Kollagenvernetzung mit Riboflavin und UVA-Licht bei Keratokonus – Dresdner Ergebnisse

Purpose

The aim of this long-term retrospective study was to prove a long-term halting effect of riboflavin and UVA-induced collagen cross-linking in progressive keratoconus.

Methods

Since 1998, within an ethics-committee-approved study (EK 310 499), patients with progressive keratoconus and a minimal corneal thickness of 400 μm have received cross-linking treatment. An increase of the maximum K-value by ≥1 D within the previous year, a patient’s statement of deteriorating visual acuity, or the need for a new contact lens fitting more than once in 2 years was considered progression. The maximum follow-up time was 7.5 years. At the first examination and all follow-up examinations, refraction, best corrected visual acuity, corneal topography, and ultrasound pachymetry were recorded.

Results

The analysis included 153 eyes of 111 patients, with a minimal follow-up of 12 months. Keratectasia significantly decreased in the 1st year by 2.29 D, in the 2nd year by 3.27 D, and in the 3rd year by 4.34 D. Visual acuity improved significantly in at least one line or remained stable (i.e., no line loss) in the 1st year in 48.9% and 23.8%, respectively; in the 2nd year in 50.7% and 29.6%, respectively; and in the 3rd year in 60.6% and 36.4%, respectively. We saw no severe side effects. Three patients showed continuous progression of keratoconus and received cross-linking treatment again. Despite the small number of patients with a follow-up longer than 3 years, therefore limiting the statistical assertions, our results indicate long-term stabilization or improvement after collagen cross-linking.

Conclusion

With regard to the size of our cohort and the follow-up time, no comparable data have been published in the literature. The results of this study indicate that collagen cross-linking appears to be an effective therapeutic option for progressing keratoconus. Besides the clinical benefit, there are enormous economic and psychosocial benefits. Cross-linking is an outpatient, minimally invasive, cost-effective treatment involving minimal effort for the persons concerned.     

Automated Keratoconus Detection Using Height Data of Anterior and Posterior Corneal Surfaces

Purpose

To develop a keratoconus detection algorithm using the corneal topographic data of the anterior and posterior corneal surfaces.

Methods

Topographic measurements of the cornea were made with a slit-scanning corneal topographer. We examined 120 subjects (165 eyes); keratoconus patients and keratoconus suspect patients comprised the keratoconus group, and post-photorefractive keratectomy patients, with-the-rule astigmatism patients, and controls without disease comprised the nonkeratoconus group. Two variables of the anterior corneal surface, two variables of the posterior corneal surface, and one corneal thickness variable were obtained by applying the Fourier harmonic decomposition formula. By performing a logistic regression analysis with a training set to differentiate the keratoconus group from the nonkeratoconus group, the Fourier-incorporated keratoconus detection Index (FKI) was created. The validity of the FKI was determined by using independent validation sets.

Results

The FKI distinguished the keratoconus group from the nonkeratoconus group with 96.9% sensitivity and 95.4% specificity in the validation set.

Conclusions

A newly developed automated keratoconus classifier can be used to screen keratoconic patients. The index is based on information obtained by Fourier analysis from not only the anterior corneal surface but also from the posterior corneal surface and corneal thickness.?Jpn J Ophthalmol 2006;50:409–416 © Japanese Ophthalmological Society 2006     

Narbenbildung nach Hornhautvernetzung beim Keratokonus

Background

Corneal scar development after riboflavin-UVA-induced corneal collagen cross-linking (CXL) was retrospectively evaluated.

Patients and methods

A total of 163 CXL-treated eyes in 127 patients with stage 1–3 keratoconus according to Krumeich’s classification were included in this retrospective analysis. The follow-up period was 1 year. At the first and at all follow-up examinations uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), biomicroscopic findings, corneal topography and corneal thickness were recorded.

