Understanding Low Vision Therapy Principles

How can we help?

So, before we look at how we can actually help with low vision, we’re going to take a little diversion, into gardening.

Understanding Gardening

Growing a healthy garden

Wait, what? Isn’t this supposed to be about vision impairment?

Trust me, all will become clear.

I was a terrible gardener. I’m still not great. But (now) I understand enough to know that growing plants isn’t as simple as just watering them and watching them thrive. There’s much more to it than that. For a plant to grow, it needs many things, and if any single one of them is wrong then your plant won’t grow properly. To be a good gardener, you should understand all the things your plants need, and you need to be able to recognise when they are missing something.

If you don’t get this, you should watch Ingmar Bergman’s The Seventh Seal (1957) — or at least Bill and Ted’s Bogus Journey (1991).


Plants all need enough water. But beware — too much can be bad for some plants, so you can damage a plant by over-watering too.


All plants need light, but different plants need different amounts of light. Again, you’ve got to get the amount right — too much can be bad for some plants.


The soil has to have all the nutrients the plant needs — enough nitrogen, phosphorus, selenium, and so on. If any are missing, your plant won’t grow right. But again, sometimes too much can be a problem too.


If your plant is being eaten by caterpillars, snails, aphids or goats, or your garden gets frosts and your plant is tropical, clearly it won’t grow well.

Principles of Gardening

We need to fix the right thing

If you’ve got a plant dying from lack of sunlight, don’t expect to fix it by watering it more. There’s no point trying to fix a different problem. Identify and fix the actual problem.

We might need to fix more than one thing.

If you’ve got a plant that’s dying because it’s in the dark and it’s dying because of lack of water, you can’t fix it by just putting it in the sun. Nor can you fix it by just watering it. If you want to save your plant, you need to put it in the sun and water it.

For a plant to survive, all of the factors must be within the survival range. If even one of those factors is outside of that range, the plant will die.

Helping a plant flourish is harder than just helping it survive.

For me, having a plant survive is definitely a win. But good gardeners want better than that. They don’t want their plants to just survive, they want them to thrive.

How? It’s basically the same as above, but with a narrower range. Plants have an optimal level of watering that they love, and an optimal level of sunlight that they love, and so on. If you can keep everything within those optimal ranges, the plant will flourish. If even one factor is outside of that optimal range, the plant becomes stressed, and it won’t grow well. Too far out of that optimal range and you get outside of the survival range, and then you’ve got a dead plant.

Sometimes, survival is the best even an expert gardener can achieve.

You might give your plant just the perfect amount of water, nutrients and light. But if the leaves are constantly being nibbled off by your neighbour’s goat, or the climate is too cold and the plant’s not frost resistant, it’s never going to really flourish.

We can’t control everything. Sometimes the conditions are such that just keeping our plant alive is the best anyone can do. We might find it frustrating that we can’t make it flourish, but we should never lose sight of the fact that in those conditions, just keeping it alive is still a win.

Okay, back to our scheduled programme:

Low Vision Care is Like Gardening

Okay, that’s a sentence you’re unlikely to find anywhere else. But in principle, vision is similar. As we’ve seen in the previous sections, there are different aspects to vision — such as size, contrast and illumination — and different eye conditions/diseases affect those aspects in different ways. If we want to improve the situation, we can use devices to change the situation in a range of different ways — such as making things bigger, or brighter, or bolder. But which change is best? Or do we need two? Or more? And how much?

I’m still a poor gardener, but I’m a very experienced optometrist.

In the next sections of this website, we’ll have an in-depth look at a range of interventions we can make, and in what situations they might be most effective.