Differentiating nuclear sclerosis from early cataracts during an ophthalmic exam

In this interview on his Fetch dvm360 Conference lectures in Nashville, Tennessee, Benjamin Bergstrom, DVM, MS, DACVO, owner of The Eye Vets in Nashville, guides viewers through how to distinguish between nuclear sclerosis and cataracts. He explains what each condition is and breaks down their key visual characteristics, describing how to use illumination techniques and the slit beam function of a direct ophthalmoscope to help general practitioners distinguish between these 2 commonly confused conditions.

Below is the transcript of the video, which has been lightly edited for clarity:

Benjamin Bergstrom, DVM, MS, DACVO: So, the differentiation in its simplest form between nuclear sclerosis and cataracts is that nuclear sclerosis is a normal age-related hardening of the lens that causes just kind of a generalized haze to the surface of the eye or to the lens, to the inside of the eye. Cataracts form because of something has changed metabolically in the lens that has caused a true opacification. And it's always, it's always kind of an odd thing to say, ‘Well, nuclear sclerosis is a haziness to the lens, and a cataract is an opacification’. When you kind of think about it, they're one and the same.

However, in opacification, you no longer can see through that opacification. Now it's tricky because in cataracts, they can be small, so you can see around them.

The best way to differentiate between the two is when you shine a light—so you directly illuminate the light—cataracts will look bright white. Nuclear sclerosis may look hazy, but you can see straight through.

When you retro illuminate with a light source, which means you use the back of the eye, you shine a light, use the back of the eye to reflect back forward, again, nuclear sclerosis will just kind of look like a haze. Cataracts will look dark or black. And it's easier said than done, it takes practice differentiating the two with an exam.

The last thing that I would encourage general practitioners to do if they're trying to decide if this is a cataract or if it's nuclear sclerosis is using the slip beam function on their direct ophthalmoscope. They use a slip beam. There is a beam that will hit the surface of the eye, of the cornea. There's a continuation of the beam that will hit the anterior lens capsule and then there's a continuation of the beam that will hit the posterior lens capsule.

Cataracts will look like very obvious, very clear, opacifications between the second and third beams of light. Nuclear sclerosis just looks like an increased haze. I think that's probably the best way to describe the difference between the 2.