by William Corkins, O.D.
When I examine a patient who is 40-something years old and the need for bifocal or reading glasses arise, the question of bifocal or multifocal contact lenses also enters the conversation. The first thing I tell patients is that we can try a multifocal/bifocal/monovision lens, but your vision will not be as good when compared to the vision you get with bifocal or reading glasses. You must be willing to compromise. We do not talk about great vision; we talk about functional vision. Can you function in your environment when wearing contacts? If you can, then a prescription for the contacts is given if the fit and comfort are acceptable.
You have three choices in the way you can wear contacts. You will get the best vision if you wear contacts for distance and then wear over the counter readers to see up close. This works but logistically it becomes annoying to have to put on and take off the readers all the time. Plus, you are wearing contacts and still must wear glasses! The next choice is called monovision. This is when you wear a distance contact in your dominant eye and a near contact in your non-dominant eye. Statistically this is 50% successful. In other words, if I try this method on 100 people, 50 of them can accept this and 50 of them cannot tolerate it. The reason why you may not like this method is because we are reducing your depth perception. Out of the 50% who like it, they do not like it at nighttime. Why? Because we are reducing your depth perception, and the near contact lens causes considerable glare problems. The final choice is to fit you in multifocal contacts. When fitting the multifocal contacts, most of the time you must bias the contacts. What does this mean? A truck driver is spending most of his seeing at distance. I will bias the contacts to make the distance vision good, but the near vision will not be as good. If I make the near vision better, I will take away the distance vision. A jeweler, in contrast, needs to see well at near so I will bias the contacts for near vision. The distance vision will be slightly blurry. If I make the distance vision better, the near vision becomes worse. The multifocal contact lens success rate may be a little higher than the 50% success rate for monovision.
Monovision and multifocal contacts are light dependent. The brighter the light you have the better they work. I will hear patients say that they can read their newspaper in the morning when the sun is bright, but they cannot read the menu at a restaurant at night. The other problem is when you try to wear sunglasses over the monovision or multifocal contacts. The wearing of sunglasses reduces the light going to the eye and the pupil becomes larger. When the pupil dilates you lose depth of field, which reduces your near vision. The distance vision becomes worse because the dilated pupil picks up the imperfections of the contact lens design.
When a person wants to try monovision or multifocal contacts, I try to reduce their expectations and tell them that multiple contact trials and multiple visits may be required. If the person can accept the idea that their distance and near vision will not be perfect, then this person may be a good candidate for monovision or multifocal contact lens wear. Even if you are a good candidate and you can function with the contacts, there are other things to consider. Your vision may not be good enough to pass the DMV, FAA Class 1, 2, 3, or CDL exam and a pair of glasses with a current prescription may be required. If you are doing any of these activities while wearing monovision or multifocal contacts, you could be putting yourself and others at risk.
Bio: Dr. William Corkins is a board-certified optometrist who practices at the Lakeland-Highlands location for Eye Specialists of Mid-Florida. He is currently accepting new patients. Call 800-282-3937 or visit us online at eyesfl.com to schedule your next eye care exam.
This column is sponsored by Eye Specialists of Mid-Florida, and the opinions expressed herein may not reflect those of CFHN or of its advertisers.