From the CPS website:
"Grievous bodily harm means really serious bodily harm. It is for the jury to decide whether the harm is really serious. However, examples of what would usually amount to really serious harm include:
injury resulting in permanent disability, loss of sensory function or visible disfigurement;
broken or displaced limbs or bones, including fractured skull, compound fractures, broken cheek bone, jaw, ribs, etc;
injuries which cause substantial loss of blood, usually necessitating a transfusion or result in lengthy treatment or incapacity;
serious psychiatric injury. As with assault occasioning actual bodily harm, appropriate expert evidence is essential to prove the injury"
A defence barrister might argue that a broken nose isn't as serious as, say, a broken jaw. If a court accepted that (and the eye injury turned out to be less serious than first thought) it's just possible that the Crown might have to settle for an ABH conviction, rather than a GBH one. However, given the eye problem, I think that a charge of (and conviction for) GBH would be far more likely.
The question then needs to be asked as to whether 'with intent' can be added to that charge. Again from the CPS website:
"Factors that may indicate the specific intent include:
a repeated or planned attack;
deliberate selection of a weapon or adaptation of an article to cause injury, such as breaking a glass before an attack;
making prior threats;
using an offensive weapon against, or
kicking the victim's head".
Based upon that, the charge is most likely to be 'GBH with intent'.
See here:
http://www.cps.gov.uk/legal/l_to_o/offences_against_the_person/#a15