OPTHALMOLOGY
Keratoconjunctivitis
Sicca (KCS):
Common and
Underdiagnosed
Dr Ramona Allen
BSc (Med) Hons BVSc
MMedVet (Ophthalmology Resident)
Johannesburg Animal Eye Hospital
Tears are needed to lubricate the cornea, and remove
debris and pathogens which may cause harm.
Additionally tears function to nourish with oxygen,
glucose, electrolytes, cleanse, lubricate, and maintain
corneal clarity and protect with immunoglobulins,
enzymes, anti-bacterial, growth factors and
fibronectin. Changes in any of the above may lead
to discomfort, infection, poor wound healing, visual
abnormalities, and adjacent tissue dysfunction of the
conjunctiva and eyelids.
Normal tear film distribution relies on normal anatomy,
normal tear film quality, and normal tear film quantity.
The tear film is composed of lipid, mucin and water.
A deficiency in the aqueous layer is referred to as
quantitative KCS, whereas a lipid or mucin deficiency
is termed qualitative KCS. Any condition which limits
the production of any of these components has the
ability to result in “dry eye”.
Traditionally, dry eye was always considered a
deficiency of the aqueous layer of the tear film,
however more recently the definition of dry eye
disease has been updated by the Dry Eye Workshop II
(2017) and is described as,
“ … a multifactorial disease of the ocular surface
characterised by a loss of homeostasis of the tear
film, and accompanied by ocular symptoms, in which
tear film instability and hyper-osmolarity, ocular
surface inflammation and damage, and neurosensory
abnormalities play etiological roles.”
Eyes affected with KCS are generally red and painful,
and the condition can be uni- or bilateral. Concurrent
corneal ulcers and conjunctivitis may be present.
Chronic, untreated KCS may can result in scarring,
neovascularisation and pigmentation and, if severe,
decreased vision.
Causes of KCS are numerous but can be classified
aetiologically:
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Sounds complicated, right? Well it is!
The most common clinical signs seen with KCS include:
Mucoid discharge, hyperaemia, neovascularisation,
blepharospasm, epiphora, and a dull lacklustre cornea
vet360
Issue 03 | JULY 2018 | 14
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Congenital
Senile atrophy
Immune-mediated
- - Local
- - Systemic e.g. Sjögren’s syndrome, systemic
lupus erythematosus, pemphigus foliaceus,
rheumatoid arthritis, polymyositis and
polyarthritis, atopy, glomerulonephritis, and
ulcerative colitis
Infectious
- - Canine Distemper Virus
- - Viral or bacterial conjunctivitis
- - Feline Herpes Virus
Endocrine Disease
- - Diabetes Mellitus
- - Cushings Disease
- - Hypothyroidism
Irradiation
Neurogenic
Iatrogenic
- - removal of the gland of the third eyelid
- - uncorrected prolapsed gland of the third eyelid
("cherry eye")
- - Facial nerve damage e.g. after total ear canal
ablation surgery
Breed-related
- - American cocker spaniel
- - Bloodhound
- - Boston terrier