the flames or allow them to smolder if not too severe. Reconstruction is not carried out while the fire is still active.

Once the disease has become quiescent, surgery may be offered to rectify damage resulting from the active stage, including reducing proptosis, aligning muscles, narrowing eyelid apertures, and debulking fat pockets in the eyelids. This would be similar to repairs being carried out after the house fire was suppressed.

Reactivation of disease is fairly uncommon,19 occurring in less than 5% of individuals, and is

sometimes associated with a major life stressor such as a family death, divorce or loss of job.

Clinical Classification

One of the challenges in TAO is how to classify and grade its various clinical manifestations so that appropriate management can be instituted.

Most ophthalmologists are familiar with Dr Werner’s NO SPECS classification that graded various symptoms and signs associated with the disease and assigned a global severity score.20 While this has served as a useful mnemonic for the different features of TAO, it is weak in terms of defining management and doesn't assess whether the disease is in the active or inactive, postinflammatory phase.

In 1989, Drs Mourits et al introduced a clinical activity score (CAS) to stage and grade the inflammatory phase of the disease.21

The VISA Classification

We have recently introduced the VISA classification which is a clinical recording form designed for the office, and which separates the various clinical features of TAO into four parameters: V (vision, optic neuropathy); I (inflammation, congestion); S (strabismus, motility restriction); A (appearance, exposure).22

The basic visit form (Figure 6.6) includes the four sections recording historical symptoms on the left and signs on the right. After each section is a progress row (better, same, worse), recording both the patient's and clinician's impression of the course of the disease since the last visit. The layout is designed to simplify data recording and possible later research data collation. Individual measurements may be completed in as much or little detail as the clinician chooses. At the end of the form is a summary grade for the activity and severity for each of the four disease parameters and a space for investigations and management plan.

On the first visit, the date and rate of onset of both the systemic and orbital symptoms should be recorded, since this may help predict the ultimate severity of the inflammatory phase.

a) Vision/optic neuropathy: The focus of this section is to identify TAO optic neuropathy. The history includes visual blurring or color desaturation and the progress and duration of symptoms.

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Objective measures of optic neuropathy include a loss in central visual acuity and color vision, an afferent pupil defect, and infrequently congestion or pallor of the optic nerve.

Ancillary testing includes coronal CT or MR Scans to confirm crowding of the orbital apex, standardized visual fields, and rarely VEP or optic nerve head photos. As a summary grade, VISA lists optic neuropathy as present or absent since most clinicians would attempt some treatment for this condition if present. The severity of the neuropathy is reflected in the individual measurements of central and color vision.

My usual treatment for TAO optic neuropathy initially is high dose corticosteroids either by intravenous route (1 gram Methyl-prednisolone over 30 minutes on alternate days for 3 treatments) or oral route (100 mg prednisone daily on a tapering dose) with an expectation that vision should improve within days of therapy. In most cases, this treatment will cause incomplete or only temporary visual improvement so that surgical decompression of the medial wall is required (through a Lynch, transcaruncular or endoscopic transethmoidal approach) in order to relieve pressure more permanently on the optic nerve at the crowded orbital apex (Figure 6.5A and B).

I often arrange adjunctive radiotherapy subsequent to the decompression if the disease is active to prevent further enlargement of the muscles and recurrence of neuropathy. Radiotherapy is administered using a lateral port focused behind the globe to minimize the risk of retinal or lens exposure; it is divided into 10 fractions of 200 rads over two weeks23 and is contraindicated in diabetics because of the risk of inciting or aggravating retinopathy.24 Although radiotherapy remains controversial, it is still widely used and many clinicians believe it is beneficial for certain aspects of TAO, including optic neuropathy and significant inflammation.25 Success of therapy for TAO optic neuropathy from both a clinical or research standpoint is based on specific improved measurements for central vision, color vision and visual fields.

b) Inflammation/congestion: Symptoms of ocular and periocular soft tissue inflammation include orbital aching at rest or with movement, and eyelid or conjunctival swelling and redness.

