Recent developments in refractive corneal surgery.

T Seiler

Home/Archive/PubMed

PubMed · 10147735

Recent developments in refractive corneal surgery.

T Seiler

View original source ↗Export metadata ↓

Abstract

The 4- and 5-year results of the Prospective Evaluation of Radial Keratotomy Study reveal a hyperopic shift of more than 1.0 D within the follow-up time in 22% and 24%, respectively, of the eyes that underwent radial keratotomy. The number of eyes with this complication increased progressively from 6 months to 4 years. Attempts to correct this progressive hyperopia are discussed. Results of clinical studies of myopic photorefractive keratectomy performed with the excimer laser are reviewed. Regarding safety and short-term efficacy, photorefractive keratectomy is a promising technique. In the past, corneal topography has been interpreted qualitatively. Ray-tracing analysis now allows quantitative estimation of the influence of aspheric corneas on the degradation of the retinal image. Three approaches to correct hyperopia, radial thermokeratoplasty, laser thermokeratoplasty, and hexagonal keratotomy are reviewed and discussed. Additional concave intraocular lenses for correction of high myopia are still undergoing clinical evaluation. Endothelial damage is the most dangerous short-term complication of implantation with these lenses.

Explore related subjects

Cornea Humans Keratotomy, Radial Laser Therapy Lenses, Intraocular Refractive Surgical Procedures Journal Article Review

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

T Seiler. 1992. Recent developments in refractive corneal surgery.. https://pubmed.ncbi.nlm.nih.gov/10147735/

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed2000

Atomic force microscopic study of the human cornea following excimer laser keratectomy.

The aim of this study was to examine the corneal surface structures with a new investigative method, the atomic force microscope following 193 nm excimer laser photoablation. Fresh human corneas were irradiated in vitro with an increasing number of impulses emitted by a 193 nm ArF laboratory excimer laser in order to produce either smooth flat surfaces or stair-like formations within the cornea. The corneas were investigated in a Topometrix(R) atomic force microscope in their native state. For comparison, three corneas were fixed with glutaraldehyde and processed for scanning electron microscopy. Atomic force microscopy and scanning electron microscopy revealed the same surface characteristics of photoablated corneas, though the preparation for scanning electron microscopy induced considerable shrinkage of the tissues. The layers of the cornea could be distinguished from each other and deeper ablations of the stroma produced a rougher surface. On the lateral walls of ablated stairs small droplets of ejected material could be seen with scanning electron microscope. Atomic force microscope produces three-dimensional images of the scanned native corneal surfaces and it could be a valuable tool to investigate the corneal smoothness. Our investigations have provided similar results as those obtained with scanning electron microscopy showing that the laser-ablated corneal surface remains relatively smooth. We suggest that the formation of condense droplets of ejected materials is based on hydrodynamic motions induced by boiling water solutions.

Cornea↗

PubMed2000

Removal of corneal foreign bodies that project into the anterior chamber: use of a suture needle.

PURPOSE: To describe and illustrate a simple and reliable technique for removing penetrating corneal foreign bodies. METHODS: A 6-mm needle was placed through the cornea beneath the corneal foreign body to provide support and illumination posteriorly. RESULTS: In eight eyes of eight patients all penetrating corneal foreign bodies were removed completely without severe complications. CONCLUSIONS: The use of a suture needle during removal of penetrating corneal foreign bodies is simple, effective, reliable, and inexpensive.

Cornea↗

PubMed2000

Quantitative topographic irregularity as a predictor of spectacle-corrected visual acuity after refractive surgery.

PURPOSE: To evaluate a new topographic index called topographic irregularity as a quantitative predictor of corrected vision after refractive surgery. METHODS: We defined topographic irregularity as the summed difference at all points between a topographic refractive corneal power map and its best-fit spherocylinder. We prospectively studied 107 eyes of 107 patients 3 months after a variety of refractive procedures. Topographic irregularity was calculated from topographic maps, and the correlation between topographic irregularity and spectacle-corrected visual acuity was determined using both high-contrast and low-contrast acuity charts. This correlation was compared with correlations for the surface regularity index and the surface asymmetry index. Next, we analyzed 54 of these topographic maps to create a regression scale relating surface regularity index, surface asymmetry index, and topographic irregularity to predict spectacle-corrected visual acuity. This scale was then used to predict spectacle-corrected visual acuity on the remaining 53 postoperative patients. RESULTS: The correlation of topographic irregularity with spectacle-corrected visual acuity (R(2) =.36) was comparable to the correlation for the surface regularity index (R(2) =.36) and stronger than for the surface asymmetry index (R(2) =.11) when spectacle-corrected visual acuity was measured with high-contrast eye charts. Topographic irregularity correlated more strongly with spectacle-corrected visual acuity (R(2) =.42) than either the surface regularity index (R(2) =.28) or the surface asymmetry index (R(2) =.14) when spectacle-corrected visual acuity was measured with low-contrast eye charts. Using the regression scale, prediction of high-contrast and low-contrast spectacle-corrected visual acuity from topographic irregularity was superior to or comparable to predictions using the surface regularity index and the surface asymmetry index. CONCLUSIONS: Topographic irregularity has a closer correlation with spectacle-corrected visual acuity than existing topographic indexes. Topographic irregularity is also an accurate predictor of spectacle-corrected visual acuity and may be a more sensitive tool for evaluating postoperative visual performance than current topographic measures.

Cornea↗