Alireza Mirshahi

In vivo and in vitro repeatability of Hartmann-Shack aberrometry

Purpose: To assess the in vivo and in vitro repeatability of objective refraction and higher‐order aberrations (HOAs) measured by a commercially available Hartmann‐Shack wavefront sensor. Setting: Department of Ophthalmology, Johann‐Wolfgang‐Goethe University, Frankfurt am Main, Germany. Methods: After pupil dilation of 40 myopic or myopic, astigmatic eyes of 20 patients, wavefront measurements were performed 6 times in each eye and in a test object provided by the manufacturer by 2 experienced examiners using a Hartmann‐Shack wavefront sensor (Zywave®, software version 3.21, Bausch & Lomb). The mean standard deviation (SD) and the coefficient of variation (CV) for sphere, cylinder, and each Zernike polynomial were computed for a 7.0 mm pupil diameter. Vector analysis was performed for the astigmatism. After the data were subdivided into 2 groups with 3 measurements in each, one measurement that best matched the subjective manifest refraction was chosen in each group and the difference between them was calculated. Results: The mean SD (CV) was 0.15 diopter (D) (7%) for the sphere value of the predicted phoropter refraction and 0.16 D (22%) for astigmatism. Thirty‐two eyes had an axis deviation of at least 10 degrees. Vector analysis revealed a mean SD of 0.24@109.8. Other results for mean SD and mean CV were as follows: total in vivo higher‐order RMS, 0.097 &mgr;m, 13.4%; sphere in myopic test device, 0.034 D, 0.65%; sphere in hyperopic test object, 0.035 D, 0.72%. The difference between the 2 best‐matched refractions was significantly different from zero (0.11 D, P<.001). The CV was significantly higher for HOAs than for the 2nd‐order aberrations (defocus and astigmatism). Conclusions: Repeatability of Hartmann‐Shack aberrometry by the Zywave wavefront sensor was not satisfactory, particularly for small amounts of HOAs. Under these conditions, aberrometry measurements should be repeated several times and outliers should be excluded in calculating the means.

LASIK mit superiorem Hinge und Scanning-Spot-Excimerlaserablation zur Korrektur von Myopie und myopem Astigmatismus: Einjahresergebnisse einer prospektiven klinischen Studie an 100 Augen

