Matched case-control comparison of surgical success after XEN45 Gel Stent and PRESERFLO MicroShunt implantation in a Caucasian population.

BACKGROUND: The aim of this study was to compare the outcome of implantation of a XEN45 Gel Stent with the outcome of implantation of a Preserflo MicroShunt in a matched-pair analysis in eyes being naïve to filtering surgery. METHODS: In this comparative, retrospective study, 50 eyes that had undergone XEN45 Gel Stent implantation were compared with 50 eyes after Preserflo implantation. Follow-up was at least 6 months, and surgical success was measured by criteria A (IOP < 21 mmHg, IOP reduction >20%, no repeat surgery); criteria B (IOP < 18 mmHg, IOP reduction >20%, no repeat surgery); and criteria C (IOP ≤15 mmHg, IOP reduction ≥40%, no repeat surgery). RESULTS: After a follow-up period of 12 months, mean IOP had decreased from preoperative 25.2 ± 4.8 mmHg in the XEN group to 14.5 ± 4.0 (n = 35) and from 25.3 ± 6.8 mmHg to 11.9 ± 2.9 (n = 41) in the Preserflo group, respectively. The IOP at the last follow-up of the two groups differed significantly (p < 0.01). The probability of surgical success did not differ concerning Criteria A and B, but surgical success was significantly higher in the Preserflo group for Criteria C (60%, p < 0.01). CONCLUSION: Both the Preserflo and XEN45 Gel Stent provide an effective and safe treatment option for advanced glaucoma and have a high potential to reduce intraocular pressure. Absolute IOP levels of <16 mmHg after 12 months were significantly more frequent in the Preserflo group.

Combined versus standalone XEN45 Gel Stent implantation in either phakic or pseudophakic patients: a case-matched study.

PURPOSE: To determine differing outcomes among either phakic or pseudophakic patients who received standalone XEN45 Gel Stent (Allergan, an AbbVie Company, CA, USA) implantation and patients who underwent combined surgery with phacoemulsification. METHODS: This retrospective single-center study involved 180 eyes of 180 participants who underwent XEN45 Gel Stent implantation, of which 60 eyes received combined surgery with phacoemulsification (combined group). Standalone stent implantation was performed on 60 phakic (phakic group) and on 60 pseudophakic eyes (pseudophakic group). The groups were matched in a ratio of 1:1:1 based on multiple criteria. Successful surgery was defined by three scores: IOP at the longest follow-up of < 21 mmHg (Score A) or < 18 mmHg (Score B) and an IOP reduction > 20% or IOP ≤ 15 mmHg and an IOP reduction ≥ 40% (Score C). In all scores, one open conjunctival revision was allowed, and additional repeat surgery was considered a failure. RESULTS: After an average follow-up time interval of 20.6 ± 12.6 months, there was a mean IOP-reduction by 37% among the entire cohort. Comparative analysis between the three groups did not show significant differences regarding postoperative IOP, postoperative medication score, side effects, revision rate, repeat surgery rate or success rate. A dysfunctional stent was detected in eight eyes (4%) during open conjunctival revision in 76 eyes. CONCLUSION: The clinical endpoints investigated did not differ significantly among either phakic or pseudophakic patients who received standalone stent implantation and patients who underwent combined surgery. However mean latency between primary stent implantation and first revision surgery after combined surgery was markedly shorter.

Predictability of success for combined iStent inject trabecular bypass implantation with phacoemulsification in the subsequent eye.