The Clinical Activity Score (CAS) described and validated by Mourits and the Amsterdam Orbitopathy group assigns one point for each of the following: orbital pain at rest, orbital pain with movement, chemosis, caruncular edema, eyelid edema, conjunctival injection and eyelid injection.21

The VISA Inflammatory Score modifies the CAS slightly by widening the grade for chemosis and lid edema from 0-2. Chemosis is graded as 1 if the conjunctiva lies behind the grey line of the lid and as 2 if it extends anterior to the grey line (Figures 6.3A and 6.7A). Lid edema is graded as 1 if it is present but not causing overhanging of the tissues, and as 2 if it causes a roll in the lid skin including festoons in the lower lid (Figures 6.3A and 6.7A). The worst scores from any of the four eyelids are recorded in the inflammatory score table on the far right section of the table. The pain score is based on the patient's report of deep orbit discomfort rather than ocular surface irritation (0 = no pain, 1 = pain with movement, 2 = pain at rest). The additional grading scores for chemosis and lid edema allow for documentation of more subtle changes in inflammatory features between visits. An additional point is assigned for diurnal variation of symptoms, to reflect the variability in congestion typically seen during the active phase.

Treatment of active inflammation in TAO depends on its inflammatory score and evidence of progression. If the score is less than 4 out of 10, and there is no deterioration based on history or sequential clinical examination, conservative management is offered with reassurance, cool compresses, nocturnal head elevation, and nonsteroidal anti-inflammatories. In general, if the inflammatory grade is 5 or more, or if there is subjective or objective evidence of progression in the inflammation, more aggressive therapy should be considered, including oral or intravenous corticosteroids, radiotherapy, and in refractory cases, immunosuppressive agents (Figures 6.3A and B, 6.7A and B). Combination therapy is receiving increasing attention in severe, progressive cases and interest is also turning to new immunomodulatory agents, such as anti-tumor necrosis factor agents (etanercept, infliximab) or B-lymphocyte directed therapy (rituximab).28 The hope from greater understanding of the immunogenic mechanisms in this disease is to

Figure 6.7A: Patient with severe active orbitopathy: V = 1/1 (optic neuropathy present); I = 10/10 (2/2 pain, 2/2 chemosis with conjunctiva overlying eyelid margins, 2/2 eyelid edema of left lower eyelid, 1/1 caruncular edema, 1/1 redness of conjunctiva, 1/1 redness of eyelid,

1/1 progression in symptoms over past month)

Figure 6.7B: Same patient 2 days following 3 doses of intravenous methyl-prednisolone with marked reduction in inflammatory signs.

VISA Score: V = 1/1 optic neuropathy (improved vision, but still showing impaired central and color vision); I = 4/10 (0/2 pain, 1/2 chemosis with conjunctiva behind grey line of lower lid, 1/2 eyelid edema, with resolution of eyelid overhang, 0/1 caruncular edema, 1/1 conjunctival redness, 0/1 eyelid redness, 1/1 diurnal variation)

identify markers of progressive, more severe disease so that earlier treatment and more specific immunotherapy may be developed.

c) Strabismus / motility restriction: The symptoms for strabismus include a progression from no diplopia, diplopia with horizontal or vertical gaze, intermittent diplopia in straight gaze, and constant diplopia in straight gaze.

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Ocular ductions can be graded from 0° to 45° in four directions using the Hirschberg principle: the patient is asked to look as far as possible up, down, right and left while the observer points a bright light at the eyes and studies the light reflex on the surface of the eye. If the light reflex hits the edge of the pupil, the eye has moved 15°, between the pupil edge and the limbus, 30° and at the limbus, 45° (Figure 6.4).

Strabismus can be measured objectively by prism cover testing in different gaze directions.

Ancillary testing includes using the Goldmann perimeter to quantify ocular ductions in four directions.29, 30 The patient keeps both eyes open and follows the V4e light target, tapping a coin when the image becomes double.

Management of strabismus depends on whether the orbitopathy is inflamed (measured in the previous section) or if there is evidence of progression in symptoms and signs. If inflammation is present, this is managed first, either with conservative treatment or with anti-inflammatories or radiotherapy (Figure 6.8A). During this stage, the strabismus can be managed with patching one eye or with Fresnel prisms. Once the inflammatory score has dropped to zero and there is no evidence of progression, management of strabismus might include prisms or surgical alignment (Figure 6.8B).

d) Appearance/exposure: Symptoms in this category include appearance concerns such as bulging of the eyes, eyelid retraction and fat pockets, as well as exposure complaints of foreign body sensation, glare, dryness or secondary tearing.

Objective measures of appearance change include eyelid retraction (measured in millimeters), proptosis (measured with the Hertel exophthalmometer), and documentation of redundant skin and fat prolapse. Measures of exposure include corneal staining or ulceration.

Photographs can document the appearance changes.

