November 2019

IN FOCUS

Managing Irregular Corneas Prior to Cataract Surgery
Managing lumps and bumps: Paving the way to optimum cataract outcomes


by Chiles Samaniego EyeWorld Contributing Writer

“If the ocular surface is
optimized, a patient may become an excellent toric candidate...”
—Terry Kim, MD, and
Mark Goerlitz-Jessen, MD



Figure 1. Corneal topography of an eye with Salzmann’s nodules prior to superficial keratectomy (left) and 3 months after superficial keratectomy, prior to cataract surgery (right).
Source: Terry Kim, MD, and Mark Goerlitz-Jessen, MD

Corneal abnormalities—mainly pathologies such as pterygium, Salzmann’s nodules, and epithelial basement membrane dystrophy (EBMD)—may be visually significant. “All of these conditions can impact the final visual outcome with cataract surgery, because they can affect the shape of the cornea and, as such, affect the measurements we need to accurately determine what lens implant the patient needs,” Shahzad Mian, MD, told EyeWorld.
Managing these “lumps and bumps” is essential for optimizing refractive outcomes in cataract surgery. EyeWorld consulted various experts about handling these conditions.

The impact of lumps and bumps

W. Barry Lee, MD, shared a case to illustrate the impact of visually significant corneal abnormalities—particularly a pterygium—on cataract surgery. “Any time a corneal lesion (lump or bump) is found prior to cataract removal, consideration of how it affects the corneal topography and biometry is critical,” he said in an email.
For a 75-year-old with pterygium who consulted for simultaneous pterygium excision and cataract surgery, Dr. Lee performed pterygium excision first and planned for cataract surgery 8–10 weeks later.
On preoperative evaluation, the eye had 7.25 D of cylinder, with subsequent IOL calculations predicting a 24.5 D IOL for a plano postoperative refractive target. After pterygium excision, the eye had only 0.50 D of cylinder, with IOL calculations predicting a 20.5 D IOL for plano.
“Without removing the pterygium first, I would have placed a 24.5 D IOL in the left eye,” Dr. Lee wrote. “Given the uncorrected vision was 20/20 uncorrected after pterygium surgery followed by cataract surgery 10 weeks later, the IOL would have been 4 D from target due to the induced astigmatism and incorrect K values on biometry.”
Terry Kim, MD, and Mark Goerlitz-Jessen, MD, shared the case of a 75-year-old who underwent superficial keratectomy for Salzmann’s nodules (SNs) before undergoing cataract surgery 4 months later. In addition to undergoing biometric assessment prior to superficial keratectomy, the patient had three additional biometric assessments “to confirm an improved ocular surface and stable corneal parameters” between the two procedures (Figure 1).
Final biometry prior to cataract surgery revealed an against-the-rule astigmatism of 1.08 D at 177 degrees—a significant change from the 1.28 D at 3 degrees measured preop. In this case, they selected a toric IOL, resulting in postoperative uncorrected distance visual acuity of 20/20 with a refraction of +0.50 – 0.25 x 92 (or +0.375 SE).
“This case highlights the significant corneal changes induced by SN, the importance of managing these lesions prior to cataract surgery, and the success of toric IOLs in such cases,” they wrote.