Results

At 1 year following CXL, 149 eyes (91.4%) of 114 patients had a clear cornea without corneal scar (control group), while 14 eyes (8.6%) of 13 patients developed clinically significant corneal scar (scar group). Preoperatively, the mean K value of the apex was 62.1 ± 13.8 D in the control group and 71.1 ± 13.2 D in the scar group (P=.02). The mean value of corneal thickness before the procedure was 478.1 ± 52.4 μm in the control group and 420.0 ± 33.9 μm in the scar group (P=.001). The UCVA and BCVA, which were preoperatively similar between groups (P=.59, P=.75 respectively), were postoperatively improved in the control group (P=.023, P=.001 respectively), but reduced in the scar group (P=.012, P=.004 respectively).

Conclusion

K-values and corneal thickness could be considered as predictive factors for the possible development of corneal scarring after riboflavin-UVA-induced CXL. Advanced keratoconus appears to be associated with a higher risk of corneal scar development due to lower corneal thickness, greater curvature and intrinsic tissue characteristics.     

Hornhautvernetzung mit hypoosmolarer Riboflavin-L?sung beim Keratokonus mit d��nner Hornhaut

Background

The aim of this study was to evaluate the 1-year results of 32 keratoconic eyes with thin corneas which were treated by hypo-osmolar riboflavin solution and ultraviolet A (UVA) collagen cross-linking (CXL).

Patients and methods

Patients with progressive keratoconus and a corneal thickness (CT) less than 400???m (without epithelium) were included in this study. The CT was measured with an ultrasound device (Tomey SP-3000, Nishi-ku, Nagoya, Japan). An increase in the maximum topographic K-value at the apex of keratoconus and a reduction in corneal thickness with or without changes in visual acuity (VA) within the last year were considered to be progression. A total of 32 eyes with an additional follow-up within 1 year were evaluated before and after the procedure. Examinations consisted of an evaluation of VA, corneal topography, slit-lamp microscopy and corneal thickness measurements.

Results

Preoperatively the mean corneal thickness (with epithelium) was 382.3±41.9???m and after removal of the epithelium the thickness of the cornea was reduced to 337.0±51.9???m. After the application of hypo-osmolar riboflavin solution the mean value increased to 451.8±46.7???m. Preoperatively the mean K-value of the apex of the keratoconus was 65.6±11.2 dopters, and 1 year after treatment this value remained relatively unchanged at 64.9±11.0 diopters (P=0.839). Mean VA at the time of the treatment was 0.63±0.37 logMAR and 1 year after the treatment this value was not statistically different (0.59±0.42 logMAR; P=0.662). In the last follow-up examination 1 year after the procedure all corneas were transparent without any scarring lesions in the stroma.

Conclusions

The results of this study using hypo-osmolar riboflavin solution in a cross-linking procedure for thin corneas showed a stability of keratoconus 1 year after CXL. Application of the hypo-osmolar riboflavin solution prevented cross-linked corneas from developing stromal scars.     

Evaluierung der dynamischen Konturtonometrie bei Keratokonus

Purpose

The gold standard for measuring intraocular pressure (IOP) until now has been Goldmann applanation tonometry (GAT), which depends on the central corneal thickness (CCT) and curvature. In patients with keratoconus who have an abnormal corneal geometry and thickness, measurement of pressure with GAT is often difficult and not very reproducible. We compared the impact of the central corneal thickness (CCT) on the IOP measured with dynamic contour tonometry (DCT), a digital method which is adapted to the corneal geometry, and GAT in patients with keratoconus.

Methods

IOP was measured in 54 patients (38 men and 16 women, mean age of 36±9.9 years) with GAT and DCT in randomized order. All patients had a keratoconus which was assured by topography. In addition central corneal thickness (CCT) was measured with the Pentacam. For statistical analysis the Pearson correlation was calculated and a Bland-Altman diagram plotted.

