Bojan Pajic

Flattening of the cornea after collagen crosslinking for keratoconus

PURPOSE: To identify preoperative parameters that may predict flattening of the keratoconic cornea after collagen crosslinking (CXL). SETTING: Institut für Refraktive und Ophthalmo‐Chirurgie (IROC), Zurich, Switzerland. DESIGN: Cohort study. METHODS: Patients with verified progressive primary keratectasia received standard corneal CXL. Factors such as corrected distance visual acuity (CDVA) and Scheimpflug tomography (Pentacam) were used to follow the evolution from preoperatively to 12 months after CXL. Statistical analysis included U tests and Spearman rank correlation tests to detect risk factors for flattening of the keratoconus. RESULTS: The study enrolled 151 eyes of 151 patients; more than 80% completed the 12‐month follow‐up. The flattening rate (flattening of the maximum curvature >1.00 diopter [D]) was 37.7%. A preoperative maximum keratometry (K) reading of more than 54.00 D was identified as the only significant risk factor for this effect (odds ratio, 1.88; 95% confidence interval, 1.01‐3.51). A restriction to corneas with a maximum K value greater than 54.00 D would have resulted in a significant flattening in 51% of the cases. CONCLUSIONS: Statistically significant flattening occurred during 1 year after CXL in more than 50% of cases when the preoperative maximum K reading was more than 54.00 D. None of the other preoperative parameters evaluated (eg, age, sex, diagnosis, CDVA, corneal shape factors) had a statistically significant impact on corneal flattening after CXL. Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned.

Corneal Collagen Cross-Linking for Ectasia after LASIK and Photorefractive Keratectomy: Long-Term Results

PURPOSE To report the long-term results of corneal collagen cross-linking (CXL) in ectasia after LASIK and photorefractive keratectomy (PRK). DESIGN Retrospective, interventional cases series. PARTICIPANTS Twenty-six eyes of 26 patients (18 male, 8 female) with postoperative ectasia after LASIK (23 eyes) and PRK (3 eyes) were included with a mean age of 35 ± 9 years at the time of treatment and a mean follow-up of 25 months (range, 12-62 months). METHODS All consecutive patients treated with CXL for progressive ectasia after LASIK or PRK at the Institute for Refractive and Ophthalmic Surgery, Zurich, Switzerland between 2004 and 2010 were included. MAIN OUTCOME MEASURES Corrected distance visual acuity (CDVA), maximum keratometry readings (K(max)), minimum radius of curvature (R(min)), and 6 corneal topography indices were assessed in this study. RESULTS Mean CDVA before CXL was 0.5 logarithm of the minimum angle of resolution (logMAR) units, which improved to a mean of 0.3 logMAR units (P<0.001). Corrected distance visual acuity improved 1 line or more in 19 cases and remained unchanged in 7 patients. Mean K(max) after CXL of 50.9 ± 4.9 diopters (D) was significantly lower (P<0.001) than mean pre-CXL K(max) of 52.8 ± 5 D. The R(min) after CXL was increased significantly (P = 0.006), whereas the index of surface variance (P = 0.03), the index of vertical asymmetry (P = 0.04), the keratoconus index (P = 0.03), and the central keratoconus index (P = 0.016) were reduced significantly. CONCLUSIONS Ectasia after LASIK and PRK was arrested by CXL with stabilization or improvement of CDVA and K(max) after a mean follow-up of 25 months. There were improvements in 4 topography indices, suggesting a more regular corneal surface.

Continuous IOP Fluctuation Recording in Normal Tension Glaucoma Patients

Background: Intraocular pressure (IOP) remains the only treatable risk factor of progressive glaucoma. Recently a device became available to continuously record IOP fluctuation in contrast to classical, discreet IOP measurements. Objectives: To perform 24-h IOP fluctuation monitoring using a CE-marked silicone lens-embedded strain gauge sensor (SENSIMED Triggerfish) in five normal tension glaucoma patients in the presence and absence of anti-glaucomatous treatment and to show the clinical importance of this diagnostic tool. Methods: 24-h continuous IOP fluctuation monitoring was performed on two occasions separated by at least 6 weeks in each patient. In the control session patients were untreated or previous IOP-lowering medication was washed-out for at least 6 weeks. In the treatment session patients received IOP-lowering medication for at least 6 weeks. The continuous recordings were analyzed for differences between daytime and nighttime data and for repeatability over time. Furthermore, profiles recorded in each patient in treated and non-treated conditions were compared. Results: Highly individual and repeatable profiles were obtained. Data recorded during daytime portions of the recordings showed higher coefficients of variation than nighttime data. Positive and significant linear slopes for the transition period from wake time to sleep time were detected in all patients in the absence of anti-glaucomatous treatment, while in three patients of five no significant slopes were detected under treated conditions. Conclusion: Our data suggest that the continuous IOP fluctuation monitoring device is sensitive to individual IOP rhythms and to differences in such rhythms due to anti-glaucomatous drug therapy.

