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iPhone Slit Lamp Adapter – Full Review

iPhone 6 Camera
iPhone 6 Camera

A smart way to take great slit lamp pictures is with an iPhone slit lamp adapter.

If you are a curious person then by now you have been trying taking pictures through your slit lamp with your iPhone, right?

I will go into details on the advantages of using an iPhone slit lamp adapter as your main tool for digital photography, the different options you will find in the market and how to use it to create awesome pictures.

What was the first thing  your tried to do when you got your first iPhone? For me it was the camera. The TV ads would not stop promoting the idea that this new iPhone will be the only camera we needed. So I had to test it…and I was not disappointed.

While Apple kept busy launching new versions of the iPhone; 3, 4, 4s, 5, 5s, etc. the camera has been always one of the main focus of improvement: from the starting 3 megapixels on the first version to today’s 8 megapixels, bigger sensors, improved focus and faster pictures.

Considerations for a high quality picture

You will get an excellent picture when the main parameters of the camera are in perfect balance. These are:

Number of megapixels

Resolution Comparison
Resolution Comparison

One of the most important camera’s parameters to take in consideration when deciding what iPhone version to use for slit lamp’s photography, is the number of megapixels it has. Even though, more megapixels doesn’t necessarily translate into better pictures .

There are other parameters to consider for better pictures, like the sensor size and the quality of the slit lamp. The iPhone slit lamp adapter has a 10X ocular so it won’t affect the quality of the picture.

More megapixels means you can print the picture bigger, also that you can crop the picture and maintain the same quality, but that’s about it. If you are just going to display them on a computer screen, 3 megapixels is enough.

When using an iPhone slit lamp adapter you will get more than 5 megapixels if using iPhone 4 or 5.  As you see in the picture to the right, when taking zoom photography you won’t see any noticeable difference between 3 and 12 megapixels.

For a more extensive explanation check this article : Do More Pixels Mean Better Photo Quality?

Sensor Size

The Sensor size will determine how much light and the range of colors of a picture, that’s why Apple has been improving the iPhone’s sensor and other camera features instead of just increasing the megapixels.

You’ll find an interesting discussion on this topic here: Why did Apple use an 8-megapixel camera in the iPhone 6 and iPhone 6 Plus?

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Slit Lamp quality

Another important parameter to consider is the quality of the slit lamp. The lenses on the slit lamp are the most valuable component and it will make a major difference in the quality of the picture. So next time you are thinking in getting a better camera , think instead about the possibility of getting a new slit lamp. When using the iPhone slit lamp adapter with different kinds of slit lamps you will notice the big difference in output quality from an economy slit lamp to a brand name one.

Here are pictures from a Haag Streit slit lamp. Notice the high definition:

Click Images to Zoom

eye-hs1 eye-hs2 eye-hs3

Why using an iPhone slit lamp adapter?

Although a slit lamp camera has advantages over a smartphone when taking anterior eye pictures, it is also known that the best camera is the one you have in your hand.

That’s how ophthalmology students began using their smartphones to take pictures; cause they have them in their pockets. Sometimes you don’t have access to the slit lamp camera like when on a remote location, in this situation you can use your smartphone for a quick picture of the eye. You may not get the best pictures using this method, but they will be good enough.

An appropriate iPhone slit lamp adapter will allow you to focus better and cover a wider area of the eye.

Do I need background illumination?

An iPhone slit lamp adapter is perfect for anterior segment photography, but having the right illumination can make a difference. You will need to experiment with the lighting and background illumination to find out what works better for you. This photography shows how different illumination affects the picture.

Slit Lamp Photography Illumination
Slit Lamp Photography Illumination

Components of an iPhone Slit Lamp adapter.

You will find a few different slit lamp iPhone adapters on the market, with all of them sharing this basic structure.

Holder for iPhone

There are two kinds of iPhone’s holders – Exact Fitting and Universal. Each has its advantages and disadvantages.

Exact Fitting Holder

iPhone Slit Lamp adapter
iPhone Slit Lamp adapter

This type of case will fit exactly to the  shape of your phone, which means that to use your phone with the iPhone slit lamp adapter, you will need to first take off the current case.

If you have a very tight case, or a double case for better protection of your phone, then taking it out every time you want to take a picture can be an issue.

In this case I recommend to use an iPhone exclusively  for slit lamp photography. You can get a used iPhone 4s in eBay for $75 or an iPhone 5s for $240. Another option will be if you are upgrading soon just leave the old phone for this purpose.

