proper. It is a comparatively serious disease which
may cause visual impairment and even loss of the
eye if treated inadequately. Fortunately, its incidence
is much less than that of episcleritis. It usually occurs
in elderly patients (40-70 years) involving females
more than the males.
Etiology
It is found in association with multiple conditions
which are as follows:
1. Autoimmune collagen disorders, especially
rheumatoid arthritis, is the most common
association. Overall about 5% cases of scleritis
are associated with some connective tissue
disease. About 0.5 percent of patients (1 in 200)
suffering from seropositive rheumatoid arthritis
develop scleritis. Other associated collagen
disorders are Wegener's granulomatosis,
polyarteritis nodosa (PAN), systemic lupus
erythematosus (SLE) and ankylosing spondylitis.
2. Metabolic disorders like gout and thyrotoxicosis
have also been reported to be associated with
scleritis.
3. Some infections, particularly herpes zoster
ophthalmicus, chronic staphylococcal and
streptococcal infection have also been known to
cause scleritis.
4. Granulomatous diseases like tuberculosis,
syphilis, sarcoidosis, leprosy can also cause
scleritis.
5. Miscellaneous conditions like irradiation, chemical
burns, Vogt-Koyanagi-Harada syndrome, Behcet's
disease and rosacea are also implicated in the
etiology.
6. Surgically induced scleritis follows ocular
surgery. It occurs within 6 month postoperatively.
Exact mechanism not known, may be precipitation
of underlying systemic cause.
7. Idiopathic. In many cases cause of scleritis is
unknown.
Pathology
Histopathological changes are that of a chronic
granulomatous disorder characterised by fibrinoid
necrosis, destruction of collagen together with
infiltration by polymorphonuclear cells, lymphocytes,
plasma cells and macrophages. The granuloma is
surrounded by multinucleated epitheloid giant cells
and old and new vessels, some of which may show
evidence of vasculitis.
Classification
It can be classified as follows:
I. Anterior scleritis (98%)
1. Non-necrotizing scleritis (85%)
(a) Diffuse
(b) Nodular
2. Necrotizing scleritis (13%)
(a) with inflammation
(b) without inflammation (scleromalacia
perforans)
II. Posterior scleritis (2%)
Clinical features
Symptoms. Patients complain of moderate to severe
pain which is deep and boring in character and often
wakes the patient early in the morning . Ocular pain
radiates to the jaw and temple. It is associated with
localised or diffuse redness, mild to severe
photophobia and lacrimation. Occasionally there
occurs diminution of vision.
Signs. The salient features of different clinical types
of scleritis are as follows:
1. Non-necrotizing anterior diffuse scleritis. It is the
commonest variety, characterised by widespread
inflammation involving a quadrant or more of the
anterior sclera. The involved area is raised and salmon
pink to purple in colour (Fig. 1).
 |
| Fig.1. Non-necrotizing anterior diffuse scleritis. |
2. Non-necrotizing anterior nodular scleritis. It is
characterised by one or two hard, purplish elevated
scleral nodules, usually situated near the limbus (Fig.
2). Sometimes, the nodules are arranged in a ring
around the limbus (annular scleritis).
 |
| Fig. 2. Non-necrotizing anterior nodular scleritis. |
3. Anterior necrotizing scleritis with inflammation.
It is an acute severe form of scleritis characterised by
intense localised inflammation associated with areas
of infarction due to vasculitis (Fig. 3). The affected
necrosed area is thinned out and sclera becomes
transparent and ectatic with uveal tissue shining
through it. It is usually associated with anterior
uveitis.
 |
| Fig. 3. Anterior necrotizing scleritis with inflammation. |
4. Anterior necrotizing scleritis without
inflammation (scleromalacia perforans). This specific
entity typically occurs in elderly females usually
suffering from long-standing rheumatoid arthritis. It
is characterised by development of yellowish patch
of melting sclera (due to obliteration of arterial supply);
which often together with the overlying episclera and
conjunctiva completely separates from the
surrounding normal sclera. This sequestrum of sclera
becomes dead white in colour, which eventually
absorbs leaving behind it a large punched out area of
thin sclera through which the uveal tissue shines
(Fig. 4). Spontaneous perforation is extremely rare.
 |
| Fig. 4. Anterior necrotizing scleritis without inflammation (Scleromalacia perforans). |
5. Posterior scleritis. It is an inflammation involving
the sclera behind the equator. The condition is
frequently misdiagnosed. It is characterised by
features of associated inflammation of adjacent
structures, which include: exudative retinal
detachment, macular oedema, proptosis and limitation
of ocular movements.
Complications
These are quite common with necrotizing scleritis and
include sclerosing keratitis, keratolysis, complicated
cataract and secondary glaucoma.
Investigations
Following laboratory studies may be helpful in
identifying associated systemic diseases or in
establishing the nature of immunologic reaction:
1. TLC, DLC and ESR
2. Serum levels of complement (C3), immune
complexes, rheumatoid factor, antinuclear
antibodies and L.E cells for an immunological
survey.
3. FTA - ABS, VDRL for syphilis.
4. Serum uric acid for gout.
5. Urine analysis.
6. Mantoux test.
7. X-rays of chest, paranasal sinuses, sacroiliac
joint and orbit to rule out foreign body especially
in patients with nodular scleritis.
Treatment
(A) Non-necrotising scleritis. It is treated by topical
steroid eyedrops and systemic indomethacin 100 mg
daily for a day and then 75 mg daily until inflammation
resolves.
(B) Necrotising scleritis. It is treated by topical
steroids and heavy doses of oral steroids tapered
slowly. In non-responsive cases, immuno-suppressive
agents like methotrexate or cyclophos-phamide may
be required. Subconjunctival steroids are
contraindicated because they may lead to scleral
thinning and perforation.
