Cataract Surgery Following Cornea Transplant

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Article initiated by:

Hoon Jung, MD, Randy Yang Lu, Sina Vahedi, MD

All contributors:

Chatchada Kharuhayothin M.D., Susama Chokesuwattanaskul, M.D., Ph.D., Alpa S. Patel, M.D., Hoon Jung, MD, Derek W DelMonte, MD, Brandon Baartman, MD, Sina Vahedi, MD, Angela Verkade, MD, Susama Chokesuwattanaskul, M.D., Ph.D.

Assigned editor:

Angela Verkade, MD

Review:

Assigned status Update Pending

 by Angela Verkade, MD on December 29, 2025.

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Contributing Editors:	add

Introduction

Cataract surgery after corneal transplantation requires careful assessment of graft stability and optimization to enable accurate intraocular lens (IOL) selection while preserving graft function, as cataract surgery can cause corneal endothelial cell loss. Surgical planning depends on the type of corneal graft; treatment of cataracts after full-thickness penetrating keratoplasty (PKP) and treatment after Descemet's membrane endothelial keratoplasty (DMEK) differ on many levels.

Fig 1. DMEK graft with detached peripheral edge

Patient counseling is of paramount importance. Patients should understand the known risks to their current graft as well as refractive goals, predictability and likely outcomes. Offering cataract surgical treatment should take into account numerous factors, including but not limited to: vision, fellow eye status, patient needs, graft status, type and duration of graft, lens density and medical necessity.

Methods

Optimizing the ocular surface

Optimizing the ocular surface is important before cataract surgery. This is even more pronounced in the context of prior corneal surgery. Ocular surface optimization in the form of increased lubrication or other dry eye treatments is often warranted to blunt the expected increase in ocular surface inflammation and secondary ocular surface disease which happens even after routine cataract surgeries.

Preop-Biometry and Topography/ Tomography

The corneal graft must be clear to allow for optical biometry with good signal strength. If the corneal graft is not clear, A-scan biometry could bypass the non-clear cornea. Though cataract surgery in the setting of a "non-clear" cornea is often a combined procedure (cornea graft, lens extraction, intraocular lens implantation), which has its own challenges and is a topic of separate discussion.

Compared to combined procedures, performing cataract surgery after corneal transplantation has the advantage of more predictable refractive outcomes. Care should be taken to confirm the stability of the keratometry. In these patients, all corneal sutures should be removed, if possible, before final keratometry readings are obtained. Topography/ Tomography will be especially helpful in cases of PKP/Therapeutic Keratoplasty/Lamellar Keratoplasty (LK)/Deep Anterior Lamellar Keratoplasty (DALK) as these grafts are known to have higher rates of significant astigmatism (regular and irregular), confounding IOL planning. IOL calculations are more reliable for endothelial keratoplasty compared to PKP/DALK.

Pre-operative evaluation of the risk of graft failure and the possibility of corneal re-grafting

         The risk of graft failure and re-grafting in eyes following PKP is not uncommon. Therefore, the optical changes following the new PKP should be taken into consideration. The incidence of graft failure and corneal re-grafting after cataract surgery in patients with a prior keratoplasty varies depending on multiple factors, including the type of keratoplasty performed, the time elapsed since the corneal transplant, pre-existing corneal endothelial cell count, and surgical technique. One of the primary concerns is the endothelial cell loss, which are crucial for maintaining corneal clarity. Surgical trauma, even in skilled hands, can lead to additional endothelial cell loss.

Table 1. Summary of pre-operative evaluations for cataract surgery in eyes following PKP: A comprehensive pre-operative assessment is crucial for successful cataract surgery

The risk of graft failure

The risk of endothelial trauma and subsequent graft failure is influenced by the surgical approach and the management of intraocular pressure, as well as by complications such as prolonged surgery time or posterior capsule rupture. Moreover, cataract surgery can trigger inflammatory responses or exacerbate low-grade inflammation, increasing the risk of graft rejection. Additionally, if the endothelial cells are expected to be lower than 500-800 cells/mm2 postoperatively, the maintenance of corneal transparency is unlikely, resulting in corneal decompensation.

The possibility of corneal re-grafting

         Even in the case of non-complicated cataract surgery, graft survival should also be considered. Overall, the 10-year survival rate of corneal grafts following PKP was 65%. A previous study reported that patients with keratoconus achieved the best survival rate of 95% at 10 years, and the lowest survival was observed in patients with chemical burns, who had a survival rate of 14% at 10 years.  However, while the 10-year survival rate of the primary PKP graft was 81%, the rate for second grafts dropped to 33% and 16% for the third or more grafts. Additionally, the rate of endothelial cell loss following PKP was 7.8% per year during 3-5 years postoperation and 4.2% per year during 5-10 years. 

Once the endothelial cell loss of the graft falls below the pumping capacity to maintain the corneal transparency, endothelial failure occurs, resulting in graft failure. Therefore, endothelial keratoplasty, either Descemet’s membrane endothelial keratoplasty (DMEK) or Descemet stripping automated endothelial keratoplasty (DSAEK), may be an alternative to repeat PKP. Hyperopic shift commonly occurs after DMEK and DSAEK due to the increased corneal thickness; the hyperopic shift was estimated to be 0.98 ± 0.89 diopters for DMEK and 1.75 - 4.25 diopters for DSAEK. Additionally, the posterior curvature change may also occur. A thorough pre-operative assessment is essential to reduce the likelihood of corneal regrafting. This assessment can guide surgical planning and may indicate the need for a combined procedure involving cataract surgery and corneal transplant if the endothelium is already compromised. Surgical techniques that minimize endothelial damage, such as using less ultrasonic energy and protective viscoelastic substances, can also help reduce the possibility of corneal re-grafting.

