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.     

Therapeutic effect of deep anterior lamellar keratoplasty for active or quiescent herpetic stromal keratitis

Purpose

To evaluate the therapeutic effect of deep anterior lamellar keratoplasty (DALK) in patients with herpetic stromal keratitis (HSK).

Methods

Forty-three eyes belonging to 42 patients with HSK, including 22 eyes in the active phase and 21 eyes in the quiescent phase, underwent DALK at the Shandong Eye Institute from January 2006 to December 2009. All patients with active disease had received intravenous acyclovir and amniotic membrane implants prior to DALK. Herpes simplex virus type 1 (HSV-1) antigens from excised corneal buttons were detected by immunohistochemistry.

Results

The follow-up ranged from 1 to 4?years (mean, 29.1?months). Graft rejection occurred in one eye (2.3%) and was reversed. Among the other 42 survived grafts (97.7%), 37 remained clear at the last visit. The best spectacle-corrected visual acuity was 20/200 or better in 95.2% of eyes and 20/40 or better in 38.1% of eyes. Six eyes (14.0%) developed recurrent HSK, one of which received a second keratoplasty due to ineffective antiviral medication. There were no significant differences in endothelial cell density between 6?months and 12?months after the surgery. By immunohistochemistry, HSV-1 antigens were observed in the stroma of 18 of 32 corneal buttons.

Conclusions

DALK can not only remove the corneal lesions of HSK but also reduce latent or persistent viral loads in the cornea. In eyes with active or quiescent HSK but otherwise healthy endothelia, DALK seems to be safe and promising for its favorable visual outcome, graft survival rate, and low endothelial cell loss.     

Effects of the Matrix Metalloproteinase Inhibitor GM6001 on the Destruction and Alteration of Epithelial Basement Membrane During the Healing of Post-alkali Burn in Rabbit Cornea

Purpose

To examine the alteration in structure and matrix composition of epithelial basement membrane (BM) during the healing of alkali-burned rabbit cornea, and the roles of matrix metalloproteinases (MMPs) in these alterations.

Methods

The central cornea of one eye of 78 albino rabbits was exposed to 1?N NaOH for 180?s under general and topical anesthesia and allowed to heal with or without subconjunctival injection of GM6001 (an MMP inhibitor). Cryosections of affected corneas were observed by H&;E staining, immunohistochemistry for type IV collagen subtypes, or in situ zymography for detection of localization of MMP activity.

Results

Uninjured corneal epithelial BM exhibited α5 (IV)-immunoreactivity, but lacked the α1/α2-immunoreactivity of collagen IV. Epithelial BM in healing burned cornea transiently exhibited α1/α2-immunoreactivity. Examination by in situ zymography showed an upregulation of MMP activity in the regenerated central epithelium and anterior stroma of the burned corneas at days 7 and 14. GM6001 suppressed degradation of α5-containing epithelial BM in vivo and also in organ culture.

Conclusions

Epithelial BM was degraded by endogenous MMPs during healing following an alkali burn in rabbit cornea. GM6001 had an inhibitory effect on the degradation of the epithelial basement membrane in burned cornea in vivo.?Jpn J Ophthalmol 2006;50:90–95 © Japanese Ophthalmological Society 2006     

Comparison of deep anterior lamellar keratoplasty and penetrating keratoplasty with respect to postoperative corneal sensitivity and tear film function

Purpose

To investigate tear film function, central and peripheral corneal sensitivity and corneal subbasal nerve morphology in the cornea after deep anterior lamellar keratoplasty (DALK) compared with penetrating keratoplasty (PK).

Methods

This prospective study compared the changes in 16 eyes of 16 patients who underwent DALK (DALK group) with those in 28 eyes of 28 patients who underwent PK (PK group). Thirty healthy volunteers were also included as controls. Tear functions were evaluated using tear break-up time (TBUT), tear meniscus height (TMH) and corneal fluorescein staining. Corneal sensation was measured with a Cochet-Bonnet esthesiometer. Corneal subbasal nerve morphology was evaluated using in vivo confocal microscopy (IVCM). The patients were examined 1, 3, 6, 9 and 12 months after keratoplasty.

