Marita Amm

Histopathological Comparison of Photorefractive Keratectomy and Laser In Situ Keratomileusis in Rabbits

BACKGROUND After 193 nm excimer laser photorefractive keratectomy (PRK) for myopia, superficial opacities in the ablation zone and regression of refractive results can occur. Clinical studies have emphasized that corneal clarity and early refractive stability can be achieved with laser in situ keratomileusis (LASIK). We present clinical and histological results that compare PRK and LASIK for the treatment of myopia in rabbits. MATERIALS AND METHODS We treated 12 New Zealand white rabbits with PRK and 12 with LASIK using a 193-nm excimer laser (Aesculap Meditec). In both techniques, the identical excimer software and ablation parameters of -10 D treatment depth were used. Six months after surgery, all eyes were removed and prepared for light, fluoresence and transmission electron microscopy. RESULTS At the time of enucleation, nine eyes in the PRK group had a moderate to high degree of haze (grade 2 to 3), whereas after LASIK, all corneas showed an almost clear interface in the ablation zone. Correspondingly, all histological investigations after LASIK showed a regular stromal architecture, in contrast to the obvious anteri or stromal disorganization after PRK. CONCLUSION The preserved integrity of the superficial corneal layers after LASIK ensures quick wound healing with minimal tissue proliferation, resulting in a transparent corneal interface. This technique appears especially suitable for correcting high myopia.

Excimer laser correction of high astigmatism after keratoplasty

Purpose: To assess the effectiveness of excimer laser correction of high astigmatism after keratoplasty. Setting: Kiel University Eye Hospital, Kiel, Germany. Methods: In a prospective study, we treated high astigmatism in 16 patients using a 193 nm excimer laser with a rotating mask system to make a toric ablation. Thirteen patients had postkeratoplasty astigmatism, 3, idiopathic natural astigmatism. Preoperative refractive cylinder ranged from 3.0 to 9.0 diopters (D). Minimum follow‐up was 6 months. Results: Mean uncorrected visual acuity increased by 3.3 lines in 13 patients. Best corrected visual acuity decreased by no more than two lines in 6 patients and improved by at least one line in 6 patients. Mean cylindrical reduction was 2.8 D. Haze was classified from 0.5 to 2.0. Conclusions: In this study, the excimer laser technique effectively reduced high corneal astigmatism. The main problems incurred were development of a hyperopic shift and, in some patients, an uncertain refractive outcome. Reasons for inadequate correction of post keratoplasty astigmatism included a slightly decentered mask and irregular astigmatism from the circular scar.

Implantation torischer Intraokularlinsen zur Korrektur hoher postkeratoplastischer Astigmatismen

ZusammenfassungHintergrund. Der hohe postkeratoplastische Astigmatismus bleibt eine therapeutische Herausforderung. Es werden Erfahrungen nach Implantation einer torischen IOL bei 3 Patienten mit hohem postkeratoplastischen Astigmatismus und zusätzlicher Katarakt berichtet. Patienten und Methode. Im Rahmen einer geplanten Routine-Katarakt-Operation erhielten die Patienten bei hohem, relativ regelmäßigen postkeratoplastischen Astigmatismus eine individuell angefertigte torische PMMA-Hinterkammer-IOL über einen sklerokornealen Tunnelzugang der Breite 6 mm. Ein Patient wurde bei Verdacht auf zirkuläre Instabilität der Zonulafasern zusätzlich mit einem Kapselspannring versorgt. Prä- und postoperative Diagnostik umfaßte neben den Standarduntersuchungen eine korneale Topographie, Bestimmung der VK-Tiefe, Ultraschallbiomikroskopie und eine Gesichtsfeldprüfung. Ergebnisse. Implantation und intraoperative Ausrichtung der torischen IOL verliefen komplikationslos. Der refraktive Astigmatismus, der präoperativ bei 5,0, 6,0 bzw. 7,5 cyl dpt lag, war 10 bzw. 12 Monate postoperativ auf 2,0, 1,75 bzw. 3,0 cyl dpt reduziert. Der Patient mit dem Kapselspannring wies während des Nachbeobachtungszeitraumes keine morphologische oder refraktive Veränderung auf. Die beiden anderen Patienten zeigten 6 Monate nach Kataraktoperation eine IOL-Drehung um 20° bzw. 30°. Kapselfibrose oder Kapselfalten des optischen Zentrums waren nicht zu beobachten. Schlussfolgerung. Die Entwicklung torischer Intraokularlinsen bedeutet einen weiteren Fortschritt in der Kataraktchirurgie mit Verbesserung des refraktiven Effektes. Die gleichzeitige Implantation eines Kapselspannringes scheint die Stabilität des Ergebnisses zu verbessern.AbstractBackground. High postkeratoplasty astigmatism remains a challenge for the surgeon. First experiences after implantation of a toric PMMA IOL in three eyes from patients with cataracts are reported. Materials and methods. After routine phacoemulsification we implanted an individually manufactured toric PMMA posterior chamber IOL via a sclerocorneal 6 -mm tunnel incision in three postkeratoplasty eyes with high, topographically relatively regular astigmatism. One eye with the intraoperative aspect of circular zonular instability also received a capsular tension ring. A complete standard ocular examination was performed pre- and postoperatively including corneal topography, evaluation of anterior chamber depth, ultrasonic biomicroscopy and perimetry. Results. Implantation and intraoperative alignment of the toric IOL were uneventful. The refractive astigmatisms of 5.0, 6.0 and 7.5 cyl D preoperatively, were reduced to 2.0, 1.75 and 3.0 cyl D, 10 and 12 months post-operation, respectively. The eye with the capsular tension ring showed no morphological or refractive changes during follow-up. In the other two eyes we observed IOL rotation of 20 and 30 , respectively after 6 months. There were no posterior capsule opacification or capsular folds in the optical centre. Conclusion. Toric IOL technology allows enhancement of IOL surgery with improved refractive outcome. Simultaneous implantation of a capsular tension ring may improve long-term stability.