Management of appearance and exposure changes depend on the inflammatory stage of the disease. During the inflammatory phase (documented progression in any of the parameters or an inflammatory score > 5), lubricant drops and

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Figure 6.8A: Patient with active TAO and strabismus (VISA Score: I = 7/10, S = 3/3, strabismus in primary gaze). Anti-inflammatory treatment was instituted and one eye was patched for comfort

Figure 6.8B: Once the disease had progressed into the postinflammatory (inactive) phase, alignment surgery was performed:

(VISA Score: V = 0/1; I = 0/10; S = 0/3, A = 0/3)

ointments can relieve ocular irritation. Rarely a tarsorrhaphy or emergency orbital decompression may be required for severe exposure or corneal ulceration. Once the inflammatory phase has settled, management for proptosis might include orbital decompression and for eyelid retraction may include upper lid lowering from an anterior or posterior approach or lower lid elevation.31 These surgical measures often relieve many of the exposure complaints (Figures 6.2A and B, 6.3A and B).

e) Application of the VISA classification: The VISA Classification clusters the four functions disrupted by TAO in a logical sequence for recording and management. Subjective input and reproducible objective measurements are recorded for each section and a global severity grade can be assigned for each function. The subjective and objective progress and

tempo of disease can be documented to reflect disease activity. The classification system has been validated by showing that two clinicians could use the forms to assess patients independently with different manifestations of TAO and to choose similar management plans.22 It is currently being assessed by members of the International Thyroid Eye Disease Study (ITEDS) Group and further refinements and validation will be conducted. A common method of documenting and classifying the disease parameters is critical for conducting multicenter clinical trials and to assess response to different therapies.

General Management Guidelines

Patients with TAO are often misdiagnosed initially, because the majority present with mild, nonspecific complaints such as tearing, irritation and light sensitivity as a result of exposure from mild lid retraction. Occasionally mild inflammatory features such as eyelid or conjunctival swelling may be interpreted as allergies or viral infections. Many of these patients are frustrated with their medical care by the time the correct diagnosis has been reached. More serious manifestations of the disease such as myopathy, proptosis and visual impairment generally develop rapidly and are more readily recognized.

Understanding what bothers the patient most about their condition helps to build rapport and to plan future management. Patients appreciate reassurance and education about the natural course of TAO. Clarify that their endocrinologist and family practitioner will work to control any thyroid dysfunction, and that while their orbitopathy may be linked to thyroid immune disorders, a euthyroid state does not necessarily lead to resolution of the orbitopathy. Emphasize that they can take positive steps to help their condition by quitting smoking and relieving stressors in their lives.

I take the time to explain what is predictable about the disease, mentioning that the disease is selflimited, and that those with a mild presentation and younger age are unlikely to progress to more serious complications. For those with more serious complications, I use the house-fire analogy to clarify the two stages of orbitopathy, and the role of antiinflammatory or immunomodulatory therapy in the active phase and surgical reconstruction if necessary in the postinflammatory stage. The internet provides a number of support groups and I also identify

patients who I have treated who are willing to talk to newly diagnosed patients to allow sharing of their experiences.

REFERENCES

1.Bahn RS, Heufelder AE. Pathogenesis of Graves' Ophthalmopathy. N Engl J Med 1993;329(20):1468-75.

2.Garrity JA, Bahn RS. Pathogenesis of Graves' Ophthalmopathy: Implications for Prediction, Prevention and Treatment. Am J Ophthalmol 2006;142(1):147-53.

3.Rootman J, Dolman PJ. Thyroid Orbitopathy (Chapter 8) in: Diseases of the Orbit. A Multidisciplinary Approach. Hagerstown: Lippincott Williams & Wilings, 2003.

4.Gerding MN, Terwee CB, Dekker FW et al. Quality of life in patients with Graves' Ophthalmopathy is markedly decreased: measurement by the medical outcomes study instrument. Thyroid 1997;7(6):885-89.

5.Bartley GB. The epidemiologic characteristics and clinical course of ophthalmopathy associated with autoimmune thyroid disease in Olmsted County, Minnesota. Trans Am Ophthalmol Soc 1994;92:477-588.

6.Kendall-Taylor P, Perros P. Clinical presentation of thyroid associated orbitopathy. Thyroid 1998;8:427-28.

7.Burch HB, Wartofsky L. Graves' Ophthalmopathy: current concepts regarding pathogenesis and management. Endocr Rev 1993;14:747-93.