BACKGROUND: To investigate in combined iStent inject implantation with phacoemulsification carried out bilaterally, whether intraocular pressure (IOP)-lowering effectiveness in the first eye has a predictive potential for the outcome of the second eye in primary open-angle glaucoma (POAG). METHODS: This retrospective study included 72 eyes from 36 participants, who underwent trabecular bypass implantation in combination with cataract surgery at two study centres (Düsseldorf, Cologne). Surgery was classified as either 'success' or 'failure' based on three scores: IOP at follow-up <21 mmHg (Score A) or IOP < 18 mmHg (Score B), with an IOP reduction >20% respectively, without re-surgery and IOP ≤ 15 mmHg with an IOP reduction ≥40%, without re-surgery (Score C). RESULTS: The IOP lowering outcomes of first and second eyes did not differ significantly. There was a significantly higher chance of success in the second eye after effective surgery in the first eye compared with cases after a preceding failure. Within our cohort, a 76% probability of success for the subsequent eye was determined following prior success for Score A. This probability was reduced to 13% if surgery in the first eye failed. The respective probabilities were 75% and 13% for Score B and 40% and 7% for Score C. CONCLUSIONS: In bilateral trabecular bypass implantation combined with cataract surgery, there is a high predictive potential for subsequent eyes based on the extent of IOP-lowering in the initial eye, which should be considered by the surgeon for second eye surgeries.

TREATMENT OF PERSISTENT MACULAR HOLES WITH HEAVY SILICONE OIL.

BACKGROUND/PURPOSE: To determine anatomical success and best-corrected visual acuity after secondary surgery with heavy silicone oil tamponade in patients with persistent full-thickness macular holes. METHODS: In this retrospective study, 63 eyes with persistent full-thickness macular holes after primary pars plana vitrectomy and internal limiting membrane peeling underwent secondary surgery with heavy silicone oil tamponade. Macular spectral domain optical coherence tomography and best-corrected visual acuity measurements were performed during the follow-up. RESULTS: Fifty of 63 eyes (79.4%) achieved anatomical success. In eyes achieving anatomical success, best-corrected visual acuity before primary vitreoretinal surgery was significantly better (0.77 [∼20/125 Snellen] ± 0.24 [1.3-0.3] logarithm of the minimum angle of resolution) compared with eyes not achieving anatomical success (0.88 [∼20/160 Snellen] ± 0.17 [1.1-0.6] logarithm of the minimum angle of resolution, P = 0.044). Minimum linear diameter of full-thickness macular holes was significantly smaller in eyes achieving anatomical success, both before primary (403.4 ± 128.7 [199.0-707.0] µ m vs. 568.1 ± 209.1 [307.0-953.0] µ m, P = 0.009) and secondary surgery (464.1 ± 215.0 [178.0-1,521.0] µ m vs. 663.3 ± 228.5 [451.0-1,301.0] µ m, P = 0.010). Patients remaining phakic during all three surgeries did not benefit from best-corrected visual acuity improvement, although anatomical success was achieved. CONCLUSION: Heavy silicone oil tamponade in secondary surgery for persistent full-thickness macular holes is a safe and efficient surgical method. Best-corrected visual acuity and minimum linear diameter before surgery may be indicators for anatomical success.

Predictability of ab-interno trabeculectomy success in the subsequent eye: A contralateral eye comparison study.

BACKGROUND: To determine whether the outcome of the first eye may serve as a predictor for intraocular pressure (IOP)-lowering effectiveness in the second eye following bilateral ab interno trabeculectomy. METHODS: This retrospective single-centre study included 168 eyes from 84 participants, who underwent combined Trabectome surgery with phacoemulsification cataract surgery in a hospital setting. The clinical endpoint was defined as either 'success' or 'failure' based on four separate scores at the longest follow-up time point: IOP at follow-up <21 mm Hg (Score A) or IOP < 18 mm Hg (Score B), without re-surgery and IOP reduction >20%; IOP ≤15 mm Hg without re-surgery and IOP reduction ≥40% (Score C); and the sole absence of re-surgery according to the discretion of the surgeon (Score D). RESULTS: No significant difference was observed between the outcomes of first and second eyes. The frequency of success in the second eye after effective surgery in the first eye significantly exceeded that after prior failure. Within our analysis, the probability calculations determined a 75% chance of success following prior success for Score A. If surgery in the first eye failed, the chance of success in the subsequent eye was 37%. The corresponding probabilities were 79% and 32% for Score B, 56% and 9% for Score C, and 99% and 50% for Score D. CONCLUSION: The results of our study offer a useful tool to assess the success of subsequent eye surgeries based on the outcome in the initial eye, owing to the high predictive potential.

