We have experienced a case, probably without precedent in Japan, of "removal of MiniWELL PROXA and exchange for MiniWELL Ready Toric," and would like to share the information with those considering these lenses. Also, through the patient's kindness, we received a detailed report on the differences in vision between MiniWELL PROXA and standard MiniWELL, which we publish at the end as part of this information.
Things had been hard to see for about a year and a half and his vision did not come up even with correction; his previous doctor pointed out cataracts, and he first visited us without a referral letter in November 2020. He had high myopia and was a hard contact lens user, and since he did not want to wear glasses after surgery he was considering surgery with multifocal lenses; he already had visual impairment from strong cortical cataracts, and was in a state where surgery could be done at any time.
Perhaps because of his work, he had studied the optical properties of various lenses himself and struck me as someone who placed great importance on quality of vision; perhaps partly because we did not actively push surgery, he came back several times but did not reach a decision.
It seemed difficult for our clinic's skills to deliver a result that would satisfy him, so we also recommended a second opinion at another clinic, which he actually visited, but in the end he came back and booked surgery with us. Fully a year had passed since his first visit; at first the left eye's cataract had been more advanced, but at some point the vision in his dominant right eye had become worse.
He seemed to have been considering MiniWELL from the start, so after discussion he wished for surgery with the WELL FUSION System®, using MiniWELL Ready Toric in the dominant right eye and MiniWELL PROXA in the non-dominant left eye.
We usually operate on the two eyes one week apart, but he was cautious and wanted to decide and order the left eye's lens after the right eye's MiniWELL vision had stabilized, so to be safe we planned the two surgeries one month apart.
First, the right eye. Being the dominant eye, we set the power to reliably secure distance vision, and to fully correct corneal astigmatism, we operated with the astigmatism-correcting MiniWELL Ready Toric. Toric lenses under the regular elective treatment system or insurance are made only from 1.5 D, but MiniWELL is made from 1.0 D, so even mild with-the-rule astigmatism can be corrected without overcorrecting it (turning it into against-the-rule astigmatism).
There was no zonular weakness during surgery, but we also inserted a CTR (capsular tension ring) to prevent contraction and adhesion of the capsular bag; the cortical opacity was strong but the nucleus was not very hard, so little ultrasound was needed and the surgery was completed without problems. After surgery he was satisfied with good vision of 1.5 / 1.2 for distance and near uncorrected, but as time passed he came to wish to see things at hand a little more easily even in dim light, so for the left eye he still wished for MiniWELL PROXA.
The left eye likewise had mild with-the-rule corneal astigmatism, but MiniWELL PROXA has no toric version, so we operated after telling him that, depending on the postoperative situation, astigmatism reduction by LRI (limbal relaxing incisions) might be needed. The target refraction was decided by placing plus and minus lenses in front of the right eye, shifting slightly toward near or distance to simulate the vision; but the best power was not manufactured, so he had to choose between slightly toward distance or slightly toward near. After discussion, since he was already fully satisfied with the dominant right eye's distance vision, and since the left was the non-dominant eye, we avoided a hyperopic target and ordered a lens slightly on the minus side.
The right eye continued without major changes in refraction or vision, and the left eye was operated on one month later as planned. Here too we inserted a CTR, also added a modest intraoperative LRI to correct even a little of the residual astigmatism, and the surgery was completed without problems.
Uncorrected vision on the day after surgery was 1.0 distance / 1.0 near, which I thought was reasonable, but on postoperative day 11 it was 0.8p distance / 1.2 near, with distance vision trending down. Objective refraction on testing had barely changed, but his subjective poor distance vision and complaints of halos and starbursts, even in daytime, grew stronger day by day, so to determine whether the symptoms were due to residual astigmatism or to the lens's structure itself, we had him wear a contact lens fully correcting the refractive error, including astigmatism. However, he reported, disappointed, that although distance vision improved subjectively, the photic phenomena did not. In other words, even adding LRI to further reduce the astigmatism could not be expected to improve the halos and starbursts. Hoping for neural adaptation, so-called "getting used to it," we decided to wait a month, but compared with the right eye he still felt halos in particular even in daytime and found them intolerable, so after discussion we decided to exchange it for a MiniWELL Toric, as in the right eye. He had always struck me as demanding about quality of vision, so although I had not told him beforehand, I had considered that an exchange might be needed and had ordered and secured a MiniWELL Toric as a backup when ordering the PROXA; thanks to that, we did not have to wait another month for a lens to arrive and could schedule the exchange surgery at a safer time.
