Very high frequency ultrasound analysis of a new phakic posterior chamber intraocular lens in situ.

PURPOSE: To use very high frequency ultrasound scanning for in situ analysis of a new phakic posterior chamber intraocular lens (No-Touch; International Visions Inc, Cincinnati, Ohio). METHODS: In this pilot study, very high frequency ultrasound (50 MHz) wide-angle (15 mm) full anterior segment scans were obtained in two patients who had undergone phakic posterior chamber intraocular lens implantation into legally blind eyes with normal anterior segment anatomy. RESULTS: Very high frequency ultrasound B-scan images delineated the phakic posterior chamber intraocular lens within the posterior chamber. The relations to the sulci were clearly imaged. Anatomic relations of the phakic posterior chamber intraocular lens optic and haptics were visualized in both static (light/dark) and kinetic (distance/accommodative) states. CONCLUSION: Very high frequency ultrasound wide-angle scanning provides a unique tool to noninvasively evaluate the eye preoperatively and the static and kinetic relations of this new refractive device within the posterior chamber.

Combined wedge resection and relaxing incisions for astigmatism after penetrating keratoplasty.

BACKGROUND: Videokeratography may provide information for surgical correction of astigmatism after penetrating keratoplasty. We used a combination of wedge resection and relaxing incisions to treat high refractive astigmatism after penetrating keratoplasty. METHODS: Videokeratography using the normalized scale of the Topographic Modeling System was used as a guide in determining the location and the length of incisions and resections. Nine eyes were treated with both relaxing incisions and a wedge resection. All patients had more than 3.00 diopters (D) of refractive astigmatism. All patients were intolerant of spectacles or contact lenses. The depth of the corneal relaxing incisions was constant at 0.5 mm and the width of the corneal wedge resections was constant at 0.75 mm. RESULTS: The relaxing incisions produced flattening of the steeper meridian and the wedge resection produced steepening of the flatter meridian. The average preoperative keratometric astigmatism was 7.44 D (range, 3.50 to 11.00 D) and the average refractive astigmatism was 5.56 D (range, 4.00 to 8.00 D). The average preoperative spherical equivalent was 0.08 D (range, -7.00 to 4.25 D). Postoperatively, the average keratometric astigmatism was 2.97 D (range, 1.00 to 5.00 D) and the average refractive astigmatism was 2.58 D (range, 0.00 to 5.00 D). The average postoperative spherical equivalent refraction was -0.32 D. CONCLUSIONS: Combined corneal wedge resection and relaxing incisions appears to be effective in reducing high refractive astigmatism following corneal transplantation.

High frequency ultrasound evaluation of radial keratotomy incisions.

Radial keratotomy is a surgical procedure to correct myopia that involves placing corneal incisions of precise partial thickness to induce flattening. It has yielded positive but sometimes unpredictable results. Many surgical variables influence the final result. Among them, incision depth is probably the most difficult to control and evaluate. In this study, we used very high frequency (50 MHz) ultrasound (HFU) to image radial keratotomy incisions in post-radial keratotomy human corneas to obtain high definition images of the cornea. The images allowed us to measure the depth of incisions as a percentage of corneal thickness.

Control of astigmatism aided by intraoperative keratometry.

An evaluation of the final "sutures out" postoperative astigmatism in two groups of keratoconus patients undergoing penetrating keratoplasty is presented. Group I consists of a retrospective evaluation of keratoconus patients who underwent penetrating keratoplasty without using the Troutman Keratometer prior to suturing the button into position. Group II patients had their donor button rotated in the recipient bed until approximate sphericity was indicated by a circular reflex from the Troutman Keratometer before suturing into position. The mean final astigmatism with all sutures removed from Group I was 4.64, SD 1.89, and for Group II 2.27, SD 1.27. Selective positioning of the donor button using the Troutman Keratometer leads to a significant reduction in the final sutures out astigmatism in patients undergoing penetrating keratoplasty for keratoconus.

Astigmatism after penetrating keratoplasty using the Krumeich guided trephine system.

BACKGROUND: The use of a suction trephine during penetrating keratoplasty has the potential to reduce trephination errors and astigmatism after suture removal. METHODS: In this study, we evaluated refractive astigmatism after suture removal in 26 eyes that had penetrating keratoplasty for keratoconus using refraction, keratometry, and videokeratography. Group I (11 eyes) had manual trephination with an open disposable blade of both the donor (8.2 mm) and the recipient (8.0 mm). Group II (10 eyes) had manual trephination with an open disposable blade of the donor (8.2 mm) and Krumeich guided trephine system trephination of the recipient (8.0 mm). Group III (5 eyes) had guided trephination of both the donor (8.0 mm) and the recipient (8.0 mm). RESULTS: The guided trephine groups II and III demonstrated statistically significant less refractive cylinder when compared to manual trephination group I (p < .01). The mean keratometric cylinder for group I was 6.50 diopters (D) (range, 1.50 to 9.00 D), for group II was 3.00 D (range, 0.50 to 7.00 D), and for group III was 2.55 D (range, 0 to 4.00 D). CONCLUSION: The Krumeich guided trephine system produced less keratometric astigmatism than manual trephination after penetrating keratoplasty for keratoconus.

Excimer laser keratectomy for astigmatism occurring after penetrating keratoplasty.

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.