Trabectome, trabecular aspiration and phacoemulsification in a triple procedure for treating exfoliation glaucoma: A long-term follow-up.

PURPOSE: This study investigates the long-term intraocular pressure (IOP) lowering potential, risk profile and success rate of a triple procedure comprising phacoemulsification, trabecular aspiration and trabectome (Microsurgical Technology, Redmond, WA, USA) for treating exfoliation glaucoma. METHODS: A total of 117 eyes of 117 patients with exfoliation glaucoma underwent a combination of phacoemulsification, trabectome and trabecular aspiration. They were followed up for up to 7 years. The success rates were designated according to criteria based on the Tube versus Trabeculectomy Study and the World Glaucoma Association guidelines: A (no resurgery); B/C (IOP < 21/18 mmHg, no resurgery, IOP reduction > 20%); D (IOP ⩽ 15 mmHg, no resurgery, IOP reduction ⩾ 40%). RESULTS: The mean follow-up period was 46 months. IOP showed a 38% reduction from 24.5 ± 6.1 to 15.2 ± 3.6 mmHg (p < 0.0001). The Medication Score decreased by 23% from 2.2 ± 0.9 to 1.7 ±1.0 (p < 0.0001). The success rates were 87, 76, 74 and 38% according to criteria A, B, C and D. In eyes with an initial IOP of >30 mmHg, a 57% reduction from 34.2 ± 4.4 to 14.8 ± 3.2 mmHg (p < 0.0001) was observed, and the success rates were 91, 91, 82 and 59% for criteria A, B, C and D, respectively. DISCUSSION: We conclude that the triple procedure may effectively lower IOP in patients with exfoliation glaucoma over a mean follow-up period of 46 months without significant side effects. Therefore, the triple procedure may serve as first-line surgery for patients with exfoliation and cataract, even with a high initial IOP.

Primary Versus Posttrabeculectomy XEN45 Gel Stent Implantation: Comparison of Success Rates and Intraocular Pressure-lowering Potential in Pseudophakic Eyes.

PRECIS: The XEN45 Gel Stent can be implanted after failed trabeculectomy without disadvantages compared with primary implantation. PURPOSE: We aimed to compare the outcomes of XEN45 Gel Stent implantation in pseudophakic eyes after failed trabeculectomy and in pseudophakic eyes without other previous surgeries. PATIENTS AND METHODS: In this retrospective study, we included 30 pseudophakic eyes of 30 patients who underwent XEN45 Gel Stent implantation after failed trabeculectomy (trabeculectomy group) and 60 eyes of 60 patients with primary XEN45 Gel Stent implantation (control group). The groups were matched for preoperative intraocular pressure (IOP), preoperative medication score, cup-to-disc ratio, follow-up time, visual acuity, and age at a ratio of 1:2. Eyes with concomitant eye diseases, those who had undergone previous surgery, and those with a follow-up duration <6 months were excluded. We compared the success rates on the basis of different criteria: Criteria A (IOP<21 mm Hg, IOP reduction>20%, no repeat surgery); Criteria B (IOP<18 mm Hg, IOP reduction>20%, no repeat surgery); and Criteria C (IOP≤15 mm Hg, IOP reduction≥40%, no repeat surgery). RESULTS: After an average follow-up period of 20 months, the mean IOP was reduced from 24.4±5.7 to 14.0±4.1 mm Hg in all the study subjects (90 patients). There were no significant differences between the 2 groups in postoperative IOP, postoperative medication score, revision rate, and repeat surgery rate or success rate. CONCLUSIONS: XEN45 Gel Stent implantation is a viable option after failed trabeculectomy. According to our results, it has no disadvantage compared with primary XEN45 Gel Stent implantation.

Influence of oral anticoagulation on success rates and risk of bleeding events after iStent inject implantation combined with phacoemulsification.

