History of Anterior Lamellar Keratoplasty

Sujatha Mohan, MBBS, DO, MCh, FRCS, FACS; Bina John, MBBS, DNB, FRCS; and Sriram Annavajjhala, MBBS, DOMS (DNB)

EARLY HISTORY OF CORNEAL TRANSPLANTATION

The history of corneal transplantation can be traced as far back as the 2nd century AD when the Greek physician Galen (130–200 AD) proposed abrasiocor’naea (precursor of superficial keratectomy) as a means of restoring corneal transparency.¹ From then to the 17th century can be called the Dark Ages of corneal transplantation when there were no reports regarding any significant progress as far as corneal experimentation and research are concerned. In the 18th century, the French surgeon Guillame Pellier de Quengsy published a monograph where he suggested that an opaque cornea could be replaced by a transparent material to restore vision.²

The blinding Egyptian ophthalmia (trachoma) of the early 19th century led to experiments with corneal transplantation from the initial work of Samuel Bigger who did the first successful allograft in a gazelle in the year 1837³ and Richard Kissam, who replaced a young Irishman’s opaque cornea with a xenograft from a pig in the year 1838.⁴ The rest of the 19th century saw divided opinions among ophthalmologists between those who favored allografts to xenografts and also between lamellar and full-thickness keratoplasties.

The first successful human allograft transplantation was performed in 1905 by Edward Zirm, who transplanted a donor cornea from the enucleated eye of an 11-year-old with penetrating injury to a patient with bilateral alkali burns.⁵ The Russian ophthalmologist Vladimir Filatov (1875–1956) was the first to suggest the use of cadaver eyes for corneal transplants.⁶ Penetrating keratoplasty (PK) had been the gold standard for corneal transplantation from then until the end of the 20th century (Figure 1-1). However, PK with its attendant problems of intraoperative complications secondary to the open-sky technique and postoperative problems, including glaucoma, uveitis, cataract, cystoid macular edema, surface irregularity, and astigmatism, led to research into a suitable alternative to PK, leading to the beginnings of lamellar keratoplasty (LK), which is now slowly replacing PK as the surgery of choice in patients with corneal opacities (Figure 1-2).

LAMELLAR KERATOPLASTY

Selective transplantation of diseased layers of the cornea is performed while retaining healthy tissue. It can be either anterior or posterior LK depending on whether the anterior or posterior corneal layers are transplanted based on the site of corneal pathology.

Anterior Lamellar Keratoplasty

Anterior lamellar keratoplasty (ALK) involves removal of diseased corneal tissue leaving behind healthy stroma, Descemet’s membrane (DM), or endothelium. ALK is indicated for disorders with a healthy endothelium, such as keratoconus, superficial scars, and anterior corneal dystrophies. ALK can be superficial anterior lamellar keratoplasty (SALK) or deep anterior lamellar keratoplasty (DALK).

Superficial Anterior Lamellar Keratoplasty

SALK is performed when the anterior 30% to 50% of the cornea is affected and replaced with a similar amount of donor tissue. Stroma-to-stroma interface may, however, lead to degradation of visual acuity over time.⁷

Deep Anterior Lamellar Keratoplasty

In DALK where the recipient cornea is dissected up to the DM, the stroma-DM interface is reported to have better visual results^8,9 (Figure 1-3).

ALK has several advantages over PK in that donor corneal requirements are not as stringent as for PK,10 endothelial graft rejection is eliminated,¹¹ suture removal and discontinuation of topical steroids can be done earlier, and it also avoids the complications of an intraocular procedure.¹² Comparing PK with modern ALK did not see much difference with respect to postoperative refractive error and best-corrected visual acuity if residual stromal bed is minimal, but intraoperative complications like DM perforation forcing a conversion to PK, incomplete or irregular dissection, increased surgical time due to technical challenges, and postoperative complications, like interface haze (Figure 1-4), interface neovascularization, and pupillary block are some of the complications associated with LK.¹²

Posterior Lamellar Keratoplasty

Posterior lamellar keratoplasty involves replacing the host endothelium with healthy donor tissue in patients affected by Fuchs endothelial dystrophy and aphakic or pseudophakic bullous keratopathy.

