Effect of recipient corneal pathology on Pascal tonometer and Goldmann tonometer readings in eyes after penetrating keratoplasty.

PURPOSE: To assess the influence of recipient corneal pathology on the performance of the Pascal dynamic contour tonometer (PDCT) (Swiss Microtechnology AG) by comparing it to Goldmann applanation tonometry (GAT) in post-penetrating keratoplasty (PKP) eyes. METHODS: Intraocular pressure (IOP) was measured in 40 post-PKP eyes of 40 patients using PDCT and GAT. The study patients were divided into two groups. Group A included patients who had undergone PKP for ectatic corneal disorders (keratoconus, n=20) and group B included patients who had undergone PKP for other non-ectatic corneal disorders (Fuchs, post-corneal ulcer, post-chemical burn,post-trauma, n=20). Keratometric measurements were obtained in all eyes using Orbscan II (Bausch &Lomb) and central corneal thickness (CCT) was measured using Corneo-Gaze Plus (Sonogaze). RESULTS: In group B, a correlation between PDCT and GAT IOP measurements was observed. In group A, GAT IOP measurements were significantly lower than PDCT measurements (3.7 +/- 1.8 mmHg,p<0.001). Additionally, CCT affected GAT IOP measurements much more than PDCT measurements,while corneal curvature did not significantly affect IOP measurements of any instrument in either group. CONCLUSIONS: In post-PKP eyes, PDCT appears to be less influenced than GAT by CCT and pre-existing recipient corneal pathology. Therefore, PDCT may be better suited for monitoring IOP in post-PKP eyes.

Assessment of the pascal dynamic contour tonometer in measuring intraocular pressure in keratoconic eyes.

PURPOSE: To assess the performance of the Pascal dynamic contour tonometer (PDCT) (Swiss Microtechnology AG) by comparing it to Goldmann applanation tonometry (GAT) and noncontact air tonometry (NCT) in keratoconic eyes. METHODS: Intraocular pressure (IOP) was measured in both eyes of 32 patients with keratoconus using PDCT, GAT, and NCT. IOP measurements were also obtained with all 3 instruments in 46 patients with healthy eyes in the same age range, which served as controls. Keratometric measurements were obtained in all eyes using Orbscan II (Bausch & Lomb) and central corneal thickness was measured using Corneo-gaze plus (Sonogaze). RESULTS: In the control group, a correlation between PDCT, GAT, and NCT IOP measurements was observed. In keratoconic eyes, GAT and NCT IOP measurements were significantly lower than PDCT measurements (5.3+/-2.2 mm Hg and 4.75+/-1.7 mm Hg, respectively). Unlike GAT and NCT, PDCT measurements in both groups were not significantly affected by central corneal thickness. Additionally, the mean IOP measurement in the keratoconic eyes was lower than that of the control group, particularly when measured with GAT and NCT. Corneal curvature, did not significantly affect IOP measurements of any instrument in either group. CONCLUSIONS: The corneal abnormalities characteristical of keratoconus seem to influence more GAT and NCT IOP measurements than PDCT IOP measurements. Therefore, PDCT may be better suited for monitoring IOP in keratoconic eyes.

Assessment of the Pascal dynamic contour tonometer in monitoring intraocular pressure in unoperated eyes and eyes after LASIK.

PURPOSE: To assess the performance of the Pascal dynamic contour tonometer (PDCT) (Swiss Microtechnology AG) by comparing it to Goldmann applanation tonometry (GAT) and noncontact air tonometry (NCT) before and after laser in situ keratomileusis (LASIK). SETTING: Vlemma Eye Institute, Athens, Greece. METHODS: Intraocular pressure was measured in 118 eyes before and 1 and 4 weeks after LASIK using GAT, NCT, and the PDCT, which allows direct, digital, transcorneal measurement of intraocular pressure. RESULTS: Preoperatively, central corneal thickness (CCT) correlated with GAT and NCT measurements but not with PDCT measurements. After LASIK, the mean reduction in CCT ranged from -3.0 to -171.0 microm (median 78 microm). The mean GAT measurement dropped by -4.9 mm Hg +/- 2.7 (SD) at 1 week and was -5.4 +/- 3.0 mm Hg at 4 weeks. Similar drops were observed in NCT measurements. The observed post-LASIK changes in GAT and NCT IOP measurements were not directly proportional to the change in CCT, refractive error, or mean keratometric readings. The preoperative and postoperative PDCT measurements did not differ significantly. CONCLUSIONS: The structural corneal changes induced by LASIK appeared to influence GAT and NCT measurements but not PDCT measurements. Therefore, PDCT may be better suited for monitoring IOP in unoperated eyes and in eyes that have had LASIK.

Autorefractometry after laser in situ keratomileusis.

