Cataract after
laser surgery

A population now reaching the age of cataract

LASIK and PRK developed widely from the late 1990s, then throughout the 2000s and 2010s. Patients operated on at the time, around 40 or 50, for their myopia, hyperopia or astigmatism are now reaching the age at which cataract develops naturally.

It is a growing population, and often a slightly surprised one. Surprised to learn that their former refractive surgery now changes the way the implant they are about to receive is calculated. Surprised, at times, to be described as “special patients” when for twenty years they had considered themselves successfully treated — which they are, incidentally.

Cataract arrives normally, even after laser

This is one of the first misunderstandings I make a point of clearing up in consultation: the laser did not “cause” your cataract.

Refractive laser acts only on the cornea — the transparent surface at the front of the eye. The lens, located deeper, was never touched by the procedure. It continued to age normally after the laser, as it would have done without any intervention. The cataract appearing today is the result of this natural ageing of the lens, independent of your surgical past.

This distinction is not trivial: it changes the way you may perceive your situation. You are not experiencing a late complication of your laser. You are going through an ophthalmic stage that the great majority of adults will know sooner or later.

The real challenge: calculating the implant

This is where the situation becomes technically distinctive.

When cataract surgery is planned, the clouded lens is replaced with an artificial implant. The power of this implant must be calculated precisely to reach the desired refractive goal — distance vision, multifocality, and so on. This calculation relies on biometric formulas that combine the measurement of the eye's length and the power of your cornea.

Now, these formulas were developed assuming a cornea whose geometry has not been surgically modified. After a LASIK or PRK, this is no longer the case. The cornea has been reshaped — thinned at the centre for myopia correction, steepened for hyperopia correction. Standard keratometry, which measures corneal power in the usual way, then systematically underestimates or overestimates the true power of the cornea.

Using these measurements directly would lead to significant postoperative refractive errors: a patient who wanted to be well corrected for distance could end up residually hyperopic or myopic, without this being due to any surgical error.

To address this problem, specific formulas have been developed: Barrett True-K, Haigis-L, the ASCRS Post-LVC Online Calculator. They incorporate corrections that take the refractive history and the modified corneal geometry into account. Ideally, the preoperative data from your original laser — keratometry before the laser, the spherical equivalent treated — further improve the accuracy of the calculation. If these data are not available, alternative methods based on the current topographic analysis of your cornea still provide a reliable estimate.

What this changes for you in practice

Three practical consequences.

First, the preoperative assessment takes more time. Several calculation methods are used in parallel, and their results are cross-checked to identify the most likely implant power and to discuss the margins of uncertainty.

Next, the residual margin of error remains slightly higher than for an eye that has never been operated on. This is an honest reality to be aware of: the precision expected in a post-laser patient, even with the best formulas, does not quite equal that obtained in a “virgin” eye. This does not mean the result will be poor — it is generally very satisfactory — but that a small residual imprecision is statistically more likely.

Finally, secondary solutions exist in the rare cases where the final refractive result does not reach the desired goal. A laser enhancement, when technically possible, can refine the result. In some cases, rotating the implant or adding a supplementary implant may be discussed. These options are worth knowing about, but they remain the exception, not the rule.

Choosing the implant after laser: a few important nuances

The choice of implant — monofocal, EDOF, multifocal, toric — follows the same principles as for an eye that has never been operated on, but with a few specific nuances.

Multifocal implants are possible in certain cases, but more delicate. A cornea that has already been reshaped to create multifocality — for example after a previous PresbyLASIK — is generally not suited to a multifocal implant, because the two optical systems would combine poorly and degrade image quality rather than improve it.

EDOF implants are often a good option in this setting: they offer reasonable spectacle independence while remaining more tolerant of the residual corneal irregularities a previously operated cornea may present.

Monofocal implants remain a safe choice, particularly when the cornea shows significant irregularities or when predictability of the result is the absolute priority.

The decision therefore depends on the residual optical quality of your cornea as much as on your preferences. The choice of implant type (monofocal, EDOF, multifocal, toric) is discussed in detail during the preoperative assessment.

What helps your surgeon: recovering your records

If you can, find the documents from your original laser surgery: your refractive surgery booklet, your spectacle prescription before the laser, the operative reports from the surgeon who treated you at the time. These documents make it possible to use the most precise implant-calculation methods available.

Their absence does not prevent you from being operated on in good conditions — most patients no longer have these documents twenty years later — but their presence improves the accuracy of the calculation. If there is any chance of finding them, it is worth the effort.

What happens in consultation

In this context, the preoperative assessment includes high-precision biometry performed by optical interferometry, detailed corneal topography to analyse the residual geometry of your cornea, an examination of the retina and macula, and an in-depth discussion of your refractive history and visual goals.

This consultation is longer than a standard cataract assessment. That is normal and necessary. It makes it possible to establish an individualised strategy — which implant calculation to use, which type of implant to offer, and which margins of uncertainty to accept together.