ZusammenfassungHintergrund. In den letzten Jahren wird die Laser-in-situ-Keratomileusis (LASIK) vermehrt zur Korrektur von Fehlsichtigkeiten eingesetzt. Ziel der vorliegenden Auswertung war es, Sicherheit, Wirksamkeit, Vorhersagbarkeit, Stabilität sowie die Komplikationen der LASIK mit Scanning-Spot-Excimer-Technologie zu bewerten. Patienten und Methode. Hundert konsekutive LASIK-Operationen im Zeitraum zwischen 2/1998 und 2/1999 [60 Patienten im mittleren Alter von 37 Jahren (Spannbreite: 20–55 Jahre)] wurden ausgewertet. Als Schnittgerät für die Keratomileusis wurde das Hansatome™ Mikrokeratom mit superiorem Hinge eingesetzt (Flapdurchmesser: 9,5 mm), die Laserablation wurde mit einem Scanning-Spot-Excimerlaser (Technolas-C-Lasik-217) durchgeführt. Das sphärische Äquivalent der subjektiven manifesten Refraktion lag im Mittel bei −6,96±2,87 dpt, die mittlere Sphäre bei −6,47±2,71 dpt, der mittlere Astigmatismus bei −0,98±0,94 dpt. Vor der Behandlung erreichten 6% der Augen mit bester Korrektur nur einen Visus von 0,5. Kontrolluntersuchungen fanden präoperativ, nach 1 und 7 Tagen sowie nach 1, 4 und 12 Monaten statt. Sicherheit, Wirksamkeit, Vorhersagbarkeit, Stabilität der refraktiven Werte sowie die Komplikationen wurden mit der Datagraph-Software (Version 1.11) ausgewertet. Ergebnisse. Am ersten postoperativen Tag und nach einer Woche konnten alle 100 Augen nachuntersucht werden, nach einem Monat 96, nach vier Monaten 95 und nach einem Jahr 92 Augen. Nach einem Jahr verlor kein Auge zwei oder mehr Zeilen an Sehvermögen, 99% lagen im Bereich von ±1 Zeile und 1% gewann 2 Zeilen (Sicherheitsindex: 1,03). Es erreichten 92% aller Augen einen unkorrigierten Visus von ≥0,5, 77% ≥0,8 und 51% von ≥1,0 (Wirksamkeitsindex: 0,89); 60 Augen (65,21%) lagen im Bereich von ±0,5 dpt, 82 Augen (89,13%) im Bereich von ±1,0 dpt und 91 Augen (98,91%) im Bereich von ±2,0 dpt. Das mittlere sphärische Äquivalent betrug nach einem Jahr −0,15±1,31 dpt. Zwischen 1 und 12 Monaten zeigte sich eine mittlere Regression von −0,14 dpt. Auf Wunsch der Patienten wurden 5 Augen während der Studienperiode wegen Unter- oder Überkorrektur nachbehandelt. Schnittkomplikationen traten nicht auf. Hornhautinfektionen wurden nicht verzeichnet, eine diffuse lamelläre Keratitis (DLK) wurde 12-mal beobachtet, aber alle Fälle heilten komplikationslos ab. Bei 7 Augen kam es zu einer leichten Dezentrierung (<1 mm) der Ablation, die in einem Fall zu einer erhöhten Blendempfindlichkeit führte. Schlussfolgerung. Die LASIK-Operation mit superiorem Hinge und Scanning-Spot-Excimer-Photoablation ist zur refraktiven Behandlung von Myopie (bis maximal −12 dpt) und myopischem Astigmatismus (bis maximal −5 dpt cyl.) geeignet. Die refraktiven Ergebnisse zeigten über den Verlauf des 12-monatigen Untersuchungszeitraums hohe Stabilität. Die Vorhersagbarkeit der refraktiven Ergebnisse lässt sich weiter verbessern.AbstractPurpose. Recently laser-in-situ-keratomileusis (LASIK) has been increasingly used to correct refractive errors. The purpose of this investigation was to evaluate the safety, efficacy, predictability, stability and complications using the scanning spot excimer LASIK technology. Patients and methods. The results of 100 consecutive LASIK operations carried out between 2/1998 and 2/1999 on 60 patients (mean age 37 years, range 20–55 years) have been evaluated. The Hansatome™ microkeratome with a superior hinge (flap diameter: 9.5 mm) and a scanning spot excimer laser (Technolas C-Lasik 217) were used in all cases. The mean spherical equivalent of the subjective manifest refraction was −6.96±2.87 diopters (D), the mean sphere was −6.47±2.71 D and the mean astigmatism was −0.98±0.94 D. In 6% of the eyes preoperative visual acuity was not better than 20/40. Examinations were performed preoperatively, after 1 and 7 days, after 1, 4 and 12 months. Safety, efficacy, predictability, stability and complications were calculated using the datagraph software (version 1.11). Results. All 100 eyes were examined after 1 day and 1 week, 96 after 1 month, 95 after 4 months and 92 after 1 year. Following 1 year none of the eyes lost 2 or more lines of best corrected visual acuity, 99% were within ±1 line and 1% gained 2 lines (safety index 1.03). In 92% of all eyes an uncorrected visual acuity of ≥0.5 was reached, in 77% ≥0.8 and in 51% ≥1.0 (efficacy index 0.89). For 60 eyes (65.21%) a refractive correction of±0.5 D was necessary, for 82 eyes (89.13%) ±1.0 D and for 91 eyes (98.91%) ±2.0 D. The mean spherical equivalent after 1 year was −0.15±1.31 D. Between 1 and 12 months a mean regression of −0.14 D occurred. On the request of the patients, 5 eyes were retreated during the study period for under- or overcorrection. Complications due to the microkeratome did not occur. Corneal infections were not observed, a diffuse lamellar keratitis (DLK) was seen in 12 cases, but all cases healed with no loss of visual acuity. In 7 eyes a slight decentration of the ablation was observed using corneal topography, which in one case caused an increase in glare sensitivity. Conclusions. LASIK with superior hinge and scanning spot excimer photoablation is suitable for the correction of myopia (up to a maximum of −12 D) and for myopic astigmatism (up to a maximum of −5 D). The refractive results showed a high stability during the 12-month study period but there is still room for improvement of the predictability.