Because each iPhone model has a different shape, you will need to get an iPhone slit lamp adapter case designed for your particular model. i.e. if you bought the one for the iPhone 4 and upgraded to the iPhone 5 you will need to get a new adapter case for the new phone.

This is another reason to have a dedicated iPhone for the exclusive function of taking slit lamp pictures.

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Universal Holder

Smartphone slit lamp adapter - Universal
Smartphone slit lamp adapter – Universal

This adapter has one or two sets of clamps that will hold the sides and bottom of the smartphone. A sliding system will move to align the smartphone camera lens with the adapter hole.

One of the advantages of this adapter is that you can use it as an iPhone slit lamp adapter and will fit almost every smartphone on the market as well, so you don’t have to purchase a new case every time you upgrade phones. However I find that the adapter is not as solid as the “exact fit” one case I mentioned before.

Ocular attachment.

iPhone adapter's Ocular
iPhone adapter’s Ocular

There are two ways to attach the iPhone slit lamp adapter case to the ocular:

  1. Slide-in adapter
  2. Over the eyepiece adapter

Let’s look more into this 2 options:

Slide In Ocular Adapter

The slide-in adapter is not just a metallic empty tube, it’s a 10x ocular itself. It will give the best picture’s quality.

It will require you to first slide out the ocular and slide in the iPhone slit lamp adapter attached to the case. So first you should confirm this information:

  • You are able to slide out the eyepiece. There are a few slit lamps in which you have to unscrew the eyepiece. In this case you will need to use the “over the eyepiece adapter”
  • Measure the eyepiece’s diameter. The adapter’s ocular will be replacing the original ocular, so it has to be the same size.  Usually the eyepieces are from 23 to 30 mm.

The iPhone slit lamp adapter ‘s ocular will fit the slit lamps with the smaller eyepieces. If you need a bigger diameter you will have to either purchase an adapter with that diameter or get an additional adapter sleeve.

This sleeve goes on top of the original eyepiece to fit on your slit lamp. You will find some companies that sell just the adapter that fits your slit lamp, while other companies will give you all the 3 or 4 sleeves, that way you will be covered for most of the slit lamps in the market.

Over the Eyepiece Adapter

Smarphone Adapter Clamp
Smarphone Adapter Clamp

This iPhone slit lamp adapter will use a clamp that holds the phone to the ocular. If you have a slit lamp in which you can not slide out the eyepieces then this is your only option.

It works with all sizes of eyepieces. These adapters come with a system of plastic covers that you will need to put one on top of the other until the clamp fits tightly. The smaller the diameter, the more covers you need, after taking the picture you have to take off the adapter and the 2 or 3 covers, this is not as easy as just replacing the ocular, but works.

Steps and Tips to take the best pictures

Once you setup the iPhone slit lamp adapter these are the steps to take your first picture.

  1. Turn off the iPhone’s Flash – No need for it. If you need more illumination you can set up a background light on the slit lamp, but normally iPhone camera sensitivity is enough.
  2. You will focus through the iPhone touchscreen. What you see is what you get in the picture.
  3. Focus the slit lamp as you will normally do.  A couple of tips here:
    1. Zoom: Do all the zooming using the slit lamp’s magnification, not through the iPhone’s zoom . You will get better results, as the iPhone will do a digital zoom, instead of a manual one.
    2. Focus: Unless you are in the lowest slit lamp magnification you will not see the complete eye focused. The way you focus on the iPhone camera is by touching on the screen the spot you want to be in focus. This action will do both  focus and adapt the illumination of the whole picture to that spot.
    3. If you want to focus on one spot while changing the illumination you do this: Instead of just tapping once on a spot, tap and hold for 2 seconds. You will see a yellow square and a “AF locked” label, now you can move your finger up and down for more or less light.

This are some sample shoots from an iPhone 4:

iPhone Eye Picture
iPhone Eye Picture

iPhone Eye Picture
iPhone Eye Picture 2

iPhone Eye Picture
iPhone Eye Picture

Thanks to the HDR (high dynamic range) setting on the iPhone you will get pictures with a greater dynamic range of luminosity that with a standard camera, even though some of the newer cameras come with HDR function, the HDR on the phone will take 3 pictures at different light levels, instead of one. Then it will combine them finding the best light from all areas of the picture, and will create one last improved picture.

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Thanks to all these technological advances an iPhone slit lamp adapter is becoming indispensable in every optical practice. Now you know why.