EPISCLERITIS

Introduction

Episcleritis is a benign inflammatory condition of the external eye[1], specifically the episcleral tissues, which form the membrane between the conjunctiva and the sclera. It is a relatively common, recurrent[2], but self-limited acute red eye presentation[3]. It presents as either a “simple” episcleritis- a diffuse inflammation of the conjunctival and superficial episcleral vascular plexi, or as a “nodular” form- a localised process with a well-defined area of elevation[4]. Simple episcleritis accounts for 70% of cases[3] relative to the more striking and symptomatic nodular form. It is most common in young adults, and females appear to be affected a little more than males[3, 5, 6]. Episcleritis is often unilateral-2/3 of cases[6], presenting as a relatively asymptomatic acute onset of redness. Some patients may complain of mild tenderness or pain, while others may also have photophobia and watery discharge. Most cases are idiopathic, but about 30% of presentations have been shown to have an underlying systemic origin[3, 5-7]. Episodes usually last about a week, and it tends to completely resolve on its own within a time frame of one to three weeks[8]. Symptomatic patients can benefit from the use of lubricant drops, cold compresses, topical corticosteroids, or non-steroidal inflammatory drugs (NSAIDs).

Case Study

A 23-year-old female AK presented complaining of sudden redness in her left eye, which began suddenly two days before. She describes mild discomfort, but no pain, or discharge. There was no headache, no photophobia, and no blurry vision. There was no history of recent illness/ collagen vascular disease, general health was unremarkable, and there were no significant family histories. She did not recall any previous similar episodes.

Entering acuities were 6/6 OU, pupils equal and reactions normal. Motilities were smooth and accurate, and no pain or tenderness upon eye movements.

IOPs were 14mmHg in OU measured with Icare Tonometry @4.05pm.

Slit-lamp examination revealed a quiet looking right eye. Her left eye however, showed a sectorial slightly elevated area of injection in her temporal/ bulbar conjunctiva. It looked bright red in colour. Closer inspection showed engorged episcleral vessels. Corneas were clear with no staining, and no foreign body present. No anterior chamber reaction was seen. Lids/lashes were clear, with no sign of any blepharitis or trichiasis. Lid eversion ruled out a foreign body under the lid. Van Herrick angles were wide open.

Ophthalmoscopy (un-dilated) showed healthy retinas/maculae, cup-to-disc ratios 0.3, NRR healthy. Optos Ultrawide imaging was unremarkable.

Diagnosis

A diagnosis of Simple Episcleritis was made, based on a few factors, the main being the physical/ clinical appearance of the left bulbar conjunctiva, revealing a localised inflammation of the episcleral tissue, and injection of the superficial vessels. The other factor was the relatively asymptomatic presentation. The unilateral nature of the attack, patient’s age, along with the negative medical/ systemic histories, also helped to solidify this diagnosis.

Differential Diagnosis

There are a few red-eye conditions we must exclude, the most significant being scleritis, due to its potential for sight-threatening sequelae.[9]

Scleritis. A more dangerous disease requiring a quick diagnosis for prompt management. It is much less common than episcleritis and has a significantly higher predilection for systemic disease[8], specifically connective tissue and vasculitic diseases. Episcleritis can be differentiated from scleritis by the lack of a deep, boring pain (around the entire globe), and the absence of scleral edema[10]. The pain will appear disproportionate to the appearance clinically[11]. We would also see a bluish/ purple hue/discolouration in scleritis, versus the bright red seen in episcleritis[12]. An important and widely used clinical tool for differentiating these two conditions, is the use of Phenylephrine 2.5% blanching[8, 13], whereby a drop of this vasoconstrictor is instilled in the affected eye, and acts on the congested conjunctival and superficial episcleral blood vessels (requiring 10-15 minutes). If the deep episcleral plexus doesn’t blanch, then we can diagnose scleritis[13].

Conjunctivitis. Is easily distinguished from episcleritis based on symptoms and presentation. The engorged vessels are typically anterior and can easily be manipulated by a cotton tip, unlike episcleritis, whereby the engorged vessels appear deeper[14]. Conjunctivitis won’t be sectorial but presents with a more generalised conjunctival congestion (360-degree appearance). A discharge (watery/stringy/ mucopurulent) will also be seen in conjunctivitis, and absent in episcleritis.  Allergic conjunctivitis will exhibit more intense itching and chemosis.