Results

Postoperatively, TMH recovered significantly faster in the DALK group than in the PK group (p?p?p?p?Conclusions Tear film function was restored more rapidly after DALK compared with PK, but there was no significant difference in corneal sensitivity between PK and DALK.     

Reproduzierbarkeit der Femtosekundenlaserschnitte bei der posterioren lamellären Keratoplastik in vitro

Purpose

In the last decade surgeons have tried to use posterior lamellar keratoplasty (PLAK) in a way that maintains the biomechanical stability of the intact cornea. Femtosecond lasers can be used to cut a lenticle out of the posterior part of the stroma. The purpose of this study was to assess the reproducibility of the generated lenticles.

Methods

The FEMTEC-Laser (20/10 Perfect Vision, Heidelberg, Germany) was used to perform posterior lamellar dissections. The goal was to assess the real thickness of the graft in comparison to the intended thickness predefined with the laser. The histological preparations were viewed using light microscopy (Olympus microscope). Main outcome measures included difference of intended versus real distance of the horizontal plane from Bowman’s layer and quantification of the created bubbles.

Results

The intended distance was reached with a precision of 115–160 µm and was constant over the whole length of the lenticle depending on the depth of the laser action. The number and size of the generated bubbles was equal in the different layers. At least one zone of stromal condensation could be found in 88.9% of the corneas and 63% of the corneas showed a partial perforation or minimal lesions of Descemet’s membrane. The distance of the two closest bubbles to Descemet’s membrane increased in thinner lenticles, i.e. a greater distance from Bowman’s layer. No damage occurred due to compression or heat.

Conclusions

As the laser generates a reproducible number of bubbles of the same size, precise incisions can be achieved. Thus the femtosecond laser proved to be an accurate tool for PLAK. In the majority of cases a lesion of Descemet’s membrane could be found which seems to make the removal of the lenticles easier. A disadvantage is a decreasing probability of a lesion of Descemet’s membrane as well as the decreasing precision in thinner lenticles.     

Properties of Corneas Reconstructed with Cultured Human Corneal Endothelial Cells and Human Corneal Stroma

Purpose

To examine the properties of corneas tissue-engineered with cultured human corneal endothelial cells (HCEC) and human corneal stroma.

Methods

Primary HCEC cultures were established from endothelial cell layer explants and propagated on culture dishes coated with bovine corneal endothelial extracellular matrix. A cell suspension of HCEC at the fifth passage was transferred onto human corneal stroma deprived of endothelial cells, and the corneas were gently centrifuged to enhance cell attachment. The cell density of the tissue-engineered corneas was examined after staining with alizarin red and trypan blue. The tissue-engineered corneas were histologically examined by light and electron microscopy. The pump function of the tissue-engineered corneas was measured using an Ussing chamber.

Results

The mean endothelial cell density of four tissue-engineered corneas was 2380 ± 264 cells/mm² (mean ± SD). HCEC on the tissue-engineered corneas had a morphology similar to HCEC in vivo. The pump function parameters of the tissue-engineered corneas were 55%–75% of those of normal corneas.

Conclusions

HCEC on the tissue-engineered corneas have morphology and cellular density similar to HCEC in vivo, whereas the pump function of the tissue-engineered corneas was lower than in normal corneas. Jpn J Ophthalmol 2005;49:448–452 © Japanese Ophthalmological Society 2005     

Use of trypan blue dye during conversion of deep anterior lamellar keratoplasty to penetrating keratoplasty

We describe a technique that uses trypan blue dye to identify residual recipient corneal stroma and Descemet membrane (DM) during conversion of deep anterior lamellar keratoplasty (DALK) to penetrating keratoplasty (PKP). After the host cornea is dissected, trypan blue dye (0.06%) is used to highlight the remaining host corneal stroma and DM, if any. In 8 DALK procedures that had to be converted to PKP because of DM perforation, trypan blue staining identified remnants of DM and parts of the posterior corneal stroma in 7 eyes. Improved visualization of the residual host tissue enabled complete excision and an overall optimal recipient wound profile.     

