Risk factors for and management of anterior chamber intravitreal dexamethasone implant migration

Background

This study aimed to investigate the incidence of and risk factors for the anterior chamber migration of an intravitreal dexamethasone implant (Ozurdex®).

Methods

A retrospective review of 640 consecutive intravitreal dexamethasone implant injections was conducted from February 2011 through February 2018 at the University Eye Hospital in Tübingen, Germany. Those patients who experienced anterior chamber dexamethasone implant migrations were identified, as well as the reasons for the anterior chamber migration. The surgical histories were obtained and comprehensive ophthalmic examinations were conducted for all of the eyes. Cross-tabulations, chi-squared tests, and Fisher’s exact tests were used to assess the influences of different factors on the anterior chamber implant migrations.

Results

Overall, 4 eyes of four patients (0.63%) showed anterior chamber implant migrations. All four of the eyes were pseudophakic, and they had undergone prior vitrectomies. Three eyes had sclerally-fixated intraocular lenses, and one eye had a posterior chamber intraocular lens in the capsular bag, with a capsular tension ring due to partial zonular dehiscence. When comparing the vitrectomized eyes with reduced zonular/capsular bag complex integrity to the vitrectomized pseudophakic eyes with intact zonular/capsular bags, the former were significantly associated with an increased risk of anterior chamber implant migration (P = 0.008). The vitrectomized pseudophakic eyes, in contrast to the nonvitrectomized pseudophakic eyes, were significantly associated with an increased risk of anterior chamber implant migration (P = 0.009).

Conclusions

The anterior chamber migration of an intravitreal dexamethasone implant is a serious complication. To minimize the risk of permanent corneal edema, immediate removal of the implant with a 20-gauge alligator forceps over a 2.75-mm long clear corneal tunnel is important. Those patients with insufficient zonular support, defects, or missing posterior capsular membranes and vitrectomy histories present a high risk of anterior chamber dexamethasone implant migration.

Establishment of a retinal hypoxia organ culture model

Hypoxia plays an important role in several retinal diseases, especially in central retinal artery occlusion (CRAO). Although CRAO has been known for over a hundred years, no cure or sufficient treatment is available. Potential therapies are being evaluated in several in vivo models or primary cultures. However, in vivo models or primary cultures are very time-consuming, expensive, and furthermore several therapies or agents cannot be tested. Therefore, we aimed to develop a standardized organotypic ex vivo retinal hypoxia model. A chamber was developed in which rat retinal explants were incubated for different hypoxia durations. Afterwards, the retinas were adjusted to normal air and incubated for 24, 48 or 72 h under standard conditions. To analyze the retinal explants, and in particular the retinal ganglion cells (RGC) immunohistology, western blot and optical coherence tomography (OCT) measurements were performed. To compare our model to a standardized degeneration model, additional retinal explants were treated with 0.5 and 1 mM glutamate. Depending on hypoxia duration and incubation time, the amount of RGCs decreased and accordingly, the amount of TUNEL-positive RGCs increased. Furthermore, β-III-tubulin expression and retinal thickness significantly decreased with longer-lasting hypoxia. The reduction of RGCs induced by 75 min of hypoxia was comparable to the one of 1 mM glutamate treatment after 24 h (20.27% versus 19.69%) and 48 h (13.41% versus 14.41%) of incubation. We successfully established a cheap, standardized, easy-to-use organotypic culture model for retinal hypoxia. We selected 75 min of hypoxia for further studies, as approximately 50% of the RGC died compared to the control group after 48 h.

Summary: An easy-to-use ex vivo retinal hypoxia model is introduced that reliably induced retinal damage on a morphological (retinal thickness), and molecular (protein expression and apoptotic markers) level.

Transfer characteristics of subretinal visual implants: corneally recorded implant responses

PURPOSE

The subretinal Alpha IMS visual implant is a CE-approved medical device for restoration of visual functions in blind patients with end-stage outer retina degeneration. We present a method to test the function of the implant objectively in vivo using standard electroretinographic equipment and to assess the devices' parameter range for an optimal perception.

METHODS

Subretinal implant Alpha IMS (Retina Implant AG, Reutlingen, Germany) consists of 1500 photodiode-amplifier-electrode units and is implanted surgically into the subretinal space in blind retinitis pigmentosa patients. The voltages that regulate the amplifiers' sensitivity (V _gl) and gain (V _bias), related to the perception of contrast and brightness, respectively, are adjusted manually on a handheld power supply device. Corneally recorded implant responses (CRIR) to full-field illumination with long duration flashes in various implant settings for brightness gain (V _bias) and amplifiers' sensitivity (V _gl) are measured using electroretinographic setup with a Ganzfeld bowl in a protocol of increasing stimulus luminances up to 1000 cd/m².

RESULTS

CRIRs are a meaningful tool for assessing the transfer characteristic curves of the electronic implant in vivo monitoring the implants' voltage output as a function of log luminance in a sigmoidal shape. Changing the amplifiers' sensitivity (V _gl) shifts the curve left or right along the log luminance axis. Adjustment of the gain (V _bias) changes the maximal output. Contrast perception is only possible within the luminance range of the increasing slope of the function.