IOL choices

A significant level of consistency and confidence in analyses (and counseling) is needed if considering IOL models other than standard monofocal IOLs (e.g., toric, see astigmatism management below). Caution must be taken when using any IOL model that induces aberrations significantly or lowers contrast sensitivity, as corneal grafts present a range of compromised optics, whether in the form of opacity (such as interface haze for lamellar-based procedures or scarring at the graft-host junction) or significant aberrations from astigmatism. It is often challenging to characterize higher-order aberrations for PKP/DALK. Therefore, emphasis should be placed on correcting lower-order aberrations, including second-order Zernike optics (myopia/hyperopia/astigmatism).

IOL choices for irregular and aberrated corneas may include pinhole IOL optics and adjustable optics, such as the Light Adjustable Lens (LAL), to allow for correction or reduction in refractive errors after cataract surgery.

Table 2. Summary of IOL types and properties

Other critical factors in IOL selection are optical changes following PKP and the risk of regrafting, either re-PKP or lamellar keratoplasty. Table 2 summarizes the types and properties of IOLs currently available.

Considering the potential option of performing endothelial keratoplasty in a previously failed PKP, it is advisable to use a hydrophobic IOL. Hydrophilic IOLs are prone to opacification after the use of endotamponade, which is commonly employed in endothelial keratoplasty. Following PKP, corneal changes that would affect the IOL calculation include the anterior and posterior corneal curvatures, axial length, anterior/posterior corneal ratio, central corneal thickness, and anterior chamber depth. However, the extensive IOL formula is not discussed here.

IOL designs and properties: Toric IOLs

         The general recommendation for IOL selection in eyes following PKP is to choose the simplest IOLs or monofocal non-toric IOL. However, despite cataract surgery, significant astigmatism of the eyes following PKP is the most common obstacle to achieving desirable visual outcomes. In one study, the mean refractive cylinder at 12 months following PKP was 2.88 ± 1.60 D, which can significantly affect the visual acuity of the patients. Therefore, toric IOL has emerged as a promising option for correcting residual astigmatism following PKP. However, there are additional considerations for toric IOL in eyes following PK, including the characteristics of astigmatism, either regular or irregular, the risk of graft failure, the risk of disease progression or recurrence on the graft, the possibility of corneal re-grafting, and the life expectancy of the patients. A previous study on the use of commercially available toric IOLs in eyes following PKP that had moderate to high symmetrical residual astigmatism after all suture removal reported a significantly reduced manifest refractive cylinder. 

Anesthesia Considerations

Anesthesia considerations should follow what would be best suited for the patient, ranging from topical to general anesthesia, based on the patient's ability to cooperate with the surgery. If anticipating maneuvers that include scleral tunnel, manual extracapsular cataract extraction (ECCE), small-incision cataract surgery (SICS), then a retrobulbar or peribulbar block +/- a facial nerve block can be utilized. Positioning for these larger incision treatments should aim to minimize posterior pressure.

Incision locations and types

Standard clear corneal incisions are a viable option as long as care is taken not to extend near the edges of the graft, to avoid causing detachments of endothelial grafts or dehiscence of full-thickness grafts. Shorter uniplanar wounds that are sutured at the end may offer a compromise approach to achieve this.

Scleral tunnel utilization in preparation for standard phacoemulsification with IOL implantation, ECCE, SICS offers advantages of decreasing the above risks by moving the incision away from the cornea.

Soft-shell techniques and viscoelastic choices

The use of a dispersive ophthalmic viscosurgical device (OVD) that coats the endothelium is likely to be universally employed in intraocular surgery, particularly cataract extraction by phacoemulsification (and to some degree manual ECCE) to reduce endothelial loss.

Phacoemulsification, femtosecond laser-assisted cataract surgery (FLACS), Manual ECCE, Manual SICS

The choice of method for cataract extraction should factor in the graft's endothelial cell count as well as the surgeon's preference and confidence with the technique. When using phacoemulsification, an adequate distance from the corneal endothelium should be maintained to avoid excessive ultrasound energy and aggressive fluid flow near the graft. Methods of nuclear disassembly, such as phaco-flip or stop and chop, should be chosen with caution.

Astigmatism management

Particularly for eyes with PKP/DALK grafts, attention must be paid to the presence of astigmatism, both irregular and regular, as this can significantly affect operative planning and refractive goals. For clinically significant regular astigmatism, management can include a variety of adjunct techniques in isolation or in combination, such as the use of corneal relaxing incisions (in the graft-host junction, internal to the wound interface) and toric IOLs. Limbal relaxing incisions in the context of PKP/DALK likely have a limited role, as the biomechanical effects likely have little translation to the central optical zones. Laser refractive treatments may be used postoperatively, but with caution regarding the effects on ocular surface health. If utilized, the newer platforms using topography-guided ablation algorithms may offer some tactical advantage of optical rehabilitation for cases with a component of irregularity.

Fig 2. High astigmatism post PKP

Preoperative regional pachymetry, OCT or confocal microscopy may be adjunct imaging modalities to aid in decision-making on wound depth and the amount of existing fibrosis (versus epithelial plug) at graft-host junctions. Incisions can be made with various instruments ranging from dedicated keratotomy knives to a femtosecond laser.

Preoperative treatment with additional immune modulating therapies

There may be extra considerations for an adjunct increase in topical steroids or other ways to decrease immune-mediated response against the graft perioperatively for cataract surgery. The decision to add additional immune-modulating agents can be made on a case-by-case basis.

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