Cataract diagnostic tests

At Issue posed the following question to a panel of experts: What diagnostic tests are essential for the best outcomes in cataract surgery?

Preoperative OCT a significant step

Noel Alpins

Noel Alpins, FRANZCO, FRCOphth, FACS:

Refractive cataract surgeons are continually attempting to keep pace with increasing patient expectations, seeking a consistent optimum visual outcome. A significant step has been the preoperative optical coherence tomography scans of the macula becoming routine in preoperatively diagnosing subtle or significant macula problems. Patients, after detection this way, can be counseled on revised surgical expectation or referred for retinal management before their cataract surgery. OCT has recently proved to be an invaluable tool to assist the cataract surgeon in avoiding disappointing surgical surprises.

Several other essential diagnostic tests are routinely required. These start with an accurate manifest refraction and best corrected visual acuity, which can assess the effect of the cataract on vision and indeed whether surgery is yet necessary. Naturally, an accurate biometry with laser interferometry or immersion ultrasound is needed, with separate manual keratometry being a useful tool to confirm corneal astigmatism and its meridian. Corneal topography is essential when limbal relaxing incisions, toric implants or multifocal implants are planned, not only to gauge corneal astigmatism but to quantify irregularity that may help determine the mode of treatment. Interpreting the axial length readings and then selecting the correct IOL power formula play a crucial part in determining the accuracy of the refractive outcome.

After surgery, a stable postoperative refraction is essential to track outcomes and further optimize IOL constants to improve the personalized accuracy of the formulas used.

• Noel Alpins, FRANZCO, FRCOphth, FACS, can be reached at NewVision Clinics, 7 Chesterville Road, Cheltenham 3192 Victoria, Australia; email: nalpins@unimelb.edu.au.
• Disclosure: Dr. Alpins has no relevant financial disclosures.

Biometry key to good outcomes

Michael Amon

Michael Amon, MD:

Preoperatively, I would say that biometry is essential for good results. The IOLMaster (Carl Zeiss Meditec) and the new equipment from Haag-Streit are maybe the most important tools for getting good postoperative results concerning biometrical results.

I think laser interferometry has increased the results after surgery because of the precision. For me, that is the main advantage in the last few years.

It is important that you have a good preoperative diagnostic concerning the retina condition of the eye. Also, optical coherence tomography is important, both anterior and posterior. With anterior OCT, we can measure the anterior chamber area and the lens, and with posterior OCT, we can see if there are any changes in the macula. These are also important diagnostic tools to get a prognosis for the patient. The posterior OCT can only be done when the media are clear enough. So if you have a dense cataract, you cannot perform this kind of examination.

New equipment includes the intraoperative-performed OCT, but I think it is more of an academic tool to find something changing within the anterior chamber. But I do not think that it has a big influence on the postoperative outcome. Nevertheless, one could mention that intraoperative OCT also is quite an important tool.

There is also the option in which an autorefraction is performed intraoperatively. As soon as you have implanted the lens, you get the result of the refraction. That is quite an interesting tool. Intraoperatively, you may decide if you have to put a toric lens in, or if you have done a keratotomy, if you have done it precisely and if the axis is well-aligned and so on. I think is a nice, new tool to increase the results by measuring these kinds of things intraoperatively, not just postoperatively.

• Michael Amon, MD, is based in Vienna, Austria. He can be reached at amon@augenchirurg.com.
• Disclosure: Dr. Amon has no relevant financial disclosures.

Successful results rely on thorough preop

Ashok Garg

Ashok Garg, MD, PhD:

Modern cataract surgery is a high-tech customized surgery with optimal visual results. For best visual results and satisfying cataract surgery beyond the operating eye surgeon’s skills and the uneventful postoperative phase, the preoperative workup, especially systemic and local ocular exam, is crucial in every case. In fact, preoperative tests and examinations are mandatory and a key stepping stone to successful cataract surgery. Broadly, diagnostic tests are grouped into two categories: systemic and local ocular exam. We follow this schedule in every cataract surgery case at our institute.