CONCLUSIONS

The technical function of subretinal visual implants can be measured objectively using a standard electroretinographic setup. CRIRs help the patient to optimise the perception by adjusting the gain and luminance range of the device and are a useful tool for clinicians to objectively assess the function of subretinal visual implants in vivo.

The influence of axial length on confocal scanning laser ophthalmoscopy and spectral-domain optical coherence tomography size measurements: a pilot study

PURPOSE

To investigate the influence of axial length on SD-OCT and cSLO size measurements from the Heidelberg Spectralis.

METHODS

In this pilot study, eight emmetropic pseudophakic eyes with subretinal visual implant were selected. The axial length was measured in three short (<22.5 mm), three medium (22.51-25.50 mm) and two long (>25.52 mm) eyes. The known size of subretinal implant sensor field (2800 × 2800 μm) was measured on 15 images per eye with cSLO and SD-OCT.

RESULTS

The mean axial length was 20.8 ± 0.8 mm in short eyes, 23.3 ± 0.4 mm in medium eyes, and 26.3 ± 0.5 mm in long eyes respectively. We found in short eyes, in medium eyes and in long eyes a mean value of sensor field size measurements from cSLO of 3327 ± 9 μm, 2800 ± 9 μm and 2589 ± 12 μm and from SD-OCT of 3328 ± 9 μm, 2800 ± 12 μm and 2585 ± 19 μm respectively. The size measurements decreased in SD-OCT and cSLO measurements with longer axial lengths significantly (p < 0.0001).

CONCLUSION

The present findings demonstrate accuracy of the scaling in cSLO and SD-OCT measurements of the Heidelberg Spectralis for emmetropic medium eyes. The size measurements from SD-OCT to those from cSLO were approximately equal. Caution is recommended when comparing the measured values of short and long eyes with the normative database of the instrument. Further studies with larger sample sizes are needed to confirm findings.

[Development and first results of fast and cost-effective examination methods for an ophthalmological screening within the National Cohort]

BACKGROUND

For an implemented ophthalmological screening within a German long-term cohort study (National Cohort) simple and effective methods for an examination of visual acuity and for non-mydriatic retina photografies should be evaluated. Furthermore standard operating-procedures (SOP) should be developed.

METHODS

In the years 2011 and 2012 pinhole visual acuity measurements and automated retina photographies (DRS, CenterVue S. p. a., Padua, Italy) were made at three different epidemiological study centers within Germany. Furthermore, anterior segment images were taken by the camera. Standard operating procedures (SOP) regarding the ophthalmological screening were developed and evaluated within the study. The main question was whether it is possible to implement the screening methods within the National Cohort. Further main outcomes were quality and interpretability of the taken images.

RESULTS

457 subjects (914 eyes) were examined within the investigation. Median VA was 0.8 for right and left eyes (p > 0.42). Image quality of the photographies was good in 491 cases (54 %), fair in 239 cases (26 %) and bad in 179 cases (20 %). The usability of the images was without limitations in 686 cases (75 %), limited in 152 cases (17 %) and not given in 71 cases (8 %). Increasing age of the subjects was slightly correlated with decreasing image quality (r = 0.26) and decreasing image usability (r = 0.2). Anterior segment photographies were usable in 176 eyes (56 %).

CONCLUSION

The developed screening method fulfilled the specifications of the National Cohort. The used pinhole visual acuity examination was fast and cheap. Image quality and usability of the retina photographies could be improved with prolonged pupil recovery times. The quality of the anterior segment images could not fulfill the expectations and were taken out of the further examinations of the ophthalmological screening. The written SOP showed good acceptance within the investigators' daily routine. The ophthalmological screening within the National Cohort generates information (e. g., pathologies of the vessels or of the retina) which are useful not only from an ophthalmological point of view.

[Improvement of power and illumination source of the indirect binocular ophthalmoscope designed by Foerster]

BACKGROUND

Since 1982, the indirect binocular ophthalmoscope designed by Foerster has been in use in ophthalmology. The option to implement a new illumination technique using a light-emitting diode (LED) and a new power source should be evaluated in terms of technical feasibility and patient safety.

METHODS

The cooling element was redesigned to accommodate the new LED electronics and their components, including an option for a variable brightness control. A more compact rechargeable battery was utilized with variable fixation at the headband or elsewhere. Photometric measurements of light intensity and the operating time were planned. Furthermore, a review of the new lighting technology in terms of EN ISO 15004-2 and EN ISO 10943 was necessary.

RESULTS

Technical adjustments to accommodate the LED inside the cooling element could be realised. The power source was a modern rechargeable lithium-ion battery with variable fixation. The luminous intensity of the LED is superior to that of the halogen lamp and the operating time was increased to 520 minutes. The required limits according to DIN EN ISO 15004-2 for ophthalmic devices were met by our measurements.

CONCLUSION

The optimisation of the indirect binocular ophthalmoscope brings improvements in illumination intensity and operating time. A conversion for models already in use is possible. A certified appraisal for compliance with the appropriate standards is the next step.

Characterisation of novel uveal melanoma cell lines under serum-free conditions

BACKGROUND

The establishment of long-term uveal melanoma (UM) cell lines is difficult. However, studying living cells and their behaviour in the presence of other cells and the extracellular matrix is important in terms of understanding tumour biology and malignant behaviour. We have established three UM cell lines and report a first characterisation of these cell lines.

