Reading Speeds Tell Us about Adaptation to Multifocal IOLs

One of the most interesting things about the multifocal intraocular lenses (IOLs) used in cataract surgery and presbyopia surgery is how the brain learns to select the proper image from among the multiple images these lenses cast on the retina.

Multifocal lenses allow you to see objects at different distances by having a number of focus zones, each dedicated to a particular task, some focusing on close objects, others on far objects, and often balanced for both bright and low-light conditions. Although this solution ensures that for most objects there will always be a focal zone that focuses light from the object you're looking at onto the retina. However, it also means that there will be a number of unfocused images of the same object on the retina at the same time. Your mind just learns to sort them out, the sort of visual trick it already does every day, although not everyone adapts well to the new visual system. One question people have about the process is "How long does it take for the brain to adapt?"

Recent research suggest that it may take 18 months or longer for the brain to fully adjust to using the lenses. Although people get full visual acuity (on average 20/40 vision) by 6 months after surgery, it does not mean that their eyes and brains are fully adapted at this point. Instead, it seems that their eyes are continuing to adjust. A recent study looking at 25 patients who received either the Tecnis or Acrysof ReSTOR at 6, 12, and 18 months after bilateral implantation of the IOLs. The study looked at visual acuity and reading time. Although visual acuity showed no significant deviation over the follow-up period, reading speed continued to increase over the entire follow-up period, which indicated to researchers that patients' brains were continuing to adapt to the novel visual system over the entire study period.

If you are considering a multifocal IOL for correction of presbyopia or during cataract surgery, you should talk about the adaptation period for IOLs with your ophthalmologist. Please call or email us today to contact a local ophthalmologist experienced in cataract surgery.

The Quality of Life Impact of Refractive Correction

The quality of life impact of refractive correction (QIRC) was developed to measure the impact your choice of vision correction has on your overall quality of life. It was originally designed using patients from the presbyopic age group, although the designers did not comment on the degree its subjects actually suffered from presbyopia. Although the authors note the limitation of designing the questionnaire for the presbyopic age group, many people use the QIRC to measure the impact of various refractive procedures, such as laser vision correction procedures like LASIK or PRK.

The QIRC is made up of 20 questions designed to evaluate how various vision correction options affect people's quality of life. It was developed from 2002-2004. The QIRC originally contained 90 items that were winnowed down to the 20 items most likely to produce consistent results that correlated with other evaluations of a person's quality of life. It includes questions related to four basic categories of quality of life: convenience, economic issues, health concerns, and general well-being. Refractive surgery patients generally show improvement in 15 of the 20 categories when given the QIRC before and after laser vision correction surgery. The largest difference was related to convenience factors like being inconvenienced by glasses or contacts when swimming or going to the gym. Another factor that showed major improvement is that people felt they would grow increasingly to rely on glasses or contacts, whereas they felt their refractive surgery freed them from dependence.

People taking the QIRC generally show a better quality of life if they have had refractive surgery than if they were using glasses or contacts. The average QIRC score for LASIK patients was 50.23, which was significantly higher than either contact lens wearer (46.7) or glasses wearers (44.13). Some people boast that the QIRC shows how much higher the quality of life is for people with LASIK than with glasses, but it seems to have been designed intentionally to highlight the changes effected by LASIK.

Which is not to say that LASIK does not lead to real quality of life improvements. To learn more about LASIK, please contact a local ophthalmologist today.

Nonsurgical Treatment Option for Cataracts

When the crystal lens of the eye has lost its clarity, how shall it be made clear again? And if it does not admit the light of the world, what good is it?

Traditionally, the only treatment available for the obscuring of the eye's lenses with cataracts was the removal of the lens. This procedure has been practiced in some form or another since the 5th century BC. Early cataract procedures merely pushed the lens out of the way using a stick, called "couching." This was later improved to breaking the lens up into smaller pieces so it could be absorbed. Finally in 1748, the first successful lens removal was performed, though anesthesia was not added to the procedure for another century. Since the 1960s the implantation of intraocular lenses to replace the removed lens has allowed people to have very good vision after cataract surgery, but there still exists no nonsurgical option for treating cataracts without removing the eye's clear lens.

Now, though, such a treatment may be on the horizon. Researchers at Glostrup Hospital of the University of Copenhagen have reported using femtosecond lasers in the infra-red range to bleach the cloudy lens of the eye. They reported that treated areas showed a lightening of cataracts and an increased transmission of light equivalent to an optical rejuvenation of 3 to 7 years.

Although the technology is a long way from seeing clinical application, the researchers imagine it could make a huge difference in parts of the world where access to cataract surgery is very limited. Treatments could be performed by a mobile automated cataract clinic that could travel to isolated villages to perform cataract surgery without the need for an extensive surgical suite, a skilled cataract surgeon, and support staff.

Until this procedure becomes available, though, cataract surgery remains the only viable treatment option for a cloudy lens. If your vision is being impacted by cataracts, you should talk to a local ophthalmologist to learn more about corrective surgery.