Glaucoma: Are you a suspect or a person of interest?

Segun, my nephew, is a funny character. He was called to the Bar just a couple of months ago and prefers to see the world only through the legal window. Recently, he paid a visit to an eye clinic for the first time and became very worried when the ophthalmologist told him he was a Glaucoma suspect. So he asked me, “Uncle, what is the difference between a glaucoma ‘suspect’ and ‘a person of interest’?

“Segun, this is not a legal forum. We use the term ‘glaucoma suspect’ but we don’t use the term, ‘person of interest.’ But if you would find it easier to understand using legal jargons, you have to define the two terms for me first.” I requested.

Segun’s eyes glowed with excitement as he rose to speak. “A suspect is a person who a law-enforcement agent or prosecutor has reasonable grounds (suspicion) to believe he may be involved in a crime. An accused is a person who has been formally charged to court by the prosecutor for a crime. A person of interest is someone the police want to talk to for information about a case.”

“My dear SAN (Segun’s full initials), thanks for the precise definitions. I can now explain to you, using your preferred legal terms, what the ophthalmologist meant when he called you a glaucoma suspect. Technically, everyone is a glaucoma suspect, just like everyone at the scene of a crime is regarded as a suspect at first. However, after a quick preliminary assessment, the police officer may delete some names from the list. Until you have a full eye examination, you are technically a glaucoma suspect because you may have the disease.

“Glaucoma is the leading cause of irreversible blindness in Nigeria. It is a silent disease; there are no symptoms and signs in the early stages; damage must occur before a diagnosis can be made. Thus an examination revealing no signs of the disease cannot permanently exclude the presence of glaucoma!

“All it tells us is that there is no damage at the time of the examination. The disease may actually be in the offing and signs may appear later. The investigating officer (an ophthalmologist – a medical doctor who specialises in eye care and surgery) cannot, therefore, exonerate you completely from the disease. You need to repeat the visit and examinations at least every year. That is the meaning of the term ‘glaucoma suspect’ in its broad sense.

However, the term, ‘glaucoma suspect,’ specifically describes a person with one or more risk factors that may lead to glaucoma. A risk factor for glaucoma is any attribute, characteristic or exposure of an individual that increases the likelihood of developing the disease. Examples include an elevated intraocular pressure (IOP); a family history of glaucoma, advancing age and signs inside the eye suggestive of likely damage to the nerve of sight (the optic nerve).

Labelling a person a suspect means the person must be thoroughly investigated before his name can be temporarily removed from the list. He is not acquitted but remains on the watch-list.

The normal IOP is 10  to 21mmHg. We must always bear in mind that this is mere statistics. The NORMAL helps us to define the IOP value of an individual in relation to the rest of the population when he is seen for the first time. Thus a person with an IOP of 18mmHg (which is within the limits of normal), who shows evidence of optic nerve damage and vision loss on a Central Visual Field test, may actually have glaucoma and be on the way to blindness.

This IOP may be abnormal for his own eye! IOP are often prone to errors of measurement and what is thought to be a high pressure may actually be normal and vice versa, a low pressure may turn out to be abnormally high. Thus, Glaucoma is not just about IOP, there are other criteria to be met before a diagnosis can be established.

So, my dear SAN, your ophthalmologist called you a suspect because you have one or more risk factors that may lead to glaucoma but could not yet find definite evidence of optic nerve damage or vision loss due to glaucoma.

In your legal language, there is insufficient evidence to prosecute you! Since a great overlap can exist between findings in people with early glaucoma and in those who are glaucoma suspects without the disease, regular eye examinations with an ophthalmologist are very important for glaucoma suspects. By monitoring them for the earliest signs of glaucomatous damage, visual function can often be preserved.

Who then is a glaucoma “person of interest”? You are a person of interest if you are a family member of a person with glaucoma or have any of the other risk factors and have not had an eye examination to exclude glaucoma.

SAN looked at me and smiled. I thought my ‘submissions’ had made a deep impression on him. Alas, he exclaimed, “Thank you uncle, you’ll make a brilliant lawyer after four years in the law school!” Do I really need a day more after this beautiful defence? Lawyers are arrogant, aren’t they?