Results

Mean corneal thickness was 486.2±45.5 μm. DCT measured the IOP at a mean value of 14.9±2.6 mmHg and GAT at 13.3±2.9 mmHg. With a mean difference of 1.6±2.4 mmHg DCT measured significantly higher than GAT (p≤0.05) Neither IOP measurements with GAT (r=?0.03; p>0.05) nor those with DCT (r=0.08; p>0.05) showed a significant correlation to central corneal thickness.

Conclusion

The example of keratoconus confirms that IOP measured by GAT is lower than if measured by DCT. Because both methods are independent of the CCT they are equally acceptable for IOP follow-up in eyes with keratoconus, which may result in progressive corneal thinning in the long term.     

Biomechanische Zustand der Hornhaut als neuer Indikator für pathologische und strukturelle Veränderungen

Aim

Several methods permit the measurement of geometric parameters of the cornea, but until now biomechanical conditions of the cornea have been ignored (e.g. in refractive corneal surgery). Besides the geometric condition, biomechanical properties of the cornea have been shown to influence applanation measurement of intra-ocular pressure (IOP) and epidemiological studies have identified corneal thickness as an independent risk factor for the development and progression of glaucoma. The aim of this investigation was to characterize the biomechanical properties of the cornea using the ocular response analyzer (ORA).

Methods

The ocular response analyzer (ORA) is a new method available for non-contact measurement of the biomechanical properties of the cornea. We evaluated the reproducibility of measurements, the difference between static and dynamic factors and the impact of independent factors (e.g. IOP, age, CCT, swelling of the cornea) on 2,500 measurements of corneal hysteresis (CH) and corneal resistance factor (CRF).

Results

In a large sample size we observed changes in CH and CRF after refractive surgery procedures (LASIK, UV-A cross-linking, keratoplasty) and in other corneal disorders (keratoconus, corneal dystrophies).

Conclusions

CRF and CH changes may reflect structural changes of the cornea. Thus, the ORA provides valuable information for a better understanding and characterization of the biomechanical condition of the cornea, especially with regard to diseases such as keratoconus and glaucoma.     

Intrakorneale Ringsegmente beim Keratokonus

Introduction

The spectrum of stage-related therapy of keratoconus has been broadened through surgical implantation of intracorneal ring segments (INTACS) as a possible method of reducing irregular astigmatism, leading to a reduction of corneal grafts especially in young, working-aged patients with keratoconus. The purpose of the present study was to evaluate the preoperative and postoperative results of femtosecond laser-assisted implantation of INTACS in ectatic corneal diseases.

Patients and methods

From August 2011 to January 2013, 20 eyes from 16 patients with a clear cornea in the visual axis suffering from hard contact lens intolerance underwent surgery in the Homburg/Saar Keratoconus Center (HKC) by the same surgeon (MEH). Among these were 16 keratoconus eyes, 1 eye with pellucid marginal degeneration und 3 eyes with post-LASIK iatrogenic keratectasia. The insertion of the INTACS ring segments was achieved by a femtosecond laser-assisted procedure that created a precise 360° tunnel at a depth of 80?% of the corneal thickness (395.8?±?38.5 μm) in the 6–7 mm zone.

Results

At 6 months follow-up mean uncorrected distance visual acuity improved from 0.07?±?0.07 preoperatively to 0.6?±?0.26 postoperatively. Mean best-corrected distance visual acuity changed from 0.4?±?0.15 preoperatively to 0.9?±?0.29 postoperatively. Mean sphere decreased from ??7.6?±?6.1 dpt to ??1.4?±?2.8 dpt. Astigmatism decreased from ??6.0?±?2.8 dpt preoperatively to ??4.3?±?2.0 dpt postoperatively. There was also a reduction in the mean flat K from 47.8?±?4.7 dpt preoperatively to 44.2?±?5.0 dpt postoperatively and in mean steep K from 51.9?±?5.0 dpt to 48.4?±?6.6 dpt. The central eccentricity index in the Pentacam was reduced to around 50?%. Neither intraoperative nor postoperative complications (including non-responders) were observed.

