Systemic lupus erythematosus and the eye

Keratoconjunctivitis sicca

Keratoconjunctivitis sicca (KCS, “dry eye syndrome”) occurs due to secondary Sjögren syndrome and affects around 25% of patients with SLE. It is associated with the autoantibodies, anti-Ro (SSA) and anti-La (SSB). Patients may be asymptomatic, or have symptoms ranging from slight irritation to severe pain and blurred vision. Examination with a biomicroscope (“slit lamp”) reveals a reduced tear meniscus with a tear film break-up time of under 10 s. Fluorescein drops and cobalt blue light highlight the corneal changes, which may include punctate epitheliopathy, mucus filaments, and a reduced tear film breakup time. Additional staining with Lissamine Green eye drops reveals a typical “interpalpebral” pattern in which most staining is nasal and temporal to the corneal limbus.

The Schirmer test can be used to detect reduced tear production. If the test strip is wet by less than 5 mm after 5 min in the unanesthetized eye, this indicates severe tear deficiency. In one series of patients with SLE the median value was 7.5 mm. Symptoms do not correlate well with signs in this context. Many more patients report “dry eyes” than have visible disease. Conversely many asymptomatic patients do have some degree of keratoconjunctivitis sicca on clinical examination. Dry eye can be objectively measured and monitored using the OSDI score, which is a validated assessment tool.

Other corneal disease

Interestingly, superficial punctate keratitis, even in the absence of KCS, may be observed in patients with SLE and DLE, with one series reporting evidence of corneal staining in as many as 21 out of 24 (88%) SLE patients. A response to the immunomodulator quinacrine hydrochloride was noted, suggesting a direct autoimmune phenomenon. Occasionally, deeper corneal involvement may occur, resulting in peripheral ulcerative keratitis, interstitial keratitis, and keratoendotheliitis.

Alterations in the measurement of intraocular pressure have been reported in patients with SLE due to altered biomechanical properties of the cornea. Such mechanical differences may occur from reduced corneal hysteresis and corneal resistance factor, which in turn lead to lower measured intraocular pressures when tested by applanation techniques.

Episcleritis

Episcleritis is reported in up to 2% of SLE patients. Patients present with a red eye with mild (if any) discomfort. Clinically, either sectoral or diffuse injection of the episcleral vasculature, superficial to the sclera, will be seen.

Scleritis

Scleritis is reported in 1% of SLE patients and may indeed be the presenting feature. Scleritis is classified anatomically into “anterior” and “posterior” forms.

Anterior scleritis is the most common type, classically presenting with a severely painful, deeply injected, “beefy red” eye. Involvement of the deeper vascular plexus (cf. episcleritis) is seen with either a “diffuse” or a “nodular” (i.e., focal and associated with a nodule) pattern. It is important to recognize the presence of tissue destruction indicative of “necrotizing scleritis,” although this occurs rarely in SLE. Tissue thinning due to scleritis is seen as dark areas on the globe due to the underlying uveal tissue being revealed through the thinned sclera. This may cause high degrees of astigmatism, and in extreme cases globe perforation. Diffuse light (such as from a window) often reveals the degree of inflammation and scleral thinning more easily than the bright focal light of a slit lamp.

The less common “posterior scleritis” may present with ocular pain of variable severity (which may be referred to the brow or jaw), reduced vision, increased long-sightedness, double vision, or photopsia. On examination, features may include shallowing of the anterior chamber, choroidal folds or detachment, exudative retinal detachment, and edema of the macula or optic disc. There may also be lid edema, proptosis, lid retraction, and restricted ocular motility. B-scan ultrasound is the investigation of choice (see “Investigations”).

Scleritis is potentially sight threatening and may be an indicator of significant systemic activity. Urgent referral to an ophthalmologist is warranted and systemic therapy is generally indicated.

Other anterior segment complications

Rare anterior segment complications include iris neovascularization (rubeosis iridis, usually indicating severe retinal ischemia) and anterior uveitis, which may be isolated or associated with either scleritis or posterior segment inflammation.

Lid disease

Both SLE and DLE may affect the eyelids resulting in raised scaly lesions resembling chronic blepharitis. Lid biopsy reveals hyperkeratosis, focal intracellular edema, and degeneration of the basal layer, and lymphocytic infiltrates especially around the vessels. The lids may also be involved in the classic malar rash of SLE.