METHODS

Three established UM cell lines (UMT2, UMT26 and UMT33) were analysed according to their morphologic characteristics, melanocytic differentiation, adhesion on different extracellular matrices and proliferative activity. Copy number changes of chromosomes 1, 3, 6 and 8 were studied by multiplex ligation-dependent probe amplification (MLPA). Oncogenic mutations in UM involving exons 4 and 5 of GNAQ and GNA11, respectively, were analysed by sequencing.

RESULTS

All cell lines grew in suspension. UMT2 cells were homogeneous, UMT26 and UMT33 cells heterogeneous with regard to cell size and pigmentation. All UM cell lines revealed a melanocytic differentiation. UMT2 and 33 adhered on various extracellular matrices, while UMT26 only adhered to basal membrane extract (BME). This difference corresponded to the different expression of various integrins. Ki67 was expressed by 89% of UMT2 and 95% of UMT33 cells, which thus were in a proliferative stage, while only 2% of UMT26 cells revealed immunostaining for this proliferation marker. The doubling time of UMT2 was 3 days, 12 days for UMT33, and circa 3-4 months for UMT26. MLPA revealed disomy 3 in UMT2 and monosomy 3 in UMT33. The same point mutation was found in UMT2, 26 and 33, in exon 5 of GNA11 at codon 209 (p.Q209L).

CONCLUSIONS

The establishment of UM cell lines under serum-free conditions is possible. Characterisation of UMT2, 26, and 33 revealed obvious differences in cytomorphology, melanocytic differentiation, adhesion on extracellular matrices, and proliferative activity. UMT2, 26 and 33 showed the same oncogenic mutation in exon 5 of GNA11.

[Chronic central serous chorioretinopathy (cCSC): differential diagnosis to choroidal neovascularisation (CNV) secondary to age-related macular degeneration (AMD)]

Central neurosensory detachments (NSD) with time-dependent height constitute a disease called central serous chorioretinopathy (CSC), if not arising from uveitis, choroidal neovascularisations (CNV) or leaking retinal vessels. In 10 % of these patients, CSC develops into a chronic disease with recurrent NSD, atrophy of photoreceptors and severe drop in visual acuity. This review article summarises recent progress in understanding this disease and its appearance in funduscopy, FLA, ICG, OCT, autofluorescence as well as its progress, therapy and possible development into secondary CNV. The provided examples illustrate the progression of acute CSC into chronic CSC and with CNV over years. The different appearance of polypoidal choroidal vasculopathy (PCV) in ICG and some of the signs of atypical chronic CSC are discussed. To distinguish between cCSC and wet AMD--both exhibiting leakage in FLA--typical signs are helpful, e.g., "gravitational tracks", retinal precipitates and missing drusen. However, in small lesions, it may be difficult or almost impossible to ensure the correct diagnosis of the underlying disease. The same holds for occult and classic secondary CNV in cCSC vs. CNV in AMD, where photodynamic therapy (PDT) can be successful only in cCSC-CNV and in cCSC without CNV. Corticosteroids often lead to further impairment, even in cases of atypical cCSC, when frequently misdiagnosed as uveitis. As a duration of NSD of more than 4 months is suspected to induce an impairment of photoreceptors, regular examinations are necessary not only in chronic CSC but also after acute CSC (as this form can develop into chronic CSC), while effective therapies are available to resolve the NSD (PDT, anti-VEGF).

[Therapy of myopic choroidal neovascularization]

Recently published studies have shown that myopic choroidal neovascularization (mCNV) is efficiently treated by anti-vascular endothelial growth factor (VEGF) drugs. Within a prospective executive study, photodynamic therapy failed to prove a significant difference over the duration of 2 years. Although a systematic evaluation of different retreatment algorithms still has to be done the administration of single injections depending on specialist assessment of morphological changes, predominantly spectral domain optical coherence tomography (SD-OCT) and fundus, has achieved a marked visual improvement. The experience of treating age-related macular degeneration should not be simply transferred to mCNV and an individual approach, not only for female patients of childbearing age, is necessary.

[What can blind patients see in daily life with the subretinal Alpha IMS implant? Current overview from the clinical trial in Tübingen]

The subretinal visual implant is a scientific research approach to restore partial vision in end-stage hereditary retinal diseases by replacing the function of the degenerated photoreceptors by microelectronic chips. In a clinical trial in Tübingen these implants were tested on voluntary blind patients. By using the implants in daily living the patients reported valuable visual information. The subretinal microchip mediates subjectively useful visual information in near as well as in distant vision.

[Clinical results after cataract surgery in patients with Behçet's disease]

BACKGROUND

Behçet's disease is a systemic vasculitis disorder of unknown aetiology. Ocular involvement, especially with vasculitis, is detected in up to 80 % of the cases. Anterior segment involvement such as cataract is also seen in the follow-up of patients who are then treated surgically. In this study, we aimed to analyze the outcomes of cataract surgery in patients with Behçet's disease retrospectively.

PATIENTS AND METHODS

The records of 9 patients (12 eyes) with Behçet's disease who underwent phacoemulsification with IOL implantation in 11 eyes and extracapsular cataract extraction (ECCE) with IOL implantation in one eye between June 2001 and September 2009 were evaluated retrospectively. The visual outcome and complications were analysed.

