Intraoperative videokeratography in penetrating keratoplasty and excimer laser-assisted lamellar keratoplasty for keratoconus.

PURPOSE: To evaluate the usefulness of intraoperative computerized corneal topographic data in excimer laser-assisted lamellar keratoplasty (ELLK) and penetrating keratoplasty (PK). METHODS: Prospective, comparative, interventional case series. Intra- and postoperative videokeratography (Keratron Scout) evaluation was performed on 30 eyes of 30 consecutive patients affected by keratoconus (16 men and 14 women; mean age 32.63±8.02 years) submitted to ELLK (15 eyes) using 16 interrupted 10-0 nylon stitches or to PK (15 eyes) using a 12-bite 10-0 nylon double-running continuous suture. RESULTS: In the ELLK group, the mean intraoperative keratometric astigmatism was 12.06±4.86 diopters (D), which changed to 5.19±2.51 D after topography-guided intraoperative suture adjustment. In the PK group, intraoperative keratometric astigmatism was 10.18±3.88 D, which changed to 3.49±0.41 D. After 24 months (sutures out), the mean videokeratographic keratometric astigmatism was 3.35±1.96 D in the ELLK group and 3.37±0.92 D in the PK group. The Alpins method of vector analysis showed some significant changes especially in the ELLK group. CONCLUSIONS: In keratoplasty surgery, videokeratography is useful for suture adjustment. In the PK group, using a double-running suture technique, the postoperative astigmatism (after all sutures were removed) was similar to the astigmatism measured intraoperatively by videokeratography.

Excimer laser-assisted lamellar keratoplasty for the surgical treatment of keratoconus.

PURPOSE: To evaluate the anatomical and functional results of excimer laser-assisted lamellar keratoplasty (ELLK) in keratoconus patients. SETTING: Eye Clinic, University of L'Aquila, L'Aquila, Italy. METHODS: This prospective case series comprised patients with keratoconus who had ELLK and were examined preoperatively and 3, 6, 12, and 24 months postoperatively. Outcome measures were uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), refraction, computerized videokeratography, pachymetry, and endothelial specular microscopy. RESULTS: Forty-one eyes (41 patients) were examined. The UCVA and BSCVA were significantly better at all follow-up examinations than preoperatively. After the 24-month follow-up (33 patients), the UCVA was better than 20/60 in 11 patients (33.3%) and the BSCVA was 20/40 or better in 29 patients (87.9%). The mean refractive astigmatism was 2.20 diopters (D) and the mean manifest refraction spherical equivalent refraction, -1.18 D. Corneal topographic patterns were regularly astigmatic in 28 (84.8%) of 33 eyes, and the mean corneal thickness (440.0 mum) was significantly greater than preoperatively (553.0 mum). No statistically significant changes in mean corneal endothelial cell density were observed postoperatively. Complications included corneal melting treated with penetrating keratoplasty (PKP) (1 case) and postoperative high refractive error requiring topographically guided excimer laser photorefractive keratectomy (7 cases). CONCLUSIONS: Two-year findings indicate that ELLK is as efficacious as PKP for the surgical treatment of moderate to advanced keratoconus. The procedure is relatively simple. Most steps can be standardized, and there are no time-consuming maneuvers.

Comparison of optical low coherence reflectometry and ultrasound pachymetry in the measurement of central corneal thickness before and after photorefractive keratectomy.

PURPOSE: To compare an ultrasound pachymeter with an optical low coherence reflectometry (OLCR) pachymeter for measuring pre- and postoperative central corneal thickness of patients undergoing photorefractive keratectomy (PRK). METHODS: In a prospective, noncomparative, interventional study, 48 myopic eyes (mean manifest refractive spherical equivalent: -4.93 +/- 2.93 diopters [D]) of 30 healthy patients underwent PRK. Pre- and postoperative central corneal thickness was measured by two examiners (E1, E2) with an ultrasound pachymeter and an OLCR pachymeter. Agreement and inter-rater repeatability were determined using the comparison method described by Bland and Altman. RESULTS: The limits of agreement between the two devices ranged from 17.8 microm (E1) to 20.5 microm (E2) preoperatively and from 22.4 microm (E1) to 16.9 microm (E2) postoperatively. The coefficient of inter-rater repeatability ranged from 9.1 microm (ultrasound pachymeter) to 5.4 microm (OLCR pachymeter) preoperatively and from 7.1 microm (ultrasound pachymeter) to 4.7 microm (OLCR pachymeter) postoperatively. CONCLUSIONS: The OLCR pachymeter seems to show better pre- and postoperative repeatability compared to the ultrasound pachymeter. The agreement between the two devices should be considered acceptable for clinical practice. Photorefractive keratectomy did not affect the postoperative agreement and repeatability of the pachymeters.