Conclusions

The femtosecond laser-assisted INTACS implantation provides a valid alternative to early keratoplasty for keratoconus patients with a clear central cornea and contact lens intolerance. It is a minimally invasive and reliable method for stage-related surgical management of keratoconus.     

Corneal radius of curvature after anterior lamellar versus penetrating keratoplasty

Background

Keratoplasty may induce major spherical refractive error related to abnormal corneal radius of curvature (CRC).

Methods

Two hundred and thirty-eight consecutive eyes of 238 patients with clear graft and at least one postoperative Orbscan examination performed after suture removal (average follow-up time, 86 months) were retrospectively analyzed. Anterior lamellar keratoplasties (ALK group, n?=?119) and penetrating keratoplasties (PK group, n?=?119) were matched for preoperative diagnosis and lens status.

Results

The average postoperative, suture-out, Orbscan 3-mm CRC was 7.17 mm with a wide 95 % confidence interval [6.26 mm; 8.37 mm]. It was 7.05 mm in the ALK group and 7.31 mm in the PK group (p?<?0.01). In the ALK group, this figure was 7.00 mm for oversized grafts and 7.67 mm for non-oversized grafts (p?<?0.001). CRC values were significantly lower for eyes with keratoconus (7.00 mm) or stromal scar after infectious keratitis (7.06 mm) compared with stromal scar after trauma (7.74 mm) or stromal dystrophies (8.17 mm). Values were significantly lower for big-bubble ALKs (6.92 mm) and manual dissection-ALKs (7.14 mm) compared with PKs (7.31 mm) and microkeratome-assisted ALKs (7.45 mm). The average Orbscan 3-mm SimK cylinder, irregularity, and refractive power symmetry index were, respectively, 4.7 D/4.8 D/1.9 D for ALKs and 5.2 D/4.8 D/1.8 D for PKs (p?=?0.99).

Conclusions

The CRC is lower after ALK compared with PK, and features important variability. In eyes with ALK, non-oversized grafts result in postoperative CRC close to normal values and corneal diseases associated with stromal thinning and DALK result in lower postoperative CRC.     

Visus und Astigmatismus nach Keratoplastik

Background

The purpose of this study was to assess the differences in postoperative visual acuity, astigmatism, and selected postoperative complications between a guided trephine system (GTS) and motor trephine after penetrating keratoplasty.

Patients and methods

In this retrospective analysis 74 patients who had undergone penetrating keratoplasty either by GTS (n?=?53) or by motor trephine (Motortrepan) (n?=?21) were included. Both patient groups included in this analysis were selected to ensure a homogeneous distribution of preoperative parameters to the greatest possible extent. However, some significant differences in patient selection between the two groups could not be avoided. Patients in the motor trephine group were older (mean age 68.4 years vs 56.4 years; p?<?0.01) and had Fuchs’ endothelial dystrophy more often (47.6 % vs 26.4 %) and significantly less keratoconus (14.3 % vs 32.1 %).

Results

No significant differences regarding visual acuity outcomes could be found between GTS and Motortrepan. In both patient groups there were no differences in the amount of preoperative astigmatism (1.36 vs. 2.0 dpt., p?=?0.39). However, at the time of final corneal suture removal (2.23 vs. 3.5 dpt., p?=?0.03) and at a postoperative control 1 year after final suture removal (2.29 vs. 3.85 dpt., p?=?0.005) the amount of astigmatism in the motor trephine group was found to be significantly higher.

Conclusion

In summary penetrating kerastoplasty using the motor trephine was found to result in significantly higher postoperative astigmatism than those performed with the GTS.     

Comparative analysis of the relationship between anterior and posterior corneal shape analyzed by Scheimpflug photography in normal and keratoconus eyes

Background

To analyze and compare the relationship between anterior and posterior corneal shape evaluated by a tomographic system combining the Scheimpflug photography and Placido-disc in keratoconus and normal healthy eyes, as well as to evaluate its potential diagnostic value.