RESULTS

The mean follow-up was 33.8 months (range 3 to 88 months). The mean preoperative LogMAR BCVA was 1.15 ± 0.53 (95 % CI: 0.81 - 1.49) and increased to 0.36 ± 0.32 (95 % CI: 0.15 - 0.56) at last medical visit (p < 0.001). The most frequent postoperative complication was posterior capsular opacification, which developed in 2 eyes (17 %). Other complications were mild fibrinous reaction in 1 eye (8 %).

CONCLUSIONS

The outcomes of cataract surgery in patients with Behçet's disease were satisfactory. The great majority of the patients regained and retained a good visual outcome and had fewer postoperative complications.

[Preservative-free triamcinolone versus purified triamcinolone preparations]

BACKGROUND

Intravitreal injections of triamcinolone are not only an important therapeutic tool for a variety of vitreo-retinal disorders, but can also be employed for visualisation of the vitreous during pars plana vitrectomy. Triesence® is a preservative-free triamcinolone suspension that has been approved for visualisation during vitrectomy via intravitreal administration and as intravitreal therapy for certain rare ocular diseases. However, the differences between Triesence® and purified (and thus also preservative-free) triamcinolones such as Volon A® or Kenalog® are not well specified, although the manufacturer of Triesence® advertises the product as "specifically formulated for the eye".

METHODS

The publicly available FDA application material and information provided by the manufacturer for Triesence®, Kenalog® and Volon A® were analysed with respect to the differences between Triesence® and older triamcinolone preparations.

RESULTS

According to the publicly available FDA documents the approval of Triesence mainly was based on studies that have been conducted with the older triamcinolone preparations Kenalog® or purified Volon A®. Apart from the absence of preservative the differences between Triesence® and the "older" triamcinolone preparation seem marginal. Published experimental or clinical studies in respect to the possible advantages of Triesence® compared to Kenalog® or Volon A® are lacking. Triesence® has been approved for sympathetic ophthalmia, temporal arteriitis, uveitis unresponsive to topical corticosteroids and for enhancing tissue visualisation during vitrectomy. Recently, the manufacturer of Kenalog® added a warning label ("not for intraocular use") on each vial of Kenalog®. The motifs for this re-labelling of Kenalog® remain unclear.

CONCLUSION

Apart from the intraoperative use during vitrectomy Triesence® has only been approved for sympathetic ophthalmia, temporal arteriitis, and ocular conditions unresponsive to topical steroids. Consequently, the use of Triesence® like the older triamcinolone preparations (Kenalog® or Volon A®) for diabetic macular oedema, for Irivine-Gass syndrome, for neovascular AMD or after retinal vein occlusion is off-label.

The effects of ranibizumab (Lucentis) on retinal function in isolated perfused vertebrate retina

BACKGROUND

Intraocular ranibizumab (Lucentis, Novartis, Basel Switzerland) is the primary choice in the treatment of neovascular age-related macular degeneration (AMD). Vascular endothelial growth factor (VEGF) is known to be a survival factor for neuronal cells. Therefore, blockage of all VEGF isoforms by ranibizumab could induce retinal dysfunction.

METHODS

Using isolated bovine retinas, the electroretinogram (ERG) was recorded as a transretinal potential using Ag/AgCl electrodes, while the retinas were perfused with an oxygen preincubated nutrient solution. For 45 min, ranibizumab was applied at a concentration of 0.2 mg/ml and alternatively the solvent carrier without the active agent. The ERG was monitored before, during and after exposure.

RESULTS

The concentration of 0.2 mg/ml ranibizumab induced a non-significant b-wave reduction of 22.32% after exposure (p = 0.13). For the a-wave amplitude only a reduction of 4% was detected (p = 0.18). The solvent carrier induced no significant reduction of the a- and b-wave amplitudes (p = 0.30 and p = 0.979, respectively).

CONCLUSION

In the ex vivo model, the isolated perfused vertebrate retina, ranibizumab has been proven to be a safe compound at the concentrations applied. The stability of the ERG-amplitudes rules out a considerable retinal dysfunction after an injection of up to 1 mg ranibizumab.

Implications of bevacizumab on vascular endothelial growth factor and endostatin in human choroidal neovascularisation

AIM

To evaluate the implications of intravitreal bevacizumab on proangiogenic vascular endothelial growth factor (VEGF) with regard to the endogenous angiogenesis inhibitor endostatin in human choroidal neovascularisation (CNV) secondary to age-related macular degeneration.

METHODS

Retrospective review of an interventional case series of 48 patients who underwent full macular translocation surgery with removal of CNV. Twenty-five patients were treated with intravitreal bevacizumab injection 1 to 154 days prior to surgery (bevacizumab CNV). Twenty-three CNV without any kind of previous treatment were used as controls (control CNV). CNV were stained for CD34, cytokeratin18, VEGF, endostatin and E-selectin. A "predominance score of VEGF over endostatin" (PS) was defined by the difference between VEGF and endostatin staining scores.

