Vitreous Cutter Research Articles

Efficacy and safety of primary posterior capsulotomy in combined phaco-vitrectomy in rhegmatogenous retinal detachment.

ObjectiveTo evaluate the efficacy and safety of posterior capsulotomy by analyzing the long-term visual outcomes in patients with rhegmatogenous retinal detachment (RD), who underwent combined phaco-vitrectomy with or without primary posterior capsulotomy.MethodsA retrospective longitudinal cohort analysis was performed by using data of rhegmatogenous RD patients undergoing combined phaco-vitrectomy. Patients were divided into two groups; Group A (68 eyes of 68 patients) with capsulotomy, and Group B (39 eyes of 39 patients) without capsulotomy. We reviewed the best-corrected visual acuity (BCVA), incidence of posterior capsule opacification (PCO), clinical features at the diagnosis of rhegmatogenous RD, and intraoperative or postoperative complications following posterior capsulotomy.ResultsThe modified BCVA measured by the logarithm of the minimum angle of resolution at initial diagnosis and 3, 6, and 12 months after surgery was 0.67 in Group A versus 0.85 in Group B (p = 0.258), 0.40 in Group A versus 0.50 in Group B (p = 0.309), 0.27 in Group A versus 0.45 in Group B (p = 0.055), and 0.21 in Group A versus 0.47 in Group B (p = 0.014), respectively. In subgroup with macula-on RRD, Group A exhibited better visual outcomes compared to Group B at 6(0.17 versus 0.40 [p = 0.037]) and at 12 months(0.14 versus 0.39 [p = 0.030]). The incidence of PCO in Group B was higher than Group A(28.2% versus 4.4% (p < 0.001)). There were no complications associated with posterior capsulotomy.ConclusionsA primary posterior capsulotomy during combined phaco-vitrectomy using a 23-gauge vitreous cutter was a safe and effective surgical procedure in patients with RRD patients for preventing postoperative intraocular lens-related PCO.

SHORT-TERM OUTCOMES OF HYBRID 23-, 25-, AND 27-GAUGE VITRECTOMY FOR COMPLEX DIABETIC TRACTIONAL RETINAL DETACHMENT REPAIR.

To describe the short-term outcomes of complex diabetic retinal detachment repair using hybrid 23-gauge or 25-gauge vitrectomy instruments with a 27-gauge vitrectomy system. Retrospective, interventional, consecutive case series. Ten eyes of 10 patients undergoing hybrid pars plana vitrectomy for diabetic tractional retinal detachment were reviewed. Combined use of 25-gauge and 27-gauge instrumentation was used in 8 of 10 eyes and combined use of 23-gauge and 27-gauge instrumentation in 2 of 10 eyes. In all cases, a 27-gauge vitreous cutter was used for membrane dissection and delamination. All eyes had successful anatomical reattachment at a mean follow-up of 207 ± 55 days. Snellen visual acuity improved from a mean of 20/822 preoperatively to 20/566 at the final follow-up (P = 0.55). Mean intraocular pressure remained stable at 13 ± 3.4 mmHg preoperatively to 13.6 ± 5.4 mmHg at the final follow-up (P = 0.76). No intraoperative or postoperative complications were encountered. Concurrent use of the 27-gauge vitreous cutter with 23-gauge or 25-gauge instrumentation was effective during diabetic tractional retinal detachment repair. This hybrid technique was not associated with any significant intraoperative or short-term postoperative complications.

Vitrectorhexis in penetrating eye injuries in adults.

Vitrectorhexis is an alternative for manual continuous curvilinear capsulorhexis originally developed for paediatric cataract surgery. The aim of our study was the evaluation of the technique in adult patients with penetrating ocular injury and traumatic cataracts. Eight eyes of 8 patients (23-41 years, all males) had penetrating mechanical corneal trauma. Anterior lens capsule was penetrated in all cases and additional posterior capsule defect in five cases. Intraocular foreign body was detected in one case in the crystalline lens and in two cases in the posterior segment. Standard 23G infusion cannula and vitreous cutter were applied to perform anterior capsule opening, removal of lens material, anterior vitrectomy and pars plana vitrectomy if needed. No phacoemulsification or irrigation/aspiration probe was used. Vitrectorhexis could be performed in 7 out of 8 cases with the preservation of peripheral anterior capsule; primary implantation of posterior chamber intraocular lens was possible in all cases (in the bag in three eyes and into the sulcus in five eyes). Anterior chamber was stable in all cases intraoperatively, and no dropped nucleus or lens fragment loss was observed. Surgery was combined with pars plana vitrectomy in three cases, with foreign body removal (when necessary). No postoperative complication occurred. Vitrectorhexis was found to be an effective and safe alternative method in the management of complex anterior segment trauma cases. With its use, traditional cataract surgical devices can be substituted and additional benefits of vitreous cutter can be utilized in selected cases, especially in young adults.