First experience with the new high-frequency femtosecond laser system (LDV Z8) for cataract surgery

Background The purpose of this work is to report our experience using the new Z8 laser system for femtosecond laser-assisted cataract surgery (FLACS) and to provide a sample of the performance and safety results using this new technology. Methods This prospective observational study was performed at the Swiss Eye Research Foundation, Eye Clinic ORASIS, Reinach, Switzerland. Fourteen patients were subjected to unilateral FLACS. Capsulotomy and lens fragmentation were performed with the aid of the LDV Z8 femtosecond laser system. Ease of phacoemulsification (on a 4-point scale), completeness of capsulotomy (on a 10-point scale), time for preparation of femtosecond laser (minutes), effective phacoemulsification time (seconds), total duration of surgery (minutes), and safety of the procedure were evaluated. Results Ease of fragmentation and completeness of capsulotomy were estimated at 3.9 and 9.9, respectively. The preparation time for femtosecond was 3.6±0.7 minutes, effective phacoemulsification time was 2.5±3.1 seconds, and total duration of the FLACS procedure was 16.3±4.5 minutes. No major complications were observed. Approximately 42% of all patients (6/14) showed Descemet’s folds directly postoperatively. Conclusion FLACS with the LDV Z8 system was characterized by complete capsulotomy and highly effective and reproducible lens fragmentation. The safety of the procedure was very good as perceived by the surgeon operating in this observational case series. The cost to benefit ratio should be further debated by assessing the results of a major prospective study, which is required for valid evaluation of the efficiency and safety of the LDV Z8 laser system and of FLACS in general.

Corneal sensitivity and morphology of the corneal subbasal nerve plexus in primary congenital glaucoma.

BackgroundTo quantify the corneal subbasal nerve density and the total number of nerve fibers in primary congenital glaucoma (PCG) and to evaluate their impact on corneal sensitivity.MethodsForty eyes of 26 PCG patients were compared with 40 eyes randomly selected from 40 non-glaucoma patients who populated the control group. Central corneal sensitivity (CCS) was assessed by means of Cochet–Bonnet esthesiometry. The mean subbasal nerve density and the total number of nerve fibers were quantified by laser-scanning confocal microscopy. Normality of data was assessed by Kolmogorov–Smirnov testing. Differences in parameters were assessed with Student’s t-test, while correlations with CSS were assessed with Pearson’s correlation.ResultsSignificant differences were identified in the mean subbasal nerve density (2108±692 μm in PCG, 2642±484 μm in controls, P=0.003) and in the total number of nerve fibers (12.3±4.2 in PCG, 15.4±3.1 in controls, P=0.02). Both groups presented comparable mean CCS and tortuosity. Both groups presented strong correlations between CCS and mean nerve density (r=0.57 in PCG, r=0.67 in controls, all P<0.05), and between CCS and total number of nerve fibers (r=0.55 in PCG, r=0.56 in controls, all P<0.05).ConclusionPCG exerts significant changes in both the mean subbasal nerve density and the total number of nerve fibers. However, these changes do not appear to affect central corneal sensitivity.

Prospective study on exclusive, nonsurgical strontium-/yttrium-90 irradiation of pterygia.