Anterior Uveitis. In episcleritis, congestion is limited to the radially orientated superficial episcleral vessels[3] while in uveitis we get a ciliary flush appearance. The onset of episcleritis is more acute, the sensation is not of pain but mild grittiness, there is no corneal or intraocular involvement, and vision is unaffected. The phenylephrine test also helps distinguish the two because in uveitis, the conjunctival hyperemia will not blanch[15].

Phlyctenular Conjunctivitis. A nodular inflammation that results from a hypersensitive reaction to a bacterial antigen[8]. In our simple episcleritis, no nodule is seen. This nodule is differentially diagnosed from nodular episcleritis by its mobility with the conjunctiva[8].

Superior Limbic Keratoconjunctivitis (SLK). An inflammation of the superior bulbar conjunctiva, characteristically involving the superior limbus. It presents with an adjacent epithelial keratitis (with associated punctate staining) which is usually absent in our simple episcleritis patient. In SLK lid eversion shows marked inflammation of the upper lid tarsal conjunctiva[15]. This condition is also usually binocular, and there is a filamentary discharge present[15].

Foreign Body. Slit-lamp examination is enough to exclude this differential. The absence of a foreign body, and any tractional staining will rule out this diagnosis. The patient in episcleritis will not complain of a foreign body sensation, and we have no history of hammering/ chiselling that could have led to the foreign body.

Pingueculitis. A condition where a pinguecula becomes inflamed. Careful slit-lamp examination of the conjunctiva will show the pinguecula underlying the inflammation (usually centred on the pinguecula).

Conjunctival Tumour/ Neoplasia. Malignant conjunctival lesions are uncommon and tend to have a characteristic “salmon patch” appearance[16]. These malignancies can masquerade episcleritis, therefore we must beware of treatment-resistant red eyes in our practice.

Management

Ms AK was comforted that her red eye was harmless, non-infectious, self-limiting, and will likely improve on its own. Symptomatic relief was suggested through use of Optive lubricant 4 times/day, and I instructed her to use cold compresses (ice wrapped in a towel) if the eye feels itchy or sore. I advised her to review in one week, and should the symptoms get worse, to return promptly.

She returned after 8 days, and reported that while she had improved slightly, the redness was still present- still no pain or any other symptoms. Slit-lamp exam revealed similar redness and anterior eye health to initial presentation, and in the absence of any serious symptoms I re-assured her to continue with the same treatment, and follow-up in another week.

She presented 5 days after that and was happy to report that her redness had dissipated, and she was totally asymptomatic.  Slit-lamp exam confirmed clear conjunctivae, and no staining with fluorescein. I stressed to her the importance of future follow-up in the case of recurrence, and otherwise routine testing every two years.

Discussion

Episcleritis is characterised by the abrupt onset of inflammation in the episclera in one or both eyes[8, 15]. The episclera is the fibrous coat of tissue beneath the bulbar conjunctiva that overlies the sclera. It is highly vascularised, consisting of two layers, that are joined by interconnecting fibres[17]. The inner layer is adjacent to the sclera and moves nutrients to the avascular sclera. The outer and more vascular layer inserts posteriorly at the optic nerve and anteriorly 2mm posterior to the limbus[18]. These superficial vessels are mobile, while the deeper ones are firmly attached to the sclera[19].

Episcleritis has an annual prevalence of 5.2 persons per 100,000[20]. Episcleritis presents with a bright and sectorial redness overlying the sclera. This salmon coloured hyperemia, which radiates from the limbus will usually blanch with the use of topical phenylephrine. The hyperemic vessels are also mobile over the sclera if gently prodded with cotton bud. Vision is not affected, and there is no corneal involvement, although long-standing and recurrent episodes have been shown to lead to dellen formation[2]. The inflamed area is not tender, and there is no photophobia or discharge. Anterior chamber reaction is also absent. Patients may complain of an uncomfortable feeling, but rarely pain[3]. Inflammation of the episclera very rarely progresses to scleritis[2, 21].

The two clinically distinctive types of episcleritis are simple/ diffuse, and nodular/ focal, with the latter referring to the inflamed area clustering around discrete nodules. The more prevalent simple episcleritis sometimes presents frequently every few months. Nodular episcleritis patients have more prolonged attacks of inflammation, and noticeably more pain than simple episcleritis[15]. They are also more likely to have associated systemic disease[22].