Assessment of the fluid dynamic performance of a vitreous cutter

Vitreous cutters are surgical devices used during vitrectomy to remove the vitreous humor from the eye and replace it with tamponade fluids. The aim of the present work is to assess the performance of the EVA Phaco-vitrectomy System vitreous cutter (Dutch Ophthalmic Research Center (DORC) BV; Zuidland, The Netherlands) used with diff erent needle sizes and blade shapes. The analysis is based on laboratory measurements of fluid flow performed using the particle image velocimetry (PIV) technique.

Combined Femtosecond Laser-Assisted Cataract Surgery and Small-Gauge Pars Plana Vitrectomy Using Different Devices: A New Trend for Vitreoretinal Surgery?

To report the efficacy, safety, and benefits of femtosecond laser-assisted cataract surgery (FLACS) combined with sutureless 23-gauge pars plana vitrectomy (PPV). This multicenter, retrospective study evaluated patient records and videos of 43 cases with retinal pathologies and cataract who underwent the combined procedure. In 44.2% and 55.8% of cases, respectively, the LenSx Laser (femtosecond machine; Alcon, Fort Worth, TX) and the Constellation (vitreous cutter; Alcon, Fort Worth, TX), and the Victus (femtosecond machine; Bausch + Lomb, Rochester, NY) and Stellaris PC (vitreous cutter; Bausch + Lomb, Rochester, NY) were used. No complications developed during capsulorrhexis, even without a red fundus reflex, retrobulbar block, or scleral indentation. Foldable intraocular lenses remained stable in the capsular bag during the vitreoretinal surgeries and postoperative visits. The mean times of femtosecond phacoemulsification, vitreoretinal surgery, and total surgery were 22.9 minutes ± 4.7 minutes, 43.1 minutes ± 9.8 minutes, and 65.3 minutes ± 8.6 minutes, respectively. This emerging technology is safe and offers several potential benefits for the success of the combined procedure. [Ophthalmic Surg Lasers Imaging Retina. 2018;49:374-379.].

Successful recovery from misdirection syndrome in nanophthalmic eyes by performing an anterior vitrectomy through the anterior chamber

PurposeTo determine the effectiveness of iridectomy, capsulotomy and anterior vitrectomy through the anterior chamber to treat misdirection syndrome in pseudophakic nanophthalmic eyes.MethodsThis was a non-comparative study of seven nanophthalmic eyes from four consecutive patients. All eyes developed misdirection syndrome after successful cataract surgery. Treatment for misdirection syndrome involved capsulotomy and anterior vitrectomy through a peripheral iridectomy from the anterior chamber using a 25-gauge vitreous cutter. The best-corrected visual acuity, intraocular pressure and anterior and posterior segment findings were recorded before and after surgery.ResultsResolution of the aqueous misdirection was achieved in all but one eye. The single case of recurrence was observed after a mean follow-up of 45.6 ± 21.5 months and was caused by closure of the capsule hole by Elschnig’s pearls. This eye was successfully treated by enlargement of the lens capsule hole with a vitreous cutter. The mean intraocular pressure before surgery was 28.7 ± 4.4 mmHg, and this was significantly reduced to 13.7 ± 1.3 mmHg at the final visit. All but one patient, who had uveal effusion, maintained their best-corrected visual acuity.ConclusionIn this study, we investigated an alternative option for the treatment of misdirection syndrome in nanophthalmic eyes. We undertook a lens capsulotomy and anterior vitrectomy through a peripheral iridectomy from the anterior chamber using a 25-gauge vitreous cutter, which was able to create a communication hole between the anterior and posterior chambers.

A Frag Bag for Efficient Removal of Dislocated Nuclear Material.

Dislocated nuclear material may be present in the vitreous cavity following complicated cataract surgery, closed globe injury, or spontaneous dislocation of the crystalline lens. The authors report herein a method to remove larger pieces of retained nuclear material during vitrectomy surgery with a retractable basket made from nitinol referred to as the "Frag Bag" (patent pending). Although originally designed for cystoscopic removal of kidney stones, this instrument fits easily through a 23-gauge vitrectomy port. The basket allows for retrieval of larger pieces of retained nuclear material with stabilization of the lens material in the mid-vitreous cavity and softening of the nuclear material to allow efficient and safe removal with the vitreous cutter, away from the retinal surface. Use of the Frag Bag may potentially improve the safety and efficiency of a pars plana lensectomy by obviating the need for a phacofragmatome and decreasing the number of times instruments are brought close to the retinal surface. [Ophthalmic Surg Lasers Imaging Retina. 2017;48:1006-1008.].

PREVENTING PUPILLARY CAPTURE AFTER VITRECTOMY AND TRANSSCLERAL FIXATION OF AN INTRAOCULAR LENS: Iridotomy Using a Vitrectomy Probe.