8.Fatourechi V, Pajouhi M, Fransway AF: Dermopathy of Graves disease (pretibial myxedema). Review of 150 cases. Medicine (Baltimore) 1994;73(1):1-7.

9.Perros P, Kendall-Taylor P. Natural history of thyroid eye disease. Thyroid 1998;8:423-25.

10.Bartalena L, Marcocci C, Bogazzi F, et al. Relation between therapy for hyperthyroidism and the course of Graves Ophthalmopathy. N Engl J Med 1998;338:73-78.

11.Dolman PJ, Rootman J. Predictors of disease severity in thyroid-related orbitopathy. (Chap18) Orbital Disease. Present status and future challenges. Taylor and Francis, 2005.

12.Prummel MF, Wiersinga WM. Smoking and risk of Graves' disease. JAMA 1993;269:479-82.

13.Pfeilschifter J, Ziegler R. Smoking and endocrine ophthalmopathy: impact of smoking and current vs lifetime cigarette consumption. Clin Endocrinol (Oxf) 1996;45: 477-81.

14.Cruz AA, Akaishi PM, Vargas MA, et al. Association Between Thyroid Autoimmune Dysfunction and NonThyroid Autoimmune Diseases. Ophthalmic Plastic & Reconstr Surg 2007;23(2):104-08.

15.Pritchard J, Horst N, Cruikshank W, et al. Igs from patients with Graves' disease induce the expression of T cell chemoattractants in their fibroblasts. J Immunol 2002; 168: 942-50.

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16.Pritchard J, Han R, Horst N, et al. Immunoglobulin activation of T cell chemoattractant expression in fibroblasts from patients with Graves' disease is mediated through the insulin-like growth factor 1 receptor pathway. J Immunol 2003;170:6348-54.

17.Rundle FF. Development and course of exophthalmos and ophthalmoplegia in Graves' disease with special reference to the effect of thyroidectomy. Clin Sci 1945;5:177-94.

18.Rundle FF. Ocular changes in Graves' disease. QJM 1960; 29:113-26.

19.Selva D, Chen C, King G. Late reactivation of thyroid orbitopathy. Clin & Exp Ophthalmol 2004;32(1),46-50.

20.Werner, SC. Classification of the eye changes of Graves' disease. American J Ophthalmology 1969;68:646-48.

21.Mourits MP, Prummel MF, Wiersinga WM, et al. Clinical activity score as a guide in the management of patients with Graves' Ophthalmopathy. Clin Endocrinol 1997;47: 9-22.

22.Dolman PJ, Rootman J. VISA Classification for Graves' Orbitopathy. Ophthal Plast Reconstr Surg. 2006;22(5): 319-24.

23.Beckendorf V, Maalouf T, George J-L, et al. Place of radiotherapy in the treatment of Graves' orbitopathy. Int J Radiation Oncology Biol Phys 1999;43:805-15.

24.Viebahn M, Marricks ME, Osterloh MD. Synergism between diabetic and radiation retinopathy: a case report and review. Br J Ophthalmol 1991;75:29-32.

25.Cockerham KP, Mourits MPh, McNab AA, et al. Does radiotherapy have a role in the management of thyroid orbitopathy? Debate. Br J Ophthalmol 2002;86:102-04.

26.Kahaly G, Schrezenmeir J, Krause U, et al. Ciclosporin and prednisone vs prednisone in treatment of Graves' Ophthalmopathy: a controlled, randomized and prospective study. Eur J Clin Invest 1986;16(5):415-22.

27.Bartalena L, Marcocci C, Chiovato L, et al. Orbital cobalt irradiation combined with systemic corticosteroids for Graves' Ophthalmopathy: comparison with systemic corticosteroids alone. J Clin Endocrinol Metab 1983;56(6): 1139-44.

28.Leandro MJ, Edwards JC, Cambridge G. Clinical outcome in 22 patients with rheumatoid arthritis treated with B lymphocyte depletion. Ann Rheum Dis 2002;61:883-88.

29.Gerling J, Lieb B, Kommerell G. Duction ranges in normal probands and patients with Graves' ophthalmopathy, determined using the Goldmann perimeter. Int Ophthalmol. 1998;21(4):213-21.

30.Dolman PJ, Kendler D, Rootman J. Measuring ocular excursions in Graves' Orbitopathy. (Abst) International Congress of Ophthalmology 2004.

31.Looi, A, Sharma B, Dolman PJ. A Modified Posterior Approach for Upper Eyelid Retraction. Ophthalmic Plast Reconst Surg 2006;22(6).

