The Light Adjustable Lens (LAL; RxSight) is an excellent way to extend your advanced technology IOL (ATIOL) toolbox and increase the number of patients to whom you can offer cutting-edge solutions. It is the only lens implant currently available that can be adjusted after implantation — the surgeon can achieve adjustments of up to 2 D of sphere and from 0.5 D to 3 D of astigmatism based on the postoperative refraction. This is extremely useful for fine-tuning refractive outcomes, especially in cataract patients with a history of prior refractive surgeries or monovision.
The implantation procedure for the LAL is no different from that of other IOLs in cataract surgery. It’s during the post-surgery process that the LAL manifests its contrast to other ATIOLs.
I will share what I have learned about patient selection, presurgical counseling and efficiently incorporating the LAL procedure in practice.
THE LAL IN PRACTICE
Following implantation of the LAL (which is composed of photo-sensitive macromers), patients live with their new lenses for a predetermined period. Then comes a series of follow-up appointments, where they communicate their visual preferences to their ophthalmologist based on this trial period. The doctor adjusts the shape and focusing characteristics of the lens accordingly through a series of in-office, noninvasive UV treatments delivered with RxSight’s proprietary Light Delivery Device (LDD).
These postoperative light treatments are performed on both eyes. The initial light treatment is typically delivered 2 to 3 weeks after surgery. Any necessary additional light treatments are performed at least 3 days after the previous treatment. Patients receive up to three light treatments for refractive adjustment, then two lock-in treatments to prevent any further refractive change of the LAL. At my practice, the time from surgery to final lock-in is typically 7 weeks or more.
Patients are given a set of UV-blocking glasses that they must wear full-time from the time of their surgery until 24 hours after their final, lock-in treatment.
SUITABLE CANDIDATES
Post LASIK or PRK
LAL is an excellent option for patients who have a history of LASIK or photorefractive keratectomy (PRK). Structural changes induced by keratorefractive surgeries can increase the likelihood for hyperopic surprise and decrease the chances of achieving a refractive outcome within +/- 0.5 of the desired target.1,2 The LAL enables the surgeon to home in on the desired refractive outcome postoperatively and increase the chances of achieving the desired target.
Post RK
For similar reasons, LAL is also useful in patients with history of four-cut radial keratotomy (RK) who do not have significant corneal irregularity on topography. However, I recommend exercising caution when dealing with post-RK patients. Because the LAL treats spherico-cylindrical refractions, it does not address the higher-order aberrations that often reduce the quality of vision in post-RK patients. Nor does it treat visual fluctuations, so patients with significant diurnal visual fluctuations may not be the best candidates for this technology.
Monovision
For patients to be happy with monovision, the ophthalmologist needs to nail the refractive target on the distance eye. LAL offers multiple opportunities to get the refractive outcome in the distance eye exactly right. It also allows you to refine the reading distance to exactly the patient’s preference without the patient having to undergo additional invasive procedures.
CONTRAINDICATIONS
As with every technology, the LAL is not for everyone. Patients who should not receive this lens include those with:
- Current use of medications that can increase sensitivity to UV light (doxycycline, amiodarone, psoralens, hydroxychloroquine)
- History of macular disease or taking retinotoxic medications (tamoxifen)
- History of herpetic keratitis
- Inability to maintain follow-up appointments and wear UV protective glasses
- Dilation <6 mm (the surgeon must be able to see the optic-haptic junction in order to properly focus the adjustments on the IOL)
- Significantly irregular corneas (despite having no residual sphericocylindrical refractive error, patients with irregular corneas may still have poor quality of vision and therefore be dissatisfied with their result regardless of pre-operative counseling)
- Unrealistic expectations, such as 100% freedom from spectacles
PATIENT COUNSELING
Post-refractive
Patient education before surgery is always critical to a successful outcome. My most common patient profiles for this lens are post-refractive and monovision, though I primarily use it in post-refractive patients. I explain to this group that we take many different measurements of their eyes and use sophisticated formulas prior to cataract surgery to estimate the correct lens strength. However, their previous refractive surgery has changed the shape of their cornea, and this makes the measurements and calculations to determine the correct lens implant for their eyes less accurate. This decreased accuracy of the calculations increases their chances of needing glasses or contacts after cataract surgery.
In the past, if a patient did not want to have to wear eyeglasses or contact lenses, additional surgical treatments such as IOL exchanges or PRK were required to fine-tune the result. But now, with the LAL, we can refine the vision after the lens is implanted with painless in-office light treatments.