Methods

Comparative case series including a sample of 161 eyes of 161 subjects with ages ranging from 7 to 66 years and divided into two groups: normal group including 100 healthy eyes of 100 subjects, and keratoconus group including 61 keratoconus eyes of 61 patients. All eyes received a comprehensive ophthalmologic examination including an anterior segment analysis with the Sirius system (CSO). Antero-posterior ratios for corneal curvature (k ratio) and shape factor (p ratio) were calculated. Logistic regression analysis was used to evaluate if some antero–posterior ratios combined with other clinical parameters were predictors of the presence of keratoconus.

Results

No statistically significant differences between groups were found in the antero–posterior k ratios for 3-, 5- and 7-mm diameter corneal areas (p?≥?0.09). The antero–posterior p ratio for 4.5- and 8-mm diameter corneal areas was significantly higher in the normal group than in the keratoconus group (p?<?0.01). The k ratio for 3, 5, and 7 mm was significantly higher in the keratoconus grade IV subgroup than in the normal group (p?<?0.01). Furthermore, significant differences were found in the p ratio between the normal group and the keratoconus grade II subgroup (p?≤?0.01). Finally, the logistic regression analysis identified as significant independent predictors of the presence of keratoconus (p?<?0.01) the 8-mm anterior shape factor, the anterior chamber depth, and the minimal corneal thickness.

Conclusions

The antero-posterior k and p ratios are parameters with poor prediction ability for keratoconus, in spite of the trend to the presence of more prolate posterior corneal surfaces compared to the anterior in keratoconus eyes.     

Corneal crosslinking for keratoconus in Japanese populations: one year outcomes and a comparison between conventional and accelerated procedures

Purpose

We retrospectively investigated the efficacy of corneal crosslinking (CXL) on progressive keratoconus in a Japanese population and compared the outcomes of conventional and accelerated CXL.

Study design

A retrospective cohort study

Methods

A total of 108 consecutive eyes in 95 patients (75 men; 21.9 ± 6.2 years) with progressive keratoconus were enrolled. The epithelium was ablated in all eyes. After presoaking the corneal stroma in riboflavin, UV-A was irradiated at 3.0 mW/cm² (conventional CXL) for 30 min on 23 eyes and 18.0 mW/cm² for 5 min (accelerated CXL) on 85 eyes. Best spectacle-corrected visual acuity (BSCVA), manifest refraction, keratometric value, corneal thickness, corneal endothelial cell density (ECD), intraocular pressure, and complications were evaluated at 1, 3, 6, and 12 months after the procedure.

Results

BSCVA, manifest refraction, ECD, and corneal thickness did not change significantly after both procedures. The keratometric value was significantly decreased from the preoperative value at 12 months (p < 0.001). Progression to more than 1.0 D after CXL was observed in 10 eyes (9.3%). The ΔKmax was negatively associated with preoperative Kmax (p < 0.001) and positively associated with preoperative thinnest corneal thickness (p < 0.001). Both treatment modules showed no significant difference in all parameters.

Conclusion

CXL was as effective in treating keratoconus in Japanese patients as in individuals of other ethnicities. Overall, CXL could be performed using either the conventional or accelerated approach to halt the progression of keratoconus in Japanese populations.

     

Hornhauttopografie und Keratokonusdiagnostik mittels Scheimpflug-Fotografie

Background

Corneal Scheimpflug tomography is a commonly used non-invasive imaging technique.

Objectives

This review article summarizes the principles of the technique and recent results from the literature with a focus on keratoconus diagnostics.

Material and methods

Review of the literature, own data and expert opinions.

Results

Corneal Scheimpflug tomography allows topography of the anterior and posterior surfaces as well as spatially resolved pachymetry and densitometry. Measurements obtained with currently available systems are highly reproducible but not interchangeable. Combining topographic and pachymetric data allows a highly sensitive and specific diagnostic modality for the early diagnosis of keratoconus.

