Answering key questions on preoperative planning and IOL selection in complex cataract surgery
Cataract surgery is one of the most commonly performed ophthalmic procedures, but decision-making can become more complex in eyes with high myopia, keratoconus, previous penetrating keratoplasty, ocular trauma or irregular corneal measurements. In these cases, success depends not only on surgical skill, but on careful preoperative assessment, appropriate IOL selection and clear counselling around realistic visual outcomes.
In the first article in this two-part FAQ series, based on our Expert Pearls series, we bring together expert insights on how to assess complex cataract cases before surgery, select an appropriate IOL strategy and manage patient expectations.
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How should cataract surgery be planned in patients with high myopia?
Cataract surgery in high myopia should be approached as both a refractive and retinal procedure. Preoperative assessment should include careful examination of the central and peripheral retina, with OCT to assess the macula and widefield imaging or indirect ophthalmoscopy to detect lattice degeneration, retinal tears or myopic maculopathy.
Glaucoma screening is also important, as high myopia can make optic nerve assessment more difficult. Biometry can be challenging because posterior staphyloma and fixation instability may affect axial length measurements, so repeated measurements, and sometimes both optical and ultrasound biometry, can help improve accuracy. Surgical timing may also need to be earlier than in routine cases if the cataract interferes with monitoring of retinal or glaucomatous disease.
→ Read the full article: Expert pearls: Cataract surgery in patients with high myopia
What are the key considerations before cataract surgery after penetrating keratoplasty?
In eyes with previous penetrating keratoplasty, the priorities are graft protection, stable measurements and realistic refractive expectations. Surgery should usually be planned only once the graft is quiet and keratometry is stable, ideally after sutures have been removed.
Assessment should include graft clarity, endothelial reserve, pachymetry, wound integrity, peripheral thinning, ocular surface quality, glaucoma risk and steroid response. Patients should understand that the aim is meaningful visual improvement, not guaranteed refractive perfection, and should also be counselled about the risk of persistent corneal oedema, graft rejection or late endothelial failure.
→ Read the full article: Expert pearls in cataract surgery after penetrating keratoplasty
How should traumatic cataracts be assessed before surgery?
Traumatic cataracts require individualised planning because the lens opacity may be only one part of a wider ocular injury. Assessment can be limited by swollen lids, corneal oedema, hyphaema, fibrin, other anterior chamber material, swollen lens particles or a small pupil.
The decision is often a balance between removing a damaged lens early enough to assess the posterior segment and avoiding unnecessary removal of a lens that may not be permanently damaged. A clear diagnosis, structured surgical plan and flexibility during surgery are essential.
→ Read the full article: Expert pearls on traumatic cataract management
What makes cataract surgery in keratoconus challenging?
In keratoconus, the key question is how much visual improvement cataract surgery can realistically provide. Decision-making should include assessment of regular and irregular astigmatism, higher-order aberrations on corneal aberrometry and the presence of corneal opacities.
The patient’s visual needs and wider clinical context should also shape the plan. In patients with Down syndrome or intellectual disabilities, the goal may be improved function and quality of life rather than refractive precision.
→ Read the full article: Expert pearls for optimising cataract surgery in keratoconus
How should complex eyes be assessed before choosing an IOL?
Complex eyes need a multimodal diagnostic approach. No single device or measurement should be relied on in isolation. Axial length and anterior chamber depth are foundational, while corneal tomography, topography and total corneal power assessment are important in eyes with irregular astigmatism, keratoconus, post-refractive surgery changes or extreme axial lengths.
Measurements should be checked across platforms. If the magnitude or axis of astigmatism is inconsistent between devices, measurements should be repeated or IOL planning delayed until they are reproducible before finalising the IOL strategy.
→ Read the full article: Expert pearls on selecting the optimal IOL
How should IOL power be calculated in highly myopic eyes?
IOL power calculation is less predictable in highly myopic eyes, particularly in very long eyes. Modern formulas such as Barrett Universal II, Kane and Hill-RBF can be useful, and comparing or averaging outputs from multiple formulas may help reduce the risk of refractive surprise.
Many surgeons target mild residual myopia, as this may better match the patient’s lifelong visual habits and reduce dissatisfaction from unexpected hyperopia. Patients should be counselled that refractive outcomes are less predictable than in routine cataract surgery and that further refractive correction may be needed.
→ Read the full article: Expert pearls: Cataract surgery in patients with high myopia
What IOL considerations are important in high myopia?
IOL selection should take account of the altered anatomy of highly myopic eyes, including the possibility of zonular weakness, a large capsular bag and an increased risk of IOL instability. Premium and multifocal IOLs require particular caution, as reduced contrast sensitivity, dysphotopsia or coexisting retinal pathology may limit visual quality.
Patients should also be counselled carefully about near vision. Many highly myopic patients are accustomed to good unaided near vision, so aiming for emmetropia may remove a visual habit they value.
→ Read the full article: Expert pearls: Cataract surgery in patients with high myopia
How should IOL calculation and IOL choice be handled in keratoconus?
Keratoconus-specific formulas, such as Barrett True-K for keratoconus and the Kane keratoconus formula, can support IOL planning. Targeting approximately −1 to −2 D may help avoid an unwanted hyperopic outcome.
Toric IOLs can be useful in selected keratoconus cases, particularly when the regular astigmatic component is dominant and higher-order aberrations are not excessive. However, when irregularity is significant, visual quality may remain limited even if the refractive result appears technically successful.
→ Read the full article: Expert pearls for optimising cataract surgery in keratoconus
When should toric IOLs be avoided?
Toric IOLs may be appropriate when astigmatism is regular, stable and consistently measured across devices. However, they should be used cautiously, or avoided, when astigmatism is irregular, the axis is unstable or higher-order aberrations are significant.
In these cases, a monofocal IOL with planned postoperative visual rehabilitation may be a more appropriate strategy than attempting to correct unstable corneal measurements with a toric lens.
→ Read the full article: Expert pearls on selecting the optimal IOL
How should surgeons counsel patients about refractive expectations?
Refractive counselling is especially important in complex cataract surgery. Patients with high myopia, keratoconus, previous corneal transplantation or trauma may have less predictable outcomes than routine cataract patients, even with careful planning and modern formulas.
Counselling should cover the possibility of residual refractive error, the need for spectacles or contact lenses, further procedures, and the possibility that retinal, corneal or traumatic pathology may limit final vision. This is particularly important when considering premium, toric or multifocal IOLs.
→ Read the full article: Expert pearls on selecting the optimal IOL
Key takeaway
In complex cataract surgery, success depends on adapting technique to risk. Protecting vulnerable structures, recognising when to modify the surgical plan and managing postoperative complications carefully can help improve outcomes in eyes where routine approaches may not be enough.
Coming soon: Cataract surgery FAQs: Surgical technique and postoperative management
Cite: Long-term ocular symptoms after mild COVID-19 linked to corneal nerve loss and immune dysregulation. touchOPHTHALMOLOGY. July 9, 2026.
Disclosure: This article was created by the touchOPHTHALMOLOGY team utilizing AI as an editorial tool (Claude [Sonnet 5]. https://claude.ai.) The content was developed and edited by human editors. No funding was received in the publication of this article. Thank you to the authors who shared their practice pearls within our Expert Pearls series.
Editor: Nicola Cartridge, Director of Content
