Cataract Surgery in the Setting of Corneal Opacities

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Article initiated by:

Ahmed Omar, Blake A. Boehm, MD

All contributors:

Ahmed Omar, Blake A. Boehm, MD, Colleen Halfpenny, M.D.

Assigned editor:

Isa S. K. Mohammed, MD

Review:

Assigned status Up to Date

 by Isa S. K. Mohammed, MD on May 13, 2026.

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Contributing Editors:	add

Background

Performing cataract surgery in patients with corneal opacities is a common challenge encountered by ophthalmologists. Corneal haze and scars can create significant light scatter and glare which reduces visibility and may increase risk of surgical complication. The impact that a corneal opacity can have on visibility of anterior segment structures is dependent on the size, location, and density of the opacity. Not all patients who have corneal opacities will undergo corneal transplantation, therefore surgeons should recognize strategies that can be utilized when performing cataract surgery for these patients. This article will provide a review of preoperative, intraoperative, and postoperative considerations and techniques that surgeons can use when performing cataract surgery for patients with corneal opacities.

Surgical Options

• Phototherapeutic Keratectomy (PTK) followed by cataract surgery – for superficial corneal opacities
• Simultaneous keratoplasty and cataract surgery – known as “triple procedure” (Cataract Surgery Combined With Corneal Transplant Surgery)
• Keratoplasty followed by cataract surgery – 2-stage procedure
• Cataract surgery alone – focus of this article

Patient Selection & Preoperative Workup

It is important to obtain a complete medical and ocular history and complete a thorough examination for patients with a cataract and corneal opacity. Standard cataract evaluation should be performed, including visual acuity, refraction, glare testing, tonometry, slit lamp examination, dilated fundus examination, and biometry/IOL calculations. Additional imaging such as corneal topography, optical coherence tomography (OCT) of the retina and retinal nerve fiber layer, and B-scan may be obtained as well. Detailed evaluation of the size, location, and density of the corneal opacity can help determine the impact on visual acuity and guide treatment decision-making. It is important to discuss the patient’s expectations and goals from surgery to determine whether to pursue cataract surgery plus keratoplasty or cataract surgery alone.

Below are some instances when a patient and surgeon may believe that cataract surgery alone is most appropriate:  

• Small and/or peripheral corneal opacity with minimal impact on visual acuity
• Cataract surgery alone could provide the patient with enough improvement in vision to meet the needs and expectations of the patient
• The patient is unable to commit to long-term postoperative follow up and management of a corneal graft including long-term usage of topical corticosteroid eye drops
• History of multiple corneal transplant rejections in the same eye
• High risk of corneal graft failure
• Monocular patients who wish to avoid the increased risk of corneal transplantation, and require quick visual recovery to maintain independence
• A cornea specialist or donor corneal tissue is unavailable, particularly in resource limited regions

IOL Selection, Biometry, and Target Refraction

Multifocal IOLs can increase spectacle independence; however, they have been associated with reduced contrast sensitivity as well as increased glare and halos. Therefore most surgeons prefer to implant monofocal IOLs in patients with corneal opacities. If a patient has a paracentral corneal opacity, IOLs with small optics less than 5 mm should be avoided. The IC-8 (Bausch & Lomb, Inc) is an extended depth of focus (EDOF) IOL that has demonstrated promising results after it was used in a few patients with non-central corneal scars. This monofocal lens has a central 3.23 mm opaque mask with a 1.36 mm wide central aperture. It was originally developed to increase range of vision and decrease spectacle dependence but has also been found to reduce higher order aberrations. These higher order aberrations are reduced by utilizing the pinhole effect of the lens where the unfocused peripheral light rays are filtered out by the small aperture of the IOL.

Obtaining IOL biometry and power calculations can be difficult for patients with corneal haze and opacities. Axial length may need to be obtained using A-scan if optical biometry cannot be obtained. Corneal refractive power (K-value) can also be difficult to obtain, therefore corneal topography and tomography can be used. It is important to recognize that full-thickness corneal scars can alter the posterior corneal curvature as well.

