More recent research has established two forms of this condition the more serious of which is now referred to as:

Commonly referred to by its initials PRA, is a progressive inherited eye abnormality, which causes eventual blindness. First discovered in Collies during the early 60s, the Kennel Club were quick to extend its Eye Scheme to the Rough Collie, and despite the fact that its mode of inheritance was not fully understood breeders concentrated their efforts on eliminating the condition from their breeding stock, their vigilance being responsible for its virtual eradication.

“A Window Into Their
Soul” may sound a
fanciful description
for Rough Collies
eyes; they should
however reflect
their personality.
Displaying their
innate steadfastness
and gentle nature with
its spark of mischief,
together with a desire to
please coupled with
personal initiative and high
intelligence

Rough Collie enthusiasts have always emphasised the importance of eyes to breed type, the 1898 Breed Standard describing them thus:

‘The EYES are a very important feature and give expression to the dog; they should be of a medium size, set somewhat obliquely, of almond shape and of a brown colour except in the case of “merles”, when the eyes are frequently (one or both) blue and white or china; expression full of intelligence, with a quick alert look when listening.’

while the most recent Standard, revised by the Kennel Club in 2008/2009, reads:

‘Eyes — Very important feature giving sweet expression. Medium size (never very small) set somewhat obliquely, of almond-shape and dark brown colour, except in the case of blue merles when eyes are frequently (one or both, or part of one or both) blue or blue-flecked. Expression full of intelligence, with quick, alert look when listening.’

proving how little the ideal has varied in the intervening years.

Research, funded by three separate health research foundations interested in Choroidal Hypoplasia [CH] plus the American Border Collie Association, has recently isolated the mutation which causes CH in our own species and CEA in the wider collie family. This in turn has allowed the development of a DNA test for the underlying condition, and although more work is necessary before the two more sever forms, which can cause sight deterioration, can be detected in this way it would appear to be the way forward.

Generalised Progressive Retinal Atrophy or GPRA is of early onset and typically apparent by the time a puppy reaches six weeks of age. Current opinion is that this condition does not affect Rough Collies in their country of origin, although it is known to affect Collies in North America, which explains why the Collie Club of America’s Health Foundation funded the research into its genetic inheritance which has since established a DNA test for the condition. This has little relevance to breeders in the United Kingdom or Europe unless they intend incorporating North American blood lines into their breeding programme.

Central Progressive Retinal Atrophy or CPRA is in many ways a more insidious condition, which can not be detected until it manifests itself sometime after the first year of life, and frequently not until quite late in life explaining why breeders are urged to submit their breeding stock for regular eye screening. The condition’s development is also
somewhat unpredictable often taking many years before
serious loss of sight is experienced if ever. It is also
considered that improvements in canine nutrition may have
been largely responsible for today’s low incidence of the
condition as it is known that Vitamin E deficiency can affect
the eventual outcome and most modern feeds use
Vitamin E as a preservative.

The possibility of a DNA test being discovered remains
slim as the actual mode of inheritance is still not fully
understood, and with the number of confirmed cases
being less than 0•25% of all dogs tested under the
BVA/KC Eye Scheme there is little encouragement
for further research.

Collie Eye Anomaly more usually  referred to as CEA is a non-progressive congenital, present at birth, hereditary abnormality of the eye which affects members of the wider Collie family. Originally thought to be a simple recessive its mode of inheritance no longer appears to be quite so simple and it is probable that its more severe expressions involve additional gene mutations that have yet to be identified.

Usually bilateral, affecting both eyes, in its milder forms it is no more than a slight lack of pigment to, or thinning of the optic disc which does not appear
to affect the sight in any way. In its more severe forms, which thankfully represent less than 9% of the total Rough Collie population, it can manifest itself as Colobomas of varying sizes and/or partially or wholly detached retina, this latter condition producing blindness.

Just as Collie breeders were beginning to congratulate
themselves on a reduction in the incidence of PRA, a new
and far more far-reaching eye abnormality was diagnosed.
Initially discovered shortly after PRA was diagnosed in Rough
Collies few were to realise the seriousness or extent of this more
wide spread condition for another decade due to the concentration
of veterinary and breeders efforts on one known to caused eventual blindness.

Eye Test Certificates issued under the BVA/KC Eye Scheme have changed little during the last thirty plus years — this one, dated 1990, was issued to a Collie who tested clear for CEA and PRA but who had a small scar, due to an accident, on its left cornea, and this fact is noted on the certificate

Being a congenital condition CEA can be detected at an early age, and as there are no known genetically clear Rough Collies in this country, the only method of discovering which if any puppies are clear or only mildly affected by CEA is to have the whole litter eye screened for the condition, by a BVA listed ophthalmologist, at the age of 6 to 7 weeks.