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Age-related cataract is a chronic, slowly progressive opacification of the natural lens of the eye that ultimately results in symptomatic disturbance of vision. Globally, cataract is the leading cause of blindness and impaired visual acuity and cataract surgery is one of the most commonly performed elective surgical procedures in the western countries. As the opacities grow in size and depth, there is progressive deterioration in quality and quantity of vision.

Symptoms of cataract

• Blurred, dim, hazy, or cloudy vision, as if looking through a dirty or smudged window. Patients may find themselves squinting or blinking more often, to get better focus.
• Problems in night driving because of glare and increased sensitivity to light, from oncoming headlights.
• Halos around light sources like lamps, headlights, and glare from the sun.
• Patients may feel the need for increased or brighter lights for indoor activities, like reading.
• There may be fading or yellowing of colors, so that there is trouble differentiating between colors of the same family, such as blue and purple.
• Colors may look faded and not as bright as before.
• Double vision in the cataractous eye.
• Frequent changes in the prescription of eyeglasses or contact lenses.
• In more advanced cataract, the patient may be able to appreciate a whitish or gray film over the eye, in the mirror.

When a cataract becomes visually significant, cataract surgery is the only established method of treatment. The definition of “visually significant” has evolved over time, to its current meaning of a visual acuity of ²⁰⁄₄₀ (⁶⁄₁₂) or worse. With the older techniques of surgery, a visually significant cataract was used to describe an advanced or mature cataract, with vision impairment approaching blindness. As the definition of visually significant cataract has changed, so has the timing of surgery. From waiting till the entire lens was opaque (white), “mature cataract”, to getting cataract surgery done when the lifestyle of the patient is affected, has been possible because of changing techniques of cataract surgery. A mature cataract was much easier to operate with the older techniques than a cataract that was not mature.

The oldest known technique of cataract surgery was Couching, possibly practiced by the ancient Egyptians and Babylonians. Though written evidence of this procedure is found in “Sushruta Samhita, Uttar Tantra”, an Indian medical treatise (800 B.C.) written by Maharshi Sushruta, an ancient Indian surgeon. The diagnosis of mature cataract was easy because of the white pupillary reflex and inability of the patient to see anything, except light, from that eye. Many centuries later, in 1747, came the procedure of cataract extraction by Jacques Daviel. His method involved leaving the capsule of the lens in the eye, which was something like the ExtraCapsular Cataract Extraction (ECCE) of the 1970ies. It remained the prevalent approach for cataract extraction for over 100 years, until the 19th century, when Intracapsular cataract extraction (ICCE) became, for a time, the preferred method of cataract removal. The ICCE involved removal of the entire cataractous lens (including the capsule). It was first performed by Samuel Sharp in 1753. With improvements in operative tools and techniques, there was reemergence of ECCE in the 1970s as the preferred approach over ICCE.

Earlier the surgeries were being done without implantation of an artificial lens (Intraocular Lens-IOL) in the eye, leaving the patient aphakic in the operated eye. This meant that the patient had to wear very high powered plus spectacle lenses after the surgery, with all the associated problems. In 1950 the first PMMA IOL was implanted by Sir Nicholas Harold Lloyd Ridley in England, resulting in a much better quality of vision than with ICCE. In 1967, an American ophthalmologist, Charles Kelman, revolutionized cataract surgery when he introduced phacoemulsification (often referred to as “phaco”) as an alternative approach to ECCE. Phacoemulsification involves ultrasonic emulsification and aspiration of the lens through a considerably smaller (3 to 4 mm) incision compared to the conventional incision of ECCE. It is now considered the safest and the preferred method of cataract surgery. The small incision size has led to much shorter recovery times, less postoperative astigmatism and better visual results.

The timing of surgery is a matter of weighing the benefits against the risks, and particular attention has to be paid to the patient’s wishes and lifestyle. More patients are being operated at a younger age and with better preoperative visual acuities. The annual number of surgeries is increasing and is expected to double within the next two decades. This probably reflects increasing demands for optimum visual function by the patients as well as improved outcomes and safer procedures, lowering the physician’s threshold for advising surgery. By and large the physician’s dictum in the Hippocratic oath of “do no harm” has determined the indications for cataract surgery over time.

The expected postoperative visual results are important when advising the patient on whether to have cataract surgery. It has been found that the postoperative objective and subjective visual improvement is independent of preoperative visual acuity. There is a lack of scientific evidence to guide the clinician in deciding which patients are most likely to benefit from surgery. What is of utmost importance is, a thorough preoperative examination of the anterior and posterior segment (retina and optic nerve) of the eye. This is essential for assessing the expected visual outcome and planning for any anticipated intraoperative and postoperative complications. The preoperative evaluation of the retina and optic nerve may be challenging in patients with very dense cataracts. Potential vision tests, such as critical flicker frequency and optimal reading speed, potential acuity meter and laser interferometry, have been suggested as indicators of postoperative visual gain, but their predictive value is limited.

Per the American Academy of Ophthalmology Preferred Practice Patterns, the indications for cataract surgery:

• The visual function no longer meets the needs of the patient.
• Cataract surgery provides a reasonable likelihood of improvement in vision.
• There is clinically significant anisometropia in the presence of a cataract.
• Lens opacity inhibits management of posterior segment disease like Diabetic Retinopathy.
• The lens causes inflammation, angle-closure, or medically unmanageable open angle glaucoma.

Important contraindications to consider:

• The patient does not desire surgery.
• When glasses or visual aids already meet the patient’s needs.
• When surgery will not improve visual function.
• When the patient’s quality of life is not compromised.
• When a patient cannot safely undergo surgery.
• When informed consent cannot be obtained from the patient.
• When postoperative care cannot be arranged.

Late surgery on an eye with poor vision means increased risk for complications, whereas early surgery with excellent preoperative visual acuity means increased risk for poorer visual acuity. The optimal timing for cataract surgery lies between these two stages of cataract growth.

For good results and a satisfied patient, it is very important to assess the visual goals of the patient. This means factoring in their lifestyle, distance and near vision needs, the desire for reduced dependence on glasses, their financial resources, and their satisfaction with residual refractive error. The surgeon determines the suitability of different options to achieve these goals. This involves selection of the right type of IOL, astigmatism correction during surgery and coordinating with the other operated or unoperated eye. The patient should be counseled in multiple formats, such as written material, videos, by speaking with a technician or counselor, and by speaking directly with the physician.

The great majority of patients experience an improvement in visual function after cataract surgery but one out of ten patients perceive increased visual difficulties even six months after surgery, compared to the preoperative state. On the other hand, even patients with very good preoperative visual acuity (²⁰⁄₂₀) may have a subjective improvement in visual functions postoperatively. Even in patients with low predicted probability for improvement in visual function, cataract surgery has been shown to be cost‐effective.

Cataract is a unique age related change that has a very satisfactory treatment in the form of cataract surgery with Intraocular Lens implantation. There is no perfect time for the surgery. The decision, about when to get operated, effectively lies with the patient, once the doctor decides that there are no contraindications to the surgery.