Conclusions

Due to the versatility, precision and easy handling, corneal Scheimpflug tomography is the most important imaging technique for the anterior segment of the eye.     

Perspektiven der tiefen anterioren lamell?ren Keratoplastik

Purpose

The current indications, techniques, results and complications of deep anterior lamellar keratoplasty are described.

Methods

The study comprised a literature review and own clinical and experimental results.

Results

The main advantage of DALK in patients with keratoconus and other anterior stromal diseases is the avoidance of endothelial immune reactions and the main drawback is the conversion rate to penetrating keratoplasty of around 15%.

Conclusions

Using the big bubble approach DALK is a safe and reliable technique for treating keratoconus and anterior stromal dystrophy.     

Corneal biomechanical properties in eyes with no previous surgery, with previous penetrating keratoplasty and with deep anterior lamellar keratoplasty

Purpose

To compare the biomechanical properties of the cornea in eyes with no previous surgery, with keratoconus with previous penetrating keratoplasty (PK) and with keratoconus with previous deep anterior lamellar keratoplasty (DALK) using the Reichert Ocular Response Analyzer (ORA).

Methods

One hundred twenty eyes of 120 patients were included in this prospective comparative study. Forty eyes were with no previous ocular surgery (group 1), 40 eyes were with previous PK for keratoconus (group 2), and 40 eyes were with previous DALK for keratoconus (group 3). Corneal hysteresis (CH) and the corneal resistance factor (CRF) were measured with ORA.

Results

The CH and CRF values in group 2 were significantly lower than in group 1 and group 3 (p = 0.001). The CH and CRF values were similar in group 1 and group 3. There was no statistically significant difference between group 1 and 3.

Conclusion

Although the post-PK keratoconus cornea has weaker biomechanical properties, post-DALK keratoconus cornea is similar to normal cornea. A cornea weakened by keratoconus can be strengthened with lamellar keratoplasty.     

Meta-analysis of Pentacam vs. ultrasound pachymetry in central corneal thickness measurement in normal, post–LASIK or PRK, and keratoconic or keratoconus-suspect eyes

Background

The aim of this meta-analysis is to evaluate the central corneal thickness (CCT) measurement differences between Pentacam (Oculus Inc., Germany) and Ultrasound Pachymetry (USP) in normal (unoperated eyes , myopic and astigmatic eyes without corneal disease or topographic irregularity), after laser in situ keratomileusis (LASIK) or photorefractive keratectomy (PRK), and keratoconic or keratoconus suspected eyes. We assess whether Pentacam and USP have similar CCT differences in normal, thinner corneas after LASIK or PRK procedures, and kerotoconic or keratoconus suspected eyes.

Methods

Data sources, including PubMed, Medline, EMBASE, and Cochrane Central Registry of Controlled Trials on the Cochrane Library, were searched to find the relevant studies. Primary outcome measures were CCT measurement between Pentacam and USP. Three groups of eyes were analyzed: normal; LASIK or PRK eyes; and keratoconus suspected or keratoconic eyes.

Results

Nineteen studies describing 1,908 eyes were enrolled in the normal group. Pentacam results were 1.47 μm ,95 % confidence interval (CI) -2.32 to 5.27, higher than USP without statistically significant difference (P?=?0.45). Nine studies with total 539 eyes were included in the corneas after LASIK or PRK. The mean difference in the CCT measurement with Pentacam and ultrasound pachymetry was 1.03 μm, with the 95 % CI ?3.36 to 5.42, there was no statistically difference (P?=?0.64). Four studies with a total of 185 eyes were included in the keratoconic eyes or keratoconus-suspect group, however,the mean difference was ?6.33 μm (95 % CI ?9.17 to-3.49), which was statistically different between Pentacam and ultrasound pachymetry in the CCT measurement (P?<?0.0001).