PURPOSE: We conducted a retrospective study to evaluate the intraocular pressure (IOP) lowering effect, the success rates, and the risk of bleeding events of patients receiving an iStent inject combined with phacoemulsification under anticoagulation therapy compared with a matched control group. METHODS: In this retrospective study, sixty-four eyes underwent an iStent inject implantation combined with phacoemulsification at two centers. Thirty-two eyes received surgery while under anticoagulation therapy, and another thirty-two eyes served as a control group matched for visual acuity, IOP, and medication score. Success was defined as criteria A and B (IOP < 18/21 mmHg, > 20% IOP reduction, no resurgery) and criteria C (IOP ≤ 15 mmHg, IOP reduction ≥ 40%, no resurgery). The clinical goal of the study was to determine the difference between the study and control groups with respect to IOP, medication score, and the frequency of intraoperative and postoperative bleeding events. RESULTS: After a mean follow-up time of 1 year, the IOP lowered 28% from 20.1 ± 4.8 to 14.5 ± 3.7 mmHg in the group of 64 eyes. The medication score lowered 38% from 2.1 ± 1.1 to 1.3 ± 1.2. The two groups with and without anticoagulant agents did not significantly differ in postoperative IOP, medication score, success rates, or number of bleeding events. CONCLUSION: We conclude that in cataract surgery combined with the iStent inject a discontinuation of anticoagulant agents might not be necessary. It might be a good option in glaucoma surgery when anticoagulation treatment should not be interrupted and the target pressure is not very low.

Long-term follow-up after implantation of a telemetric intraocular pressure sensor in patients with glaucoma: a safety report.

IMPORTANCE: To investigate the long-term safety of a novel intraocular telemetric pressure sensor. BACKGROUND: Acquisition of accurate intraocular pressure (IOP) data is vital for sufficient medical care of glaucoma patients. Non-invasive self-tonometry with a telemetric IOP sensor can provide important information regarding the individual IOP profile. DESIGN: Retrospective analysis of long-term follow-up data assessed during outpatient visits in a university hospital. PARTICIPANTS: Six patients with open-angle glaucoma were included. Unfortunately, one patient passed away shortly after completion of the original 1-year study. METHODS: Within the scope of a prospective 1-year pilot clinical trial, a telemetric IOP sensor was inserted into the ciliary sulcus after intracapsular lens implantation during planned cataract surgery. Patients were regularly examined as outpatients even beyond the duration of the 1-year study. Data concerning sensor functionality, safety parameters and home self-tonometry were assessed. MAIN OUTCOME MEASURES: Long-term sensor functionality and safety. RESULTS: Sensor measurements were always successful in every patient. Additionally, home self-tonometry was conducted without any problems by every patient. The average follow-up period was 37.5 months (21-50 months). During this period, the average number of IOP measurements performed per patient was 1273 (223-2884 measurements). No severe adverse events were reported. A varying degree of pupillary distortion was observed after 6-12 months in every patient; this remained unchanged thereafter with only one exception. CONCLUSIONS AND RELEVANCE: Telemetric IOP sensors showed good functionality and tolerability during long-term follow-up. Non-invasive self-tonometry with a telemetric IOP sensor can provide useful additional data for future monitoring of patients with glaucoma.

Goldmann Applanation Tonometry Versus Dynamic Contour Tonometry After Vitrectomy.

PURPOSE: The aim of the study was to investigate the agreement of intraocular pressure (IOP) measurement using dynamic contour tonometry (DCT) and Goldmann applanation tonometry (GAT) in eyes after vitrectomy with intraocular gas endotamponade, in eyes after vitrectomy with no tamponade, and in controls. METHODS: In this prospective comparative study IOP was measured with GAT and DCT in 41 eyes with gas endotamponade (sulfur hexafluoride 20%) 1 to 3 days after vitrectomy, in 32 postvitrectomy eyes with intraocular water, and in 46 control eyes with no history of glaucoma or intraocular surgery. Corneal pachymetry and axial length measurements were additionally performed. RESULTS: The mean difference between GAT and DCT (GAT-DCT) in gas-filled eyes was 3.1 mm Hg [SD=6.2 mm Hg], that in eyes after vitrectomy with no tamponade was 0.4 mm Hg (SD=4.8 mm Hg), and in control eyes was 0.4 mm Hg (SD=3.8 mm Hg). No significant correlation was found between the differences of GAT and DCT (GAT-DCT) and the mean IOP of GAT and DCT in water-filled eyes (r=-0.25, P=0.18) and control eyes (r=0.23, P=0.13), but a significant correlation was found in the gas-filled eyes (r=0.71, P<0.0001). A significant correlation between central corneal thickness and the mean difference of both methods was seen only in the control group (r=0.36, P=0.03). CONCLUSIONS: IOP as determined by DCT underestimates IOP in gas-filled eyes compared with GAT, as GAT values were on average 3.1 mm Hg higher compared with those of DCT. The extent of IOP underestimation using DCT increases with higher IOP values. In the group of eyes after vitrectomy and in normal eyes we found a generally good agreement between the 2 methods, although high interindividual discrepancies were present. Our findings suggest that the 2 devices should not be used interchangeably in IOP evaluation after vitrectomy with gas endotamponade, which remains a difficult challenge.