RESULTS

Bevacizumab CNV revealed a weaker VEGF expression in endothelial cells (p = 0.0245) but significantly more intense endostatin in retina pigment epithelium (RPE) (p = 0.0001) and stroma (p<0.0001). Consequently, PS was significantly lower in RPE (p = 0.02), vessels (p = 0.03) and stroma (p = 0.0004) in bevacizumab CNV. The intensity of E-selectin expression in bevacizumab CNV was comparable with that in control CNV.

CONCLUSIONS

A shift within the angiogenic balance in terms of decreased VEGF predominance over endostatin is detected in human CNV treated with bevacizumab.

Extraocular surgery for implantation of an active subretinal visual prosthesis with external connections: feasibility and outcome in seven patients

BACKGROUND

Due to low energy levels in microphotodiode-based subretinal visual prostheses, an external power supply is mandatory. We report on the surgical feasibility and the functional outcome of the extraocular part of an approach to connect a subretinal prosthesis to an extracorporeal connector in the retro-auricular space via a trans-scleral, transchoroidal cable.

METHODS

Seven volunteers with retinitis pigmentosa received an active subretinal implant; energy was supplied by gold wires on a trans-sclerally, transchoroidally implanted polyimide foil leading to the lateral orbital rim where it was fixated and connected to a silicone cable. The cable was implanted subperiostally beneath the temporal muscle using a trocar to the retro-auricular space where it penetrated the skin for connection to a stimulator. To avoid subretinal movement of the implant, three tension relief points have been introduced.

RESULTS

All implantations were performed as planned without complications, and no serious adverse events occurred in the postoperative period. Fixation of the implants was stable throughout the entire study duration of 4 weeks; permanent skin penetration proved to be uncomplicated. Motility was minimally restricted in downgaze and ab-/adduction. Explantation was uneventful.

CONCLUSION

The above-described procedure provides a method for stable fixation of a subretinal device with a trans-scleral, transchoroidal cable connection to an extracorporeal connector.

Vitrektomie bei Uveitis im Kindes- und Jugendalter

PURPOSE

The role of vitrectomy in pediatric uveitis has as yet not been established. Addressing this question has been reinforced since the recent introduction of the new and relatively well tolerated medical treatment options using biologicals, i. e. TNFalpha blocking agents.

METHODS

A systematic review of literature has been supplemented by results of vitrectomy performed in 41 consecutive eyes of 33 children and adolescents at our institution and followed for 0.5 to 10 years.

RESULTS

No single controlled study on the role of vitrectomy for uveitis has been identified. Beyond a total of 44 case series including 1762 eyes within the last 25 years, 3 papers specifically focussed on vitrectomy for pediatric uveitis including 73 eyes. This series included 29 eyes of our series. Published and recent own data indicate 2 specific findings consistent for all series: reduction of CME presence from 36 to 6.9% with a resulting visual improvement in 79.1% of cases and a quietening down of inflammatory activity postoperatively allowing to taper down or stop steroid and immunosuppressive therapy from preoperatively 80 and 30% to approximately 30 and 10%, respectively.

CONCLUSION

In the absence of evidence-based results, the data from case series indicate that vitrectomy for pediatric uveitis at least meets the expectations from vitrectomy in adult forms of uveitis regarding the reduction of cystoid macular edema and required systemic steroid and immunosuppressive therapies.

Full macular translocation following photodynamic therapy in neovascular age-related macular degeneration

PURPOSE

To report the long-term functional and anatomical outcome of full macular translocation (FMT) in eyes with neovascular age-related macular degeneration (AMD) following photodynamic therapy (PDT).

METHODS

Twelve eyes of 12 consecutive patients with neovascular AMD who were PDT-nonresponders and underwent FMT were analysed. Best-corrected visual acuity (BCVA) measurement, fundus photography, and fluorescein angiography at baseline and at follow-up examinations in 3 months intervals were performed. Primary end point was change of BCVA from baseline to last visit.

RESULTS

Totally 12 eyes of 12 patients were analysed. Mean time interval between the last PDT and FMT was 3.7 months (range 1-10 months). Mean follow-up after FMT was 25.6 months. BCVA ranged at baseline from 20/1000 to 20/80 (mean 20/230). At the last visit, mean BCVA was by 20/185. BCVA improved in 50% (6/12) of eyes by more than 1 line. Twenty five per cent (3/12) of eyes had final BCVA within +/-1 line from baseline. In 25% (3/12) of eyes the BCVA decreased by more than 1 line. One eye had recurrent CNV. In four eyes a cystoid macular oedema developed. No retinal detachment or disturbing diplopia was noted.

CONCLUSIONS

In the present study, FMT in PDT-nonresponders stabilised or improved visual acuity in the majority of the eyes in a mean follow-up period of nearly 2 years. FMT can be considered as a therapeutical option in eyes who are nonresponders to the PDT in neovascular AMD.

[Injector implantation of a scleral-fixated intraocular lens]

BACKGROUND

In this pilot study, a new injector technique for small-incision implantation of scleral-fixated intraocular lenses (IOLs) was evaluated for IOL stability and visual rehabilitation.

PATIENTS AND METHODS

Secondary lens implantation was performed in 18 aphakic eyes using a new small incision technique with injector implantation. This allowed for haptic suturing with the lens body inside the cartridge. All patients were followed-up for best-corrected visual acuity, refraction, IOL evaluation and ultrasound biomicroscopy.

