Aug 27, 2015
Consider ALL the Options Before Your Cataract Surgery: Working Through What’s Best For You
John C. Hagan, MD, Fellow American Academy of Ophthalmology, Fellow American College of Surgeons.
Many decisions have to be made before having cataract surgery. The first is whether you need the surgery or not. Assuming you have made the decision to have surgery this is a discussion of the many options and choices you have. THERE IS NO “BEST” TYPE OF PHACOEMULSIFICATION CATARACT SURGERY AND NO “BEST” INTRAOCULAR LENS. NO TARGETED POST SURGERY REFRACTIVE ERROR IS FOR EVERYONE. THESE DECISIONS WILL VARY FROM PERSON TO PERSON AND MUST BE INDIVIDUALIZED.
We all have different visual needs. Cataract surgery will be done earlier on a person needing perfect vision in all lighting circumstances, think airline pilots, truck drivers and heart surgeons. Surgery is done much later, if at all, on the very, very elderly, functioning combative or uncooperative dementia patients, those with terminal illnesses. In general cataract surgery is generally offered when a person is experiencing moderate or severe visual difficulties in activities they enjoy or need to do and the cataract is the sole or main cause.
Although the person is usually the one that makes the determination about how much of a problem his/her vision is in some cases surgery is strongly recommended by the ophthalmologist, optometrist or family. Examples include inability to drive safely or legally; difficulty seeing the inside of the eye, major progressive physical or psychiatric disease, and if center of the cataract is getting “rock hard” (so called ‘brunescent or brown/black cataract) or could start to break up in the eye (so called ‘too ripe’).
Assuming cataract surgery is appropriate, the decisions that must be made include: which eye to operate on first, what type of IOL to insert, desired-targeted post-operative refractive error, how much glasses will need to be worn post operatively [NOTE: glasses are almost uniformly needed post operatively and are usually modern progressive bifocals] SOME OF THE TIME a small % of people after cataract surgery can function without glasses or with inexpensive over the counter reading glasses. Equally important is the choice of surgeon-ophthalmologist (Eye MD: a physician Doctor of Medicine or Doctor of Osteopathy that has been to medical school, medical-surgical residency and in many cases taken a special surgical fellowship. Ophthalmologists provide a complete range of medical and surgical services. Eye MDs must be distinguished from non-physician optometrists (OD) and opticians).
This discussion is not meant to be encyclopedic nor to give you “the answer.” As stated previous “the correct” answer will be different for different people. Informative is based on the most common questions posted on the American Academy of Ophthalmology MedHelp Eye Forums.
1. Where there is a difference of more than 1.50 diopters between the eyes post operatively glasses are often difficult or impossible to adjust to. The condition is called "aneisometrophia". Part of the problem is due to the difference in image size each eye has with the glasses on; this is called “aneisokonia”. Seek out Eye Forum posts on this problem by JodieJ. She had this problem post operatively and she clearly outlines her struggle and eventual success.
2. With modern cataract surgery not only do we try and make the person see better but we want the best possible vision without glasses and the two eyes to "work together" comfortably. Tests are done preoperatively to help pick the proper IOL power to leave a targeted post op refractive error. This is not an exact science and the margin of error is +/- 0.50 but INCREASES with high myopia (long eye) or high hyperopia (short eye), eyes with previous RK, lasik, injury or additional eye diseases.
3. Typically the targeted post op refraction is between 0.00 (not needing glasses for distances of 20 feet (6 meter) or more) and -3.00 which has great vision for tiny detail at reading distance 13-14 inches. Any difference of greater than 1.50 diopter post op may have trouble with glasses (some people tolerate much larger numbers but you never know). The range of relatively clear vision without glasses on is called “depth of focus” and will vary from person to person based on things like pupil size and corneal structure.
4. Some people that are highly myopic or highly hyperopic that do not have cataracts elect to have the lens of the eye removed (same technique as cataract surgery) and an intra-ocular lens (IOL) put in to eliminate thick glasses and improve vision without glasses. It is called "clear lensectomy" or "clear lens cataract surgery” or “refractive lens exchange”. This is done to reduce the thickness of their glasses or make them much more glasses independent. We are not discussing whether that is appropriate surgery. The IOL and refractive problems are the same as those having cataract surgery.
5. A refractive error that makes some people happy post cataract surgery and often enables them to function without glasses for many things is 0.00 in the dominant eye for distance and -1.25 or -1.50 for the "reading eye." In good lighting they often can read without glasses. With glasses (the RX would be 0.00 distance eye -1.50 near eye and reading add of +3.00 diopters and the type glasses a no line bifocal) The glasses would be worn when best binocular vision is needed e.g. driving especially at night, sporting events or sports participation (gives the best depth perception) and prolonged reading or computer use. (This is called mini-monovision with distance bias) If a person wanted to shift the clearest vision to intermediate and near (example some accountants, engraver, graphic design artist) the numbers change: -1.25 intermediate vision and -2.75 or -3.00 for reading/near eye. The glasses RX would be -1.25 and -2.75 with +3.00 add in progressive bifocals.