PURPOSE: To correlate cycloplegic subjective refraction with cycloplegic autorefractometry in eyes that have had laser in situ keratomileusis (LASIK). SETTING: Vlemma Eye Institute, Athens, Greece. METHODS: Subjective refraction and autorefractometry under cycloplegia were performed in 73 eyes of 46 patients 1, 6, and 12 months after LASIK to correct myopia or myopic astigmatism. The preoperative subjective refraction and autorefractometry under cycloplegia in the same eyes served as controls. RESULTS: A statistically significant difference between subjective refraction and autorefraction was found in the sphere and cylinder at all postoperative times. No statistically significant difference was found in the axis. There was no statistically significant difference in the control eyes. CONCLUSIONS: Automated refractometry in eyes that had had LASIK was reliable in the axis only. Retreatments after LASIK should always be based on subjective refraction.

Efficacy of brimonidine 0.2% in controlling acute postoperative intraocular pressure elevation after phacoemulsification.

PURPOSE: To determine the efficacy of brimonidine tartrate 0.2% drops given 2 times a day in reducing intraocular pressure (IOP) spikes during the first 24 hours after phacoemulsification cataract surgery. SETTING: Department of Ophthalmology, General Hospital of Patras Agios Andreas, Patras, Greece. METHODS: In this prospective double-blind placebo-controlled study, 1 eye of 40 consecutive normotensive cataract patients having small-incision cataract surgery was randomized into 1 of 2 treatment arms. Twenty patients received a placebo (artificial tears) and 20 patients received brimonidine tartrate 0.2% drops 2 times a day the day before and the day of surgery. Diurnal IOP variation was the primary efficacy variable; IOP was measured at baseline, before surgery, and 4, 6, 12, and 24 hours postoperatively. RESULTS: The placebo group had higher IOPs at every time point after surgery. Peak elevation of IOP occurred 6 hours after surgery. The mean IOP in the placebo group (27.71 mm Hg +/- 3.75 [SD]) was statistically significantly higher than in the brimonidine group (21.45 +/- 1.32 mm Hg) (P<.001). A major IOP rise (>/=20 mm Hg above baseline IOP) occurred in 1 patient (5%) in the placebo group who required emergency hypotensive therapy. Twenty-four hours after surgery, 11 eyes (55%) in the brimonidine group and 4 eyes (20%) in the placebo group had an IOP lower than baseline. CONCLUSION: Prophylactic treatment with brimonidine tartrate 0.2% 2 times a day for 2 days was effective in reducing IOP peaks throughout the first 24 hours after phacoemulsification surgery.

Ferrara intrastromal corneal rings for the correction of keratoconus.

PURPOSE: To evaluate the safety and efficacy of Ferrara intrastromal corneal rings in the treatment of eyes with keratoconus without central corneal scarring. SETTING: Vlemma Eye Institute, Athens, Greece. METHODS: Twenty-six patients with bilateral keratoconus, clear central corneas, and contact lens intolerance participated in the study. Videokeratographic corneal topography and ultrasonic pachymetry were performed in all eyes to identify the cone area and to select the thickness of the segments to be implanted, respectively. Ferrara intrastromal corneal rings were implanted around the center of the cone in 1 eye of each patient. RESULTS: The minimum follow-up after ring implantation was 6 months. In 2 cases, the rings had to be removed early in the postoperative period because of superficial implantation in 1 patient and asymmetrical placement in the other. The rest of the operated eyes demonstrated a reduction in astigmatism and spherical correction and improved uncorrected visual acuity. No eye lost best corrected visual acuity. CONCLUSIONS: Ferrara intrastromal corneal rings reduced corneal steepening and normalized the central cornea in eyes with keratoconus. Ferrara ring implantation was a safe procedure that may be considered in patients who are unable to have other surgical techniques, particularly contact-lens-intolerant keratoconus patients whose only option is corneal transplantation.

Tear secretion following excimer laser in situ keratomileusis.

PURPOSE: To evaluate the effect of laser in situ keratomileusis (LASIK) on tear secretion. METHODS: A non-consecutive series of 42 eyes of 42 patients had LASIK for the correction of myopia and myopic astigmatism. The fellow eye served as a control. The mean preoperative spherical equivalent refraction was -5.25 +/- 1.00 D (range, -1.75 to -11.00 D). Attempted correction aimed at emmetropia. Schirmer I and II, and tear break-up time (BUT) tests were performed preoperatively and at 1, 3, and 6 months postoperatively. All tests were correlated to the amount of the attempted correction. RESULTS: Preoperatively, mean values were Schirmer I: 16.2 mm, Schirmer II: 11.6 mm, and BUT: 16.3 sec. One month after LASIK, mean values were Schirmer I: 12.8 mm, Schirmer II: 9.2 mm, and BUT: 13.3 sec. At 3 months, mean values were Schirmer I: 15.76 mm, Schirmer II: 11.3 mm, and BUT: 14.15 sec. At 6 months, mean values were Schirmer I: 15.96 mm, Schirmer II: 11.66 mm, and BUT: 16.3 sec. No correlation to the amount of attempted correction was found. Fellow eye tests were not affected at any interval. CONCLUSIONS: Tear secretion following LASIK was decreased during 3 months after surgery and was normalized by 6 months.