RESULTS

In all eyes the IOL was stable without tilt or torque. Best-corrected visual acuity improved 2.2 ETDRS lines after 1 week and 3.1 lines after a mean follow-up time of 7.9+/-2.8 months. Two eyes were complicated with small, peripheral transillumination defects (n=2), but no pigmentary glaucoma occurred.

CONCLUSION

By using a self-sealing tunnel incision and injector technique, significant fluid egress and consecutive transient hypotony is minimized throughout the whole procedure. The technique shows a high IOL stability without tilt and assures rapid visual rehabilitation.

[Changes of the triple flash electroretinogram after 360 degrees retinotomy and macular translocation for subfoveal choroidal neovascularisation in age-related macular degeneration]

BACKGROUND

The aim of the present study was to evaluate potential electrophysiological changes after 360 degrees retinotomy and macular translocation for subfoveal choroidal neovascularisation in patients with age-related macular degeneration.

METHODS

A consecutive series of 32 patients suffering from subfoveal choroidal neovascularisation secondary to age-related macular degeneration underwent 360 degrees retinotomy and macular translocation. The scotopic triple-flash ERG (TERG) served as the main parameter of the study and was recorded one day prior to the translocation surgery and no earlier than 4 weeks after the silicone oil removal.

RESULTS

The TERG amplitudes were significantly reduced after translocation surgery. Depending on the applied flash luminance the mean amplitude reduction of the first b-wave varied between 67 % (0.2 cds/m (2)) and 74 % (0.03 cds/m (2)). The latency of the second b-wave of the preoperative TERG proved to have predictive power with reference to the postoperative visual acuity. A statistically significant correlation between the latency of the second b-wave for a flash intensity of 0.03 and 0.1 cds/m (2) and the postoperative visual acuity was shown (p = 0,016 and p = 0,049).

CONCLUSIONS

In accordance with previous studies the present study indicates that a significant electrophysiological decrease is caused by surgical procedures associated with macular translocation. In future, due to predictive parameters of the TERG the preoperative selection of patients could be improved.

Surgical treatment of peripapillary choroidal neovascularisation

OBJECTIVE

To report the functional and morphological outcome of surgical treatment of peripapillary choroidal neovascularisation due to age-related macular degeneration.

METHODS

Consecutive interventional case series of eight patients with extensive peripapillary choroidal neovascularisation and accompanying haemorrhage who underwent subretinal surgery including extraction of the neovascular complex. Ophthalmic examination, including visual acuity testing, colour photography and fluorescein angiography, was performed at baseline and at 3, 6, 9 and 12 months, and then yearly.

RESULTS

Mean follow-up was 26 months (12-60 months). Preoperative best corrected visual acuity (BCVA) ranged from logMAR (logarithm of minimum angle of acuity) 1.0 (20/200) to logMAR 0.0 (20/20), with a mean of logMAR 0.5 (20/63). Mean postoperative BCVA was logMAR 0.3 (20/40). BCVA improved in six patients, was stable in one patient and deteriorated in one patient. Two years after surgery, one patient developed recurrence of the CNV that was removed surgically. One patient showed retinal detachment 5 years after subretinal surgery.

CONCLUSIONS

In this small case series of PPCNV, functional improvement was achieved after surgery in the majority of patients. Surgical extraction of the CNV represents an alternative treatment option in eyes with vision-threatening extensive PPCNV. Randomised controlled studies seem to be justified to evaluate further the beneficial effect and long-term functional outcome of this therapy approach.

[Effect of timolol on central corneal thickness and endothelial cell density]

BACKGROUND

The measurement of corneal thickness plays an increasing role in glaucoma screening and diagnosis. The influence of a variety of drugs on corneal thickness is well established. Especially for antiglaucomateous drugs this effect seems to be important. However, little is known about the influence of beta receptor antagonists on corneal thickness. The aim of this study was to provide evidence of the effect of timolol on central corneal thickness and endothelial cell density.

MATERIALS AND METHODS

Ten healthy volunteers (five women and five men) with a mean age of 29 years (range 25 to 56 years) were examined in a double-blind, prospective and randomised pilot study. Intraocular pressure, corneal thickness and endothelial cell density was estimated before as well as fifteen minutes, 24, 48, 72 and 96 hours after application of timolol 0.5 % eye drops twice daily. The partner eye received sodium hyaluronate eye drops twice daily and served as a control.

RESULTS

The application of timolol showed a decrease of intraocular pressure from initially 12 mmHg to 9 mmHg after four days (p = 0,0188) as well as an increase of corneal thickness from 537 microm to 557 microm after four days (p = 0,0659). There was no change of intraocular pressure (p = 0,9935) or corneal thickness (p = 0,9998) in the control eyes. There was also no effect of timolol (p = 0,2782) or sodium hyaluronate (p = 0,1940) on endothelial cell density.

CONCLUSIONS

The study provides evidence of the influence of beta receptor antagonists on corneal thickness. This effect may be caused by receptor mediated influences on corneal ion and fluid transport. Further studies are needed to show if the increase of corneal thickness after application of topical timolol has clinical importance.

[Current strategies for macular hole surgery in Germany, Austria and Switzerland]

BACKGROUND

Main aim of this study was to determine how macular hole surgery is currently being performed in Germany, Austria and Switzerland.

