She had first visited us about four years earlier for orbital cellulitis. Her cataracts had gradually progressed and, with a shift toward hyperopia, her uncorrected vision had fallen, so she returned after a long gap wishing to have cataract surgery.
The cataracts were entirely ordinary, age-appropriate cataracts, and corrected vision still just reached 1.2, but she was aware of blurring from cortical opacity. Given the degree of cataract, the surgical risk itself seemed low, but she works as an animation designer, and quality of vision seemed important, so we explained lenses assuming surgery with monofocal lenses. She then said she would like multifocal lenses if they would free her from glasses.
After discussion, she said that for her work near distance is important, for the computer at about 40 cm and documents at hand, and she wished for FineVision HP (POD F GF). However, the right eye had about 1.0 D of against-the-rule corneal astigmatism, so FineVision HP, which has no toric version, could not be recommended for it. The left eye, with almost no corneal astigmatism at 0.13 D, could have surgery with FineVision as she originally wished. We explained that the right eye would receive the Clareon PanOptix Toric, a toric trifocal lens, and that the left eye could receive PanOptix as well if she was satisfied with the right eye's vision, or FineVision HP depending on the result, and she agreed.
First, the right eye. As predicted, cataract removal went without problems, and we moved on to measurement with the intraoperative wavefront aberrometer (ORA system). The lens power and cylinder power recommended by the ORA system matched the preoperative predictions, so we chose the power with confidence, but the astigmatic axis during surgery differed somewhat from the preoperative prediction. The axis displayed by the ORA system is a real-time measured value, so, unlike prediction formulas, it does not account for changes in corneal astigmatism during postoperative wound healing. It is said that a toric lens 15 degrees off axis loses 50% of its correcting power, and multifocal lenses are reported to be more affected by residual astigmatism than monofocal lenses. Whether to trust the real-time value or the formula's value is a difficult question. Astigmatism has many causes and is complex, so being able to obtain the value of total ocular astigmatism without the natural lens, rather than a prediction from corneal astigmatism alone, is one of the advantages of the ORA system, and by referring to total ocular astigmatism our clinic has obtained good results. In her case, too, adjusting the axis with the real-time value in mind allowed us to bring total astigmatism to zero, as the astigmatism data at the lower right of the OPD-Scan III image below show. (Incidentally, the ORA system cannot measure accurately unless intraocular pressure is adjusted to 21 mmHg before measurement; even if the pressure varies a little, the predicted power does not change much, but the astigmatic axis changes considerably, so care is needed.)
Right eye postoperative vision was already good from the day after surgery at 1.5 distance / 1.0 near, perhaps because there was no refractive error and astigmatism was zero, so I thought PanOptix would be fine for the left eye too, but she wished for FineVision HP if possible. From the surgeon's side, the same lens in both eyes makes the tendency of power deviation easier to grasp and is reassuring, but of course we gave priority to her wishes and prepared several backup lenses for surgery.
Lens removal in the left eye also went without problems; we measured with the ORA system, chose the lens power, and the surgery was completed safely. Uncorrected vision the day after surgery was 1.0 distance / 0.9 near, and by day 10 it had settled at 1.2 distance / 1.0 near, almost the same good vision as the right eye. She was delighted that she could now do not only computer work for her job but also embroidery, her hobby, without glasses. We did not measure intermediate vision, but the focal distances are about 60 cm in the right eye / 75 cm in the left eye, so the two eyes complement each other to give continuous vision without gaps, which also seemed to add to her satisfaction.
She was the first patient at our clinic to choose different lenses in each eye in the combination of PanOptix in the right eye / FineVision HP in the left eye, so with her cooperation we asked about the difference between the eyes. She said: "The PanOptix in my right eye looks sharper. Near vision is no different between the eyes. I can't tell any difference in photic phenomena such as halos and glare."
By specification, the near add at the lens plane is +3.25 D for PanOptix / +3.50 D for FineVision, a difference of 0.25 D, only about 0.175 D at the corneal plane, so it may indeed be too small to perceive. Considering the attenuation and distribution of light energy, PanOptix allocates 44% to distance / 22% to intermediate / 22% to near (12% loss overall), while FineVision HP allocates 42% to distance / 15% to intermediate / 29% to near (14% loss overall). FineVision HP thus allocates about 7% more to near, which may contribute to its good near vision under certain conditions.
To investigate where PanOptix's sharpness comes from, we also performed a simple contrast sensitivity test. As shown below, in sufficiently bright conditions (□ photopic) there was no difference between the eyes, but in dim conditions (■ mesopic), contrary to expectations, FineVision HP on the left had higher contrast sensitivity. In other words, the sharpness she felt in the right eye was not due to a difference in contrast sensitivity between the lenses, but most likely due to residual astigmatism being zero. The results also suggested that FineVision HP's contrast sensitivity drops little even in dim light, which seems due to its apodized design (Japanese), which increases the light energy allocated to distance to 70–80% so that halos and glare do not increase as the pupil widens. At the same time, however, the relative allocation to near decreases, so care is needed for people for whom near vision in the dark is important. (*Many people with PanOptix also show almost no loss of contrast sensitivity under mesopic conditions, so please understand this as a result under the conditions of this case only.)
Personally, this case reconfirmed that, to make the most of a multifocal lens, precise astigmatism correction matters more than a slight difference in add power. It also seemed that multifocal lenses of the same diffractive type, even of different kinds, can compensate for each other's weak points and be used relatively safely. Recently, however, our clinic has seen a great increase in cases using different types of multifocal lens in each eye, the wavefront-shaping Vivity and the diffractive PanOptix, with highly satisfying results, so the type of multifocal lens and slight differences in add power may not matter much; choosing a lens that reliably reduces residual astigmatism may be more important. Unfortunately, a toric version of Clareon Vivity is not yet available in Japan, but low-power lenses for high myopia are apparently becoming available within a few months, so those considering it may do better to wait until then if surgery is not urgent. From next time we plan to publish several cases with the Vivity/PanOptix combination; we have seen a tendency for the order in which the lenses are used to affect satisfaction, so if you are interested, please check them.
2024.02.07