Persisting diplopia after bilateral laser in situ keratomileusis

We present a case of persisting diplopia after bilateral laser in situ keratomileusis in a patient with high anisometropia and amblyopia. Treatment of this complication by ocular-muscle surgery was not possible because of missing fusion. We suggest that, especially in cases with anisometropia, a complete examination of binocularity be performed before refractive surgery.

Refractive changes after phototherapeutic keratectomy

Purpose: To evaluate refractive error changes after phototherapeutic keratectomy (PTK). Setting: University Eye Hospital, Kiel, and University Eye Hospital, Hulle, Germany. Methods: The MEL 60 excimer laser (Aesculap Meditec) was used in all cases. To even out the peaks and valleys of irregular surfaces, modulating agents were applied. The study included 45 patients with various preoperative corneal diseases: central scars, recurrent erosions, corneal dystrophies, and surface irregularities. Subjective and objective refraction, keratometry, slitlamp photography, and corneal topography were performed preoperatively and postoperatively. The follow‐up was up to 24 months. Results: Twenty‐six patients had stable postoperative refractions. Thirteen patients developed a hyperopic shift; the highest observed amount was +4.0 diopters. In seven patients, the astigmatic error increased, although no significant change in axis was measured. Three patients had a myopic shift. Conclusion: After PTK, all types of refractive change can occur. The greatest risk is that of a hyperopic shift. We saw a correlation between the degree of hyperopia and the ablation depth. Methods for preventing such changes include (1) a large treatment zone, (2) use of a polishing program involving a low viscosity fluid at the end of the laser procedure, (3) a two‐step treatment in selected cases to avoid ablations that are too deep.

Phototherapeutic keratectomy (PTK) – a successful treatment for Thiel-Behnke dystrophy and its recurrences