Although there may not be a plan for corneal transplantation at the time of cataract surgery, patients with corneal disease may require partial or full-thickness corneal transplantation in the future. This should be considered when determining the postoperative refractive target for cataract surgery.

Intraoperative Strategies for Cataract Surgery

Management of Small Pupils

Patients with poor dilation can make performing cataract surgery in the setting of corneal opacities more difficult due to reduced visualization of the lens capsule, nucleus, and cortex. When available, iris hooks and rings can help to open the working area for surgeons during cataract surgery. When synechia is limiting pupil dilation, performing synechiolysis with an intraocular spatula or other instrumentation can be useful.

If iris hooks or rings are unavailable, manual iris stretching or iris sphincterotomy can be used to improve visualization, particularly if the corneal opacity is obstructing a large portion of the working area. Goh et al performed a retrospective study of 114 eyes that underwent iris sphincterotomy during cataract surgery and demonstrated that it was a safe procedure with relatively low risk of surgical complication.

Optical iridectomy can be performed by surgeons during cataract surgery to improve a patient’s functional vision by creating an alternative visual axis when central corneal opacities are blocking the visual axis. These procedures are especially useful in resource limited regions where corneal surgeons and donor tissue may be unavailable or in limited supply. A retrospective case series of 22 patients by Spierer et al found that this is a relatively safe procedure. However optical iridectomies can increase the risk of bleeding and iris scarring. Since both iris sphincterotomy and optical iridectomy permanently alter the appearance of the iris, cosmetic appearance of the eye should be discussed with the patient prior to surgery.  

Capsulorhexis

When performing the anterior capsulorhexis, it is important to avoid dropping the flap under the corneal opacity to prevent losing the flap. Intraocular forceps are preferred to allow for creation of a smooth and continuous capsulorhexis with minimal re-grabbing of the flap. The use of trypan blue stain can help with visualization of the anterior capsule during the creation of the capsulorhexis and can aid in identifying the capsulorhexis edge when performing phacoemulsification and IOL implantation.

Phacoemulsification Technique & Cortex Removal

The choice of phacoemulsification technique is dependent on surgeon preference and comfort; however, phaco-chop may be preferable to divide and conquer or stop and chop as it has shown to result in less endothelial cell damage in the setting of dense cataracts. Phacoemulsification should be performed in areas of clear cornea when possible, to avoid inadvertent puncture of the posterior capsule or cutting the edge of the capsulorhexis when the phaco tip is not well visualized under hazy or opacified cornea. Fragments of the lens nucleus can be rotated to areas of clear cornea for better visualization prior to phacoemulsification.

Depending on the location of the corneal opacity, there may be some areas of lens cortex that is not well visualized. Manual movement of the eye by the surgeon may help to visualize these areas of cortex. If a small area of remaining cortex is still poorly visualized, it is reasonable to insert the IOL in the capsular bag and then re-attempt cortex removal as the IOL can provide some protection from damaging the posterior capsule. Some surgeons may prefer bimanual I/A in these cases.

Illumination Techniques

At the start of the case, it is important to optimize the microscope light settings, magnification, and focus for best visualization during surgery. Corneal opacities can cause significant light scatter, therefore greater light intensity will not necessarily improve visualization of the anterior segment structures. Standard operating room microscopes have both coaxial and paraxial lights. Adjusting the balance of these lights, particularly the coaxial light, can improve the red reflex and visualization during surgery.

Alternatives to conventional microscope illumination:

Slit Illumination with Surgical Microscope    

Some surgical microscopes can adjust the shape of the illumination beam so that a slit beam can be created. The slit beam can reduce light scatter and reflection which can improve the red reflex during surgery. An advantage of this technique is that it does not require additional equipment.