Many disease processes such as cancers, infections, or inflammations present with overlapping clinical manifestations, because of the confined nature of the orbital space. Also, with the multitude of muscular, neurovascular, sensory, and glandular structures located close to each other in this space, precise anatomic localization of various biologic processes can be difficult.

Orbital infections and inflammations present to the clinician with similar findings: periorbital edema, erythema, proptosis, and pain. History and clinical examination determine the work-up required to better define the disease process. Orbital infections continue to be associated primarily with diseases of the paranasal sinuses.1 Hemophilus influenza type B is no longer a significant pathogen, because of an effective vaccine.2 Fungal infections extending to the orbit are becoming more frequent, due to the increased prevalence of immunocompromised patients.3

Infections of the orbit are uncommon, but they are potentially devastating infections that can quickly result in blindness, meningitis, or death. The emergency physician must make a rapid and accurate diagnosis and then quickly initiate therapy because visual loss is associated directly with the length of time to definitive treatment.

Smith and Spencer4 classified orbital infections into 5 tiers which were later modified by Chandler et al.5

• Group I — Preseptal cellulitis

•Group IV — Orbital abscess

•Group V — Cavernous sinus thrombosis.

This classification system does not necessarily imply an order of disease progression; however, it helps explain the physical signs and symptoms of the various infections and helps organize treatment plans.6

Orbital infections may be divided into preseptal cellulitis, in which infection is located anterior to the orbital septum (a thin sheet of fibrous tissue arising from the periosteum of the orbital margin and inserting into the tarsal plates), and orbital cellulitis, in which there is infection of orbital tissues posterior to the orbital septum.7 Preseptal cellulitis generally responds to oral antibiotics and rarely has important sequelae. However, orbital cellulitis is a serious infection which may be complicated by abscess formation (subperiosteal, orbital, or brain), meningitis, septicemia, cavernous sinus thrombosis, and death. Although orbital cellulitis is related to ethmoid sinusitis in 70-80% of cases8, it may also develop after orbital or sinus trauma.9, 10 Prompt and appropriate management of patients with orbital cellulitis or at risk of developing this minimises the risk of complications.10 The possible causes of Mortality/Morbidity following orbital cellulitis are:

•Cavernous sinus thrombosis

•Brain abscess or meningitis

•Permanent vision loss.

Demographic Profile

Sex

Age

•Orbital infections are more common in persons younger than 19 years

•Orbital infections are more severe in adults.

Risk Factors

Past medical history significant for HIV, diabetes, immunosuppression, steroid use, renal disease, and travel is important.

Chronologic relation with an insect sting, allergic reaction, or trauma may suggest etiologies that mimic an orbital infection.

Etiological Causes of Orbital Infections

Bacterial infections

Bacteria, most commonly Streptococcus species, as well as Staphylococcus aureus, Hemophilus influenzae, and anaerobes, cause the vast majority of orbital infections.11

The incidence of Hemophilus influenzae type B has decreased since the early 1990s.2 In communities where CAMRSA is prevalent, ophthalmologists should maintain high index of suspicion and obtain microbial cultures and sensitivity studies to help guide antibiotic therapy for severe ophthalmic infections.12

Fungal infections

Fungal infections are less common than bacterial infections and occur more commonly in patients who are immunocompromised (e.g., those with HIV or diabetes). (Rhizopus, Mucor, Aspergillus)13

Phycomycosis, also known as mucormycosis, is the most common and most virulent fungal disease involving the orbit. The specific fungal genus involved is usually Mucor or Rhizopus. These fungi can involve the blood vessel wall and produce thrombosing vasculitis.Therapeutic measures include controlling the underlying metabolic abnormality, local surgical excision of infected tissues, and administration of amphotericin B.14, 3

Parasitic infections

Parasitic diseases may be prevalent in endemic areas (e.g. Mediterranean, Eastern Africa, Australia, Middle East Asia, South America, Eastern Europe) and in travelers to these areas, such infections are

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not uncommon. The causative organisms include E granulosus, T solium,Trichinella spiralis and the Onchocerca.15

Protozol infections

Although relatively uncommon, protozoal infections (most commonly with toxoplasma gondii) are seen in immunocompromised individuals.16

They have an increased likelihood for more severe and atypical presentations; this highlights the need for increased index of suspicion for HIV infection as ocular or orbital disease may be the first manifestation of life-threatening systemic toxoplasmosis.