Komplikationsvermeidung und -management bei „Descemet membrane endothelial keratoplasty“ (DMEK) und „Descemet stripping automated endothelial keratoplasty“ (DSAEK)

Background

Posterior lamellar keratoplasty, in the form of Descemet membrane endothelial keratoplasty (DMEK) and Descemet stripping automated endothelial keratoplasty (DSAEK), has become a standard procedure for therapy of endothelial diseases of the cornea. The aim of this article is to describe strategies to prevent and manage complications in DMEK and DSAEK surgery.

Methods

The article is based on a PubMed literature search and own clinical data. Key words used were “DMEK”, “DSAEK”, “Descemet membrane endothelial keratoplasty” and “Descemet stripping automated endothelial keratoplasty”.

Results

The DMEK and DSAEK procedures are safe surgical strategies for treating endothelial corneal diseases if the indications are made correctly.

Conclusions

The DMEK procedure is the standard procedure for improvement of visual acuity especially for younger patients with Fuchs’ dystrophy and DSAEK is particularly suitable for eyes with complicated anterior chamber situations.     

Immunohistochemical Observation of Amniotic Membrane Patching on a Corneal Alkali Burn In Vivo

Purpose

To investigate by immunohistochemical observation the effects of amniotic membrane (AM) patching on myofibroblastic differentiation and matrix metalloproteinase (MMP) expression in the corneal stroma after an alkali burn in vivo.

Methods

A corneal alkali burn was made by placing a circular piece of filter paper containing 1?N NaOH on the central cornea of rabbits. Burning was done unilaterally in each rabbit. Immediately after the wounding, in the AM group, AM was sutured onto the cornea and removed on day 1. Rabbits with no AM patching were controls. On day 14, corneas were excised and immunohistochemical observation was carried out using antibodies against α-smooth muscle actin (α-SMA), vimentin, MMP-1, MMP-2, MMP-9, and membrane-type1 (MT1)-MMP. Observation after Masson trichrome staining was also performed.

Results

In the AM group, α-SMA positive cells were noticeably fewer, and MMP-2, MMP-9, and MT1-MMP expression was clearly inhibited. Also, collagen fibers were more regularly arranged than in control eyes. The more proximate the cells were to the epithelial side, the fewer α-SMA-positive cells were observed in the AM group.

Conclusions

AM patching suppressed myofibroblastic differentiation and MMP expression in the stroma after an alkali burn. An inhibition gradient suggests that AM may release unknown soluble factors possessing some antiscarring capability.?Jpn J Ophthalmol 2007;51:3–9 © Japanese Ophthalmological Society 2007     

Comparison of corneal haze and visual outcome in primary DSAEK versus DSAEK following failed DMEK

Background

Descemet membrane endothelial keratoplasty (DMEK) is being proposed as the procedure of choice in corneal endothelial disease as it achieves better visual and refractive outcomes than Descemet stripping automated endothelial keratoplasty (DSAEK). Nevertheless, primary graft failure is frequent, especially during the learning curve, and secondary back-up procedure consists on DSAEK. We aim to compare corneal haze and visual acuity of patients undergoing primary DSAEK vs. patients undergoing DSAEK as a back-up procedure after primary DMEK failure.

Methods

This study is a comparative case series that included 19 eyes from 16 patients with early stages of corneal failure and limitation of daily activities after primary DSAEK or secondary DSAEK. A control group of non-operated corneas included 10 aged-matched normal eyes. The study was conducted at University Hospital Ramón y Cajal and Vissum Hospital, Madrid, Spain. Corneal densitometry readings and postoperative best-corrected visual acuity in subjects with primary and secondary DSAEK were recorded 6 months after the surgery using the Pentacam Scheimpflug system (Oculus, inc.,Wetzlar, Germany).

Results

In primary DSAEK median densitometry values (range) were statistically significantly higher (p?<?0.05) than normal subjects for the full thickness, posterior and anterior part of the paracentral cornea; and the anterior part of the central cornea. In secondary DSAEK, median densitometry values were statistically significantly higher than normal subjects at all levels of the central and paracentral cornea. In secondary DSAEK, median densitometry values (range) were statistically significantly higher than in primary DSAEK in the full-thickness, anterior part and interface of the central cornea and in the full-thickness and posterior part of the paracentral cornea. Median visual acuity between groups (p?=?0.47) was statistically better for the primary DSAEK group, which also had a higher percentage of patients achieving BCVA of ≥ 20/40 and ≥20/25 than the secondary DSAEK group (100 % vs. 62 % and 60 % vs. 0 % respectively).

