Irrespective of corneal transplant (e.g., full-thickness grafts and lamellar keratoplasty), our goal in managing post-surgical keratoconus (KCN) patients with contact lenses is two-fold: to provide the best visual outcome, while protecting the health of the surgically compromised cornea. 

In this first of a two-part column on the contact lens management of KCN patients who have undergone corneal transplantation, I detail important pre-fitting clinical considerations.

Corneal health monitoring
Preliminary assessment for contact lens wear typically begins three to six months post-surgery to allow for healing.

When possible, I recommend pre-fitting and ongoing periodic photo documentation for future reference and comparison in the event complications, such as corneal neovascularization, suture rupture, or corneal scarring, arise.

We want to proceed with the anterior to posterior examination of all layers of both the host and donor corneal tissue. Using both white light and a cobalt blue filter with sodium fluorescein enables the assessment of the integrity of the epithelium, especially overlying the sutures. Fragile epithelium is a risk factor for sloughing or “micro abrasions,” which can lead to microbial keratitis. We want to pay close attention to the graft host junction and look for signs of neovascularization along the suture lines and loose or broken sutures, as these items can lead to inflammation, scarring, and possible vision loss. Additionally, we want to note and document stromal scarring haze, and Khodadoust line, as these complications can be early signs of edema or graft rejection.

Further, we want to measure baseline endothelial cell count and pachymetry or, if not equipped, obtain this information from the surgeon. This is because an endothelial cell count below 800 cells/mm2 is considered high risk for corneal edema, potential graft failure, and will be an important factor in determining contact lens modality and fitting characteristics.¹

Suture type identification
Both penetrating keratoplasty and deep anterior lamellar keratoplasty involve the suturing of a donor button. Suturing technique is surgeon dependent and may involve a single running suture, double running suture, or interrupted sutures alone, or in combination with running sutures. This is significant, as interrupted sutures create the most astigmatism, followed by a single running suture, with the least astigmatism created by a double running suture.² Selective suture removal in grafts that have interrupted sutures permits the greatest control over post-surgical astigmatism.

Fitting a contact lens a minimum of six months postoperatively allows for some stabilization in astigmatism and decreased frequency of steroid drops. Waiting until the suture removal process to initiate contact lens fitting is completed is not always possible or necessary. In these cases, the contact lens should be fit to avoid significant mechanical “rubbing” of the sutures.

In next month’s column, I discuss contact lens selection and design in post graft KCN patients. OM

References

1. I Naydis, M Klemm, A Hassenstein, G Richard, T Katz, S J Linke. [Postkeratoplasty astigmatism: comparison of three suturing techniques]. Ophthalmologe. 2011;108(3):252-9.doi: 10.1007/s00347-010-2272-y.

2. Worp EV. A Guide to Scleral Lens Fitting. 2nd ed. Forest Grove, OR: Pacific University; 2015. 

Susan A. Resnick, OD, FAAO, is president and managing partner at Drs. Farkas, Kassalow, Resnick, and Associates, a contact lens and anterior segment specialty practice in New York. She is a diplomate in the Cornea, Contact Lens, and Refractive Technology section of the AAO, a diplomate of the ABO, and a fellow of the Scleral Lens Education Society.