Intraindividual comparison of epithelial defects during laser in situ keratomileusis using standard and zero-compression Hansatome microkeratome heads

Purpose: To determine the difference between the standard and a modified (zero‐compression) Hansatome® microkeratome head (Bausch & Lomb) in the incidence of epithelial defects. Setting: Department of Ophthalmology, Johann Wolfgang Goethe‐University, Frankfurt am Main, Germany. Methods: Ninety‐three patients (186 eyes) with a mean age of 39.1 years ± 9.5 (SD) having laser in situ keratomileusis (LASIK) in both eyes were enrolled in a prospective randomized study using intraindividual comparison. In 1 eye, the flaps were created with the Hansatome microkeratome using the standard Hansatome head and in the other eye, the flaps were created with a microkeratome head with a modified design (zero‐compression head). Intraoperative evaluation of epithelial defects was done using a standardized protocol. Statistical evaluation was performed with McNemar and Bowker tests. Results: Epithelial defects occurred in 21 eyes (22.6%) in which the standard head was used and in 2 eyes (2.1%) in which the zero‐compression head was used. In the former group, 15 (16.1%) of the epithelial defects were larger than 1.5 mm2; the remaining 6 (6.4%) were smaller than 1.5 mm2. In the latter group, both epithelial defects were smaller than 1.5 mm2; both patients also had an epithelial defect in the eye in which the standard Hansatome head was used. The difference between the 2 Hansatome heads in the incidence (P<.001, McNemar) and size (P<.001, Bowker) of the epithelial defects was statistically significant. Conclusions: The Hansatome microkeratome with a zero‐compression head significantly reduced the occurrence of intraoperative epithelial defects. The change in the construction of the Hansatome head is a useful improvement in LASIK technology.

Acute psychotic reaction caused by topical cyclopentolate use for cycloplegic refraction before refractive surgery: Case report and review of the literature

A 56-year-old woman was evaluated for the surgical correction of hyperopia (+3.0 diopters). Two drops of cyclopentolate 1% were instilled in both eyes for measurement of the cycloplegic refraction and wavefront analysis. Immediately after the second instillation, the patient reported drowsiness, dizziness, nausea, and fatigue. Ten minutes later, stimulatory central nervous system symptoms in the form of restlessness, cheerfulness, and a 20-minute-long roar of laughter were observed, interrupted by a new sedative phase. Basic medical and neurologic examinations were unremarkable except for gait ataxia. Four hours later, the examination was continued uneventfully. As surgical treatment of refractive errors and measurement of cycloplegic refraction using cyclopentolate become more frequent, ophthalmologists should be aware of this unusual acute event.

Clinical course of severe central epithelial defects in laser in situ keratomileusis

Purpose: To report the clinical outcome of laser in situ keratomileusis (LASIK) cases complicated by severe central intraoperative epithelial defects (EDs) caused by the microkeratome cut. Setting: Department of Ophthalmology, Johann Wolfgang Goethe‐University, Frankfurt am Main, Germany. Methods: In a retrospective study of 1650 LASIK cases at 1 center, the preoperative data, surgical procedures, and postoperative course in 22 eyes of 14 patients who experienced severe central EDs during the LASIK procedure (1.3%) were reviewed. The surgery was performed using a Technolas® C‐LASIK 217 excimer laser (Bausch & Lomb) and a Hansatome® microkeratome (Bausch & Lomb). A follow‐up of at least 12 months was available in all but 1 case. The median follow‐up was 13.5 months (range 12 to 25 months). In the postoperative period, the following parameters were reviewed: course of refraction, best spectacle‐corrected visual acuity (BSCVA), slitlamp findings, and corneal topography. Results: The mean patient age was 42 years (range 27 to 61 years). Eight patients were affected bilaterally. Fifteen eyes (68%) had moderate to severe dry‐eye symptoms preoperatively. Almost all eyes lost BSCVA in the postoperative period, and visual acuity improved slowly. By the last follow‐up visit, no eye had lost more than 1 line of BSCVA. Diffuse lamellar keratitis (DLK) was observed in 20 eyes (91%), irregular astigmatism in 17 (77%), and microfolds in 12 (55%). In unilaterally affected patients, the refractive outcome was better in the nonaffected eye. Conclusions: A large central ED is a severe intraoperative complication of LASIK that may lead to DLK, irregular astigmatism, flap microfolds, clearly prolonged visual rehabilitation, and temporary loss of BSCVA. The improvement in BSCVA may take several months.

