Roger F. Meyer

Corneal Astigmatism after Penetrating Keratoplasty: The Role of Suture Technique

A randomized clinical trial was conducted to contrast two techniques of suturing in penetrating keratoplasty (PK) surgery: double running 10-0 and 11-0 sutures (DR), and a combination of 12 interrupted 10-0 sutures with a single running 11-0 suture (IR), followed by selective suture removal. The primary outcome evaluated in the 60 patients within each group was keratometric astigmatism. A decreasing trend in astigmatism over postoperative year 1 was observed only in the IR group (from 4.00 diopters [D] at 3 months to 2.50 D at 12 months). The difference in median astigmatism at 1 year (IR, 2.50 D; DR, 4.00 D) approached statistical significance (P = 0.06, Mann-Whitney U test). Both groups showed comparable steepening of almost 1 D during postoperative year 1. Assessment of the rate of visual rehabilitation was limited by a greater proportion of IR patients showing cystoid macular edema (CME) after surgery. These results, while favorable toward the IR/selective suture removal technique, must be substantiated by a final assessment after all sutures have been removed.

Central lamellar keratoplasty for optical indications

PURPOSE This study aims to evaluate the results of lamellar keratoplasty (LKP) for optical (nontectonic) indications over the past 19 years at our institution, noting the advantages and pitfalls of the procedure. METHODS The study is a retrospective review of 52 central LKPs in 37 patients. Snellen visual acuity, preoperative clinical indications, and postoperative status of the cornea (donor graft, graft-host interface, and recipient cornea) were assessed. RESULTS Postoperative follow-up ranged from 3 months to 18 years (median, 3 years). In descending order of frequency, corneal dystrophies, aniridic keratopathy, corneal scars, and keratoconus were the most common indications for surgery. After surgery, 38% of the eyes were able to achieve 20/50 or better visual acuity. The two most common causes of poor visual acuity were (1) opacification and/or blood vessel growth in the graft-host interface or on the graft surface and (2) high astigmatism. Persistent epithelial defects occurred in 21% of the eyes after LKP. CONCLUSION Although LKP provides a safer alternative to penetrating keratoplasty, it is limited by vision-reducing graft-host interface problems, astigmatism, and difficult surgical technique. We postulate that the current results of LKP may be improved by (1) removing as much recipient corneal stroma as possible (e.g., dissecting down to Descemets membrane) or, alternatively, using an automated microkeratome and (2) raising the currently used qualitative eyebank standards for accepting LKP donor tissue.

Assessment of success and complications of triple procedure surgery.

In an effort to quantify both the success and complications of triple procedure surgery, we studied a consecutive series of 166 patients who underwent this procedure. The average length of follow-up was 17 months. Of 166 patients, 138 (83%) achieved a visual acuity of 20/40 or better after surgery; in the most recent 52 patients, 26 (50%) achieved this within two months. The most frequent complications during the postoperative period were glaucoma (40 patients, 24%), endothelial graft rejection episodes (two-year cumulative risk, 16%), and astigmatism (mean keratometric cylinder, 4.97 D). Additional surgical interventions were required in 27 patients (16%).

Absence of Normal Keratan Sulfate in the Blood of Patients With Macular Corneal Dystrophy

We measured levels of sulfated keratan sulfate in serum using a monoclonal antibody in an enzyme-linked immunosorbent assay. Sulfated keratan sulfate was not detected in the serum of 16 patients with macular corneal dystrophy, but was present at normal levels in 66 patients with other corneal diseases. There were no differences with respect to age, sex, and other ocular findings. This monoclonal antibody recognizes a sulfated carbohydrate epitope present in both corneal and skeletal keratan sulfate. Since most serum keratan sulfate is derived from the cartilages, the defect in keratan sulfate synthesis in macular corneal dystrophy may not be restricted to corneal cells. This assay should prove useful in the diagnosis of macular corneal dystrophy, particularly in children at risk before the appearance of opacification.

Implantation of Kelman-style, Open-loop Anterior Chamber Lenses during Keratoplasty for Aphakic and Pseudophakic Bullous Keratopathy: A Comparison with Iris-sutured Posterior Chamber Lenses

The clinical and specular microscopic results of 40 cases (39 patients) of penetrating keratoplasty during which a Kelman-style anterior chamber intraocular lens was implanted were reviewed retrospectively. Thirty-one pseudophakic eyes received an intraocular lens exchange and nine aphakic eyes received a secondary intraocular lens. Postoperative follow-up averaged 24.5 months (range, 3 to 51 months). At 1, 2, and 3 years after keratoplasty, 39.3%, 63.2%, and 63.6% of eyes, respectively, had visual acuities of 20/40 or better. Ninety-five percent of the grafts remained clear. Causes of poor postoperative visual acuity included cystoid macular edema (32.5%), new glaucoma (22.5%), and age-related macular degeneration (10.0%). Other causes were endothelial rejection leading to graft failure, corneal ulceration, and retinal detachment. Corneal endothelial cell loss by specular microscopy was 11.5% at 1 years, 21.3% at 2 years, and 25.0% at 3 years. These results were compared with cell loss associated with iris-sutured posterior chamber lenses in penetrating keratoplasty. Visual outcomes and complication rates were similar between these two methods; however, the endothelial attrition at 1 and 2 years for the sutured posterior chamber lens was greater than that of the Kelman anterior chamber lens.