Monovision
The other group I frequently use this lens in is patients with monovision. For those who are very happy with monovision from contact lenses (or LASIK), I explain that the LAL is the most reliable way to exactly replicate what has worked for them in the past because it gives us multiple chances to get the targets for both their distance and near eyes just right.
Universal lessons
For all LAL patients, it is critical to emphasize the need to wear the UV-blocking glasses full-time from their surgery until 24 hours after their final lock-in treatment. Inform them that their regular sunglasses do not have the same UV-blocking coating and are not an acceptable substitute for the glasses they receive at the time of their surgery.
Patients also need counseling about the additional office visits and dilations required. These visits can be long since they require refraction and dilation, so remind them to set aside adequate time. Treatments are an average of 90 seconds long but can last anywhere from 8 seconds to 2 minutes, according to RxSight.
During the treatments, I tell patients they will see a bright light and may experience a slight pressure on the eye. It’s normal for vision to be blurry immediately after the treatments due to the coupling gel used for the contact lens and the dilation required for the procedure.
Some patients may notice a pink tint to their vision after their treatments, especially their lock-in treatments, which patients tend to perceive as brighter than the other treatments. I inform them that this after image effect is caused by the LDD and will resolve spontaneously. It may take up to 24 hours after an adjustment to notice an improvement in the vision, so I urge patience.
Take-home points
- Choose patients with realistic expectations who are good dilators.
- Use caution in post-RK patients. Look out for irregular corneas and large diurnal fluctuations as the LAL will not treat either of these issues.
- Not all patients fit the typical post-operative schedule.
- Patients with dry eye may need to have their ocular surface disease addressed first before adjustments are begun to ensure stable and accurate refractions are obtained.
- Post-RK patients may also take longer to stabilize due to edema at the RK incisions. It is best to counsel these patients about this possibility pre-operatively and to refrain from initiating adjustments until the refraction is stable.
- Schedule all the adjustment appointments together at the end of clinic, or train an optometrist or a PA to do adjustments to not pull the surgeon away from clinic or OR time.
TARGETING
Once the patient has decided on the LAL, I discuss a trial of mini-monovision, setting the dominant eye for a distance target and non-dominant eye for a -1.50 D target to give some range of vision. Since these patients pay out of pocket for an ATIOL, it is nice to be able to offer them increased independence from glasses and a range of distances.
And given that many patients who opt for LAL have a history of prior refractive surgery or contact lens wear, they are often very motivated to be as spectacle independent as possible and elect to proceed with a mini-monovision trial. This is an exceptionally appealing option due to the ability to reverse the monovision and set both eyes for distance if monovision is not tolerated. Additionally, with a -1.50D target with the LAL, many patients have J1+ vision in their near eye.
SCHEDULING
I’ve learned important lessons about how to successfully, efficiently implement the LAL from a scheduling standpoint.
The LAL can be time-consuming. One way to maximize efficiency is by clustering all the adjustment appointments together at the end of clinic. Another way is to train an optometrist or a physician assistant (PA) to do adjustments so as to not pull the surgeon away from clinic or OR time.
Patients are seen for their normal post-operative day-1 visit and then at 3 weeks postop for a refraction. If the patient can easily be refracted to 20/20 with a normal exam, then treatment 1 can be completed at this time. A caveat to this timeline is post-RK patients. These patients may also develop edema around their RK incisions after cataract surgery, which can increase the interval between surgery and a stable postoperative refraction. It is helpful to confirm refractive stability on post-RK patients before beginning adjustments on them.
As long as the patient remains in their protective glasses we can wait until the ocular surface is stable to make the adjustment.
Treatments can take place as few as three days apart from each other. However, from a clinic flow and logistical standpoint, it made sense for our practice to do all LAL treatments at the same time once a week. We schedule the LAL patients towards the end of the clinic so that the adjustments can be completed after all the clinic patients have been seen, reducing interruptions in clinic flow.
The patient then returns to the office once per week for treatments two and three and then lock-ins one and two Each treatment visit requires a refraction and dilation. Lock-in visits require dilation.
CONCLUSION
By following these guidelines in selecting the appropriate patients and implementing processes to maximize efficiency, adding LAL to your practice can be very rewarding to both you and your patients. OM
References
1. Khoramnia R, Auffarth G, Łabuz G, Pettit G, Suryakumar R. Refractive Outcomes after Cataract Surgery. Diagnostics (Basel). 2022 Jan 19;12(2):243
2. Chean CS, Aw Yong BK, Comely S, Maleedy D, Kaye S, Batterbury M, Romano V, Arbabi E, Hu V. Refractive outcomes following cataract surgery in patients who have had myopic laser vision correction. BMJ Open Ophthalmol. 2019 Apr 9;4(1)
