This is a case of a multifocal lens in one eye of a patient with high hyperopia.
She originally first visited us five years earlier, when we had just opened, to have glasses made because she could not see near.
Corrected vision was good at 1.5 in both eyes, but she had strongly hyperopic eyes, +1.5 D in the right and +4.0 D in the left, and at near the left eye was suppressed (she looked only with the right eye without using the left), so depth perception was also impaired. In addition, both eyes had a shallow anterior chamber and narrow angle, with a high risk of an acute glaucoma attack; the cataracts were not yet severe, so as a treatment priority we first recommended laser surgery (laser iridotomy) in both eyes to prevent an attack. "Laser surgery" may sound like a big deal, but it is a two- to three-minute procedure, with no restrictions on bathing or face washing afterwards.
Let me briefly explain acute glaucoma attacks. The eye is like a ball of water in which fluid called aqueous humor is constantly produced and drained, keeping the pressure constant; an attack is a state in which the drainage route (angle) narrows and becomes blocked, so that the eye becomes hard, that is, the pressure becomes abnormally high. Normal eye pressure is about 15 mmHg, but during an attack it can reach 50–60 mmHg; vision usually drops, but symptoms other than the eyes, such as headache and nausea, are often prominent, and if detection is delayed and it is left untreated, irreversible optic nerve damage from the high pressure can lead to blindness within days. As long as no attack occurs there are no symptoms, and of course an attack may never happen in a lifetime, or it may happen tomorrow; but in people like her with high hyperopia, that is, short eyes, the angle tends to be narrow structurally, and as the cataract progresses with age it compresses the angle further and raises the risk of attack, so statistically, older women with cataracts who had good eyes when young, that is, strong presbyopia, need to be careful about acute glaucoma attacks.
Laser treatment makes a small hole at the edge of the iris (the colored part of the eye) to create a bypass, changing the flow of aqueous humor to widen the drainage route (angle) and prevent attacks. Although small, it is a hole in the iris, so light can enter the eye from places other than the pupil; to avoid unwanted light after treatment, the hole is normally made in the peripheral iris at the 2 or 10 o'clock position, where the eyelid covers it. As in the figure below (the small hole at upper left), after treatment, light shone through the pupil is reflected and leaks out of the laser-made hole, confirming that the preventive hole is open all the way through, not just on the surface.
<Laser iridotomy to prevent acute glaucoma attacks>
After the laser the risk of attack was almost gone, and she came for regular check-ups every six months to a year; but because of her strong hyperopia with a large difference between the eyes (anisometropia), the difficulty seeing with her left eye worsened and bothered her even with glasses, so we suggested contact lenses as an option, or cataract surgery.
After discussion, since her right eye had uncorrected vision of about 1.0, she chose, a full five years after her first visit, cataract surgery on the left eye only, including a refractive correction element. Having long been troubled by strong hyperopia and presbyopia, she wished for surgery with a multifocal lens if she was a candidate, so after confirming that corneal higher-order aberrations were not large, we explained the pros and cons of each lens and she weighed TECNIS Synergy against PanOptix. In the end, as it was single-eye surgery and she drives at night, the surgery was done with Clareon PanOptix, now made of the new material Clareon instead of AcrySof.
As noted above, her unoperated right eye had +1.5 D of hyperopia, so the left eye's target refraction was naturally exactly zero for distance, but with a short eye and a history of laser treatment, postoperative refractive error was a concern, so this time too we decided to determine the final lens power with the ORA system.
As shown below, in the preoperative lens power calculations, on the left, both Barrett Universal II (BU II) and SRK/T recommended 26.0 D (our clinic's correction formula predicted a 0.03 D myopic result with SRK/T), Haigis gave 26.5 D, the Hoffer Q formula, said to be accurate for short eyes, also 26.5 D, and the Kane formula, which includes AI, on the right, 26.5 D as well. For lens power prediction in high myopia, that is, long eyes, along with improvements in formula accuracy, our clinic's correction formula also predicts well, with many cases and advanced optimization, so it is a strength of ours; but prediction for high hyperopia, that is, short eyes, is often more difficult. In our experience, short eyes tend to end up hyperopic, but her corneal power was relatively well balanced for her axial length, so, going by feel, we went into surgery with the 26.0 D prediction recommended by BU II and SRK/T.
The cataract was still mild, but in addition to poor fixation her zonules were weaker than expected, so we removed the cataract more carefully than usual before measuring with the ORA system. I thought it would recommend 26.0 D as predicted preoperatively, but, as shown below, both of two measurements recommended 26.5 D, predicting a postoperative refraction of −0.03 D; after some hesitation we trusted the ORA system, inserted a 26.5 D PanOptix, and completed the surgery.
During surgery her eye moved a great deal, and the reason seems to have been that she was feeling pain, for which I am very sorry. At our clinic, in addition to eye-drop anesthesia, we perform intracameral anesthesia in all cases, and for people sensitive to pain we also give sub-Tenon anesthesia. Sub-Tenon anesthesia does not involve sticking a needle into the eye; a small incision is made in the white of the eye, a blunt cannula without a sharp tip is advanced along the eyeball, and anesthetic is injected behind the eye. Its pain-relieving effect is stronger, and it sometimes also acts on the optic nerve so that things look dark, but there is no need to worry. Because the anesthetic procedure itself is invasive, we do not normally use it, but rather than continuing surgery while enduring pain, adding anesthesia to remove the pain makes the surgery itself safer, so during surgery please don't hold back and feel free to tell us if you feel pain.
Back to the case: after surgery the feared refractive error did not occur; one month after surgery refraction was S +0.25 D, C −0.50 D, Ax 3° (+0.25 D of hyperopia and −0.50 D of astigmatism, a spherical equivalent of 0.00 D), and she was very satisfied with uncorrected vision of 1.2 at both distance and near. In other words, had we used 26.0 D she would have become hyperopic, so this time the result was a win for the ORA system over our clinic's prediction.
At present at our clinic, the preoperative Barrett Universal II formula gives smaller postoperative refractive errors than the ORA system, so we use the ORA system as an aid, purely to confirm whether the power decided before surgery is correct. However, as optimization progresses it may come to exceed the accuracy of the preoperative formulas, and for lens power selection after LASIK, the ORA system has clearly given more accurate results than formulas using total corneal power, so next time I would like to present a post-LASIK case.
2022.06.05