SummaryIn recent years good results after treatment of different superficial corneal pathologies with the excimer laser 193 nm have been reported. Thiel-Behnke dystrophy is a hereditary form of anterior stromal dystrophy, a promising layer for successful phototherapeutic keratectomy (PTK). This type of dystrophy was first described in 1967 in Kiel. Patients and methods: Ten members of the original family of 1967 were re-examined at the University Eye Hospital, Kiel. A phototherapeutic keratectomy was performed in six eyes because of the typical honeycomb corneal surface irregularity and superficial haze. Two of these eyes had a recurrence of the primary disease on the graft. Four eyes had been untreated so far. The best spectacle corrected visual acuity preoperatively was between 20/200 and 20/40. For all treatments the MEL 60 excimer laser (Aesculap Meditec) was used. To even out the peaks and valleys of the irregular surfaces, modulating agents were applied in decreasing concentrations. The follow-up period is now between 8 months and 4 years. Results: All eyes showed significant visual improvement postoperatively with a best spectacle corrected visual acuity of 20/32 and higher. In one of the postkeratoplasty eyes with the longest follow-up after PTK, the original disease has begun to recur. Conclusions: Phototherapeutic keratectomy is a successful therapy for Thiel-Behnke dystrophy; it results in quick recovery of patients and their vision. Stable visual acuity and corneal transparency have been observed that last for years. Recurrences after penetrating keratoplasty or after PTK can be positively retreated. A (re-) keratoplasty may be postponed or avoided.ZusammenfassungHintergrund: Die hereditäre Thiel-Behnke-Dystrophie gehört in die Gruppe der vorderen Stromadystrophien; eine Lokalisation, die einer erfolgreichen Excimer-Photoablation zugänglich sein kann. Patienten und Methode: Insgesamt 10 Patienten mit Thiel-Behnke-Dystrophie stellten sich in der Universitäts-Augenklinik Kiel wegen allmählicher Sehverschlechterung vor. 6 Augen wurden aufgrund der typischen wabenförmigen Trübungen mit Oberflächenunregelmäßigkeiten mittels phototherapeutischer Keratektomie (PTK) behandelt. Bei 2 Augen handelte es sich um ein Rezidiv der Grunderkrankung bei Zustand nach perforierender Keratoplastik (pKP). 4 Augen waren bisher unbehandelt. Die bestkorrigierte Sehschärfe lag präoperativ zwischen 0,1 und 0,5. Alle Behandlungen wurden mit dem Excimer-Laser MEL 60 (Aesculap Meditec) durchgeführt. Stets kamen maskierende Substanzen absteigender Viskosität zum Einsatz. Die Nachbeobachtungszeit beträgt derzeit 8 Monate bis maximal 4 Jahre. Ergebnisse: In allen Fällen konnte ein deutlicher Visusanstieg erreicht werden. Die korrigierte Sehschärfe verbesserte sich zunächst postoperativ auf mindestens 0,63. Ein Auge nach perforierender Keratoplastik und mit längster Nachbeobachtungszeit nach Phototherapie zeigt seit einigen Monaten eine allmähliche Visusminderung, bedingt durch ein beginnendes Rezidiv. Schlußfolgerung: Die Excimer-Laser-vermittelte PTK stellt eine erfolgreiche Therapie der Thiel-Behnke-Dystrophie dar mit rascher Patienten- und Visusrehabilitation. Eine längerfristige Stabilität von Visus und Hornhauttransparenz konnte bei unseren Patienten beobachtet werden. Rezidive nach vorangegangener pKP oder PTK lassen sich erneut positiv beeinflußen und so eine ( Re-) pKP zeitlich hinauszögern.

[SILK--Steroid-induced lamellar keratopathy. A case report].

CASE REPORT After uneventful myopic LASIK, both interfaces of a 31-year-old, healthy male patient showed 5 days (right eye) and 7 days (left eye) postoperatively a diffuse, multifocal infiltration confined to the flap interface which was interpreted as a diffuse lamellar keratitis, stage 2-3. The routine postoperative treatment with local antibiotics and steroids was intensified to local steroids hourly. At that time intraocular pressure (IOP) was 19 mmHg (right) and 18 mmHg (left) (centrally measured by Goldmann applanation tonometry). Following 2 weeks under this therapy the keratitis did not resolve and IOP increased up to 30 mmHg. Local and systemic antiglaucomatosa were administered and IOP was reduced to 22 and 24 mmHg, respectively. Corneal interface infiltration, however, remained unchanged. Only the complete stop of the local corticosteroids induced a rapid regression and corneal transparency returned. IOP was normalized down to 10 mmHg without additional therapy. DISCUSSION 1) It is essential to measure IOP in the early postoperative phase after LASIK, especially in cases of corneal haze. 2) After corneal refractive surgery with high corneal ablation, IOP data in the upper range has to be interpreted as pathological. 3) Steroid-induced lamellar keratopathy is postulated as being a separate entity. 4) In cases of stromal infiltration after LASIK and increased IOP, local steroids have to be reduced immediately.

SILK?steroidinduzierte lamellre Keratopathie@@@SILK?Steroid-induced lamellar keratopathy: Ein Fallbericht@@@A case report

CASE REPORT After uneventful myopic LASIK, both interfaces of a 31-year-old, healthy male patient showed 5 days (right eye) and 7 days (left eye) postoperatively a diffuse, multifocal infiltration confined to the flap interface which was interpreted as a diffuse lamellar keratitis, stage 2-3. The routine postoperative treatment with local antibiotics and steroids was intensified to local steroids hourly. At that time intraocular pressure (IOP) was 19 mmHg (right) and 18 mmHg (left) (centrally measured by Goldmann applanation tonometry). Following 2 weeks under this therapy the keratitis did not resolve and IOP increased up to 30 mmHg. Local and systemic antiglaucomatosa were administered and IOP was reduced to 22 and 24 mmHg, respectively. Corneal interface infiltration, however, remained unchanged. Only the complete stop of the local corticosteroids induced a rapid regression and corneal transparency returned. IOP was normalized down to 10 mmHg without additional therapy. DISCUSSION 1) It is essential to measure IOP in the early postoperative phase after LASIK, especially in cases of corneal haze. 2) After corneal refractive surgery with high corneal ablation, IOP data in the upper range has to be interpreted as pathological. 3) Steroid-induced lamellar keratopathy is postulated as being a separate entity. 4) In cases of stromal infiltration after LASIK and increased IOP, local steroids have to be reduced immediately.