Conclusions

Pentacam offers similar CCT results to ultrasound pachymetry in normal eyes, thinner corneas after LASIK or PRK procedures. However, in keratoconic or keratoconus-suspect eyes, Pentacam slightly underestimates the central corneal thickness than does ultrasound pachymetry, which may result from the difficulty in fixation of keratoconic eyes, misalignment of Pentacam and the variation of ultrasonic velocity due to the histological deformation.     

Topische antiangiogene Therapie an der Hornhaut

Background

The efficacy and safety of novel topical inhibitors of corneal neovascularisation will be discussed.

Methods

A literature review after a PUBMED search and own clinical and experimental results are presented.

Results

The off-label use of Avastin® eye drops and GS101 eye drops against insulin receptor substrate (IRS)-1, which have been tested in phase II trial, both seem to be relatively efficient and safe ways to inhibit progressive corneal neovascularisation. Other VEGF antagonists, such as ranibizumab and pegaptanib eye drops also inhibit corneal neovascularisation.

Conclusions

Avastin® and GS101 eye drops are the first specific angiogenesis inhibitors for topical inhibition of corneal angiogenesis available for clinical use.     

DALK und perforierende Laserkeratoplastik bei fortgeschrittenem Keratokonus

Background

In cases of contact lens intolerance and/or central corneal scars, corneal transplantation is indicated for advanced keratoconus. This can be performed as deep anterior lamellar keratoplasty (DALK) or as penetrating keratoplasty (PKP). The German keratoplasty registry shows that the proportion of anterior lamellar grafts in Germany has remained stable at approximately 5?% in recent years.

Methods

Up to now DALK has not been technically standardized but can result in a good visual acuity using the big bubble technique if Descemet’s membrane is laid bare intraoperatively. In 10–20?% a conversion to PKP is required if perforation of Descemet’s membrane occurs. In cases of advanced keratoconus PKP is still the method of first choice especially after corneal hydrops due to rupture of Descemet’s membrane. Non-contact excimer laser trephination seems to be especially beneficial for eyes with iatrogenic keratectasia after LASIK and those with repeat grafts in cases of keratoconus recurrence due to the graft being too small. For donor trephination from the epithelial side, an artificial chamber is used. Wound closure is achieved by a double running cross-stitch suture according to Hoffmann. Graft size is adapted individually depending on corneal size (as large as possible and as small as necessary). Limbal centration is given priority intraoperatively due to optical displacement of the pupil.

Results

Prospective clinical studies have shown that the technique of non-contact excimer laser PKP improves donor and recipient centration, reduces vertical tilt and horizontal torsion of the graft in the recipient bed, thus resulting in significantly less all-sutures-out keratometric astigmatism (2.8 D versus 5.7 D), higher regularity of the topography (SRI 0.80 vs. 0.98) and better visual acuity (0.80 vs. 0.63) in contrast to the motor trephine. The stage of the disease does not influence functional outcome after excimer laser PKP.

Conclusions

In cases with optimal course DALK achieves the same visual outcome as mechanical PKP but the healthy endothelium can be preserved and endothelial immune reactions are prevented in keratoconus. In contrast to the undisputed clinical advantages of excimer laser keratoplasty with orientation teeth/notches in keratoconus, the major disadvantage of femtosecond laser application is still the necessity of suction and applanation of the cone during trephination.     

Changing indications for penetrating keratoplasty in Homburg/Saar from 2001 to 2010—histopathology of 1,200 corneal buttons

Background

To evaluate the trends in indications for penetrating keratoplasty (PKP) in Homburg/Saar between 2001 and 2010.

Methods

Retrospective review of 1,200 corneal buttons which underwent PKP that were performed between 2001 and 2010 at the Department of Ophthalmology of Saarland University Hospital, Germany. Indications were classified into eight different groups following histological analysis: keratoconus, Fuchs’ dystrophy, bullous keratopathy, corneal scars, keratitis, regraft, corneal dystrophy other than Fuchs’ dystrophy, and other diagnoses. Two different time periods (between 2001–2005 and between 2006–2010) were analyzed.