Implantation of a novel telemetric intraocular pressure sensor in patients with glaucoma (ARGOS study): 1-year results.

PURPOSE: We investigated the safety of a telemetric IOP sensor and the accuracy of its IOP measurements in six patients with open-angle glaucoma and cataract. METHODS: The study design was a prospective, single-center clinical trial. Here we present 1-year follow-up data. A ring-shaped telemetric IOP sensor was implanted in the ciliary sulcus after implantation of the intracapsular lens, during planned cataract surgery. The sensor is encapsulated in silicone rubber and consists of a miniature device with eight pressure-sensitive capacitors and a circular microcoil antenna. IOP measurements are performed with a reader unit held in front of the eye. IOP is calculated as the differences between the absolute pressure inside the eye (pressure sensor) and that outside the eye (reader unit). RESULTS: The sensor was successfully implanted in all patients. Four patients developed sterile anterior chamber inflammation that resolved completely within 9 days after surgery with anti-inflammatory treatment. All patients showed mild to moderate pupillary distortion and pigment dispersion after surgery. Telemetric IOP measurement was performed in all patients at all visits, and the patients successfully performed self-tonometry at home after receiving instructions. Telemetric IOP values showed similar profiles compared to those of Goldmann applanation tonometry (GAT). Three patients showed a relevant IOP step during follow-up, and in one patient, negative values were obtained throughout the study. CONCLUSIONS: Despite early postoperative anterior chamber inflammation, the IOP sensor was well tolerated by all patients. We describe the first prospective clinical study of a noncontact IOP sensor that potentially enables continuous IOP monitoring in patients with glaucoma. The sensor shape and size needs to be adapted to avoid pupillary distortion and to confirm that IOP measurements are accurately recorded in comparison to those of GAT. ( www.germanctr.de; number DRKS00003335.).

Influence of the prediction error of the first eye undergoing cataract surgery on the refractive outcome of the fellow eye.

INTRODUCTION: In addition to measurement errors, individual anatomical conditions could be made responsible for unexpected prediction errors in the determination of the correct intraocular lens power for cataract surgery. Obviously, such anatomical conditions might be relevant for both eyes. The purpose of this study was to evaluate whether the postoperative refractive error of the first eye has to be taken in account for the biometry of the second. METHODS: In this retrospective study, we included 670 eyes of 335 patients who underwent phacoemulsification and implantation of a foldable intraocular lens in both eyes. According to the SRK/T formula, the postoperative refractive error of each eye was determined and compared with its fellow eye. RESULTS: Of 670 eyes, 622 showed a postoperative refractive error within ±1.0 D (93%), whereas the prediction error was 0.5 D or less in 491 eyes (73%). The postoperative difference between both eyes was within 0.5 D in 71% and within 1.0 D in 93% of the eyes. Comparing the prediction error of an eye and its fellow eye, the error of the fellow eye was about half the value of the other. CONCLUSION: Our results imply that substitution of half of the prediction error of the first eye into the calculation of the second eye may be useful to reduce the prediction error in the second eye. However, prospective studies should be initiated to demonstrate an improved accuracy for the second eye's intraocular lens power calculation by partial adjustment.

