5 EyeWorld Asia-Pacific | December 2024 required in the majority of patients. Even with high levels of astigmatism and asymmetry, as long as the meridian of the steep axis is identifiable and the history suggests adequate vison with spectacle correction, I would recommend considering toric IOLs. Obviously, one cannot expect the same level of prediction accuracy for sphere or astigmatism postoperatively but reducing the amount of astigmatism will facilitate spectacle wear and possibly reduce spectacle dependency for some patients. Custom toric IOLs with high toric cylinder powers are available and I have found these lenses very helpful for patients with keratoconus and high levels of astigmatism beyond the normal range. In order to be successful, it is important to remove RGP lenses for at least 8 weeks prior to biometry. This can be challenging for patients who are totally RGP dependent but can be managed by separating the surgeries, operating on the denser cataract and allowing the patient to continue contact lens wear in the eye with better vision. The operated eye then provides adequate vision for the RGP lens to be removed prior to surgery in the second eye. I would recommend using the True K Toric formula selecting the keratoconus option preferably with the measured PCA option. The K calculator which combines the Ks from multiple devices is very helpful in this context. There is no need to target significant myopia when using a custom keratoconus formula as is the case with standard formulae. This is one scenario where I do consider the patients’ preop refraction (prior to the development of cataract) relevant. It is reassuring if the amount and axis of the spectacle cylinder is similar to the biometry. If the spectacle cylinder is significantly less than the biometry then consider reducing the toric cylinder as the corneal apex may be displaced and the patient may be looking through a different part of the cornea than that measured by biometry or evident on topography. In patients who have no record of adequate vision with spectacles or who prefer to continue with RGP contact lens wear, a toric IOL is not recommended. Fitting a RGP contact lens is more difficult with a toric IOL implanted typically requiring a Bitoric Contact lens. Similarly, if the plan is to continue with RGP contact lens wear I would not implant a toric IOL, I would still target a spherical outcome close to emmetropia or a modest level of myopia. Occasionally, patients present with cataract and advanced keratoconus. An RGP contact lens may not be feasible and significant corneal scarring may impact acuity. For selected patients who understand the complexity of Keratoplasty and the long wait for the final outcome, initial Keratoplasty followed by delayed cataract surgery when the sutures are removed, can provide excellent visual rehabilitation, addressing both the cataract and keratoconus. I hope these thoughts will prove helpful in overcoming some of the obstacles that arise during the management of patients who present with both cataract and keratoconus. Warmest regards, Graham Barrett
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