Diagnosis

The diagnosis of orbital infections includes the following:

•A detailed history

•Vision

•Slit-lamp examination

•Extraocular motility

•Examination to document optic nerve function; including pupillary function

•Fundus examination

•Resistance to retropulsion

•Exophthalmometry: Hertel's exophthalmometry is the gold standard.

Imaging Studies17

•Computed Tomography (CT) scan — A CT scan of the orbit, sinuses, and frontal lobe is essential for every patient showing signs of orbital involvement. 2 mm cuts are ideal for the orbit. Both Axial and coronal scans shoud be carefully looked at, to obtain a 3-dimensional perspective.

•Magnetic Resonance Imaging (MRI) — While a CT scan provides enough information in most cases, a MRI scan may improve visualization of cavernous sinus thrombosis.

•Ultrasonography (USG) B-scan — An USG B- scan is mostly supportive in role, due to difficulty in interpretation of posterior orbital lesions.

•X-rays — Waters, Caldwell, submental vertex, and lateral view are mainly of historical interest.

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Other Tests

•Fiberoptic nasopharyngeal endoscopy:18 If any suspicion of mucormycosis (i.e. elevated blood glucose, leukemia, renal disease) exists, fiberoptic nasopharyngeal endoscopy should be performed (usually, by an otolaryngologist) to seek evidence of black eschar formation. Endoscopy assisted transnasal drainage is also useful in cases with evidence of associated sinus infections.

•Rapid plasma reagin (RPR), particularly in cases of insidious onset or with a history of syphilis.

•Cerebrospinal fluid (CSF) analysis for gram stain, cell count, cultures, and antigens may be considered in patients with associated central nervous system signs.

Emergency Department Care

•Adults with preseptal cellulitis and no signs of orbital involvement can be discharged on oral antibiotics with close follow-up care.19

—Adults with orbital signs need admission and IV antibiotics or antifungals are quickly initiated, under close supervision.

—Surgical intervention should be performed immediately, in cases with CT evidence of subperiosteal or orbital abscess — for drainage.19

—Surgical drainage is not always necessary for cellulitis; however, any patient with compromised vision (20/60 or worse) should receive immediate surgery for drainage and debridement.19

—Surgical drainage of abscesses (orbital or subperiosteal) is considered, even without visual loss. Drainage of sinuses should be considered in patients with associated sinusitis.

—Some patients can be monitored for 48 hours on IV antibiotics, with surgery performed for increasing proptosis, worsening visual acuity, or isolated muscle weakness. Surgery is performed after 48 hours if fever continues or antibiotics fail.20

—Orbital drainage decreases intraorbital pressure, decreases associated pressure on the nerve and retinal circulation, creates a

potential path for further drainage (the wound is closed with spaced sutures) and provides material for appropriately guided antibiotic therapy. We recommend orbital drainage by a trained orbital specialist as tissue in these cases are extremely vascular, friable and susceptible to damage.

—All children are admitted prior to initiating therapy21 even if they lack orbital signsbecause children are deficient in IgG2 and are predisposed to bacteremia.

For orbital cellulitis, oxacillin or nafcillin can be used with the addition of ampicillin and sulbactam in children to cover H influenzae.21 Patients who are allergic to penicillin can use vancomycin, clindamycin, or chloramphenicol. More and more organisms in countries like India are becoming resistant to conventional antibiotics. Methicillicin resistant Staphylococcus Aureus (MRSA) strains are not only prevalent in the nosocomial environment but are also found in the community. MRSA orbital cellulitis can quickly progress to irreversible blindness, despite antibiotic treatment.

—Alternatively, a cephalosporin (e.g. cefuroxime, cefoxitin, cefotetan) can be used alone.

—Nasal decongestants can be used to help drain the sinuses.

—Concomitant steroid therapy, once clinical improvement is documented on antibiotics, is started to decrease inflammation associated collateral damage to tissue and edema, thereby further decreasing intraorbital pressure.

Further Inpatient Care

Underlying disorders, if present (e.g. hyperglycemia, acidosis, infection, immunosuppression) are corrected.

Consultations: Consultation with an ENT surgeon or a neurosurgeon must be considered in cases without improvement, or in cases with involvement of sinuses or the nervous system.

Necrotizing fascitis, Orbital Tuberculosis and Community Acquired MRSA (CAMRSA) induced orbital cellulitis are rare entities in the spectrum of orbital infections. Although these infections are not so common, ophthalmologists should be well aware of these conditions, especially in endemic areas as