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Clinical Examination of the Patient with Uveitis
Key Concepts
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A thorough clinical ophthalmic examination is critical for both diagnosis and assessment of response to therapy.
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Use of standardized grading scales for assessing intraocular inflammation can improve patient management.
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Standard grading scales are available for assessment of anterior chamber cells and flare and vitreous cells and haze.
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A detailed examination of the peripheral retina can reveal pars plana exudates, signs of retinal vasculitis, Delen-Fuchs nodules, or other lesions suggesting active inflammation or infection.
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Use of ancillary tests, such as optical coherence tomography angiography (OCTA), should supplement, but not replace, careful clinical examination.
The ocular examination of patients with uveitis is important not only to diagnose the disease correctly but also to determine the appropriate therapy. The examination will provide information that enables the examiner to generate a differential diagnosis and will allow the patient’s subjective complaints to be placed in the framework of objective clinical findings. In addition, the baseline examination findings become an important yardstick against which treatment success or failure will be measured. Many inflammatory diseases are chronic and require potentially toxic therapy. Therefore it is critical to accurately assess whether a patient is benefiting from treatment. This includes a thorough review of the patient’s previous medical records and accurate assessment of disease status at each clinic visit. A complete review of the patient’s medical records provides important information for planning new therapeutic approaches and guards against repeating therapies that were unsatisfactory in the past. Because a patient’s medical record is valuable in assessing response to therapy, it is important to accurately record the presence or absence of important physical findings in a reproducible and standardized manner. Furthermore, because many of the ophthalmic findings in inflammatory disease, such as vitreous cells and haze, are evaluated only by subjective means, the examiner should strive to maintain internal consistency in grading the severity of the observations and to standardize these observations, whenever possible. Importantly, standard grading scales should be used, whenever possible. The use of standard scales ensures consistency when different ophthalmologists are involved in the care of the patient over time. This also allows for comparison of cases with those reported in the literature.
Visual Acuity
Several factors can lead to reduced visual acuity in patients with uveitis or retinitis. A combination of corneal opacity, anterior chamber inflammation, cataract, and vitreous haze may exacerbate disturbance of retinal function caused by retinal edema, necrosis, or scarring. In addition, optic nerve function may be compromised after inflammation or glaucoma. It is important for the clinician to determine the cause of diminished vision because the therapeutic approach will vary, depending on the cause. For example, it would be inappropriate to increase the dose of prednisone to treat worsening vision caused by progressive posterior subcapsular cataract. Whatever type of visual acuity measurement is used, it must be performed under the same lighting conditions each time; otherwise the fluctuations induced by the testing environment will mask changes in vision caused by worsening disease or response to therapy. A best-corrected visual acuity measurement should be obtained either by refraction or, at the very least, with the use of a pinhole occluder. Near-vision measurement is also helpful because we have observed that improvement in near vision can precede improvement in distance vision by several weeks in patients with chronic macular edema.
The most common method to measure visual acuity is use of the Snellen eye chart. Like all eye charts, the Snellen chart helps assess a patient’s ability to read high-contrast letters, and its use is satisfactory if the vision is good. Unfortunately, the chart does not have enough sensitivity for use in patients with poor vision. There are no lines between 20/100 and 20/200 or between 20/200 and 20/400. In addition, there are too few letters on the lines above 20/100. Although an improvement in visual acuity from 20/200 to 20/125 may not be significant to the patient, the ability to measure this improvement is an important indicator that the current therapeutic approach is working. Because many patients with macular edema have visual acuity less than 20/80, initial improvement might be missed when the standard Snellen chart is used.
For these reasons, we have used the ETDRS chart initially developed for the evaluation of patients in the Early Treatment for Diabetic Retinopathy Study (ETDRS) ( Fig. 3.1 ). This chart has five letters per line, starting with the 20/200 line, and every set of three lines represents a doubling of the visual angle. Therefore improving from 20/40 to 20/20 represents the same level of improvement in visual function as does 20/80 to 20/40. If patients cannot read the 20/200 line while sitting 4 m from the chart, they are moved to 1 m from the chart, and the acuities are recorded as 5 over the appropriate denominator, that is, 5/200. Because each line has five letters, visual acuity can be expressed as the total number of letters read. The 1- and 4-m scales can be made continuous by adding 30 letters to those read at 4 m. The scale of visual acuity is then linear and continuous from 5/200 (five letters) to 20/12.5 (95 letters).
A computerized method for testing visual acuity for clinical research has been developed as an alternative to the standard ETDRS testing protocol. A multicenter study comparing this electronic visual acuity testing algorithm (E-ETDRS) with the standard testing protocol showed high test–retest reliability and good concordance of the electronic protocol with the standard ETDRS testing. This new method allows electronic capture of data, eliminates computational errors, reduces testing time, and may help reduce technician bias. Mobile technology is also being used to measure visual acuity, and some of these devices have demonstrated appropriate photometric characteristics, including luminance and contrast. However, reliability and validity of self-administered visual acuity measurements need to be assessed. New visual acuity charts or assessment of reading speed may be useful in assessing patients with more severe vision loss or macular disease, but, again, it is critical to validate these methods for their widespread use.
External Examination
As stated earlier, a detailed examination of the skin can provide useful diagnostic clues to the astute clinician. Not only should the skin of the lids be closely examined, but the entire skin should also be evaluated for the presence of rashes, nodules, or vitiligo. We have diagnosed sarcoidosis on the basis of the presence of lid granulomas and of lesions on the extremities and the chest, and we have diagnosed Kaposi sarcoma on the basis of characteristic vascular lesions on the upper eyelid. If any skin findings are noted, photographs, a consultation with a dermatologist, and a skin biopsy should be considered.
Pupils and Extraocular Muscles
Evaluation of the pupils is frequently difficult in the patient with uveitis because of synechiae or chronic cycloplegic therapy. The inflamed pupil, even without synechiae, may not move well as a result of iris atrophy, a parasympathetic nerve lesion caused by herpes infection, or because it is trapped by a displaced intraocular lens. When examination is possible, the status of the optic nerve can be assessed with the standard swinging flashlight test to detect an afferent pupillary defect.
Involvement of the extraocular muscles in intraocular inflammatory disease is unusual. Esotropia or exotropia resulting from long-standing visual loss may develop as a result of cataract, retinal disease, or optic nerve disease. The finding of new vertical tropia or internuclear ophthalmoplegia should alert the physician to underlying diseases of the central nervous system (CNS) that may be associated with causes of uveitis, such as multiple sclerosis, sarcoidosis, or non-Hodgkin lymphoma.
Intraocular Pressure Measurement
Either elevated intraocular pressure or hypotony can occur as a result of intraocular inflammation. Goldmann applanation tonometry is usually sufficient to measure intraocular pressure in patients with uveitis; however, fluorescein should not be instilled until slit-lamp examination and ophthalmoscopy are completed because fluorescein enters the eye and prevents accurate assessment of the amount of flare in the anterior chamber. In addition, fluorescein may obscure the view of the posterior segment if the pupil is small and may persist in the eye for longer than 24 hours, especially in eyes with hypotonia and reduced aqueous flow. Therefore applanation tonometry should be performed either with the patient under anesthesia, without using fluorescein, and with a pneumotonometer or, preferably, at the end of the examination.
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