Page 672 - Clinical Immunology_ Principles and Practice ( PDFDrive )

CHaPTEr 47 Allergic Disorders of the Eye 645

and safe to use in VKC. Lodoxamide and nedocromil are more
potent than sodium cromoglycate and are worth trying if Experimental Model of VKC
olopatadine does not appear to control symptoms. Those with In genetically susceptible rats and mice, experimental blepharo-
mild disease may be able to discontinue therapy during the winter conjunctivitis (EBC) is inducible by subcutaneous immunization
months. It is important to emphasize to patients and parents with SRW followed by conjunctival allergen challenge at day 10.
that mast cell inhibitors are safe and must be continued when In this model a significant eosinophilia is found 24 hours after
using steroids to minimize the dose of steroids required and the challenge, and EBC has therefore been used as a model for
risk of steroid complications. studying eosinophil infiltration as found in VKC. It also can be
induced by adoptively transferring Th2, but not Th1, T cells,
CLiNiCaL PEarLS consistent with our understanding that eosinophil infiltration
23
Vernal Keratoconjunctivitis is Th2-mediated.
• Chronic conjunctival inflammation with seasonal exacerbations ATOPIC KERATOCONJUNCTIVITIS
• Eosinophils and T-helper 2 (Th2) cells infiltrate the conjunctival tissues
• Usually affects young males AKC is the least common but most serious of the ocular allergies.
• Cornea can be affected It is a life-long condition that affects adults who have systemic
• Increased expression of Th2 cytokines, adhesion molecules, eotaxin atopic disease, particularly atopic dermatitis. It usually starts in
• Often requires steroids and topical cyclosporine
the late teens, but unlike VKC, the disease is persistent and
may be relentlessly progressive; occasionally the disease can
Steroids are highly potent controllers of multiple features of begin in childhood. AKC is a highly symptomatic disorder with
allergic inflammation and are frequently required in VKC. severe itching, pain, watering, stickiness, and redness of the eyelids
Unfortunately they carry a significant risk of ocular adverse and eye. 24
effects, including ocular hypertension, glaucoma, and cataract,
and they can worsen infective keratitis. This is a particular concern
in children, where examination to detect these complications CLiNiCaL PEarLS
can be difficult (e.g., tonometry for intraocular pressure) and Atopic Keratoconjunctivitis
also where iatrogenic adverse effects may have long-term visual
consequences beyond the time when the disease has spontaneously • The most severe form of allergic eye disease
regressed. To minimize the risk of adverse effects, topical cyclo- • Affects adults with atopic dermatitis or asthma
• Predominant infiltration of T cells expressing interferon (IFN)γ in severe
sporine should be used, and then steroids can be prescribed in cases
short, sharp, rapidly tapering doses during episodes of high • Cornea can be affected, often due to secondary infections
disease activity or significant keratopathy. In addition, the use • Requires steroids and cyclosporine
of surface-acting preparations with a reduced intraocular action
(e.g., fluorometholone, rimexolone, loteprednol) is advisable,
although they are not available in preservative-free formulations There is usually facial atopic dermatitis involving the eyelids.
that are preferred for high-frequency use. Systemic steroids also The lid margins show severe blepharitis (chronic inflammation
are sometimes used but expose the patient to numerous potential of the lash follicles and Meibomian glands) and are thickened
adverse effects. Supratarsal injections of steroids, either long-acting and hyperemic, posteriorly rounded, and sometimes keratinized;
(triamcinolone) or short-acting (e.g., dexamethasone), may also the lid anatomy may be distorted with ectropion (outwardly
be used to great effect, but these are not surface-acting agents turning eyelid), entropion (inwardly turning eyelid), trichiasis
and therefore do carry significant risk of local side effects; unlike (in-turning lashes), loss of lashes, and notching. The whole
drops, neither the treatment effect nor any adverse effects can conjunctiva is affected and shows intense infiltration, papillae
be terminated suddenly if problems arise. (which may be giant), and sometimes scarring with linear and
Cyclosporine is a specific T-cell inhibitor but also has a number reticular white scar tissue, lid-to-conjunctiva adhesions (sym-
of other inhibitory effects (e.g., on eosinophils, mast cells) that blepharon), shrinkage or loss of the conjunctival sac, and second-
are likely to contribute to its effectiveness in ocular allergic therapy. ary lid distortion. Marked limbal inflammation can develop,
Topical cyclosporine 2% dissolved in oil (usually corn) has been and Trantas’ dots may occur. The disease may not affect the
used to great effect in VKC and is particularly effective in treating cornea at all, in which case it is sometimes called atopic blepha-
22
corneal complications and in acting as a steroid-sparing agent. roconjunctivitis (ABC); in this situation, the overall inflammation
It has no systemic adverse effects and none of the serious ocular is generally less severe.
complications of steroids, so generally it can be used safely The cornea may be affected directly during inflammation, or
long-term. Commercially available topical cyclosporine 0.1% in it may be damaged secondarily after extensive changes to the
a cationic emulsion (Ikervis in UK; Restasis in US) has recently protective ocular surface by continual mechanical trauma, reduced
been licensed for use in dry eye. A randomized study in Europe lid protection, or severe loss of conjunctival tear production.
evaluating 4×/day topical cyclosporine 0.1% in children with Significant visual acuity reduction due to corneal involvement
VKC is ongoing. occurs in 40–70% of cases. Keratopathy may consist of punctate
Surgical interventions are sometimes required in VKC for the and macroscopic epithelial defects, filamentary keratitis, plaque
corneal manifestations; surgical or excimer laser superficial ulcer, progressive scarring, neovascularization (with or without
keratectomy may be used in conjunction with medical therapy lipid deposition), thinning, and secondary corneal infections
for plaque ulcer; rarely, corneal grafting may be required for (herpetic, bacterial, and fungal) (Fig. 47.2B). There are recognized
scarring. Surgical removal of giant papillae or conjunctival associations between AKC and eye rubbing, keratoconus, atopic
reconstruction is not generally recommended. cataract, and retinal detachment.