Biomedical subjects

L Hertzog

Publications and source records attributed to L Hertzog.

3 recordsLinked to original sources

PubMed1992

Photorefractive keratectomy for severe postkeratoplasty astigmatism.

We performed cylindric corneal ablations with the excimer laser on 12 patients to correct severe, disabling astigmatism after keratoplasty. In some patients, an additional ablation was performed to correct myopia. Patients were followed up for an average of eight months (range, six to 14 months). Uncorrected visual acuity improved in nine patients, and nine of the 12 patients had a decrease in refractive cylinder at last follow-up. The mean preoperative refractive cylinder was 7.0 +/- 3.6 diopters, which decreased to a mean of 3.1 +/- 2.6 diopters at one month (P = .0003) and 4.3 +/- 2.9 diopters at last follow-up (P = .03). Keratometric astigmatism decreased from 7.5 +/- 3.9 diopters preoperatively to 5.2 +/- 3.9 diopters at the last follow-up (P = .001). Mean spherical equivalent was reduced from -7.4 +/- 4.2 diopters preoperatively to -3.3 +/- 4.4 diopters postoperatively (P = .003). Postoperative corneal haze, when present, did not reduce visual acuity. Excimer laser superficial keratectomy thus appears to be safe when used for postkeratoplasty ametropia, although substantial regression may limit its effectiveness in some patients.

Adult↗

PubMed1992

Corneal sensitivity after photorefractive keratectomy.

Corneal anesthesia or hypesthesia can complicate refractive surgical procedures such as epikeratophakia and radial keratotomy. An esthesiometer was used to measure the corneal sensitivity in unoperated-on corneas and fellow corneas after excimer laser photorefractive keratectomy. Decrease in corneal sensitivity was noted within six postoperative weeks, with mean sensitivity being 75.2% +/- 13.3% of normal. Within the first three postoperative months, the patients operated on for correction of compound astigmatism recovered 95.7% +/- 5.3% of the corneal sensitivity, whereas the patients operated on for correction of severe myopia recovered 86.2% +/- 11.2% (P = .07). None of the patients had delayed epithelial healing or recurrent corneal erosions during the time of decreased corneal sensitivity. In otherwise normal myopic eyes, photorefractive keratectomy measurably reduced corneal sensitivity for several postoperative weeks.

Adult↗

PubMed1992

Corneal surface after deepithelialization using a sharp and a dull instrument.

Manual removal of the corneal epithelium currently precedes excimer laser photorefractive keratectomy. To assess the smoothness of the corneal surface following this procedure, six paired human eye-bank eyes (12 eyes) were manually deepithelialized using a blunt instrument (Paton spatula) on one eye and a sharp instrument (surgical blade) on the contralateral eye; all deepithelializations were done by the same surgeon. The 12 corneas were then resected and processed in an identical fashion for scanning electron microscopy. The microphotographs obtained showed that among the corneas deepithelialized with the blunt spatula, two had a smooth surface, and four had variable amounts of residual epithelial cells and basement membrane, confirmed by light microscopy. The surface of five corneas deepithelialized with the sharp instrument were slightly rougher than the former, with occasional linear scratches; one cornea retained a small amount of basement membrane. Removal of epithelium appears to be more complete when a sharp instrument is used. These findings may have clinical relevance, since residual epithelium and basement membrane after deepithelialization may influence the depth of ablation subsequently achieved with the excimer laser.

Basement Membrane↗