Sarcoidosis is an inflammatory disease that can affect multiple organs throughout the body. While it most commonly impacts the lungs and lymph nodes, sarcoidosis also significantly affects the eyes, known as ocular sarcoidosis, in approximately 25% to 50% of individuals. Early diagnosis is important for preserving vision and preventing complications.
Recognizing Ocular Sarcoidosis Symptoms
Ocular sarcoidosis symptoms can be subtle and develop gradually. Common symptoms include blurry vision, ranging from mild haziness to significant impairment. Eye pain and redness are frequently reported, often indicating inflammation within the eye structures. Sensitivity to light, known as photophobia, can also be a noticeable symptom, making bright environments uncomfortable.
Some individuals may experience dry eyes, a sensation of grittiness, or excessive tearing. The presence of “floaters,” which appear as small specks or cobwebs drifting across the field of vision, can also suggest ocular involvement. These symptoms can affect one eye or both eyes simultaneously, and their intensity can fluctuate over time.
First Steps in Eye Examination
When ocular sarcoidosis is suspected, an ophthalmologist begins with a comprehensive eye examination. This includes visual acuity assessment, measuring how clearly an individual can see at various distances. A slit-lamp examination allows the doctor to view magnified structures at the front of the eye, such as the conjunctiva, iris, and lens. This examination can reveal signs like anterior uveitis, an inflammation of the iris and ciliary body, or subtle granulomas on the conjunctiva, which are small collections of inflammatory cells.
The ophthalmologist will also measure intraocular pressure, checking for any elevation that could indicate glaucoma, a potential complication of ocular inflammation. These initial assessments provide information on the presence and extent of inflammation within the eye. The findings from these routine tests guide further diagnostic steps and help differentiate ocular sarcoidosis from other eye conditions.
Advanced Eye Diagnostic Procedures
Beyond the initial examination, specialized ophthalmic tests further assess ocular involvement. Optical coherence tomography (OCT) is a non-invasive imaging technique providing high-resolution cross-sectional views of the retina and optic nerve. OCT can detect subtle retinal edema, changes in retinal thickness, or even the presence of granulomas within the choroid or retina, which might not be visible during a standard slit-lamp exam.
Fluorescein angiography involves injecting a fluorescent dye into a vein, which then circulates through the retinal blood vessels. As the dye passes through the eye, a special camera captures images, revealing areas of vascular leakage, inflammation, or abnormal blood vessel formation, often seen as “candle-wax drippings” or periphlebitis (inflammation around retinal veins).
If there is suspicion of optic nerve or significant retinal dysfunction, electroretinography (ERG) or visual evoked potentials (VEP) may be performed. ERG measures the electrical responses of light-sensitive cells in the retina, while VEP assesses the electrical activity in the brain’s visual cortex in response to visual stimuli. These advanced tests help assess the extent of ocular damage and guide treatment strategies.
Systemic Investigations for Diagnosis
As ocular sarcoidosis is a manifestation of a broader systemic condition, investigations beyond the eyes are necessary for diagnosis. Blood tests are a common initial step; angiotensin-converting enzyme (ACE) levels are often elevated. Blood calcium levels are also checked, as sarcoidosis can sometimes lead to hypercalcemia.
Imaging studies, such as chest X-rays or CT scans, are performed to look for signs of sarcoidosis in the lungs or lymph nodes. These images can reveal enlarged lymph nodes in the chest (hilar lymphadenopathy) or lung infiltrates. In some cases, if other organs are affected and accessible, biopsies may be taken from sites like lymph nodes, skin lesions, or salivary glands to confirm the presence of non-caseating granulomas, the hallmark of sarcoidosis. This systemic approach often involves collaboration between ophthalmologists and other specialists, such as pulmonologists or rheumatologists, to establish a comprehensive diagnosis.
Establishing a Definitive Diagnosis
Diagnosis of ocular sarcoidosis integrates findings from ocular examinations, systemic investigations, and symptom review. Characteristic ocular findings, such as specific patterns of uveitis or retinal inflammation, combined with evidence of sarcoidosis in other organs, strengthen the diagnosis.
Other conditions mimicking sarcoidosis, such as tuberculosis, lymphoma, or certain autoimmune diseases like multiple sclerosis, must also be excluded through differential diagnosis.
While a biopsy showing non-caseating granulomas from any affected tissue provides the most conclusive evidence of sarcoidosis, it is not always feasible or required if the clinical and imaging evidence is strong. Many cases are diagnosed based on a combination of suggestive clinical signs, typical radiological findings, and supportive laboratory test results. This comprehensive evaluation ensures an accurate diagnosis, allowing for appropriate management and monitoring of the disease.