Partial Coherence Laser Interferometry in Highly Myopic versus Emmetropic Eyes.

PURPOSE: To investigate the reliability of partial coherence laser interferometry for optical biometry in highly myopic eyes. METHODS: Axial length measurements by the IOLMaster (Carl Zeiss Meditec, Germany) with signal-to-noise ratio (SNR) ≥2 were performed in 52 consecutive myopic subjects with axial length ≥26.5 mm and 45 emmetropic patients before cataract surgery. Axial length measurements and SNR were analyzed and compared among the two study groups. RESULTS: Axial length measurements were feasible in 46 of 52 (88.5%) highly myopic eyes and in 41 of 45 (91.1%) eyes with normal axial length. To achieve two reliable axial length values with SNR ≥2, a mean number of 2.06±0.25 measurements was necessary in myopic eyes and 2.10±0.37 in emmetropic counterparts. Mean SNR after two measurements was 4.98±2.44 in myopic eyes versus 5.56±2.32 in control eyes. Even though successful measurement was independent of preoperative visual acuity, patients with visual acuity better than 20/63 showed significantly higher SNR values. CONCLUSIONS: Partial coherence laser interferometry shows satisfying feasibility and good signal quality for axial length determination in highly myopic eyes with stable retinal condition and clear media.

The effect of cataract surgery on blue-yellow and standard-pattern visual-evoked potentials.

PURPOSE: Blue-yellow visual-evoked potentials (BY-VEPs) may be used for diagnostics of functional ganglion cell damage in glaucoma and other ocular diseases. In this study we investigated the impact of lenticular opacities on BY- and standard pattern reversal VEPs by examining patients before and after cataract surgery. METHODS: Eighteen patients with moderate cataract were included in a prospective study. Transient on/off isoluminant blue-yellow 2° checks were used for short-wavelength stimulation (BY-VEP), transient large 1° (M1) and small 0.25° (M2) black-white checks for standard pattern reversal VEPs. VEPs were acquired before (24 ± 30 days) and after cataract surgery (14 ± 16 days). The contralateral eye was used as a control. RESULTS: Amplitude and latency of M1 and M2 peaks did not change significantly from before to after surgery. The amplitude of the BY-VEPs did not change significantly after cataract surgery (pre-surgery, -7.42 ± 3.43 µV, post-surgery, -7.93 ± 3.65 µV, p = 0.42), yet the latency of the main negative peak showed a significant decrease (pre-surgery, 143.9 ± 12.9 ms, post-surgery, 133.2 ± 7.7 ms, p = 0.0006). The BCVA improvement was significant from before to after cataract surgery (pre-surgery, 0.344 ± 0.125 LogMAR, post-surgery, 0.224 ± 0.179 LogMAR, p = 0.013) yet not correlated to the absolute decrease in latency of the BY-VEP after surgery (r = 0.309, p = 0.22). No significant changes were found in the contralateral eye. CONCLUSIONS: The BY-VEP is sensitive to lenticular opacities of the human lens, presumably due to the increased short-wavelength absorption in the aging eye. This fact should be considered when applying BY-VEPs for diagnostics.

Clinical observations and occurrence of complications following heavy silicone oil surgery.

PURPOSE: To demonstrate development and complications in heavy silicone oil (HSO) surgery in 100 eyes following primary vitreoretinal surgery. METHODS: 100 eyes were included in this retrospective study that underwent vitreoretinal surgery using HSO as endotamponade. Indication diagnoses were retinal detachments (n = 76), complicated macular holes (MH) (n = 20), and others (n = 4). HSO removal was performed after a mean period of 20.2 ± 19.0 weeks. In 18 eyes with poor functional prognosis the silicone oil remained permanently for stabilisation. Overall follow-up time was 35.9 ± 51.8 weeks. RESULTS: The mean IOP before HSO surgery was 13.3 ± 5.6 mmHg and raised to an average maximum of 23.3 ± 8.5 mmHg postoperatively and decreased to 13.7 ± 7.2 mmHg after removal. Secondary IOP raise due to emulsification of the silicone oil endotamponade was seen in 29 eyes after 7.8 ± 4.5 weeks. Other complications being observed with HSO installed were persistent corneal erosion (n = 3) and prolonged anterior chamber inflammation (n = 29). In 13 eyes recurrent retinal detachments occurred during followup. CONCLUSIONS: According to our analysis HSO surgery might deliver satisfying results in complicated cases of ophthalmological surgery. However, potential complications should always be taken into account when making the decision if to use and when to remove HSO in complicated retinal surgery.