Wissenschaftliche Auswertung und Qualitätssicherung bei refraktiv-chirurgischen Eingriffen: Bewertung des Computerprogramms Datagraph med®

ZusammenfassungHintergrund. In den letzten Jahren werden refraktiv-chirurgische Eingriffe vermehrt zur Korrektur von Fehlsichtigkeiten eingesetzt. Eine genaue Erfassung und Auswertung der prä-, intra- und postoperativen Daten ist aus wissenschaftlicher Sicht erwünscht und zur Qualitätssicherung erforderlich. Ziel der vorliegenden Untersuchung war die Bewertung und Überprüfung von Datagraph med® (Version 2.5), ein Programm, das zur Erfassung und Auswertung von refraktiv-chirurgischen Daten entwickelt wurde. Material und Methode. Prä-, intra- und postoperative Daten von 169 Augen, die mittels Laser-in-situ-Keratomileusis, photorefraktiver Keratektomie, Laserthermokeratoplastik oder phaker Intraokularlinsenimplantation behandelt wurden, wurden in das Programm eingegeben und ausgewertet (bis zu einem Beobachtungszeitraum von 12 Monaten). Die Exaktheit der von Datagraph gelieferten Ergebnisse wurden durch manuelle Nachberechnungen der erstellten Daten und Graphiken überprüft. Ergebnisse. Mithilfe von Datagraph med® konnten refraktiv-chirurgische Daten präzise erfasst und in einer Datenbank gespeichert werden. Die Darstellung von Statistiken und Graphen entsprach genau den nachberechneten Daten. Weiterhin konnte das Programm alle in der internationalen Literatur geforderten Bewertungskriterien für refraktiv-chirurgische Eingriffe (Stabilität, Vorhersagbarkeit, Wirksamkeit, Sicherheit und Komplikationen) berechnen bzw. graphisch darstellen. Schlussfolgerung. Datagraph med® ist ein hilfreiches und präzise arbeitendes Programm zur Erfassung und Auswertung von refraktiv-chirurgischen Daten. Es kann sowohl für wissenschaftliche Studien als auch zur Qualitätssicherung eingesetzt werden. Eine kontinuierliche Weiterentwicklung und statistische Ergänzung des Programms wird nicht zuletzt aufgrund von Fortschritten in der refraktiven Chirurgie notwendig werden.AbstractBackground. During recent years refractive surgical procedures have been increasingly used to correct refractive errors. Exact saving and assessment of pre-, intra- and postoperative results for scientific evaluation are desired and are necessary for quality ma-nagement. The purpose of this investigation was to evaluate the database program Datagraph med® (version 2.5) which has been developed for data processing and assessment in refractive surgery.Material and methods. Pre-, intra- and postoperative data of 169 eyes treated with different refractive surgical methods (laser in situ keratomileusis, photorefractive keratectomy, laser thermal keratoplasty, phacic IOL) were collected, entered in the database and then evaluated by the above-mentioned program (with a follow-up of up to 12 months). The exactness of the Datagraph results was compared by means of manual recalculation.Results. Datagraph med® was able to precisely process the patient data and save them in a database. Statistics and graphs presented by Datagraph were as data has been entered. Furthermore all standard graphs requested by the international consensus for evaluation of refractive surgical data (stability, predictability, efficacy, safety and complications) could be imaged. Conclusions. Datagraph med® is a helpful and precisely functioning program for processing and evaluation of refractive surgical data. It can be used for both scientific studies and for quality control. A continuous deve-lopment and improvement of the program as well as the addition of statistical functions will be necessary due to the on-going progress in refractive surgery.