Most patients with episcleritis have mild, isolated symptoms that respond to topical therapy alone. Indeed, many patients with episcleritis require no treatment at all, since the condition typically resolves over a short time of 7-10 days with relatively asymptomatic patients. Therefore, a non-pharmacological approach is preferred, and it suffices to re-assure the patient that the condition doesn’t progress into a more serious ocular disorder, while advising follow-up or seeking further help if symptoms persist. Cool compresses are also useful for relief of mild symptoms. There is no need for long-term control once the acute presentation has passed. With regard to the pharmacological path, we are likely to prescribe artificial tear drops as necessary for the first one to two weeks in milder cases of episcleritis.

For moderate cases, especially with the more indolent nodular episcleritis, or patients who are wanting to minimise the symptoms and time frame of the condition, a therapeutic line consisting of artificial lubricants used four times per day, and/or topical corticosteroids, or the use of topical or oral NSAIDs. The mechanism of action in NSAIDs is thought to be the inhibition of cyclooxygenase activity and prostaglandin synthesis, leading to analgesic, antipyretic, and anti-inflammatory effects- reducing swelling, redness, and pain. Studies which have shown that topical NSAIDs (Ketorolac, Diclofenac) have no greater benefit than using artificial tears alone[11]. Oral NSAIDs however are nearly always effective in treating more severe episcleritis[8], and are the preferred approach when we decide to initiate treatment, typically 800mg ibuprofen taken three times daily. Alternatively, indomethacin 75mg twice daily, or flurbiprofen 100mg three times daily are used. Patients should take the drug with food (to reduce the likelihood of gastro-intestinal disease) and be re-evaluated in one week. If the episcleritis is under control, we reduce the dose by one half or one third, and schedule follow-up in one to two weeks, tapering the dose until stopping the drug.

When using corticosteroids for treating episcleritis, caution is exercised as we have the danger of inducing cataracts, glaucoma, and systemic complications. Also, excessive steroid use has been linked to increased recurrence, while also causing rebound redness[16]. Their therapeutic effects are a result of their anti-inflammatory, immunosuppressant, vasoconstrictive and anti-proliferative actions, thereby acting to decrease swelling, redness and itching. They act by inhibiting mRNA responsible for interleukin-1 formation thereby blocking arachidonic acid metabolism. We would treat with a short course of Prednisolone Acetate 1%, or with milder steroids like Fluorometholone 0.1%, and Fluorometholone Acetate 0.1% 1-4 times per day, and of course tapering once the condition eases. We must also monitor the patient’s IOP weekly in case the patient is a steroid responder.

Visual prognosis for patients with episcleritis is usually excellent[6]. Some are lucky enough to only have a single episode, and in those with recurrent disease, the frequency tends to diminish over time[15]. Extensive evaluation for underlying disease isn’t necessary for milder presentations, but patients with recurrent or more severe episcleritis should be carefully assessed and treated, especially given the 30% association with systemic disease[3], and because episcleritis can sometimes lead to ocular complications such as uveitis and glaucoma[23]. Patients should be referred for a review of systems to rule out the slight possibility that a patient’s episcleritis results from systemic autoimmune disease[7]. Should this be positive for joint pains, morning stiffness, rashes, nasopharyngeal ulcers, and vitiligo or if there is a strong family history of autoimmune disease, we will need to order a workup similar to that of scleritis, which involves blood counts, rheumatic factor, chest x-ray, antinuclear antibody, and serum uric acid[7, 24]. If episcleritis occurs in the context of a known autoimmune illness, most commonly rheumatoid arthritis (RA) or lupus (also polyarteritis nodosa, inflammatory bowel disease, sarcoidosis, Wegener’s granulomatosis, tuberculosis, Lyme disease, gout, herpes zoster, syphilis) then the treatment of the systemic illness needs to be increased until the episcleritis has resolved[7]. The episcleritis is evidence that a patient’s systemic disease is not under adequate control[23].

Conclusion

This condition typically looks worse than it actually is. We must however be sure to distinguish it from the more severe scleritis, which is a lot more painful, and leads to much more detrimental implications. We must utilise phenylephrine blanching for severe cases in which differential diagnosis is more challenging, while also keeping an open mind for systemic disorders which may be the reason for the episcleritis. We cannot prevent this condition, but luckily a comprehensive eye examination will be enough for diagnosis in most cases, and treatment if initiated at all is quite straight forward, and very effective.

References

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