Conclusions

There is an increase in central corneal light scattering after secondary DSAEK performed after a failed DMEK as compared to primary DSAEK. This has a negative impact on final visual acuity that needs to be considered in each patient when starting DMEK surgery.     

DMEK: posteriore lamelläre Keratoplastiktechnik

Background

Penetrating keratoplasty is at present the gold standard for surgical treatment of corneal endothelial pathologies but tremendous progress has been made in recent years in improving the technology of (posterior) lamellar keratoplasty techniques, such as Descemet membrane endothelial keratoplasty (DMEK) and Descemet stripping automated endothelial keratoplasty (DSAEK).

Methods

A review of the literature was carried out using PUBMED and own clinical and experimental data.

Results

Isolated transplantation of Descemet’s membrane with endothelial cells after stripping the host Descemet’s membrane is a new surgical technique for Fuchs endothelial dystrophy and pseudophakic bullous keratopathy. Visual rehabilitation seems to be faster and better with DMEK compared to penetrating keratoplasty.

Conclusion

Posterior lamellar keratoplasty techniques such as DMEK will replace penetrating keratoplasty as the gold standard for treatment of a large segment of corneal endothelial pathologies.     

Scheimpflug-Fotografie detektiert Veränderungen der Hornhautdichte und Hornhautdicke bei Patienten mit Keratoconjunctivitis sicca

Background

Dry eye disease is a common ocular surface disease that significantly affects the quality of life. Little is known about a potential impact of the disease on corneal morphology. This study was carried out to investigate for the first time if dry eye disease induces changes in corneal density and thickness.

Methods

In total 97 patients suffering from dry eye disease and 33 healthy age-matched individuals were included in this prospective, randomized study. Corneal morphology was documented with Scheimpflug photography and analyzed for central corneal thickness and corneal density in five anatomical layers (i.e. epithelium, Bowman membrane, corneal stroma, Descemet membrane and endothelium).

Results

Corneal density was significantly reduced in the epithelium (p?=?0.0053), Bowman membrane (p?=?0.0049) and Descemet’s membrane (p?=?0.0385) in patients with dry eye syndrome compared to healthy controls. This decrease was age-dependant. Furthermore, central corneal thickness was significantly reduced in patients with dry eye syndrome compared to the control group (p?=?0.0495). The change was again dependent on age with lower values at higher age. Central corneal thickness increased with age in the control group.

Conclusion

The results of this study indicate that corneal morphology is subject to significant alterations in patients with dry eye disease. Scheimpflug photography provides not only unique information in lens trials but is also able to detect changes of corneal anatomy. However, further investigations with other anterior segment imaging techniques, such spectral domain optical coherence tomography (SD OCT/Pentacam®) are necessary to further evaluate the clinical consequences of these findings.     

Development of an organotypic corneal construction as an in vitro model for permeability studies

Background. In vitro investigations of transcorneal permeation behaviour with new drugs in ophthalmology are mainly carried out using excised corneas taken from slaughtered or experimental animals. Analogous to previously used dermis models, an in vitro model was constructed from porcine corneal cell cultures and the permeation barrier properties were tested and compared with permeation data from excised corneas. Methods. Epithelial, stroma and endothelial cells were successfully isolated by treatment with various enzymes and a corneal equivalent was created step-by-step which morphologically resembled the original tissue. Five different drug formulations were investigated and pilocarpine hydrochloride was chosen as the model drug. The permeation studies were made with a modified Franz cell and analysis was performed by high performance liquid chromatography. Permeation data from excised corneas and from the cornea construct were compared whereby data obtained with lipophilic preparations did not differ (factor of 1) and those obtained with aqueous formulations were relatively similar (factor of 3–4). Results and conclusions. The results obtained show that the cornea construct can be used as an alternative to excised corneas for in vitro investigations of ophthalmic drug preparations.     