As a result, the exchange took place one month after surgery. Besides the CTR inserted for just such a situation, perhaps because MiniWELL, like LENTIS Comfort, is made of hydrophilic acrylic, there was almost no adhesion between lens and capsular bag, and by using the incision from the previous surgery we could exchange the lens smoothly without adding a new incision. Exchange surgery may seem very risky, but unlike cataract surgery it is largely a "static" operation, so personally I think that within a month of surgery it may be safer than ordinary cataract surgery (sudden trouble is less likely). In actual exchanges, adhesion between the anterior and posterior capsule is more often the problem than adhesion between lens and capsule. When anterior-posterior capsule adhesion is strong, it is hard to secure space for the new lens, so depending on its shape there is a risk that the desired lens cannot be inserted, or, for toric lenses, that it cannot be fixed at the target position; it is a hard decision for patients, but for safety and reliability, I think the sooner the better.
After the exchange to MiniWELL Toric, he was very satisfied with good uncorrected vision in the left eye too, 1.2 / 1.2 for distance and near, and I was relieved when he said brightly, as if a worry had been lifted, "The halos and starbursts are gone!" I am very sorry for putting him through two painful procedures where one usually suffices, but I am grateful that he made a difficult decision without compromise to the end, and I was very happy that he was ultimately satisfied with the result.
After surgery I thought a great deal about what had been different from previous cases in which patients were very satisfied with PROXA in this case of dissatisfaction with MiniWELL PROXA. Mild residual with-the-rule corneal astigmatism probably played a part, of course, but what concerned me more personally was the one-month interval between the two surgeries. MiniWELL is hard to tell apart from a monofocal lens at a glance, and it is a premium lens that in practice sees almost like a monofocal with an extended depth of focus; so I suspect that one reason for his dissatisfaction was that his right eye had first become fully accustomed to MiniWELL's high-quality vision, raising his expectations considerably before PROXA was used in the left eye, which made the difference in quality of vision all the more noticeable. The left eye's preoperative cataract was quite dense, and there must have been considerable glare at night, so we predicted he would be unlikely to find PROXA unsatisfactory compared with before surgery; but in the end, for him, the comparison was not "the eye with cataract before surgery" but "the right eye with MiniWELL," so PROXA's inferior vision compared with MiniWELL may have bothered him.
Because we want to reduce the risk of refractive error in the dominant eye as much as possible, when the cataracts are similar in both eyes we usually operate on the non-dominant eye first; but with the WELL FUSION System®, operating first on the dominant eye with MiniWELL is recommended. We asked the distributor, SIFI MedTech, why, and were told, "The reason for inserting it first in the dominant eye is that MiniWELL achieves neural adaptation, that is, gets used to, faster than PROXA," which did not quite answer the question... Perhaps it means that if someone cannot adapt even to MiniWELL in the dominant eye, that is, has trouble achieving vision, they are at higher risk of adapting even less, that is, of poorer vision, with PROXA, in which case using standard MiniWELL rather than PROXA would be safer. Incidentally, at our clinic we have operated first with MiniWELL PROXA in a patient whose non-dominant eye's cataract was much more advanced, and the course was very good, with no impression of slow adaptation (more cases to be added). So far he is the only patient who has complained of halos and starbursts with MiniWELL PROXA, but the case made me think that candidacy must be decided more carefully and from multiple angles, considering not only the desired focal distance and target refraction but also the order and interval of surgeries and the balance between the eyes.
Setting the target refraction for MiniWELL PROXA does require different approaches from standard MiniWELL, and, back-calculating from subjective refraction, I also feel that the A-constant, the value used in lens power calculation that reflects the lens's fixed position, may itself need some revision (normally lenses of the same shape have the same A-constant). Information on results at other facilities in Japan is not yet available, but we will continue to strive, based on our experience so far and information from Japan and abroad, to perform surgery that meets patients' expectations.
