What Tests Are Done Before Cataract Surgery?

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cataract surgery tests

If you have been diagnosed with cataracts and planning to undergo cataract surgery, your surgeon will advise you to undergo some medical tests first. These tests are done to assess the refractive error in your eye.

The tests can also be recommended to ensure the exact cause of your cataract, check the severity of the disease, and also determine if any treatment plan is required after the cataract surgery. In several cases, the tests help in finding any underlying medical conditions which might hinder the cataract surgery and may cause post-operative complications. 

What is cataract surgery?

Surgery for cataract is the most common and the safest procedure performed to date when compared to any other surgery. During the procedure, the cloudy natural lens in the eye is replaced with a new artificial lens. If you are cataract ridden in both eyes, the surgery is done separately for each eye. Cataract surgery is performed under local anesthesia, which means you will awake during the surgery. However, you will be sedated along with numbing gel and eye drops so that you do not feel discomfort during the procedure. 

What are the tests recommended before cataract surgery?

This is a commonly asked question from many patients diagnosed with cataracts and wants to have cataract surgery. We wanted to provide a comprehensive list of what are necessary tests before undergoing cataract surgery and their reasons.

A test for your existing glasses



This test can be done by your ophthalmologist or optometrist. This test is done for refractive error that already exists like short-sightedness (myopia), Far-sightedness (hypermetropia), presbyopia (inability to focus near objects), etc. This test is useful as your surgeon will come to know your existing glasses prescription and will be able to decide if the prescription glasses are to be corrected before the cataract surgery and the course of the treatment.

An ocular examinationAn ocular examination


This test is used to check and examine:

  • The anatomy of the eyelid and any signs of inflammation. 
  • The presence of any co-existing diseases that may increase the risk of infection post-surgery.
  • The condition of your tear film as dry eye can make cataract surgery difficult.
  • The presence of irregularities in the cornea can make the visuals of your cataract difficult during the surgery. 
  • The depth of the anterior chamber in your eye as if it is shallow, it will be difficult for the surgeon to access into the capsule.
  • The amount of dilation your iris undergoes after administering dilation drops. If the dilation is small, iris stretching is required as an extra step during the cataract surgery.
  • To detect the type of cataract. Soft cataracts are easily removed while hard cataracts require more ultrasonic energy and surgical time to break up and remove. 
  • Measure the intraocular pressure in the eye to rule out glaucoma and ensure optimal control of immediate pre-operative and intra-operative eye pressures.

Biometry Tests

Biometry Tests for cataract


This is a simple measurement to calculate the correct power of the artificial intra-ocular lens, which is implanted once after your cataract is removed. 

  • Your doctor will measure the length of the eyeball and the curvature of the cornea at the front. These readings are known as keratometry readings. These are unique in every patient, the figures are entered into a specific formula. The biometry machine then calculates the range of artificial lens powers for a range of refractive outcomes like normal distance, long distance, and short distance. Your keratometry readings can allow your cataract surgeon to check whether there is astigmatism (an imperfection in your eye’s curvature). 
  • Rarely do patients with dense cataracts need different methods of measuring the eyeball length as a standard machine might not be accurate. The test involves using a small painless ultrasound probe placed on your eyelids and takes a few minutes to take measurements. 
  • If you use contact lenses, your doctor will ask you to stop wearing them before your biometry test to ensure your readings are accurate. This is advised because contact lenses can subtly change the shape of your cornea. The doctors will recommend the following:
  • Soft daily, 2 weekly, and monthly disposable contact lenses should be stopped wearing 48 before the test.
  • Extended wear soft and rigid gas-permeable contact lenses should be stopped 1 week before the test.

Corneal Topography

                                                  Corneal Topography

This test is done to map out the corneal curvature with much more detail. This extra test is done if your biometry readings show bigger than normal differences in keratometry readings. Corneal topography can also diagnose keratoconus (a condition where the clear tissue in front of your eye bulges outward) and irregular astigmatism. Knowing this can alter your surgical management. 

OCT (Optical Coherence Tomography)

                                                  OCT (Optical Coherence Tomography)

This test visualizes the macula (the central sensitive part of the retina used for fine vision). If your doctor suspects any macular changes that might prevent you from improved vision after the cataract surgery. It is a simple test involving sitting at a machine that takes pictures of your retina cross-sectionally. 

If you have conditions like macular degeneration or macular holes, your doctor will explain that your vision might not improve as expected after cataract surgery.

Blood Pressure                                                   

It is mandatory to know your blood pressure before cataract surgery. If you have high blood pressure, there is a risk of bleeding at the back of your eye during the surgery. Your doctor will recommend delaying your cataract surgery and advise you to get it under control to avoid any complications. 

Blood sugar measurements 

Cataract surgery does not affect your blood sugar but higher blood sugar has a higher chance of post-operative infection in your eye. Therefore, your doctor might recommend delaying your cataract surgery before your blood sugar reaches normal levels. . 

Are the above-mentioned tests important before cataract surgery?

Yes, these tests are advised to rule out any potential complications post-cataract surgery. Based on your test results, your eye doctor will decide the safest surgical option. The tests will also show any risks therefore your surgeon can change the course of anesthesia or might even recommend some medicines. 

If your tests indicate some risk factors, your surgeon might suggest special eye care and your cataract surgery can be delayed until the problem is addressed or cured. These are some common tests that are suggested to almost all patients before cataract surgery and all these tests are easy and quick, they are painless with no harm. 

But for more details, it is always better to have a face-to-face consultation with an experienced and trusted ophthalmologist.


The routine tests before cataract surgery are simple, quick, and painless and you need to be worried. The tests are accurate and they contribute to excellent outcomes seen in patients. If you want to discuss any tests that can be done before the cataract surgery in more detail, contact our doctors at Medfin. They will like to discuss any aspects of tests before cataract surgery. 

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