Results

Keratoconus (25.5 %) was the most common indication for PKP in our study, followed by Fuchs’ dystrophy (21.2 %), bullous keratopathy (14.6 %), corneal scars (14.4 %), keratitis (13.0 %), regraft (7.0 %), non-Fuchs’ dystrophies (2.1 %), and other diagnoses (2.3 %). Comparing the two different time periods, a trend of significantly increasing frequency of keratoconus and Fuchs’ dystrophy, and a decreasing frequency of corneal scars, were found as indications for PKP in our study.

Conclusions

Keratoconus was the leading indication for PKP in our series, and had a significantly increasing trend from 2001–2005 to 2006–2010. The percentage of patients with Fuchs’ dystrophy increased, and became the second most common indication for PKP, while the number of PKPs for corneal scars decreased during the last 5 years in our institution.     

Performing corneal crosslinking under local anaesthesia in patients with Down syndrome

Purpose

To report on the ability to perform corneal crosslinking (CXL) under local anaesthesia for the treatment of keratoconus in patients with Down syndrome.

Methods

Nine eyes of seven patients with both keratoconus and Down syndrome were scheduled for an epithelium-off CXL procedure under local anaesthesia. Exclusion criteria were a corneal thickness under 400 µm and the presence of corneal scars. A standardized clinical decision tool was used to estimate patient cooperation and the likelihood for a successful procedure under local rather than general anaesthesia.

Results

In seven eyes, the CXL was completed successfully. The treatment was aborted in two eyes due to insufficient corneal thickness (<400 µm) prior to ultraviolet-A irradiation, even after employing hypoosmolar riboflavin. No adverse events occurred post-operatively, except for one case of delayed epithelial healing (23 days).

Conclusions

With a proper patient selection, CXL under local anaesthesia can be achieved in patients with Down syndrome.

     

The impact of tear functions on visual outcome following keratoplasty in eyes with keratoconus

Background

To investigate the impact of preoperative and postoperative tear functions on visual outcome and the recovery of visual function following keratoplasty in eyes with keratoconus.

Methods

Twenty-five eyes of 25 consecutive patients (5 females, 20 males, mean age: 34.3?±?15.8 years (range: 19–70 years) with keratoconus who underwent either penetrating keratoplasty (PKP) or deep anterior lamellar keratoplasty (DALK) were included in this prospective study. One patient who had a rejection episode during the follow-up period was excluded. All subjects underwent best corrected visual acuity (BCVA), corneal topography (refractive cylinder, surface regularity index: SRI and surface asymmetry index: SAI), Schirmer I test, tear film break-up time (BUT), corneal sensitivity, and fluorescein staining score measurements before as well as 1, 3, 6 and 12 months after keratoplasty. The relation between the tear functions and the duration until the achievement of maximum BCVA was also evaluated. Linear regression analysis was performed to study the statistical significance of the correlations and the time wise change of each examined parameter.

Results

SRI, SAI, and BCVA significantly improved after keratoplasty. The postoperative corneal sensitivity was still significantly low even at 12 months postoperatively. Postoperative BCVA at 3, 6 months and maximum BCVA showed a significant linear negative correlation with the preoperative BUT (3 months; r?=??0.461, p?=?0.036, 6 months; r?=??0.494, p?=?0.023, maximum BCVA; r?=??0.473, p?=?0.030). The duration until the achievement of maximum BCVA showed a significant negative correlation with the preoperative Schirmer test (r?=??0.429, p?=?0.036). BCVA at 1 and 3 months postoperatively showed significant linear negative correlations with BUT value at the respective periods (1 month; r?=??0.665, p?=?0.0036, 3 months; r?=??0.580, p?=?0.0059).

Conclusion

Preoperative tear functions appeared to have an influence on postoperative BCVA and the duration of visual recovery in keratoconus patients undergoing keratoplasty. Postoperative tear film stability appears to play an important role for obtaining a better BCVA in the early postoperative period after keratoplasty.