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.     

Anti-neovascular effect of chondrocyte-derived extracellular matrix on corneal alkaline burns in rabbits

Purpose

We investigated the effect of a chondrocyte-derived extracellular matrix (CDECM) on experimental corneal alkaline burns in rabbits.

Methods

Corneal neovascularization (NV) was induced by applying an 8-mm filter paper soaked in 1 N NaOH to the right central corneas of rabbits for 1 minute. Ten days later, the rabbits were randomly divided into three groups: the alkaline burn group, the CDECM transplantation group, and the human amniotic membrane (HAM) transplantation group. The left eyes were used as controls. CDECM and HAM were transplanted onto the corneal surface to completely cover the resected area and were subsequently sutured. On the 10th day after transplantation, the structural changes of the cornea were analyzed histologically. We examined the effects of CDECM on clinical NV features and on the expression of corneal NV markers.

Results

The alkaline burn produced significant NV and increased the corneal thickness. On day 10 after transplantation, the thickness, NV and opacity of the cornea were markedly decreased in the CDECM group (p?<?0.001). However, the HAM transplantation group did not exhibit improvements in these clinical parameters, and there were no significant differences relative to the burn group. In addition, the use of CDECM improved the healing of the cornea following the alkaline burn by disrupting the corneal epithelial proliferation and reducing the fibrotic changes of the stroma. The hallmarks of NV were significantly induced in the subepithelium by the alkaline burn, and these levels were also suppressed by CDECM. The CDECM suppressed corneal NV by inhibiting nuclear factor-kappa B (NF-κB) activation by blocking the PKC and Akt signaling pathways.

Conclusions

CDECM transplantation was markedly effective in healing alkali-burned corneas by modulating the translocation of NF-κB to the nucleus, thereby representing a promising material for the noninvasive treatment of ocular surface disease.     

Expression von Matrixmetalloproteinase-19 in der humanen Kornea

Background

At present there are no data in the literature on the expression of matrix metalloprotein-19 in the human cornea. The aim of this study was to analyze the expression of matrix metalloproteinase-19 in the human cornea and to investigate its potential role in corneal wound healing using a MMP-19 knock-out mouse model.

Methods

A method with Western blotting and immunohistological staining for MMP-19 was performed using paraffin embedded human corneas. Excimer laser keratectomy was performed in wild type (wt) and MMP-19 knock-out (ko) mice and the rate of re-epithelialization was analyzed after 8 h and 18 h.

Results

MMP-19 was strongly expressed in the human corneal epithelium mainly in the basal cell layer. MMP-19 was not expressed in the corneal stroma. In the mouse model the size of the corneal lesion after 8 h was 83% (wt) and 89.9% (ko) of the initial area (p=0.09). After 18 h the lesion was 17% (wt) and 13.3% (ko) of the initial area (p=0.01). Laminin-5 was expressed in the migrating epithelial cells with no differences between wild type and knock-out mouse.

Conclusion

MMP-19 showed a strong expression in the basal cells of the human corneal epithelium. Corneal re-epithelialization was slightly faster in the MMP-19 knock-out mouse. No differences in the expression of laminin-5 could be detected.     

Corneal biomechanical properties in 3 corneal transplantation techniques with a dynamic Scheimpflug analyzer

Purpose

To compare the corneal biomechanical properties of eyes that have undergone penetrating keratoplasty (PK), deep anterior lamellar keratoplasty (DALK), and Descemet stripping automated endothelial keratoplasty (DSAEK).

Methods

This case–control study comprised 20 post-PK eyes, 14 post-DALK eyes, 15 post-DSAEK eyes, and 50 normal control eyes. A dynamic Scheimpflug analyzer (the Corvis ST) was used to evaluate the corneal biomechanical properties including deformation amplitude (DA) and radius at the highest concavity (R _hc).

Results

In post-PK eyes, the mean DA was 1.20 ± 0.13 mm, which was significantly higher than those of the control eyes (1.07 ± 0.09) and the post-DSAEK eyes (1.08 ± 0.12). The DA (1.18 ± 0.18) in the post-DALK eyes was significantly higher than in the control eyes. The R _hc in the post-PK (6.34 ± 0.37 mm), -DALK (6.04 ± 1.22), and -DSAEK (6.44 ± 0.58) eyes was significantly smaller than in the control eyes (7.57 ± 0.78).