Early History of Lamellar Keratoplasty

The German professor Arthur Von Hippel (1841–1916) advocated lamellar xenografts as far back as the end of the 19th century.¹ In 1877, Von Hippel used a trephine to prepare a human donor corneal graft of the same size and shape as the defect in the recipient cornea, which was left sutureless and kept in place only by pressure of the eyelids.¹³ Eleven years later, von Hippel presented his new technique of circumscribed lamellar keratoplasty where he replaced a partial-thickness disc of the host’s leucomatous cornea with a full-thickness xenograft from a dog. Von Hippel claimed that this technique was easier to perform than full-thickness keratoplasty and that complications of vitreous loss and displacement of other intraocular structures, such as the lens, was less when compared to full-thickness procedures resulted in complete healing at the end of 3 weeks with improvement in vision.¹³ His outstanding experimental and clinical work showed that corneal endothelium and DM should remain intact if a corneal graft is to succeed.¹⁴ Experiments in which partial thickness of the cornea was removed with a clockwork mechanical trephine and replaced with a full-thickness donor graft were attempted with good results as far back as the late 19th century.

In 1892, Fuchs reported on 30 lamellar grafts from rabbit, dog, and human eyes with disappointing results.15

Further modifications of lamellar keratoplasty was published in 1908 by Plange, who inserted oval full-thickness corneal grafts, like the face of a watch, into a corneal stromal pocket, and in 1910 by Lohlein, who used conjunctival flaps of the donor for securing a full-thickness corneal transplant.¹³

The mid-20th century saw a revival of lamellar keratoplasty with better clinical results from many corneal surgeons from around the world, including Barraquer in Columbia, Arruga in Spain, Rycroft in England, and Francheschetti in Switzerland.¹⁶

LK has evolved over time with attempts to achieve precision of depth and smoothness of both donor and recipient tissue to facilitate a smooth interface and optimize visual outcomes with the help of automation and sophisticated microsurgical instruments. The technical difficulties of LK and the suboptimal visual outcomes when compared to PK have led to numerous innovations in technique to overcome these drawbacks.

Lamellar corneal surgeries have undergone considerable evolution from the initial surgical attempts and the history of anterior and posterior LKs will be discussed separately.

Anterior Lamellar Keratoplasties

Initial attempts at LK toward the end of the 19th and beginning of the 20th century did not see much progress in the next 50 years due to the technical difficulties and interface haze of LK. The mid-20th century saw a resurgence in interest in LK with several innovations in LK giving better results. Peripheral lamellar grafts, large diameter grafts, and free-hand deep lamellar corneal dissection were attempted.¹⁶

Brown, while performing a PK in 1965, found it was possible to do deep dissection up to the DM leaving only bare DM and endothelium.¹⁷ Baring of the DM provides a near perfect optical surface, but corneal surgeons of that period, including Anwar, felt that free hand dissection up to the DM was challenging, requiring a dry field and an operating microscope.¹⁸

The introduction of the microkeratome by Barraquer in 1964 to perform mechanical lamellar dissection of the cornea led to renewal in interest in lamellar procedures.¹⁹

Deep Anterior Lamellar Keratoplasty

DALK, the term coined for the surgical procedure in which the DM is bared, was first described by Sugita and Kondo²⁰ and has undergone numerous innovations in technique, including the use of air, fluid, or viscoelastic into the stromal layers to facilitate dissection

Direct Open Dissection (1974)

Anwar²¹ used a partial-thickness trephine of 60% to 80% depth of the cornea after which the corneal stroma was removed in layers that became progressively more difficult as the DM was approached. This technically challenging procedure can still be used for patients with deep stromal scarring or inadequate visualization.

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