Accuracy of intraocular lens power calculation using partial coherence interferometry in patients with high myopia.

PURPOSE: Ultrasound-A-scan-biometry intraocular lens power calculation for cataract surgery sometimes shows lack of accuracy in patients with high myopia. The purpose of this retrospective study was to assess the accuracy of lens power calculation with optical biometry using the Zeiss IOLMaster across a large range of myopia levels. METHODS: We included 37 consecutive, myopic eyes with an axial length >26.5mm (31 patients, 62±13years old, average preoperative refraction of -14.46±6.61D, range -3.5 to -32.0D which underwent phacoemulsification and implantation of an intraocular lens following biometry using the IOLMaster. For lens power calculation, the Haigis formula was used in all cases. For comparison, refraction was back-calculated using the SRK/T and Holladay I formulae. RESULTS: The preoperative mean axial length was 29.37±2.44 mm with a range of 26.50-35.52mm. Thirty eyes (81.1%) showed a postoperative spherical equivalent which differed 1.00D or less from the predicted value, in 20 cases (54.1%) the postoperative refractive error was within±0.50D. The mean absolute error (MAE) was 0.70±0.59D (Holladay I, 0.85±0.68; SRK/T, 1.01±0.61D). CONCLUSIONS: Optical biometry for intraocular lens power calculation seems to deliver reliable results for cataract surgery in patients with high myopia, although our data describe an increasing lack of accuracy beyond an axial length of 30mm. The Haigis formula provided the best predictability of postoperative refractive outcome for myopic eyes in general.

Does surgical experience have an effect on the success of retinal detachment surgery?

PURPOSE: To examine the relationship between surgeon experience and success rates in retinal detachment surgery. METHODS: Success rates during a follow-up of 11 months of 8 surgeons who performed in total 375 retinal detachment procedures ranging from 14 to 115 cases between December 1997 and January 2002 were correlated to the total number of vitreoretinal procedures ranging between 176 and 2,587. All patients received either scleral buckling or vitrectomy, and complicated cases were excluded. RESULTS: Mean primary anatomical success rates were 0.69 ± 0.14 for scleral buckling and 0.9 ± 0.05 for primary vitrectomy (P < 0.05). The primary anatomical success rates did not correlate to the number of vitreoretinal procedures. Seven of the eight surgeons showed an intraindividual learning effect with better success rates in the second versus the first half of the observed procedures. The learning effect was correlated to the total number of procedures with a higher effect in inexperienced surgeons. CONCLUSION: An intraindividual learning effect that was higher in inexperienced surgeons could be demonstrated. The learning effect was reduced by half after 500 vitreoretinal procedures while the primary anatomical success rates were not correlated to the number of vitreoretinal procedures.

Ocular pulse amplitude before and after cataract surgery.

PURPOSE: To investigate the impact of cataract surgery on the association of the ocular pulse amplitude (OPA) and intraocular pressure (IOP) with respect to the interpretation of OPA as an estimate of ocular blood flow. METHODS: Twenty-four patients with cataract were included in a clinical study. OPA was measured using dynamic contour tonometry (DCT, Pascal(®), SMT Swiss Microtechnology AG, Switzerland). IOP was measured by means of Goldmann applanation tonometry (IOP GAT) and DCT (IOP DCT). All measurements were performed before and one day after cataract surgery. RESULTS: At baseline, OPA was correlated to IOP GAT (r = 0.67, P = 0.0002) and IOP DCT (r = 0.82, P < 0.0001), but not to age or axial length. Postoperative OPA was correlated to IOP GAT (r = 0.67, P = 0.0002) and IOP DCT (r = 0.65, P = 0.0004). In 17 patients, IOP GAT decreased after surgery (IOP DCT n = 14), whereas an increase was apparent in seven patients (IOP DCT n = 10). The mean absolute deviation of IOP GAT pre- to post-surgery was 4.54 mmHg ± 2.47 (range 1-10 mmHg) and 5.4 mmHg ± 3.2 (range 1.1-13.1 mmHg) for IOP DCT. The changes of OPA were significantly correlated to changes in IOP GAT (r = 0.48, P = 0.017) and IOP DCT (r = 0.60, P = 0.001). IOP GAT and IOP DCT changes were not correlated to changes in corneal thickness. CONCLUSIONS: The OPA measured with the Pascal(®) device seems to be dependent on IOP changes. Particular caution should be taken in the interpretation of OPA in estimating pulsatile ocular blood flow.