Assessing visual significance

The cases presented clearly demonstrate that visually significant lumps and bumps need to be managed prior to cataract surgery, but their presence doesn’t always mean they are visually significant. These “lumps and bumps,” Dr. Mian said, can be chronic and stable, meaning they have no impact on the patient’s vision or corneal shape.
“I think the number one priority, first, is to assess whether it is affecting the vision,” Dr. Mian said. “If it is affecting the vision and the shape of the cornea, then the second question is whether it has a stable effect or a changing effect. If it is stable, then we can choose to leave it alone after a good discussion with the patient.”
To determine whether the pathology affects the corneal curvature and visual function, Christopher Rapuano, MD, wrote in an email to EyeWorld that he performs slit lamp examination to look for significant EBMD changes, subepithelial fibrosis, or Salzmann’s nodules within the central 6–8-mm optical zone; negative staining to identify elevation of the superficial layers particularly in the central 7–8-mm optical zone, probably indicating the need for treatment; and corneal topography, which may reveal irregular astigmatism centrally.
In any case, corneal irregularities must be “thoughtfully evaluated and treated when present in cataract patients,” wrote Dr. Kim and Dr. Goerlitz-Jessen. They cited a paper they published in the Journal of Cataract and Refractive Surgery, which highlights the impact that Salzmann’s nodules and EBMD in particular have on biometry,1 “the foundation for successful visual outcomes in cataract surgery.” They suggest assessing cases using patient symptomatology, slit lamp examination, corneal topography, and biometry.
While they agreed that “small, peripheral or astigmatically neutral corneal disease may not require intervention,” they noted that “it can be difficult to be confident with the degree to which potentially minor corneal changes may be impacting a patient’s optical system. If there is a reasonable concern that these lesions could affect a patient’s visual outcome, treatment is recommended. Certainly, patients with central disease, visual and ocular surface symptoms, corneal topographic changes, and/or biometric inconsistencies require intervention prior to cataract surgery.”

Timing procedures

Dr. Lee will always manage these conditions prior to cataract surgery. “If I see significant asymmetry between the topography in both eyes, and the eye with the corneal pathology has induced astigmatism, I will always remove the lesion prior to cataract surgery.”
Lawrence Hirst, MD, whose practice focuses solely on pterygium removal, agrees. “If they cause irregular astigmatism, then they should be dealt with first before lens surgery,” he wrote in an email.
The doctors suggest delaying cataract surgery by at least 30 days after the management corneal irregularities (ideally 90 days or more) to allow the cornea to stabilize. In any case, repeat measurements at several, separate time points are valuable to confirm the stability of corneal parameters prior to cataract surgery.
“Giving the surface time to heal ensures the correct lens implantation power is used at the time of cataract removal,” wrote Dr. Lee.

Premium IOLs

As demonstrated by the case shared by Dr. Kim and Dr. Goerlitz-Jessen, premium IOLs such as toric IOLs “can absolutely be used” in cases with corneal abnormalities, provided the abnormalities are managed properly and the stability of the cornea is carefully assessed.
EBMD, however, presents a particular challenge. “I would be worried about using a toric IOL if the EBMD is obvious and present in the visual axis,” wrote Dr. Lee. “If a
superficial keratectomy is performed and the cornea appears clear and the topography shows regular corneal astigmatism, I would be more inclined to use a toric IOL.”
“It is important to recognize that EBMD can both increase manifest astigmatism or also mask existing cylinder,” wrote Dr. Kim and Dr. Goerlitz-Jessen. “Also, EBMD often causes irregular patterns of astigmatism, which are poorly corrected with toric IOLs. If the corneal surface is not properly addressed prior to the use of a toric IOL, visual outcomes are unpredictable and patients are often unhappy.
“If the ocular surface is optimized, a patient may become an excellent toric candidate and end up doing exceptionally well,” they continued. “However, it is also important to discuss the recurrence of EBMD with patients, which is seen in up to 13% of cases.2 If EBMD recurs, the astigmatism correction from the toric IOL can be adversely affected, potentially requiring additional treatment to once again optimize the cornea and reap the benefits of their toric lens.”

Superficial lamellar vs. PTK

All the doctors agree that in most cases a superficial lamellar keratectomy is enough to manage lumps and bumps, reserving PTK for deeper, typically recurrent or refractory lesions that penetrate into the stroma. They caution that PTK, which may cut into the Bowman’s layer or even the stroma, has a greater risk of creating haze and/or scarring, although the use of mitomycin C (MMC) mitigates the risk.

Adjuncts?

