Ophthalmologists have many options for surgically treating the wide spectrum of corneal disease. The procedure of choice depends primarily on the depth and extent of corneal pathology (Table 15-5). Discussion of the surgical technique for these procedures is beyond the purview of this book; however, many excellent resources are available for this purpose and are listed in the references provided throughout the chapter. The following section discusses the preoperative evaluation of corneal transplant patients, and the rest of the chapter highlights the postoperative management of these patients in order to help the clinician make appropriate referrals and initiate treatment if necessary.
Gorovoy MS. Advances in lamellar corneal surgery. Focal Points: Clinical Modules for Ophthalmologists. San Francisco: American Academy of Ophthalmology; 2008, module 4.
Hausheer JR, ed. Basic Techniques of Ophthalmic Surgery. 2nd ed. San Francisco: American Academy of Ophthalmology; 2015.
Mannis MJ, Holland EJ, eds. Cornea. Vol 2. 4th ed. Philadelphia: Elsevier; 2017.
Preoperative Evaluation and Preparation of the Transplant Patient
A complete ophthalmic evaluation, including a history and examination, is necessary before corneal transplantation. The clinician should obtain a detailed social history to help determine whether the patient or caretakers can adhere to the potentially complex postoperative regimen. A history of amblyopia, macular degeneration, and glaucoma or other optic neuropathy will affect the visual prognosis and the decision to proceed with surgery.
The examination should include simple clinical tests, such as checking for color vision, light projection, and afferent pupillary defect, particularly in patients with media opacity. It is important to recognize that corneal and lens opacities can dramatically constrict visual fields. Overrefraction with a rigid contact lens can aid in determining the cause of decreased vision. Improvement in vision with the contact lens indicates that superficial irregular astigmatism is the cause; in such cases, the patient can be offered treatment with a contact lens. If vision does not improve, corneal opacification is the most likely cause of the reduced vision, necessitating surgical intervention. Optical coherence tomography (OCT) may help detect retinal problems such as macular edema (cystoid or diabetic) and age-related macular degeneration. If the media are completely opaque, standard B-scan ultrasonography is helpful in evaluating the posterior segment.
Prior to any corneal procedure but particularly before PK, DALK, or ALK, it is important to check for reduced corneal sensation. The loss of corneal sensation seen in herpes zoster or simplex disease may complicate the postoperative course because of prolonged epithelial healing. It is also important to diagnose and treat ocular surface problems such as dry eye, blepharitis, and rosacea, as well as eyelid problems such as trichiasis, lagophthalmos, entropion, and ectropion prior to corneal surgery. In older patients, the postoperative course may be more problematic; slower wound healing, decreased corneal sensation, and reduced or incomplete eyelid closure can lead to persistent epithelial defects, infections, and wound dehiscence. Deep corneal vascularization and a history of graft failure increase the risk of rejection in PK and DALK. The presence of an active keratitis or uveitis at the time of surgery is associated with a higher incidence of postoperative complications, such as graft rejection or failure, glaucoma, and cystoid macular edema. Ideally, there should be no ocular inflammation for several months prior to surgery. A history of glaucoma surgery, such as placement of filters or tube shunts, reduces endothelial cell survival and increases the risk of graft failure in EK and PK.
Fortunately, the advent of EK for endothelial dysfunction has minimized the impact of ocular surface disorders on the success of transplantation. The extent of stromal edema can be measured with corneal pachymetry, Scheimpflug imaging, or anterior segment OCT. (See Chapter 2 for more discussion of these tests.) Typically, corneal edema is worse in the morning and improves throughout the day; this fluctuation can be documented through testing in the early morning and in the afternoon. In some patients, extensive guttae alone may cause enough reduction in vision or symptoms of glare to warrant surgery. For further discussion of the evaluation and indications for corneal surgery, see the references that follow.
American Academy of Ophthalmology Cornea/External Disease Panel. Preferred Practice Pattern Guidelines. Corneal Edema and Opacification. San Francisco: American Academy of Ophthalmology; 2013. Available at www.aao.org/ppp.
Hannush SB, Riveroll-Hannush L. Preoperative considerations and decision-making in keratoplasty. In: Mannis MJ, Holland EJ. eds. Cornea. Vol 2. 4th ed. Philadelphia: Elsevier; 2017: 1256–1263.
Watanabe S, Oie Y, Fujimoto H, et al. Relationship between corneal guttae and quality of vision in patients with mild Fuchs endothelial corneal dystrophy. Ophthalmology. 2015; 122(10):2103–2109.
Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.