Cataract surgery is a commonly performed procedure and most people ae aware about it. However, it is important to understand the steps which are required from visiting a doctor to getting the actual surgery done. 

First and foremost is a detailed eye check-up by an experienced eye doctor- 
It should include: 
• Measurement of visual acuity with an updated eye power
• Pupil examination 
• External eye examination including lids and lashes. 
• Measurement of intraocular pressure, syringing of lacrimal apparatus (if required) 
• Full slit lamp examination 
• Dilated examination of the cataract and fundus 
• Biometry (To keep in mind for Long and Short eyes) 

After the detailed eye check-up, your eye doctor may or may not advice a cataract surgery. If advised your eye doctor will further ask you to undergo some investigations- 

Biometry is a test to measure the shape and size of the eye. It is commonly used to calculate the power of intraocular lens (IOL) implants required for cataract and refractive surgery. Ultrasound (US) biometry (A-Scan) and partial coherence interferometer (PCI)-based devices are the most commonly used methods for determining IOL power.

An “A” Scan is an ultrasound based precise measurement of the length of the eye which is required to determine the correct lens implant power before cataract surgery.

ULTRASOUND BIOMETER

IOL master is the most sophisticated and accurate ways to determine the power of the intraocular lens (IOL) implant for cataract surgery. The IOL Master allows for fast, accurate measurements of multiple areas of the eye, such as eye length and surface curvature, which are necessary for deciding the type and power of lens before the cataract surgery. 
IOL master which is a type of Optical biometry & is the current gold standard for intraocular lens (IOL) power calculations. It is a highly accurate non-invasive automated method for measuring the anatomical characteristics of the eye. 

OPTICAL BIOMETER 

Measuring the length of the eye accurately is extremely important in cataract surgery, as it allows the eye surgeon to select the right power lens to implant for each patient.  

For axial lengths from 22.50 mm to 24.00 mm, and central corneal powers ranging from 42.00 D to 45.00 D and a normal anterior chamber depth, most modern IOL power calculation formulas will give good outcomes. 

The axial length measurement is critical in determining the ideal IOL power. A small 1 mm change in the axial length measurement can change the IOL power by 2.5 D in average eyes and even more in shorter eyes.

Routine Blood and other body Investigations 

-For all cases: 

-Blood Pressure 
-Blood Sugar 
-CBC
-ECG for adults,
-Blood test for HBsAg/ HCV/HIV

-Physician Consultation: 

Physician opinion/clearance is required under following circumstances 
- Uncontrolled diabetes and hypertension 
- Cardiac problems
- Urinary Tract Infection
- Systemic problems, if any 
 

Special investigations : In addition to a complete dilated ophthalmic exam and Biometry, following tests may be required in selected patients:

Corneal topography: Corneal topography is essential in special situations like prior laser corneal surgery, any corneal dystrophy like keratoconus, any corneal scars etc. This helps to better decide the type and power of the IOL to be implanted during the cataract surgery.  

CORNEAL TOPOGRAPHER 

Endothelial specular microscopy: It helps in preop planning in compromised eyes. Eyes with previous surgery, Fuchs corneal dystrophy, previous corneal transplants, trauma or recurrent uveitis are a challenge for surgeons, as these issues may reduce endothelial cell counts substantially. Additional surgical procedures could compromise corneal clarity by reducing cell density further. Specular microscopy is a very valuable educational tool to let the patient and cataract surgeon be aware of potential problems. This can also help the surgeon decide the right type of cataract surgery for the patient. 

Optical coherence tomography: Optical coherence tomography is important. With anterior segment OCT, we can measure the anterior chamber area, angles and the lens, and with posterior segment 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. If the OCT is suggestive on any macular or optic nerve pathology, then the choice of lens may change. 

OPTICAL COHERENCE TOMOGRAPHER 

Once you have undergone eye and body tests and received the clearance from your physician you are ready for the cataract surgery. There will be some additional guidelines which will be informed to you by the nurse before the cataract surgery. 

1. Patient cleanliness: 

a. Head bath previous day 
b. Clean clothes to be worn 
c. Avoid using vermillion (Sindoor), ash etc; to the forehead 

2. Food to be eaten prior to surgery: 

a. Patient is advised to avoid heavy meal 4 hours prior to the surgery

3. Eye drops to be instilled prior to surgery:

a. Some eye doctors may advise you to instill a few eye drops 1 day prior to the cataract surgery

4. Medication prior to the cataract surgery:

a. Hypertension medication- To be administered as per the previous schedule
b. Diabetes medication- to be avoided prior to the cataract surgery to avoid hypoglycemia.