6. If the person having surgery has astigmatism (aspherical or not round cornea) then the glasses RX will need a "cylinder" lens (second and third part of RX indicated by “cylinder and axis). The vision without glasses will be less clear due to uncorrected astigmatism. Assuming our models listed in above example and 1.00 diopters of corneal astigmatism the mini-monofocal distance bias will be 0.00 +1.00 axis 180 and the intermediate/near bias eye will be -1.25 +1.00 axis 180 and a +3.00 add in no line bifocals. This is more blurry vision than 0.00 at distance or -1.25 for near/intermediate.
7. NOTE: glasses can be written in PLUS CYLINDERS OR MINUS CYLINDERS (you can tell which by whether the sign in front of the cylinder number is + (plus) or – (minus) The two formula look very different and prescriptions in plus cylinder cannot be compared with minus cylinder. Think about your body weight: your weight numbers will look very different whether it is recorded as pounds or kilograms since 1 kg = 2.2 lbs. A discussion of this subject and the formula for changing plus cylinder to minus cylinders or vice versa is available at http://en.wikipedia.org/wiki/Eyeglass_prescription
8. Correction of astigmatism at the time of cataract surgery is desirable. There are different ways to accomplish this; some are simple while others complex. Some will not generate extra surgical or IOL fees but others will: placement of incision along steep axis of cornea-make incision larger-use more steroid drops; surgical or laser corneal relaxing incisions; toric IOLs or toric mutifocal IOLs; rounding the cornea at time of surgery with femtosecond laser; post operatively using lasik surgery to remove residual astigmatism.
9. In cases where one eye has a cataract that is symptomatic and causing problems with important functions such as driving, reading, recognizing faces, glare avoidance, etc. but the other eye has no cataract or a cataract that is small and not troublesome in people with large refractive errors special attention needs to be made to choice of IOL. If targeting of the patient/surgeon desired refractive error post operatively generates a difference in the two eyes greater than 1.50 diopters, the person should know it may be difficult to wear glasses comfortably and/or glasses (no line bifocals usually) plus a contact lens on the un-operated eye. Or lasik or other post-operative refractive surgery may need to be done on the un-operated or operated eye to help them work together.
10. The problems outlined in #9 above may require surgery on the “other” eye to re-establish the ability of the eyes to work together with and without glasses. This can be true even if the cataract is small or even non-cataractous.
11. So called “Premium” IOLs (toric, multi-focal and accommodating) are used to reduce dependence on glasses. For almost all people they do not eliminate glasses 100% of the time. Even people that consider themselves “not needing glasses after cataract surgery” often wear glasses for special purposes such as night driving and prolonged reading or computer use. Premium IOLs are more expensive, have a greater chance of complication (although in the hands of an experienced ophthalmic surgery the risk is small), and produce unwanted glare and scattered light (dysphotopsia) more than modern aspheric monofocal IOLs.
12. It is also fair to say that some ophthalmology and optometry offices exert effort to encourage people to “upgrade’ from monofocal IOLs to “premium” IOLs. In sales this is not called “upgrading” but “upselling”. Also it’s important to know that some optometrists receive part of the surgical payment for cataract/IOL surgery, this is known as “co-management”. Premium IOLs are not better than monofocal IOLs; they are not designed to make everyone 100% glasses independent all the time. Most ophthalmologists and optometrists do present a fair discussion of each type of IOL and let an informed patient make the choice that suits them best.
13. While cataract/IOL surgery is the most common type of surgery done on adults and has a very low complication rate it is not risk free NO SURGERY IS RISK FREE; THAT’S WHY YOU READ (or have read to you) AND SIGN A SURGICAL CONSENT FORM THAT INFORMS YOU OF THE DIAGNOSIS, YOUR OPTIONS AND POSSIBLE RISKS AND COMPLICATIONS. These risks cannot be entirely eliminated. No surgery is entirely “routine and risk free” Think about driving an automobile. Driving is “routine” to most of us. Yet everyday there are people injured or killed in automobiles. We continue to drive because, with care, the risk is relatively low. Think of cataract surgery the same way.
14. In most all cases cataract surgery is elective. You can take your time and make these important decisions. There is nothing wrong with seeking a second opinion from a different ophthalmic surgeon. You can also access the many helpful discussions on these topics at the two AAO Medhelp Eye Forums by using the search feature or looking in the archives.
15. This information is not meant to give you specific recommendations. This posting is for information purposes only. You should rely on your own multi-source research and discussions with your ophthalmologist, optometrist and personal physician.
16. Coming on line are light adjusted IOLs where the IOL RX can be changed post op. The toric IOL has proved popular and in the hands of an experienced surgeon additional surgery to rotate occurs about 1.1% of the time. All "premieum" IOLs continue to be expensive, have compromised night vision, require glasses some of the time to often and have higher rates of dissatisfaction than monofocal or toric IOLs. The value of add on's like ORA technology, femtoscecond laser have yet to be demonstrated.
Original MedHelp Blog - September 2019