Visually Significant Cataract in the Presence of Corneal Disease

Case Presentation

A 76-year-old woman is referred for a cataract evaluation. On presentation, her BCVA is -1.25 +0.50 x 009 degrees = 20/60 OD and -3.00 +1.75 x 125 degrees = 20/60 OS. A slit-lamp examination reveals significant bilateral epithelial basement membrane dystrophy (EBMD) that is more severe in the left eye and a 3+ nuclear sclerotic cataract in each eye. Tomography and biometry measurements are shown in Figures 1 and 2.

Figure 1. Corneal tomography scans (MS-39, CSO) for the right (A) and left (B) eyes.

Figure 2. Biometry measurements (IOLMaster, Carl Zeiss Meditec) for the right (A) and left (B) eyes.

The patient desires spectacle independence. She has a history of monovision and enjoyed a full range of vision in the past.

Which IOL technologies would you offer? Would you proceed directly to cataract surgery or offer additional medical or surgical treatment first?

— Case prepared by Audrey Rostov, MD

Henry Bair, MD, MBA, and Zeba A. Syed, MD

Given the patient's visually significant EBMD and refractive demands, an effort would be made to smooth the anterior corneal surface to improve the quality of biometry before proceeding to cataract surgery.

First, we would recommend a superficial keratectomy (SK) with either diamond burr polishing or phototherapeutic keratectomy (PTK; with or without mitomycin C) in both eyes. Lid margin disease and tear film instability should be treated concurrently, but medical therapy alone for ocular surface disease would be unlikely to make this cornea ready for premium IOL planning. We typically wait at least 3 to 4 months after SK before performing repeat topography and biometry. Cataract surgery would be delayed until serial topography and biometry are reproducible over at least two visits held 1 month apart.

Considering the patient's prior success with monovision, a monofocal or enhanced monofocal lens with a monovision strategy could offer her the range of vision she desires while preserving her quality of vision. Toric IOL implantation would be appropriate only if her posttreatment cylinder is regular, reproducible, and clinically meaningful. Extended depth of focus and multifocal IOLs are contraindicated in the presence of significant EBMD. If the post-SK ocular surface is smooth with few irregularities and the remainder of the ocular examination is healthy, however, she could consider these lens types to reduce her spectacle dependence.

Joshua C. Teichman, MD, MPH, FRCSC

The patient has a spherical equivalent of approximately -1.00 D and -2.00 D in the right and left eyes, respectively. The refractive astigmatism is inconsistent between the two eyes, and more importantly, the axes are quite different. The rings or mires on tomography are irregular but not dramatically so. In the right eye, the keratometry is not consistent with the tomography. The amount of astigmatism is lower in the right versus left eye. Although such a discrepancy can occur in healthy eyes with low levels of astigmatism, it is a cause for concern in eyes with corneal pathology such as EBMD. Interestingly, the tomography and optical biometry correspond fairly well in the left eye, which has more severe EBMD. There is also a significant difference in axial length between the eyes. For completeness, all tests would be repeated. Assuming the values are correct and the length of the eyes truly differs, the differences in astigmatism may be inherent and not due to EBMD. Whether the aforementioned issues are due to EBMD or other causes is a question that must be addressed before additional surgery such as SK is recommended in advance of cataract surgery.

Ocular lubrication and repeat testing would be a reasonable first step. A slit-lamp biomicroscopy examination that shows central EBMD with irregular or negative staining centrally would prompt me to perform SK followed by repeat testing (I prefer to wait 3 months to allow full epithelial remodeling).

With respect to IOL selection, myopic patients who have a successful history with monovision are often happy to maintain that strategy. It can provide them with a good quality of vision without the reduction in contrast sensitivity associated with some full range of vision IOLs. Another factor to consider is that these patients have become used to monovision and may find it difficult to adjust to a change in their visual system.

Although it would not be inappropriate to offer the patient a full range of vision IOL with a distance target, I likely would not. An aspheric monofocal IOL (a toric model if necessary) approximating her current refraction (or perhaps a little closer to plano for the distance eye) and a similar aim for the near eye would be a good choice. Alternatively, a Light Adjustable Lens (LAL; RxSight) would allow the refractive targets to be fine-tuned postoperatively.

Rahul S. Tonk, MD, MBA

The central dilemma is whether to perform an SK or PTK before cataract surgery, which hinges on the patient's goals and extensive counseling. Although SK generally provides clean optics, high refractive accuracy, and maximum versatility across premium IOL choices, I would favor a conservative approach in this situation and optimize the ocular surface medically (topical antiinflammatories, preservative-free tears/gels, punctal occlusion). My reasons are as follows. First, the EBMD is likely of minor visual significance, as evidenced by symmetric vision loss despite asymmetric disease severity. Second, the case presentation does not include complaints about fluctuating vision, corneal erosion, or ocular irritation.

Third, in a 76-year-old patient, an SK or PTK would carry real risks of poor healing and delayed epithelialization. Finally, a corneal procedure would delay the definitive management of her dense cataracts and prolong the time during which she is unable to drive independently.

I would therefore recommend bilateral cataract surgery and LAL implantation, with a distance target in the right eye and a near target in the left eye. The LAL's postoperative adjustability would effectively bypass the ocular surface's biometric unpredictability, mitigating the risk of a refractive surprise and permitting accurate titration to suit the patient's monovision preferences. EBMD, however, can cause refractive fluctuations, so extreme caution would be exercised during UV light delivery because repeated contact lens applanation poses a risk of abrasion.

Alternatively, if the patient cannot commit to the intensity of the LAL adjustment process, a blended vision approach using a toric extended depth of focus or monofocal plus IOL would be a reasonable strategy. Because her refractive, topographic, and biometric astigmatism align well, a fixed (ie, nonadjustable) toric lens would offer acceptable accuracy in a one-step surgery, assuming she has realistic expectations.

What I Did: Audrey Rostov, MD

I performed SKs on both eyes, with the procedures separated by a few weeks. In addition, the patient began dry eye therapy with topical cyclosporine and perfluorohexyloctane ophthalmic solution (Miebo, Bausch + Lomb).

Corneal pathology, such as EBMD or Salzmann nodular degeneration, can affect biometry measurements, so it is important to address the cornea before the cataract. Optimizing the corneal surface medically and/or surgically is a good first step to achieving the best possible refractive outcomes, especially if a premium IOL and/or astigmatism correction is being considered.

Two months following SK, tomography with the MS-39 and biometry with IOLMaster 700 were repeated. When the measurements were consistent, laser cataract surgery with an LAL was performed on each eye. Given the patient's prior success with monovision, this strategy was implemented for cataract surgery. Refractive targets of -0.25 D for her dominant right eye and -1.00 D for her nondominant left eye were used based on the preferences with trial frames she demonstrated postoperatively before and after light adjustments.

Her UCVA was 20/20 OU and J1 OU after the light treatments and lock-in procedures.