3D Coaxial Illumination

Some newer surgical microscopes offer a 3D visualization system. This is sometimes referred to as a “heads up display” since the surgeon can operate by looking at a monitor while wearing 3D glasses rather than through the microscope oculars. A study by Wang et al compared single coaxial illumination versus the standard combination of coaxial and paraxial illumination with this 3D visualization system while performing cataract surgery in patients with a corneal opacity. Their study found that single coaxial illumination provided better red reflex and contrast without any significant loss of depth of field when evaluated by surgeons. Cost and availability of this system are potential drawbacks.

Near Infrared Operating Microscopy

A technique currently being investigated is the use of near infrared light (850 nm – 1300 nm) during cataract surgery. This has been referred to as “lightless cataract surgery” as it does not use the conventional light from the microscope. This system uses a head-mounted display rather than traditional microscope oculars. It can provide 3-dimensional viewing during surgery without the need for visible spectrum illumination from the microscope. Although minimizing the risk of phototoxicity was one of the primary goals of the system, it also has the potential to improve visualization during cataract surgery in the setting of corneal scars and opacities. This is further supported by a study using eye bank corneas which found light scattering decreases as the wavelength of light increases. A challenge of using this system is the learning curve for surgeons to become accustomed to the alterations in tissue color as viewed using the near infrared light, and operating using the head-mounted display rather than the microscope oculars. Additional considerations are the narrower field of view and small decrease in resolution when using this system; however, this may improve as the technology evolves.

Transcorneal Illumination

A light pipe can be used to provide transcorneal illumination without the need for an extra paracentesis. For this technique, the light pipe is usually held at a 45 degree angle near the periphery of the cornea to provide illumination of the anterior segment structures. A drawback is that it requires either the surgeon or an assistant to hold the light pipe. If the surgeon is holding the pipe, it can make bimanual steps of surgery such as phacoemulsification challenging.

Anterior Chamber Endoscopy

Anterior chamber endoscopy is another technique which has been attempted to improve visualization for surgeons. The endoscopy probe can perform simultaneous wide field illumination and video imaging as well as laser treatment if necessary. The major disadvantages of using this approach are the steep learning curve since most cataract surgeons are used to operating through a microscope, and the loss of depth perception since the endoscope provides a 2D image.

Intracameral Endoillumination

An endoillumination pipe can also be used during cataract surgery. There is a shield on the endoillumination pipe so it will result in less light scatter compared to chandelier light probes. By placing the light pipe in the anterior chamber, anterior segment structures can be visualized with less risk of phototoxicity since less light is directed posteriorly towards the retina. The drawbacks of using this system include the need for the surgeon to hold the illumination pipe during surgery and the potential increased risk of Descemet’s detachment with repeated manipulation of the pipe. A case series of 12 patients by Yuksel did not find any instances of Descemet’s detachment, and claimed that using the endoillumination pipe does not pose any greater risk than using a nucleus manipulator or chopper.

Chandelier Anterior Chamber Endoillumination & Retroillumination (pars plana approach)

Chandelier endoillumination probes can be placed in either the anterior chamber or posterior chamber through a pars plana approach for illumination during cataract surgery. The chandelier system uses fiber-optic probes held in place with silicone stoppers to allow for a hands-free set up during surgery. When used in the anterior chamber, the chandelier system may cause more light scattering since it does not have a shield like the intracameral endoillumination system. This can be particularly noticeable with denser corneal opacities and is therefore recommended for use with mild to moderate corneal opacities. The pars plana placement can improve visualization and red reflex during surgery but requires a pars plana incision and vitrectomy equipment, and it may pose an increased risk of retinal detachment from the vitrectomy ports. Another consideration is the increased risk of retinal phototoxicity with the pars plana placement compared to anterior chamber placement given the closer proximity of the light probe to the retina.

Combination: Transcorneal Illumination + Anterior Chamber Endoillumination

These illumination techniques can be used individually or in combination. A case report by Nishimura et al described the use of transcorneal illumination when performing the capsulorhexis and anterior chamber endoillumination for phacoemulsification.