METHODS

A questionnaire concerning the different aspects of surgery for stage 3 macular hole was developed and sent out to the 380 members of the German Retina Society.

RESULTS

This analysis is based on 129 returned questionnaires from colleagues who perform macular hole surgery. A total of 95% (n=123) of the surgeons routinely perform vitrectomy with posterior vitreous detachment, peeling of epiretinal tissue and internal limiting membrane (ILM) peeling. Some 86% (n=106) stain the ILM, with 80% of these (n=85) using indocyanine green (ICG) in concentrations ranging from 0.005% up to 10%. Fourteen percent of ICG users perform a fluid-air exchange before applying the dye. Platelet concentrate is used by 8% of the surgeons with 97% (n=125) performing a gas tamponade using SF6 (53%), C3F8 (22%), C2F6 (16%) or just air (5%) (multiple answers: 4%). Simultaneous cataract surgery is routinely performed by 8%; by 73% only if there is significant cataract.

CONCLUSIONS

There is common consent on the basic surgical steps, but several surgical details, e.g. ILM staining, are performed in substantially different ways.

[Protein kinase C isoforms in corneal epithelium and endothelium]

BACKGROUND

Protein kinase C (PKC) plays a key role in cell metabolism. Three subgroups and 12 isoforms have been isolated so far, catalysing specific functions in cell metabolism. The demonstration of PKC subtypes in corneal tissue has been inconsistent. The aim of this study was to verify the expression of several PKC subgroups and isoforms in human and bovine corneal epithelial and endothelial cells.

MATERIALS AND METHODS

PKC subgroups and isoforms were studied using polyclonal antibodies.

RESULTS

Antibodies to PKC-alpha, -delta, -epsilon and -zeta, representing all three PKC subgroups, bound in human and bovine corneal epithelium and endothelium. No binding was found for antibodies to PKC-beta2.

CONCLUSIONS

For the first time the presence of all three PKC subgroups was demonstrated in human and bovine corneal epithelial and endothelial cells. Further studies are needed to show the role of these subgroups in cellular functions such as cell proliferation and differentiation.

Intravitreal bevacizumab (Avastin) for occult choroidal neovascularization in age-related macular degeneration

BACKGROUND

The purpose of the study is to report data on short-term safety of intravitreal bevacizumab treatment and its effect on visual function, central retinal thickness, and angiographical changes of occult choroidal neovascularization due to age-related macular degeneration.

METHODS

A consecutive interventional case series of 30 patients with active subfoveal occult choroidal neovascularization secondary to age-related macular degeneration was followed after one intravitreal injection of 1.25 mg bevacizumab at baseline and subsequent injections following standardized criteria. At baseline and follow-up visits patients had visual acuity assessment, intraocular pressure measurement, fluorescein angiography, and optical coherence tomography imaging.

RESULTS

No serious ocular or systemic adverse events were identified. A significant increase of intraocular pressure or signs of retinal toxicity or endophthalmitis were not detected in any patient. Optical coherence tomography revealed significant decrease (p < 0.001) in central retinal thickness after 1 week, 4 weeks, and 12 weeks, respectively. Fluorescein leakage decreased within 1 week and improvement was maintained at week 12 in the majority of patients. Visual acuity improved or remained stable in 29 of 30 patients; improvement of 3 or more lines was seen in 14 of 30 patients; one patients showed improvement of 6 lines. No patient had severe vision loss of 6 lines or more; moderate vision loss of 3 lines was seen in one patient. Re-injections of bevacizumab according to standard criteria were performed one to two times during the follow-up period of 12 weeks with a re-injection interval of 4 to 18 weeks (median 8 weeks).

CONCLUSIONS

Short-term results suggest that intravitreal injection of bevacizumab is well tolerated and for the majority of patients with occult choroidal neovascularization in AMD results in improvement of visual acuity, decrease in central retina thickness, and reduction of angiographic leakage of the lesion. Bevacizumab as intravitreal treatment may provide a novel therapeutic option for selected patients with exudative AMD. Randomized prospective multicenter trials seem justified to further evaluate long term effects and impact of intravitreal bevacizumab on different subtypes of AMD compared to established therapies.

[(Side) effects of VEGF inhibition]

Vascular endothelial growth factor (VEGF) plays a pivotal role for embryo- and organogenesis. By regulating haemodynamics, (lymphoid) vessel architecture, haematopoiesis and immune system, endocrinology and reparative processes in adults, inhibited VEGF can cause multiple adverse events. Although the intravitreal administration of smaller doses can drastically reduce the systemic exposure, possible local side effects on retinal perfusion and survival of neuronal tissue must be taken into consideration. Before experience has been gained with VEGF inhibitors for longer than several years, individual discussion before the use, extensive informed consent and careful follow-up are necessary. From the ethical point of view, the available drugs should not be used without hesitation despite the clear benefit. First experiences with bevacizumab (Avastin), the first available (off-label) drug in Germany, are reported. In future, direct comparison of the different available drugs has to assess possible differences in the risk-benefit profile.

