She first visited us from Shizuoka City with a referral letter for consultation about cataract surgery with multifocal lenses.
Counting her previous doctors, ours was the fourth clinic she had visited; she had been told that "multifocal lenses are not suitable" because of irregular corneal astigmatism, and she came wanting us to judge her candidacy again.
As the results of the OPD-Scan III wavefront aberrometer below show, corneal higher-order aberrations were lower than expected at 0.183/0.274 µm, but corneal spherical aberration was somewhat high at 0.377/0.412 µm, and the automatic analysis also showed over 70% for suspected keratoconus. Like the clinics she had already visited, we therefore explained that her eyes were not suited to multifocal lenses (the lens's multifocal function would be unlikely to work 100%). But she very strongly wished for surgery with multifocal lenses no matter what, so we started dry eye treatment to see whether the irregular corneal astigmatism would improve. Within about two weeks the higher-order aberrations had improved to 0.111/0.168 µm, and the percentage for suspected keratoconus had also fallen substantially, so we suggested that if she really wanted multifocal lenses, the non-diffractive LENTIS Comfort might be possible. (There is no clear academic criterion, and we have not done a statistical analysis, but from experience, when using diffractive multifocal lenses, including after LASIK, I consider corneal spherical aberration of 0.5 µm or less and higher-order aberrations of at least 0.3 µm or less desirable.)
However, she presented very demanding wishes: she drives at night, plays golf as a hobby, and as an insurance agent needs to read fine application forms, and she wanted to do all of these without glasses. LENTIS Comfort naturally could not meet them all, so for reliability we recommended MiniWELL Ready in both eyes as the option most likely to come close, but she asked first to have the left eye, with the more advanced cataract, operated on with MiniWELL PROXA, wishing for surgery with the WELL FUSION System®.
Using MiniWELL PROXA in the non-dominant left eye is consistent with the WELL FUSION System®, but we explained that (1) in terms of corneal shape, the right eye was better suited to PROXA than the left; (2) PROXA had no toric version; and (3) operating first on the non-dominant left eye with PROXA, before the dominant right eye with MiniWELL, carried a risk of poor adaptation. She agreed to the possibility of a lens exchange if needed, and, though some unease remained, we decided to operate first on the left eye with MiniWELL PROXA. Considering the risk of exchange and the uncertain period of adaptation, we scheduled right eye surgery 1.5 months after the left.
In addition, her axial length was short, in the 21 mm range, and her corneal power strong at 46.5 D or more, so the risk of postoperative refractive error was very high, and surgery aiming for exactly zero refraction was a high hurdle; honestly, as a surgeon my impression was that I would rather not do it. But she had come from far away many times, and to respond to her enthusiasm we prepared carefully for surgery.
The left eye had a cataract with dense cortical opacity extending into the pupillary area and posterior subcapsular opacity, and vision had fallen considerably to 0.2, not improving with correction. In surgery we used the ORA system®, an intraoperative wavefront aberrometer, to avoid postoperative refractive error, but unfortunately MiniWELL is not globally optimized in it, so the power the ORA system® recommends is not very reliable. We therefore decided the power with reference to our clinic's regression formula of ORA measurements and postoperative refractive error with MiniWELL and measurements with a dummy lens. Given the risk of exchange, we naturally also inserted a capsular tension ring (CTR), which reinforces the zonules, and the surgery was completed without problems.
After surgery, neither the postoperative refractive error nor the poor adaptation we had feared occurred; with the incision on the steep meridian, astigmatism was almost zero, and with good uncorrected vision of 1.5p distance / 1.2 near, she was delighted, saying, "I can see better than I expected, and I can even clip my dog's nails without glasses." As a result, we also felt that, with PROXA, target refraction must be set differently from the standard MiniWELL, and that optimization of the A-constant taking postoperative subjective refraction into account was needed.
After that she said she was not bothered by photic phenomena such as halos and glare in the left eye, so, having confirmed that an exchange was almost certainly unnecessary, we ordered the MiniWELL Ready for the right eye as planned.
She said the left eye was fully satisfactory for near, so for the right eye we set the power without needing to sacrifice distance, and since we had grasped the tendency of postoperative refractive error from the left eye, we could operate with greater confidence. The right eye surgery, again with the ORA system and a CTR, was completed safely, and she was satisfied with uncorrected vision of 1.5p distance / 1.2 near here too. Numerically there was no difference in near vision between the eyes, but she said that, by feel, around 30 cm was clearly easier to see with the left eye with MiniWELL PROXA.
Recently, another patient asked me during an examination, "Doctor, are you a MiniWELL fan?" I am not a "MiniWELL fan" at all. Given the difficulty of judging candidacy and setting the power, the demand for accuracy in everything, the procedures for importing the lens, and bearing the cost of returning unused backup lenses (which we do not charge patients), as well as its being an unapproved lens, please understand that it is by no means a lens I want to use first. For people who seem likely to be satisfied with lenses approved by the Ministry of Health, Labour and Welfare, I of course recommend choosing those, and at our clinic, too, people who wish for multifocal lenses first choose from lenses covered by the elective treatment system.
This was a challenging case in which, without the patient's enthusiasm, we might not have performed surgery with multifocal lenses, but in the end she was delighted, which made us very happy, and it was a lesson in judging candidacy. As a postscript, I was surprised when, on my way to Kyoto for a cataract surgery meeting, the patient, after an examination, happened to call out to me at the Shinkansen ticket gate at Tokyo Station; perhaps we were simply meant to meet. Incidentally, "clipping nails without glasses" is a surprisingly high hurdle, so I too am very satisfied that it was cleared.
2022.09.23