Conclusions

The dynamic Scheimpflug analyzer provides a method to obtain new biomechanical information on the cornea such as the DA and R _hc, and these parameters differed among eyes that had undergone 3 different types of corneal surgery. Abnormalities in these parameters after the different corneal transplantation techniques may indicate larger deviations in the stress–strain reaction of the cornea and more uncertainty in the intraocular pressure measurements than in normal eyes.     

Short- and long-term corneal vascular effects of tafluprost eye drops

Background

Prostaglandin analogs are first line therapy in the treatment of glaucoma, but also display side effects during ocular inflammation. In this context, the potential side effects of prostaglandin analogs on the normally avascular cornea, the main application route for eye drops, are so far not fully defined. Therefore, the aim of this study was to evaluate the vascular effects of the prostaglandin analog tafluprost on the healthy and inflamed cornea.

Methods

For in vitro studies, blood and lymphatic endothelial cells were treated with tafluprost; cell proliferation was assessed after 48 h. For long-term in vivo studies under healthy conditions, naïve corneas of BALB/c mice were treated with tafluprost eye drops for 4 weeks. For short-term in vivo studies under inflammatory conditions, corneal inflammation was induced by suture placement; mice then received tafluprost eye drops for 1 week. Afterwards, corneas were stained with CD31 as panendothelial and LYVE-1 as lymphendothelial (and macrophage) marker.

Results

In vitro, tafluprost did not alter blood or lymphatic endothelial cell proliferation. In vivo, there was no change in limbal blood or lymphatic vessel anatomy after long-term treatment with tafluprost. Short-term treatment with tafluprost under inflammatory conditions did not influence the recruitment of LYVE-1 positive macrophages into the cornea. Moreover, treatment of inflamed corneas with tafluprost did not significantly influence corneal hem- and lymphangiogenesis.

Conclusions

Tafluprost does not affect blood and lymphatic vessel growth, neither under resting nor under inflammatory conditions. These findings suggest a safe vascular profile of tafluprost eye drops at the inflammatory neovascularized cornea.     

The Ex Vivo Eye Irritation Test (EVEIT) in evaluation of artificial tears: Purite?-preserved versus unpreserved eye drops

Objective

Preservatives in artificial tears cause controversy. New developments such as the Purite? system have been introduced into the market, with the promise of little damage to the corneal surface. We wanted to give insight into the differences in the effect of preserved and unpreserved artifical tears on rabbit corneas cultured with the Ex Vivo Eye Irritation Test (EVEIT) system.

Materials

We compared the two artifical tears products Hylo Comod? and Optive? being dropped for 72?hours each hour one drop onto the corneal surface.

Methods

Each cornea was mechanically wounded with four epithelial defects on each cornea with a size of 3 to 4.5?mm². With n?=?4 corneas in the Hylo-Comod? and n?=?4 corneas in the Optive? group, we exposed the corneal surfaces to repeated doses of these artificial tears for 3?days. We observed healing of corneal erosions and surface epithelial integrity with sodium-fluoresceine staining under cobalt blue light illumination.

Results

We found nearly complete healing of epithelial defects with both artificial tears. The Hylo-Comod? group healed significantly faster. After 72?hours, the vast majority of epithelial defects were closed. All corneas exposed to Purite? showed superficial stippling, whereas the HyloComod? group did not show any stippling of the cornea; this difference was significant.

Discussion

Epithelial healing and recovery in the EVEIT system is observed in both groups, confirming the concept of artificial tears as a supporting factor of corneal health and healing. The superficial stippling of the corneal epithelium was observed only in the Optive? group. This effect is considered as a marker of dry eye syndrome, and should be prevented by the application of artificial tears. Preservative-free eye drops such as HyloComod? improve healing, and prevent symptoms of dry eye syndrome in the EVEITsystem. Compared to EVEIT results of former experiments with benzalconium chloride-preserved eye drops, Optive? promoted healing of corneal erosions.     

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.