Effects of bevacizumab on retinal function in isolated vertebrate retina

BACKGROUND

Bevacizumab (Avastin) is a recombinant protein that targets vascular endothelial growth factor (VEGF). In vitro, bevacizumab inhibits VEGF induced cell proliferation and tissue factor production. Abnormal angiogenesis involving VEGF is a central event during the development of choroidal neovascularisation (CNV). The present study was designed to evaluate the short term toxic effects of bevacizumab on retinal function for a therapeutic intraocular application.

METHODS

Isolated bovine retinas were perfused with an oxygen pre-incubated nutrient solution. The electroretinogram (ERG) was recorded as a transretinal potential using silver/silver chloride electrodes. Bevacizumab was added in different concentrations to the nutrient solution for 45 minutes. Thereafter the retina was reperfused for 60 minutes with normal nutrient solution. The percentage of a-wave and b-wave reduction during the application of bevacizumab was calculated and compared to control recordings.

RESULTS

During the application of three different concentrations of bevacizumab (0.08 mg/ml, 0.25 mg/ml, 0.8 mg/ml) no significant reduction of the a-wave and b-wave amplitude was observed. During the washout, the ERG amplitudes were unchanged.

CONCLUSION

The present study suggests that an intraocular application of 0.25 mg/ml bevacizumab for the treatment of CNV is reasonable. No significant short term effects of bevacizumab on retinal function were detected, but long term effects cannot be excluded.

Bevacizumab zur Therapie des sekundären Makulaödems nach venösen Gefäßverschlüssen

Application of VEGF inhibitors represents a treatment option for macular edema secondary to retinal vein occlusion that targets the disease at the causal molecular level. First reports on intravitreal injections of bevacizumab show promising morphological and functional effects and demonstrate that bevacizumab is a potent antiedematous agent in this context. A significant reduction of the central retinal thickness followed by a rapid improvement of visual acuity may be achieved within days. In a pilot study with a review period of 3 months, we found a significant improvement of one or more lines in 93% and four or more lines in 27% of eyes. This was associated with a concomitant significant reduction in central retinal thickness, which, however, was not sustained by a single injection (64% reduction after 1 month and 28% after 3 months). No relevant adverse events were noted. The duration of action after intravitreal bevacizumab administration is currently unknown. Reinjections will be necessary to maintain a lasting beneficial effect. Prospective, controlled long-term studies are mandatory to develop standardized treatment protocols that allow a safe and effective application of this off-label therapy.

Intravitreales Bevacizumab bei der neovaskulären altersabhängigen Makuladegeneration

The efficacy and safety of the therapeutic anti-VEGF concept has already been demonstrated for pegaptanib and ranibizumab. Bevacizumab acts as an antibody against all VEGF-A isoforms and has been developed for oncological indications with intravenous application. Initial reports on intravitreal administration in patients with neovascular age-related macular disease (AMD) have shown beneficial morphological and functional effects. In the meantime, bevacizumab has been used off-label in thousands of patients with AMD. However, data from prospective, controlled, randomized trials on both safety and efficacy are lacking. Herein recent experiences with bevacizumab are summarized and discussed. Furthermore, a web-based platform for online data registration and pooled analyses is presented.

Antiproliferative and cytotoxic properties of bevacizumab on different ocular cells

AIM

To evaluate the antiproliferative and cytotoxic properties of bevacizumab, a monoclonal antibody against vascular endothelial growth factor (VEGF), on human retinal pigment epithelium (ARPE19) cells, rat retinal ganglion cells (RGC5), and pig choroidal endothelial cells (CEC).

METHODS

Monolayer cultures of ARPE19, RGC5, and CEC were used. Bevacizumab (0.008-2.5 mg/ml), diluted in culture medium, was added to cells that were growing on cell culture dishes. Cellular proliferative activity was monitored by 5'-bromo-2'-deoxyuridine (BrdU) incorporation into cellular DNA and the morphology assessed microscopically. For cytotoxicity assays ARPE19, RGC5, and CEC cells were grown to confluence and then cultured in a serum depleted medium to ensure a static milieu. The MTT test was performed after 1 day. The "Live/Dead" viability/cytotoxicity assay was performed and analysed by fluorescence microscopy after 6, 12, 18, 24, 30, 36, and 48 hours of incubation. Expression of VEGF, VEGF receptors (VEGFR1 and VEGFR2) and von Willebrand factor was analysed by immunohistochemistry.

RESULTS

No cytotoxicity of bevacizumab on RGC5, CEC, and ARPE19 cells could be observed after 1 day. However, after 2 days at a bevacizumab concentration of 2.5 mg/ml a moderate decrease in ARPE19 cell numbers and cell viability was observed. Bevacizumab caused a dose dependent suppression of DNA synthesis in CEC as a result of a moderate antiproliferative activity (maximum reduction 36.8%). No relevant antiproliferative effect of bevacizumab on RGC5 and ARPE19 cells could be observed when used at a concentration of 0.8 mg/ml or lower. CEC and ARPE 19 cells stained positively for VEGF, VEGFR1, and VEGFR2. More than 95% of the CEC were positive for von Willebrand factor.

CONCLUSIONS

These experimental findings support the safety of intravitreal bevacizumab when used at the currently applied concentration of about 0.25 mg/ml. Bevacizumab exerts a moderate growth inhibition on CEC when used in concentrations of at least 0.025 mg/ml. However, at higher doses (2.5 mg/ml) bevacizumab may be harmful to the retinal pigment epithelium.