Purpose:Prospective study to evaluate consecutive treatment results and to demonstrate safety and efficacy of nonsurgical, exclusive strontium-/yttrium-90 β-irradiation of nonoperated pterygia.Patients and Methods:Between November 1999 and March 2002, 20 patients with 21 primary pterygia and six patients with recurrent pterygia after former surgery were treated with exclusive strontium-/yttrium-90 irradiation up to a total dose of 3,600 cGy (six fractions) and 4,800 cGy (eight fractions), respectively. All patients were referred from a single institution. The mean follow-up is 35.6 ± 7.3 months (range 24–48 months).Results:Prior to irradiation the mean horizontal diameter of all pterygia was 2.6 mm and shrank to a mean diameter of 1.6 mm after treatment (p = 0.0011, Student’s t-test). The treatment led to a reduction in size of all 21 primary and all six recurrent pterygia. Visual acuity reached a value of 0.73 before and 0.82 after treatment. This improvement was not significant in Student’s t-test (p = 0.12). The visual acuity did not decrease in any patient, complications were not observed, and in none of the 27 pterygia a recurrence developedConclusion:Exclusive strontium-/yttrium-90 irradiation of the early and moderately advanced pterygium is a very efficient and very well-tolerated method of treatment. As to the therapeutic management, it is suggested to apply β-irradiation prior to the development of an astigmatism-relevant pterygium, which requires excision.Ziel:Prospektive Studie zur klinischen Evaluation der Wirksamkeit und Sicherheit der ausschließlichen Strontium-/Yttrium-90-Bestrahlung des nicht operierten Pterygiums.Patienten und Methodik:Zwischen November 1999 und März 2002 wurden 20 Patienten mit 21 primären Pterygien und sechs Patienten mit sechs nach Exzision rezidivierenden Pterygien mit einer ausschließlichen Strontium-/Yttrium-90-Bestrahlung, Gesamtdosis 3600 cGy (sechs Fraktionen) bzw. 4800 cGy (acht Fraktionen), behandelt. Die Patienten waren von einer einzigen Institution zugewiesen worden. Die durchschnittliche Nachbeobachtungszeit liegt bei 35,6 ± 7,3 Monaten (Bereich: 24–48 Monate).Ergebnisse:Der durchschnittliche Durchmesser der Pterygien betrug vor der Bestrahlung 2,6 mm und nahm nach Bestrahlung signifikant auf 1,6 mm ab (p = 0,0011, Student-t-Test). Alle 27 Pterygien—sowohl die 21 primären als auch die sechs rezidivierenden—nahmen nach der Bestrahlung an Ausdehnung und Größe ab. Die durchschnittliche Sehschärfe lag vor der Bestrahlung bei 0,73 und nach der Bestrahlung bei 0,82. Die Verbesserung war im Student-t-Test (p = 0,12) nicht signifikant. Kein Auge entwickelte nach der Behandlung eine Verminderung der Sehschärfe; es trat keine Komplikation auf, und bei keinem der 27 Pterygien musste ein Rezidiv festgestellt werden.Schlussfolgerung:Die ausschließliche Strontium-/Yttrium-90-Bestrahlung des frühen und mäßig fortgeschrittenen Pterygiums ist eine sehr effiziente und sehr gut tolerierte therapeutische Methode. Hinsichtlich des Behandlungsmanagements empfiehlt es sich, die β-Bestrahlung vor der Entwicklung eines astigmatismusrelevanten Pterygiums zu applizieren, welches eine Exzision indiziert.

Femtosecond laser versus mechanical microkeratome-assisted flap creation for LASIK: a prospective, randomized, paired-eye study

Purpose To compare a femtosecond laser with a microkeratome for flap creation during laser in situ keratomileusis (LASIK) in terms of flap thickness predictability and visual outcomes. Patients and methods This was a prospective, randomized, masked, paired-eye study. Forty-four patients (34 females) who received bilateral LASIK were included. Patients were stratified by ocular dominance, and they then underwent randomization of flap creation using the femtosecond laser on one eye and undergoing the microkeratome procedure on the other one. The visual outcome differences between the corrected distance visual acuity (CDVA) at baseline and the uncorrected distance visual acuity (UDVA) on the first day postoperatively were set as the efficiency index for both groups. All visual acuity outcome results and the deviation of flap thickness were evaluated. P-values <0.05 were considered statistically significant. Results The index of efficiency regarding the postoperative visual outcomes in the microkeratome group was lower (P<0.0001). This result was correlated with the difference between intended and achieved flap thickness (P=0.038; r=0.28), and a negative relationship in the regression analysis was confirmed (P<0.04; R2=0.1428). The UDVA in the microkeratome group improved significantly by the end of the first month (P<0.0271) in comparison to the baseline CDVA. The deviation between intended and postoperative flap thickness using either optical coherence pachymetry or Heidelberg Retinal Tomography II confocal microscopy was statistically significant (paired t-test; P<0.001) between the groups. The flap thickness deviation in the microkeratome group was higher. In the femtosecond laser group, the efficiency index was stable postoperatively (P=0.64) The UDVA improved significantly by the end of the first postoperative week (P=0.0043) in comparison to the baseline CDVA. Six months after surgery, improvement in the UDVA was significant in both groups (all P<0.001; one way analysis of variance). Conclusion Femtosecond laser was superior to microkeratome-assisted LASIK in terms of flap thickness predictability and the speed of visual acuity recovery. A negative relationship in the regression analysis between increasing flap thickness deviation and visual acuity recovery was confirmed.