Development of surgical techniques for implantation of a wireless intraocular epiretinal retina implant in Göttingen minipigs.

BACKGROUND: The aim of this study was to develop surgical methods for the implantation of a wireless intraocular epiretinal retina implant (EPI RET3) in Göttingen minipigs. This animal model resembles closely the anatomical conditions in humans, and is thus suitable for investigating the EPI RET3 implant as designed for the application in humans. METHODS: Phacoemulsification and vitrectomy was performed on the right eye of 16 Göttingen minipigs under general anesthesia. The implants, consisting of a receiver module and an electrode array connected via a flexible micro cable, were inserted through a corneoscleral incision. The receiver module was placed into the sulcus ciliaris and the electrode array was fixed onto the retina temporal to the optic disc with a retinal tack. Minipigs were monitored for intra- and postoperative ocular complications. Follow-up times were 3 (seven minipigs) and 12 weeks (nine minipigs). RESULTS: Implantation was successfully performed in all 16 minipigs. The complete implantation surgery required on average 2 hours. Intraoperative findings were a minor hemorrhage of the anterior chamber angle in two eyes, one minor iris hemorrhage, and one minor punctiform retinal hemorrhage, which were all reversible. Postoperatively, the corneoscleral incision showed good wound healing in all eyes. Intraocular reactions included mainly fibrin exudation (six eyes) and formation of iris synechiae with the receiver module of the implants (three eyes). CONCLUSIONS: The performed implantation procedures of the intraocular EPI RET3 implant are feasible and reproducible within an acceptable surgical time. The development of inflammatory responses is a specific predisposition of the minipig following any intraocular intervention; nevertheless, the surgical techniques should be further improved to minimize procedure-related reactions. Our results provide a step towards the application of the EPI RET3 system in clinical studies.

Surgical Results and Microscopic Analysis of the Tissue Reaction following Implantation and Explantation of an Intraocular Implant for Epiretinal Stimulation in Minipigs.

AIMS: For the purpose of visual rehabilitation of subjects with photoreceptor degeneration, an implantable microelectronic device for epiretinal stimulation was developed. Our study aimed to show whether implantation and explantation could be conducted safely and to investigate tissue compatibility. METHODS: The device was implanted in 5 Göttinger minipigs. Four weeks later, the implant was surgical- ly removed. Histopathological examination that followed aimed at detecting inflammatory or proliferative changes. Stains used were hematoxylin and eosin, leukocyte common antigen, CD68 and glial fibrillary acidic protein. A grinding technique was used to visualize the retinal tissue in conjunction with the retinal tacks. RESULTS: The implantation of the devices was successful in all cases. The explantation was complicated by intraoperative hemorrhages. Complete explantation could only be achieved after modifying the implantation strategy. Histopathology revealed a mild degree of cystic disaggregation of the retina. Immunohistochemically, an increased glial fibrillary acidic protein expression of Müller cells was found, which shows a moderate glial cell activation. Inflammatory cells were absent. Using the grinding technique, tissue adjacent to the retinal tacks showed a mild gliosis. DISCUSSION: The viability of implantation and explantation of the implant in minipigs has been shown. The absence of immunoreactive cells or a considerable glial reaction suggest that the device may be considered safe and suitable for further implantation in humans.