Anterior lamellar keratoplasty is an excellent option for patients with opacities or loss of tissue not involving the full thickness of the cornea. These conditions include corneal thinning (eg, Terrien marginal degeneration, descemetocele formation, pellucid marginal degeneration, keratoconus; Fig 15-13), superficial corneal tumors, and peripheral ulcerative keratitis with significant keratolysis. See Table 15-6 for additional information.
Anterior lamellar keratoplasty has many advantages over PK. It eliminates a full-thickness corneal incision into the anterior chamber, thereby avoiding the risks of glaucoma, cataract, retinal detachment, cystoid macular edema, expulsive hemorrhage, and endophthalmitis. Because the endothelium is not transplanted, it also eliminates the risk of endothelial rejection and, consequently, decreases the need for topical steroids.
Anterior lamellar keratoplasty does not replace damaged endothelium. Also, the procedure is more technically demanding and time-consuming than PK. It may be associated with irregular or significant regular astigmatism, opacification and vascularization of the graft–host interface, and stromal rejection is still possible and may be problematic.
A, Slit-lamp photograph of a descemetocele in a patient with rheumatoid arthritis. B, The same patient after lamellar keratoplasty.
Fontana L, Iovieno A. Techniques of anterior lamellar keratoplasty. In: Mannis MJ, Holland EJ, eds. Cornea. Vol 2. 4th ed. Philadelphia: Elsevier; 2017:1361–1365.
Gorovoy MS. Advances in lamellar corneal surgery. Focal Points: Clinical Modules for Ophthalmologists. San Francisco: American Academy of Ophthalmology; 2008, module 4.
John T, ed. Surgical Techniques in Anterior and Posterior Lamellar Corneal Surgery. New Delhi, India: Jaypee Brothers Medical Publishers; 2006.
Deep anterior lamellar keratoplasty
In contrast to ALK, in which the excision of tissue may extend only to the pathology found in the superficial or midstromal tissue, the goal of DALK is to remove the entire stromal layer. DALK has become more popular for the treatment of keratoconus, corneal dystrophies, and corneal scarring. (See Videos 15-3 and 15-4, which demonstrate DALK procedures.) To obtain a visual outcome similar to that achieved with PK, the surgeon must dissect down to or close to the Descemet membrane to create a clear, smooth graft– host interface. There are many techniques for dissecting stromal tissue to expose the Descemet membrane, including the Anwar big-bubble technique (see Videos 15-5 and 15-6 for animations of the big-bubble technique), the Melles technique, and, more recently, the use of the femtosecond laser. As discussion of these techniques is beyond the purview of this chapter, the reader is encouraged to consult the references that follow. Even in experienced hands, it may not always be possible to expose the Descemet membrane using these techniques. In these cases, manual dissection is possible, but it poses a risk of reduced best-corrected visual acuity due to incomplete removal of the host stromal tissue and secondary interface haze. In an OCT study of patients who underwent DALK, 20 μm of residual stromal bed was not visually significant; however, 80 μm of residual tissue caused a reduction in vision.
Deep anterior lamellar keratoplasty for keratoconus.
Courtesy of Robert W. Weisenthal, MD.
Courtesy of David D. Verdier, MD. Deep anterior lamellar keratoplasty. In: Copeland and Afshari’s Principles and Practice of Cornea. New Delhi, India: Jaypee Brothers Medical Publishers; 2013.
Formation of the big bubble in DALK.
Courtesy of Dasa Gangadhar, MD.
Decompression of the big bubble in DALK.
Courtesy of Dasa Gangadhar, MD.
Anwar M, Teichmann KD. Big-bubble technique to bare Descemet’s membrane in anterior lamellar keratoplasty. J Cataract Refract Surg. 2002;28(3):398–403.
Ardjomand N, Hau S, McAlister JC, et al. Quality of vision and graft thickness in deep anterior lamellar and penetrating corneal allografts. Am J Ophthalmol. 2007;143(2): 228–235.
Chen G, Tzekov R, Wensheng L, Jiang F, Mao S, Tong Y. Deep anterior lamellar keratoplasty versus penetrating keratoplasty: a meta-analysis of randomized controlled trials. Cornea. 2016;35(2):169–174.
Reinhart WJ, Musch DC, Jacobs DS, Lee WB, Kaufman SC, Shtein RM. Deep anterior lamellar keratoplasty as an alternative to penetrating keratoplasty: a report by the American Academy of Ophthalmology. Ophthalmology. 2011;118(1):209–218.
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.