This time the problem was solved by "intraocular lens exchange," but of course it is better if one operation suffices when no more is needed. However, as the variety of premium lenses grows and patients' demands diversify, the need for intraocular lens exchange is expected to keep increasing, and preparation and techniques to further reduce risk and invasiveness will become essential. Recently, an artificial capsular bag that does not contract or adhere seems to be under development, so in future intraocular lens exchange may become nothing special, and we may live in a world where an "upgrade exchange to the latest lens" is possible more casually.
2022.03.23
The following is a report kindly provided by the patient; please refer to it if you are interested.
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About my experience with PROXA
- Reason for the exchange
The main reason was that the marked halos did not go away. Living with this for the rest of my life would make night driving and the like very hard; some difficulty seeing at close range can be corrected with reading glasses, but I judged that the halos with the PROXA I had received were unlikely to resolve.
Also, my vision from intermediate to distance gradually worsened, and about three weeks after surgery it was around 0.5.
The PROXA lineup had no +9.5, so +10.0 was chosen, and I was also concerned that vision might not improve even with LRI later. And although PROXA was said to favor near vision, it was only slightly better than my right eye (MiniWELL Toric).
For these reasons, and since the risk of exchange surgery increases as time passes, I decided on the exchange.
- How things looked
Right after the eye patch came off the left eye (PROXA), the color temperature felt much higher than in the right eye (MiniWELL Toric). This could be because the cataract opacity had been removed, but right after the left eye was exchanged for MiniWELL Toric, conversely, the color temperature felt slightly lower than the right eye's.
As for acuity, right after the patch came off it was just under 1.0, but day by day intermediate to distance vision blurred, and I recall it being about 0.5 at the last vision test. When I was fitted with an astigmatism-correcting contact lens to help decide on the exchange, the halos did not go away, but my vision recovered dramatically to about 1.2–1.5, and I was surprised at how large the effect of the astigmatism was.
The problem halos and glare did not improve over time; using the illustrative image on the clinic's website, they were at the marked level shown below.
Even in daytime, when I looked at metal parts reflecting sunlight, or cars and bicycles with their headlights on, I saw halos, though not as much as at night.
As a supplementary note, one week after the right eye (MiniWELL Toric) surgery, on the way home (at night) on a day my pupils had been dilated for an afternoon examination, I saw marked halos, stronger than with PROXA, around every light source, such as streetlights and car headlights. Perhaps halos can be seen even with MiniWELL Toric when the pupil is wide open.
Another phenomenon with the left eye's PROXA: when passing streetlights at night, looking straight ahead, I saw several perfectly circular rings inside my eye, which moved irregularly as I walked and disappeared once I had passed the streetlight. Because the rings moved within the eye, perhaps what I saw was light reflecting off the lens edge rather than the lens edge itself.
The same phenomenon occurred with the right eye's MiniWELL Toric, but only one faint ring (even now a ring sometimes appears in the right eye, but not to a bothersome level).
With the left eye's MiniWELL Toric after the exchange, these rings inside the eye almost never appear.
It is unclear why the halos were so marked with PROXA this time, but a previous patient reportedly saw slight, not bothersome, halos in the non-dominant eye with PROXA, so perhaps marked halos can arise when some combination of conditions coincides: beyond factors from the power setting, the surgical process or PROXA's basic structure, things like manufacturing variation in the lens itself or the patient's own intraocular characteristics.
I understand the number of PROXA cases worldwide is still small, but people who want MiniWELL seem to strongly expect freedom from halos and glare, so I think this needs watching in future, including by the manufacturer.
- Finally
In choosing a lens before surgery, I went through medical literature and information from various medical institutions, and I found here and there statements, even from well-known clinics, that were clearly wrong or assertions not based on experience.
I spent many years at a company developing liquid crystal optical elements, and cutting-edge optical devices such as high-performance lenses are extremely sensitive, including in quality, demanding experience and advanced skill from those who use them.
I became convinced that having surgery at a trustworthy clinic like yours is best.
2022.2.22
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