What happens during a ptosis assessment?
During the consultation, the oculoplastic surgeon will first want to know how your eyelid ptosis concerns you.
The doctor will then take measurements of the eyelids, particularly what is called the vertical palpebral aperture. He or she will look to see whether it is just a problem of the upper eyelid or whether there is any malposition of the lower lid. They also test the strength of the eyelid closing muscle – the orbicular, the efficiency of the eye shooting up under the eyelid reflex called the Bell’s phenomena, the fatiguability of the eyelid, the eye movements, and the pupil reactions. We look carefully at a measure called levator function which is the measure of the strength of the eyelid lifting muscle. They will also look to see where the skin crease is, how high and profound it is. They will measure the number of millimetres above the lash line that the skin crease is found and observe whether there are several skin wrinkles. They will also measure the amount of skin on the upper eyelid in case they also plan to remove the skin as well as correcting the ptosis.
Individual oculoplastic tests for functional eyelid surgery
The oculoplastic surgeon may do a particular eyedrop test called the “Phenylephrine test”.
If you have an apparent ptosis in one eye, the oculoplastic surgeon will want to decide whether it is entirely on the one eyelid or whether it also affects the other eyelid as a latent ptosis. To determine whether the ptosis affects uniquely one side or a little bit of both eyelids asymmetrically, the surgeon will take precise measurements and photographic documentation. After that, a small drop of Phenylephrine 2.5% will be put onto the surface of the eye that has the ptosis or the more noticeable ptosis and then they will wait five to seven minutes to see the effect of the sharp drop.
The Phenylephrine test is to stimulate a part of the eyelid called the Muller’s muscle which has a sympathetic supply and therefore raises the eyelid mimicking the effect of surgery. If the eyelid that has a ptosis goes up five to seven minutes after the Phenylephrine drop is put in the eye, then that is termed an actual Phenylephrine test. It is very useful to show the patient:
- What they may look like after ptosis surgery.
- Demonstrate whether there is a ptosis on the other side.
The reason for this is that when one eyelid, which is the worst ptosis, is raised chemically with the Phenylephrine, often the other eyelid will then manifest a ptosis and drop. This is because of something called the Hering’s Law of equal and upper opposite innervation.
Once finishing all those measurements and photographic documentation, the oculoplastic surgeon will then decide what surgery is the best for patients; whether it should be a ptosis correction with or without some blepharoplasty to remove excess skin or fat, and if it is ptosis correction, whether one or both eyes have to be dealt with. To decide that the oculoplastic surgeon will often carry out is called a Phenylephrine test. Before doing a Phenylephrine test, they may well do your visual fields to demonstrate that your eyelids are functionally interfering with your vision.