Systemic examination, including:

1. Complete medical check-up such as
   

   a. Blood pressure for hypertension
   b. X-ray of the chest
   c. ECG

2. Complete ENT examination
3. Complete dental check-up
4. Random blood sugar, if patient has no diabetes
5. Fasting blood sugar and postprandial blood sugar, if patient has diabetes under control
6. Fasting blood sugar, postprandial blood sugar and glycosylated hemoglobin, if patient has diabetes not under control
7. P24 antigen for HIV
8. Australian antigen or hepatitis B
9. HCV or hepatitis C
10. Urine – complete examination

Preoperative systemic examination is a must before all cataract surgeries to prevent intraoperative complications such as hyphema or expulsive hemorrhage and postoperative complications such as infections or delayed healing or non-healing of the surgical wound. It helps take all the due aseptic and antiseptic precautions to prevent iatrogenic spread of diseases such as HIV, hepatitis B and hepatitis C. It also helps us in detecting and treating beforehand any systemic disease the patient might be afflicted with.

This requires thorough clinical examination, including:

1. Slit lamp examination of the anterior segment of the eye, including the angle of the anterior chamber with a gonioscope, and the posterior segment with the help of a 78 D, a 90 D or a Hruby lens.
2. Specular microscopy for endothelial cell count to rule out any postop corneal decompensation.
3. Keratometry.
4. A-scan ultrasonography to find out the power of the IOL to be implanted.
5. Indirect ophthalmoscopy and fluorescein angiography, if necessary, for a thorough fundus examination.
6. B-scan ultrasonography, if fundus cannot be visualized.
7. Ocular CT of the anterior segment, especially to know the status of the angle of the anterior chamber and of the posterior segment to know the status of macula and different layers of the retina.
8. Ultrasonic biomicroscopy to find out the details of the structures of the eyeball, in the presence of opaque media.
9. Retinal function tests to predict preoperatively the visual prognosis after the surgery.
10. CT scanning and MRI are performed to find out any additional pathology in the retrobulbar spaces and the details of the other orbital and intraorbital structures.
11. Sac syringing to prevent postoperative infection by ruling out chronic dacryocystitis, nasolacrimal duct blockage, etc.

• Ashok Garg, MD, PhD, can be reached at Garg Eye Institute and Research Centre, 235, Model Town, Dabra Chowk, Hisar-125005, India; email: drashok_garg@yahoo.com.
• Disclosure: Dr. Garg has no relevant financial disclosures.

Many tests used; corneal topography necessary

Michael A. Lawless

Michael A. Lawless, MD:

In addition to a complete dilated ophthalmic exam, I perform the following tests:

1. IOLMaster (Carl Zeiss Meditec)
2. Manual keratometry and autokeratometry
3. Corneal topography with a Pentacam (Oculus) and lens densitometry
4. Endothelial specular microscopy
5. Macular optical coherence tomography

These are the standard tests that I use in every cataract patient.

I make certain that the tear film is of good quality to enable the best possible imaging, and if in doubt, the patients are treated with topical corticosteroids and non-preserved artificial tears for 1 week before retesting.

I rely on the IOLMaster for the IOL power but autokeratometry for the axis and magnitude of toric IOLs because it gives a broader range of corneal analysis compared with the IOLMaster, and I believe it is a more certain measurement when choosing a toric IOL.

Corneal topography is essential because in a minority of patients, IOL power selection will be less than adequate, and laser corneal surgery may be required postoperatively to improve the refractive result, and I need to know that this will be possible before proceeding with cataract surgery.

• Michael A. Lawless, MD, can be reached at Vision Eye Institute, Level 4, 270 Victoria Ave., Chatswood NSW 2067, Australia; 9424 9999; fax: +61-9415-4220; email: Michael.Lawless@vgaustralia.com.
• Disclosure: Dr. Lawless has no relevant financial disclosures.