Selecting the Ideal Time & Intraocular Lens for Cataract Surgery

Cataract is mostly a problem of aging & is hence universally seen in all people. The only treatment for cataracts is surgery. The unique thing about cataract surgery is that it is a daycare procedure & is almost always an elective procedure. By day care procedure, it is implied that the surgery will not involve any hospital admissions & patients are discharged on the same day soon after surgery and by elective procedure, it is meant that the procedure can be done at any date of convenience of the patient.

Since cataract surgery is a single shot procedure & straightforward cases will not need to be operated on again, the surgery can also be thought of as a once in a lifetime event (one for each of the patient’s eyes). With that said, this article has been written to provide in-depth information about the right time to opt for cataract surgery & also about the various intraocular lenses available, to help patients planning for their cataract surgery to make informed decisions about their own health.

When should I get cataract surgery done?

The answer to this question is not straightforward and depends on a lot of factors, but the most important factors to consider are:

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1)  A drop in visual function

A decrease in visual acuity is one of the universally agreed upon indications for cataract surgery. Then again the question arises, “To how much should the vision fall?” The answer to this question varies from person to person & depends on their occupational demands and daily activities. So it is advisable to get surgery done as soon as you feel that your vision is getting in the way of your daily activities or hampering your work efficiency or is simply stopping you from being your fullest self & enjoying life. In more simpler terms, a person who enjoys driving or a person who is a voracious reader might need cataract surgery earlier & for a smaller drop in their vision than the person who spends a lot of time indoors & is engaged in tasks which don’t involve visually intensive activities.

Even when the patient does have such vision problems, s/he can still plan for a convenient time to get operated and usually a time of 2 to 3 months will not have a significant effect on cataract progression. The catch, however, is that co-existent diseases such as high blood pressure or blood sugar and other such diseases may fluctuate during this period and it is apt to consider surgery as soon as you are physically fit.

The second important advantage of getting surgery done early is the process of surgery becomes a lot simpler and easier for the surgeon in early stages, hence making post-surgery vision better after earlier surgeries than ones with more mature, harder cataracts which pose a challenge to the surgeon’s skill.

Nevertheless, the surgery is still elective and patients are recommended plan aspects such as date & specific type/ form of surgery, their health insurance issues, keeping their other bodily comorbidities under check and getting certificates from physicians regarding fitness for cataract surgery.

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2)  Glare

This refers to image clarity being affected by excessive scattering of light inside the eye. Cataracts can cause image degradation by various mechanisms & glare is one of the earliest symptoms of cataract. It is caused by an increase in the water content seen in cataractous lenses which causes light to get scattered & the image quality to go down.

This can be quite troublesome in people who are more active at night & are especially engaged in driving in low light conditions. Patients who are suffering from glare are encouraged to get an eye examination done & quite a few patients experiencing glare due to cataracts, do get operated on frequently.

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3)  Loss of contrast sensitivity

Contrast sensitivity refers to the ability of a person to distinguish nuances in shade & hue i.e the ability to pick up the different shades of a colour accurately. This ability helps with vision under low light conditions, for example, driving in dim light, this is when a person with cataracts & impaired contrast sensitivity will not be able to identify & avoid pot holes or obstructions on the road during driving in dim light. S/he will also have problems with reading & in general seeing well in low light conditions.

4)  For the treatment of retinal problems

The position of the lens in the eye is similar to a window which opens into the back of the eye; this part is referred to as the retina. So any cataract present in the lens would be obscuring a clear view of problems in the retina. Hence it becomes mandatory to get cataract surgery done to facilitate better management of the retinal problems.

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5)  Lens induced glaucoma

This is also a universally agreed upon indication. Here the cataractous lens causes a rise in the pressure of the eyes (intraocular pressure) which is detrimental to the nerve of sight (optic nerve). This condition presents with symptoms of cataract & usually with pain inside the eye. This is one of the conditions which need emergency cataract surgery.

What kind of intraocular lens should I choose?

Since cataract surgery is a one-time procedure and the intraocular lenses implanted after the surgery last for the patient’s whole lifetime, it becomes important for the patients to select the best lens to suit their own personal needs.

Intraocular lenses available can be broadly divided into monofocal & multifocal lenses. Monofocal lenses enable the viewer to have clear distance vision while the multifocal lenses are designed for clear distance, intermediate (in few cases) & near vision. Multifocal lenses may differ in having varying degrees of clarity with respect to intermediate & near vision. Professionals who spend a majority of their time using computers are best suited for lenses having good intermediate vision, while professionals whose major portion of the day is spent with books or with mobile phones, will do best with lenses offering good near vision.

To correct for astigmatism above +/-0.75, a special variety of lenses called toric lenses are used. Toric lenses come in both monofocal & multifocal variants.

To enable easier differentiation, the pros & cons of each lens type, in general, are given below –

Monofocal lenses – provide very good distance vision with blurred near & intermediate vision. Vision quality is excellent with minor distortions.

Multifocal lenses – provide a varying range of good to average near, intermediate vision & distance vision. Image quality is lesser compared to monofocal lenses with glare, halos & reduction of contrast sensitivity seen in varying degrees. These problems go down with time as the image processing centers in the brain get adapted to these changes.

A few other characteristics of a lens to consider are –

  1. Hydrophilic or hydrophobic effects
  2. Square Edge optics
  3. UV filters
  4. Asphericity

These characteristics of the lens design do play a part in image quality & lens function.

Hydrophobic lenses have a lesser tendency to accumulate leftover proliferating cataractous fibers called after cataract, this problem may need a secondary procedure called a yag capsulotomy to be done. Hydrophilic lenses cause less intraocular reaction post implantation and help patients recover faster from postoperative pain & blurred vision and to some extent prevent after cataract by lowering inflammation (a destructive reaction) inside the eye.

Square Edge optics play a part in mechanically stopping after cataract cells which cause a vision dip after surgery, UV filters help by filtering out harmful UV rays, which would normally be filtered by the natural lens, from reaching the retina of the eye.

Asphericity of a lens refers to its quality of optical design in terms of quantity of spherical aberration. Lenses manufactured mostly are of zero or negative Spherical aberration. This value of aberrations becomes important when planning for multifocal lenses & is planned in such a way as to bring the overall spherical aberration of the eye as close to zero as possible or if not to lean on the negative side slightly.

Cataract surgery these days has become very refined to that compared to what it was just a decade ago. Most of it has to do with the improvement in terms of machinery, equipment, and improvements in optics. So the cataract patients of today have a variety of options, tailored to their specific personal needs to ensure that they have the best possible results from their surgery.

Dr Manjunath Natarajan has completed his medical education from Rajiv Gandhi University, Bangalore, Karnataka and has completed his F.I.C.O (U.K), know to be a globally recognized standard of knowledge, ensuring the highest patient safety in ophthalmology. He has also been selected among several applicants for the prestigious I.C.O fellowship at The Royal Free Hospital NHS trust for higher specialist training and has cleared several fellowship exams of The Royal College of Ophthalmology (London) and The Royal College of surgeons (Glasgow).

He has since been engaged in ophthalmology practice at Bangalore and Trichy. He is actively engaged in teaching Ophthalmlogy to undergraduate students at D.S.M medical college and research centre, Trichy. He is an avid writer & has authored several research publications and case reports which have been presented at the All India Ophthalmological Society’s annual conference (AIOC). He has a passion for writing medical articles & is especially interested in writing lucid, informative & concise articles whose target audience are patients and the common man, so as to provide them with easy to understand, accurate and upto date knowledge about their medical condition.

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