Prospective Study of Exclusive Strontium-/Yttrium-90 β-Irradiation of Primary and Recurrent Pterygia with No Prior Surgical Excision

Purpose:To evaluate the consecutive treatment results regarding pterygium recurrence and the efficacy of exclusive strontium-/ yttrium-90 β-irradiation for primary and recurrent pterygia and to analyze the functional outcome.Patients and Methods:Between October 1974 and December 2005, 58 primary and 21 recurrent pterygia were exclusively treated with strontium-/yttrium-90 β-irradiation with doses ranging from 3,600 to 5,500 cGy. The follow-up time was 46.6 ± 26.7 months, with a median of 46.5 months.Results:The treatment led to a size reduction in all pterygia (p < 0.0001). Neither recurrences nor side effects were observed during therapy and follow-up in this study. Best-corrected visual acuity increased (p = 0.0064). Corneal astigmatism was reduced in recurrent pterygia (p = 0.009).Conclusion:Exclusive strontium-/yttrium-90 β-irradiation of pterygia is a very efficient and well-tolerated treatment, with remarkable aesthetic and rehabilitative results in comparison to conventional treatments, especially for recurrent lesions which have undergone prior surgical excision.Ziel:Evaluation der Behandlungsergebnisse in Bezug auf Rezidivrate, Effizienz und Funktion der ausschließlichen Strontium-/ Yttrium-90-β-Bestrahlung von primären und rezidierenden Pterygien. Analyse des kornealen und des refraktiven Astigmatismus im Vergleich zu den postoperativen Ergebnissen konventioneller Behandlungsmethoden.Patienten und Methodik:Zwischen Oktober 1974 und Dezember 2005 wurden 58 primäre und 21 rezidivierende Pterygien mit ausschließlicher Strontium-/Yttrium-90-β-Bestrahlung mit Dosen von 3 600–5 500 cGy behandelt. Die mittlere Nachbeobachtungszeit betrug 46,6 ± 26,7 Monate, median 46,5 Monate.Ergebnisse:Die Behandlung führte bei allen Pterygien zu einer Größenabnahme (p < 0,0001). Es wurden keine Rezidive und keine unerwünschten Nebenwirkungen beobachtet. Die bestkorrigierte Sehschärfe stieg signifikant an (p = 0,0064), der korneale Astigmatismus verkleinerte sich signifikant bei den rezidivierenden Pterygien (p = 0,009).Schlussfolgerung:Die ausschließliche Strontium-/Yttrium-90-β-Bestrahlung des Pterygiums ist eine sehr effiziente und gut tolerierte Behandlungsmethode mit einem bemerkenswerten ästhetischen und rehabilitativen Resultat in Vergleich zu den konventionellen Behandlungskonzepten, vor allem bei rezidivierenden Pterygien nach primärer operativer Exzision.

Prospective study of exclusive strontium-/yttrium-90 beta-irradiation of primary and recurrent pterygia with no prior surgical excision. Clinical outcome of long-term follow-up

