From the EDITOR   A large part of our society has grown up with LASIK, knowing this option is available to correct refractive error. But some people don’t seriously consider refractive surgery until they are over age 45, past the prime age for LASIK, and dealing with the frustration of presbyopia. In this issue, my colleague Melissa Dacumos discusses refractive lens exchange—an excellent treatment option for our presbyopic population.

Ami Halvorson, OD

 

PCLI Portland, OR

Refractive lens exchange (RLE) is an alternative to laser vision correction or phakic IOL refractive surgery. The primary goal is to treat refractive error and reduce or eliminate dependence on corrective lenses. This elective surgery is procedurally identical to cataract surgery. The only difference is that RLE is performed when the natural crystalline lens is clear and does not contribute to blurred vision, glare, or halos.

Benefits

RLE offers several benefits:

• High degrees of myopia and hyperopia are correctable
•  Treatment provides long-term refractive stability
•  Vision stabilizes quickly
•  Outcomes are predictable
•  There is little risk of regression
•  The need for cataract surgery in the future is eliminated

Ideal Candidates

When considering RLE, consider the following criteria:

• Better suited for ages 45 and older
  Although there are unique instances when RLE is performed on younger people, the procedure is usually best suited for those already experiencing presbyopia. However, be mindful of patients who still have accommodative reserve. An array of excellent presbyopia-correcting IOLs (PC-IOLs) are available. However, they do not perfectly simulate accommodation provided by the crystalline lens and may be associated with some dysphotopsia.

• LASIK or PRK is not an option
  When the cornea is too thin or abnormal for laser vision correction, RLE may be a better option.  This is particularly true with high myopic prescriptions when laser treatment is not possible due to insufficient corneal tissue.

• Incipient or mild cataracts
  RLE may be a good option for patients who do not have reduced BCVA or symptoms that meet the criteria for cataract surgery and do not wish to wait. In addition, we have all observed large refractive shifts that can come along with lenticular changes. In the presence of mild cataracts, RLE will eliminate frequent prescription changes due to this phenomenon.

• Presbyopes, moderate to high hyperopes, and astigmats
  With RLE, numerous PC-IOLs are available to significantly reduce or even eliminate dependence on corrective lenses. Lenses that we use include:

~ Multifocal
~ Trifocal
~ Extended depth of focus

Most of these IOLs can correct up to 2.50 diopters of corneal astigmatism.

Also, just as monovision can be considered with laser vision correction and cataract surgery, it can be achieved in RLE. Single focus toric IOLs can correct up to 4.11 diopters of corneal astigmatism. And up to 1.50 diopters of additional astigmatism can be treated with concurrent limbal relaxing incisions. In addition, light adjustable lenses (LAL) provide precise custom correction and are ideal for monovision.

Patient Satisfaction

As reported in numerous studies, satisfaction with RLE and PC-IOLs is high—often greater than 90% and as high as 97%. However, it is important to consider the IOLs implanted in each of these studies, the pre-operative refraction, appropriate candidate selection, good refractive predictability, proper dry eye management, and proper counseling of photic visual phenomena such as glare, halos and decreased contrast sensitivity.

The following findings are from a recent informal survey published in Ophthalmology Times:

• 24% of surgeons said they anticipate undergoing RLE for presbyopia with PC-IOLs
• 32% would recommend RLE to family and friends
• 19% reported they had family and friends who had undergone the procedure
• Of those surgeons not interested in pursuing RLE for presbyopia, 66% reported they were closer in age to having cataract surgery, or they had LASIK and were happy with readers, or they wanted to hold out for better technology.

This indicates that there is significant confidence in RLE and PC-IOL technology available today.

Risks

RLE is more invasive than laser vision correction and comes with slightly more risk. Retinal detachment is a significant risk (1.5 % to 8.1 % in studies with a minimum of two years follow-up) for high myopes under the age of 50 with longer axial lengths (>26.0 mm) who have not had a posterior vitreous detachment. This risk increases when the capsule is torn intraoperatively or YAG surgery is performed for PCO. In hyperopes with shorter axial lengths (<21.0 mm) and shallow anterior chambers, there is a risk for pupillary block with secondary increase in IOP and post-operative uveal effusion. Additional risks associated with RLE and cataract extraction include endophthalmitis, hemorrhage, elevated IOP, CME, ptosis, dysphotopsia, glare and halos, and reduced contrast with PC-IOLs.

Other Considerations

It may be tempting to recommend RLE with PC-IOLs for young, pre-presbyopic high myopes. However, aside from the increased risk of retinal detachment, studies have shown that preserving natural accommodation is much better than pursuing multifocality. In these instances, it would be more reasonable to consider phakic IOLs such as the Visian ICL.

Approach low myopic presbyope cases with caution. While monofocal RLE will provide great uncorrected distance vision, it will be exchanged with lost near vision. And RLE with a PC-IOL may not provide as sharp uncorrected near vision.

While several studies confirm that PC-IOLs improve uncorrected near, intermediate, and distance function, they do so at the expense of reduced contrast sensitivity and risk of photic visual phenomena such as glare and halos. Between 1% and 7% of PC-IOL patients may require exchange with monofocal IOLs due to the severity of these symptoms. This reminds us that expectations, lifestyle, personality, and occupation continue to be important factors in selecting RLE with PC-IOLs—possibly more so than with cataract patients.

If you are considering recommending RLE to patients, presbyopic hyperopes may be a good place to start as they have poor uncorrected vision at all distances.

Conclusion

RLE is an increasingly popular refractive surgery. Determination of personality type and conscientious discussion regarding goals, expectations, lifestyle, and occupation are essential—especially with PC-IOLs. Considering the prevalence of cataract surgery and how routine the procedure has become, RLE is considered a reasonably safe surgery when the benefits outweigh the risks. With advanced PC-IOL technology, we now have an excellent treatment option for our presbyopic population.