Penetrating Keratoplasty in Pseudophakic Bullous Keratopathy

We studied 25 consecutive patients who underwent penetrating keratoplasty for pseudophakic bullous keratopathy. Follow-up time averaged 20 months. Ten patients required postimplantation surgical procedures because of complications after lens implantation. The time from lens implantation to onset of corneal edema averaged 18 months in patients without postimplantation surgical procedures and five months in patients with postimplantation procedures. The lens implants were removed in 11 patients at keratoplasty. Corneal clouding caused by graft rejection occurred in three patients, while 22 grafts remained clear. Final visual acuities were 6/6 (20/20) to 6/12 (20/40) in 13 patients, 6/15 (20/50) to 6/30 (20/100) in four patients, and 6/60 (20/200) or less in eight patients. We found no difference in final visual acuity between patients with lens implants removed at keratoplasty and those with lens implants left in place. Significant retinal pathology included cystoid macular edema, macular degeneration, and retinal detachment.

The Effect of Allograft Rejection After Penetrating Keratoplasty on Central Endothelial Cell Density

We identified all patients who had undergone penetrating keratoplasty for keratoconus and were being observed longitudinally (N = 174). During the follow-up period, 57 of 174 patients (33%) showed evidence of an allograft rejection episode, which occurred at an average of eight months after the operation. We analyzed specular photographs of the corneal endothelium, taken before and after the first allograft rejection episode. A significant decrease in endothelial cell density was observed (11.8%, P less than .0001). As a control, we analyzed all available specular photographs from patients with keratoconus who showed no evidence of allograft rejection after penetrating keratoplasty. The observed endothelial cell density decrease (11.8%) in patients with keratoconus undergoing allograft rejection exceeded that found in the control subjects (6.8%) during a comparable time period (P = .06). Severe allograft rejection episodes resulted in a decrease in endothelial cell density that exceeded expected loss significantly (14.8% compared with 6.9%, P = .01), whereas mild allograft rejection episodes were not associated with a loss in endothelial cell density exceeding that expected (1.8% compared with 6.5%, P = .34).

Macular corneal dystrophy Lack of keratan sulfate in serum and cornea

An ELISA assay using a monoclonal antibody (ET-4-A-4) that recognizes a sulfated carbohydrate epitope in both keratan sulfate type I (corneal) and type II (skeletal) was employed to quantify keratan sulfate in serum and corneal tissue from patients with macular corneal dystrophy (MCD). This assay disclosed significant quantities of keratan sulfate in the serum in 45 healthy individuals (251 +/- 78 ng/ml), and in 66 patients with various corneal diseases (273 +/- 101 ng/ml). In contrast keratan sulfate was not detected (less than 2 ng/ml) in the serum of 16 patients with histopathologically confirmed MCD. Keratan sulfate was also detected in extracts of normal corneas and corneal tissue with a variety of pathologic conditions, but was virtually absent in corneal tissue from five patients with MCD. In corneas with MCD the chondroitin sulfate/keratan sulfate ratio was considerably higher than that of all normal and pathologic corneas studied. Since keratan sulfate in the serum appears to be derived predominantly from the normal turnover of cartilage these studies strongly suggest that the defect in keratan sulfate synthesis in MCD is not restricted to corneal cells and that MCD is one manifestation of a systemic disorder of keratan sulfate. The cartilage changes, however, do not have clinical significance. Moreover, since keratan sulfate can be detected in the blood of newborns it should be possible to diagnose MCD prior to corneal opacification.

Clinicopathologic features of Chandler's syndrome

The clinicopathologic features of Chandlers syndrome are elucidated based on a study of nine patients. Keratoplasty, trabeculectomy and/or iris specimens were studied by light, electron and, in six cases, specular microscopy. The prominent pathologic features were abnormalities of the endothelially-derived cells lining the posterior corneal surface, the inner surface of the trabecular meshwork, and the anterior iris surface. In all four corneal buttons, the endothelium was diffusely attenuated and focally absent, and posterior collagen layers were present. Extension of the endothelial cell layer and Descemets membrane deposition over the trabecular meshwork were observed in two trabeculectomy specimens, and similar proliferation onto the anterior surface of the iris was evident in four iris specimens. Other abnormalities of the endothelial cells included increased intracytoplasmic filaments. These pathologic alterations are consistent with the concept of Chandlers syndrome as representing one variant of the iridocorneal endothelial (ICE) syndrome. Interestingly, although both endothelial proliferative and degenerative responses can be observed in Chandlers syndrome, their occurrence within the same eye is apparently not simultaneous.

Morphologic characteristics of posterior polymorphous dystrophy. A study of nine corneas and review of the literature.

Based on their own study of nine corneas with clinically documented posterior polymorphous dystrophy and a review of the literature, the authors describe the morphologic features of this entity. Study by phase contrast light microscopy and transmission and scanning electron microscopy found that changes were primarily in the endothelium and consisted of endothelial cell degeneration and loss with focal fibroblastic and epithelial-like cell transformation. Secondary alterations of Descemets membrane were seen; they consisted of abnormal lamination with deposition of abnormal collagen material, particularly in the posterior collagen layer, and formation of guttate excrescences and pits.