MMC is a useful adjunct to prevent recurrence in the case of Salzmann’s nodules. It is, however, unnecessary in most cases of EBMD as management involves inducing some fibrosis to increase adherence of the epithelium and underlying basement membrane.
A diamond burr is helpful in this case. “I do find that a diamond burr helps reduce the risk of recurrence in my experience,” Dr. Mian said. “With the slight addition of roughening with the diamond burr, they get less erosions.”
But not everyone uses it. “Generally, we do not use a diamond burr for treating EBMD,” wrote Dr. Kim and Dr. Goerlitz-Jessen. “To remove epithelium for both SK and PTK we use dilute alcohol to loosen the tissue and then remove it with a combination of Weck-Cel sponges (BVI) and a Maloney spatula.”
Meanwhile, MMC is best avoided in cases of pterygium. “MMC has been repeatedly discussed in the scientific literature as causing blindness and I have personally seen at least six eyes lost after MMC for pterygium,” Dr. Hirst wrote. Instead, Dr. Hirst pioneered the PERFECT technique, which involves leaving the exposed sclera bare and requires no adjuvants.
Dr. Lee, who co-authored a study on MMC-associated stromalysis after pterygium surgery,3 also uses a modified PERFECT technique described by Dr. Hirst and does not feel MMC is needed as recurrence following the technique is rare. “I personally do not use MMC for a primary or recurrent pterygia but would not fault a surgeon for considering its use in a recurrent pterygium with severe conjunctival fibrosis,” he wrote. “Always take care to avoid applying it directly to bare sclera when used as it has been associated with necrotizing scleritis, scleral necrosis, scleral melts, and calcification of the sclera.”

At a glance

• Visually significant lumps and bumps should be managed with enough time for the cornea to heal and stabilize prior to evaluation for cataract surgery with IOL implantation.
• Premium IOLs can be used provided corneal abnormalities are adequately managed and a stable cornea is ensured; additional caution should be exercised when using toric IOLs in EBMD and patients should be counseled regarding the risk of recurrence.
• MMC is helpful to prevent recurrent Salzmann’s nodules but is less useful for EBMD and must be used with extreme caution, if at all, for pterygium; a diamond burr is a useful adjunct for EBMD, but not essential, with alternative techniques available.

About the doctors

Mark Goerlitz-Jessen, MD
Resident
Duke Eye Center, Duke University School of Medicine
Durham, North Carolina

Lawrence Hirst, MD
The Australian Pterygium Centre
Brisbane, Australia

Terry Kim, MD
Professor of ophthalmology
Chief, Cornea and External Disease Service
Director, Refractive Surgery Service
Duke Eye Center, Duke University School of Medicine
Durham, North Carolina

W. Barry Lee, MD
Partner Cornea, External Disease & Refractive Surgery Service
Eye Consultants of Atlanta
Medical director, Georgia Eye Bank
Atlanta, Georgia

Shahzad Mian, MD
Vice chair, Clinical Sciences and Learning
Professor, Department of
Ophthalmology and
Visual Sciences
University of Michigan
Ann Arbor, Michigan

Christopher Rapuano, MD
Director and attending surgeon, Cornea Service
Wills Eye Hospital
Professor, Sidney Kimmel
Medical College, Thomas
Jefferson University
Philadelphia

References

1. Goerlitz-Jessen MF, et al. Impact of epithelial basement membrane dystrophy and Salzmann nodular degeneration on biometry measurements. J Cataract Refract Surg. 2019 Aug;45(8):1119–1123.
2. Germundsson J, et al. Clinical outcome and recurrence of epithelial basement membrane dystrophy after phototherapeutic keratectomy: A cross-sectional study. Ophthalmol. 2011;118:515–22.
3. Lindquist TP, et al. Mitomycin C-associated scleral stromalysis after pterygium surgery. Cornea. 2015 Apr;34(4):398–401.

Relevant financial interests

Goerlitz-Jessen: None
Hirst: None
Kim: None
Lee: None
Mian: None
Rapuano: None

Contact information

Goerlitz-Jessen
: mark.goerlitz.jessen@duke.edu
Hirst: lawrie@tapc.net.au
Kim: terry.kim@duke.edu
Lee: wblee@mac.com
Mian: smian@med.umich.edu
Rapuano: cjrapuano@willseye.org

Managing lumps and bumps: Paving the way to optimum cataract outcomes Managing lumps and bumps: Paving the way to optimum cataract outcomes
Ophthalmology News - EyeWorld Magazine
283 110
220 141
,
2019-11-04T13:00:35Z
True, 11