Faculty Bibliography

PURPOSE: To review the results of photorefractive keratectomy used to treat astigmatism occurring after penetrating keratoplasty. METHODS: Seven patients who had undergone corneal transplantation previously and had significant postoperative astigmatism were included. All these patients were intolerant of spectacle and contact lens correction. Excimer laser keratectomy was performed to reduce the astigmatic error. Minimum follow-up of 12 months was necessary for study inclusion. RESULTS: The average refractive cylinder decreased from 5.32 diopters (D) preoperatively to 2.79 D postoperatively. The refractive cylinder was reduced in six of the seven eyes attempted. The average preoperative keratometric cylinder decreased from 5.54 D (range, 1.50-10.00 D) to 4.00 D (range 1.00-7.50 D) postoperatively. The best spectacle-corrected visual acuity was unchanged (within 1 line) in three eyes, improved in two, and decreased in two. The complications included a loss of at least two lines in spectacle-corrected visual acuity in two eyes and scarring in one. CONCLUSIONS: Excimer laser keratectomy can reduce the astigmatism after penetrating keratoplasty. The excellent results in some eyes offer promise for this technique in the future

BACKGROUND: Correction of irregular astigmatism has not been possible using available keratorefractive technology. METHODS: The authors used a topographic map as a guide and created a custom excimer ablation program, designed to create a more regular surface. The program consisted of a combination of phototherapeutic and photorefractive ablation patterns. The amount of tissue to be removed was calculated on the basis of the diameter and steepness of the irregular areas of the corneal surface. RESULTS: A more regular surface, as evidenced by topographic analysis, reduced astigmatism, and improved uncorrected visual acuity, was produced. CONCLUSION: Using the corneal topographical map as a guide, excimer laser ablation can be used to create a more regular optical surface with improved visual function

Floppy eyelid syndrome is a recently described entity, which characteristically involves overweight individuals. The characteristic findings are an upper lid that may be readily everted, tarsal laxity, and diffuse papillary conjunctival changes. The cause of floppy eyelid syndrome is believed to be a mechanical disorder due to the eversion of the lids while sleeping. The cause of keratoconus remains uncertain. There are strong proponents to a mechanical etiology for this disease. The authors report five cases of floppy eyelid syndrome with concomitant keratoconus. One patient with bilateral keratoconus had bilateral symmetric floppy eyelid syndrome. The other four patients had asymmetric keratoconus and floppy eyelid syndrome. In all four patients, the keratoconus was significantly worse in the eye with the more severe case of floppy eyelid syndrome. In addition, these four patients all gave a history of sleeping with their head facing predominantly on the side with the floppy eyelid syndrome and keratoconus. Two patients with keratoconus and floppy eyelid syndrome were able to undergo successful contact lens rehabilitation of their keratoconus after treatment of the floppy eyelid syndrome

Whereas specular microscopy may provide valuable preoperative information about the status of the endothelial cells in clear corneas, in many diseased corneas that come to penetrating keratoplasty, stromal opacities or epithelial edema prevents determinations about the condition of the endothelium. A method has been developed wherein diseased-host penetrating keratoplasty specimens are maintained postoperatively in McCarey-Kaufman medium and are thereafter stained as whole mounts with alizarin red S and trypan blue to evaluate the status of the endothelial monolayer. Seventy diseased corneas were studied with this method. The alizarin red S stained the intercellular junctions, while the trypan blue stained nuclei and provided information about the viability of the endothelial cells that were studied. Unusual findings were the presence of binucleated endothelial cells in decompensated cases of iris clip pseudophakos and scattered iris stromal melanocytes on barred Descemet's membrane in cases of chemical injury, trauma, and congenital glaucoma. The method was found to be rapid, reliable, and inexpensive, particularly when compared with alternative methods of evaluation, such as scanning electron microscopy