Purpose:To evaluate the consecutive treatment results regarding pterygium recurrence and the efficacy of exclusive strontium-/ yttrium-90 β-irradiation for primary and recurrent pterygia and to analyze the functional outcome.Patients and Methods:Between October 1974 and December 2005, 58 primary and 21 recurrent pterygia were exclusively treated with strontium-/yttrium-90 β-irradiation with doses ranging from 3,600 to 5,500 cGy. The follow-up time was 46.6 ± 26.7 months, with a median of 46.5 months.Results:The treatment led to a size reduction in all pterygia (p < 0.0001). Neither recurrences nor side effects were observed during therapy and follow-up in this study. Best-corrected visual acuity increased (p = 0.0064). Corneal astigmatism was reduced in recurrent pterygia (p = 0.009).Conclusion:Exclusive strontium-/yttrium-90 β-irradiation of pterygia is a very efficient and well-tolerated treatment, with remarkable aesthetic and rehabilitative results in comparison to conventional treatments, especially for recurrent lesions which have undergone prior surgical excision.Ziel:Evaluation der Behandlungsergebnisse in Bezug auf Rezidivrate, Effizienz und Funktion der ausschließlichen Strontium-/ Yttrium-90-β-Bestrahlung von primären und rezidierenden Pterygien. Analyse des kornealen und des refraktiven Astigmatismus im Vergleich zu den postoperativen Ergebnissen konventioneller Behandlungsmethoden.Patienten und Methodik:Zwischen Oktober 1974 und Dezember 2005 wurden 58 primäre und 21 rezidivierende Pterygien mit ausschließlicher Strontium-/Yttrium-90-β-Bestrahlung mit Dosen von 3 600–5 500 cGy behandelt. Die mittlere Nachbeobachtungszeit betrug 46,6 ± 26,7 Monate, median 46,5 Monate.Ergebnisse:Die Behandlung führte bei allen Pterygien zu einer Größenabnahme (p < 0,0001). Es wurden keine Rezidive und keine unerwünschten Nebenwirkungen beobachtet. Die bestkorrigierte Sehschärfe stieg signifikant an (p = 0,0064), der korneale Astigmatismus verkleinerte sich signifikant bei den rezidivierenden Pterygien (p = 0,009).Schlussfolgerung:Die ausschließliche Strontium-/Yttrium-90-β-Bestrahlung des Pterygiums ist eine sehr effiziente und gut tolerierte Behandlungsmethode mit einem bemerkenswerten ästhetischen und rehabilitativen Resultat in Vergleich zu den konventionellen Behandlungskonzepten, vor allem bei rezidivierenden Pterygien nach primärer operativer Exzision.

Femtosecond laser-assisted in situ keratomileusis multifocal ablation profile using a mini-monovision approach for presbyopic patients with hyperopia.

Purpose To report the visual outcomes of the femtosecond laser-assisted multifocal aspheric corneal ablation profile using a mini-monovision approach and to evaluate if corneal multifocality was effective, and to report the relative benefits of this approach. Patients and methods Bilateral femtosecond laser-assisted in situ keratomileusis using a multifocal aspheric corneal ablation profile was performed on 19 hyperopic patients (38 eyes). They were divided into two groups based on eye dominance: dominant eye (DE) group targeting emmetropia and the nondominant eye (NDE) group targeting −0.5 D slight myopia. The uncorrected distance visual acuity (UDVA), uncorrected intermediate visual acuity (UIVA), uncorrected near visual acuity (UNVA), and retreatment rates were reported from baseline to 6 months. Results The UNVA, UIVA, and UDVA improved significantly in both groups (Kruskal–Wallis test, DE and NDE: P<0.00001, P<0.000005, and P=0.00001, respectively). Corrected distance visual acuity (CDVA) baseline was better in both groups in comparison to UDVA at 6 months (Wilcoxon test, DE: P<0.001, 95% confidence interval (CI) of the median 0.0–0.0 LogMAR and 0.1000–0.1218 LogMAR and NDE: P=0.010, 95% CI of the median 0.0–0.0 LogMAR and 0.00–0.10 LogMAR). There was a significant loss of lines between CDVA baseline and UDVA at 6 months in both groups (DE group: 68% of eyes lost one line or more; NDE group: 58% of eyes lost one line or more). The corrected near visual acuity baseline compared to UNVA at 6 months was not statistically important (Wilcoxon test, DE: P=0.8125, 95% CI of the median 0.0–0.0 LogMAR and 0.0–0.0 LogMAR and NDE: P=0.82, 95% CI of the median 0.0–0.0 LogMAR and 0.0–0.0 LogMAR). The comparison among the UDVA, UIVA, and UNVA between the two groups at baseline and during all follow-ups was not statistically important. Two cases from the DE group were retreated (6%). Conclusion Use of this multifocal aspheric corneal ablation profile in patients with hyperopic presbyopia significantly improved UDVA, UIVA, and UNVA. This improvement was due to created multifocality of the cornea. The mini-monovision seems not to affect UDVA, UIVA, and UNVA between the two groups. The retreatment rates at the 6-month evaluation were significantly less in our study when compared with other studies. This method seems to improve UDVA, UIVA, and UNVA but could result in a significant statistical difference between CDVA baseline and UDVA at 6 months that leads to loss of lines in distance vision. Despite promising results, this is a preliminary evaluation of this new profile, and a larger number of eyes are needed to verify visual outcomes, retreatment rates, and safety.