To investigate the effects of concurrent iridotomy using a vitreous cutter probe on the prevention of pupillary capture in patients undergoing transscleral fixation of intraocular lens implantation. A total of 79 eyes from 79 patients, who underwent transscleral fixation of intraocular lens without preexisting vitreoretinal disorders and who were followed up for 6 months were included. Subjects were divided into a noniridotomy group (51 eyes) and an iridotomy group (28 eyes). After conventional 23-gauge vitrectomy and transscleral fixation of intraocular lens implantation in all patients, 28 patients underwent concurrent iridotomy intraoperatively. The patients were followed up to evaluate the incidence of surgery-related complications, including pupillary capture. There were no statistically significant differences in the preoperative demographic findings between the two groups (all P > 0.05). There was a significant difference in pupillary capture in 15 eyes (29.4%) of the noniridotomy group, compared with 1 eye (3.6%) of the iridotomy group (P = 0.007). There were no differences in postoperative best-corrected visual acuity between the two groups, and no iridotomy-related complications were observed. Concurrent iridotomy using a vitreous cutter probe is an easy, rapid, and effective procedure to prevent possible pupillary capture after combined vitrectomy and transscleral fixation of intraocular lens implantation.

VITRECTOMY-ASSISTED BIOPSY FOR MOLECULAR PROGNOSTICATION OF CHOROIDAL MELANOMA 2 MM OR LESS IN THICKNESS WITH A 27-GAUGE CUTTER.

Fine-needle aspiration biopsy of small choroidal melanomas 2 mm or less in thickness may be associated with a low biopsy yield. This report describes our center's experience using the 27-gauge vitreous cutter to perform tumor sampling in these small melanomas. This was a retrospective analysis of all patients who underwent a 27-gauge vitreous cutter biopsy for molecular prognostication at the time of iodine-125 plaque placement for local treatment of choroidal melanoma ≤2.0 mm in height. Seventeen consecutive patients with a mean baseline tumor height of 1.67 mm (range, 1.31-2.03 mm) and median follow-up time of 7.0 months (range, 3.3-19.5 months) were included. The 27-gauge cutter biopsy yielded sufficient material for multiplex-ligation probe amplification (MLPA) or gene expression profiling (GEP) in 17/17 (100%) patients. Complications were limited to focal vitreous hemorrhage in 13/17 patients and diffuse vitreous hemorrhage in 1/17 patients, with no instance of retinal detachment or nonclearing vitreous hemorrhage. Tumor sampling of small choroidal melanoma with a 27-gauge vitreous cutter is safe and offers excellent biopsy yield for molecular prognostication when cancer prognosis is desired by patients.

Association between aqueous humor and vitreous fluid levels of Th17 cell-related cytokines in patients with proliferative diabetic retinopathy.

Inflammation is known to be involved in the progression of diabetic retinopathy. We have recently reported that vitreous levels of IL-4, IL-17A, IL-22, IL-31, and TNFα are higher than the respective serum levels in proliferative diabetic retinopathy (PDR) patients, and that vitreous levels of these cytokines are higher in PDR than in other non-inflammatory vitreoretinal diseases or uveitis associated with sarcoidosis. In the present study, we investigated inflammatory cytokines including Th17 cell-related cytokines in aqueous humor samples obtained from eyes with PDR, and analyzed the association between the aqueous humor and vitreous fluid levels of individual cytokines. The study group consisted of 31 consecutive type 2 diabetic patients with PDR who underwent cataract surgery and vitrectomy for vitreous hemorrhage and/or tractional retinal detachment. Undiluted aqueous humor was collected during cataract surgery, and then vitreous fluid was obtained using a 25G vitreous cutter inserted into the mid-vitreous cavity at the beginning of vitrectomy. IL-1β, IL-4, IL-6, IL-10, IL-17A, IL-17F, IL-21, IL-22, IL-23, IL-25, IL-31, IL-33, IFN-γ, soluble CD40 ligand (sCD40L), and TNFα levels in the aqueous humor and vitreous fluid were measured using a beads-array system. Although IL-17A was detected in the aqueous humor of eyes with PDR and the level correlated with IL-17A level in the vitreous fluid, both percent detectable and level of IL-17A in the aqueous humor were significantly lower than those in the vitreous fluid. Vitreous IL-17A level was related significantly to IL-10, IL-22, and TNFα levels in aqueous humor as well as in vitreous fluid, On the other hand, aqueous IL-17A level was not related significantly to aqueous or vitreous levels of IL-10, IL-22 or TNFα level. The present study demonstrated that IL-17A level and detectable rate in the aqueous humor of patients with PDR are markedly lower than those in the vitreous fluid and aqueous IL-17A does not correlate with vitreous levels of other cytokines, and hence should not be used as a surrogate for IL-17A in the vitreous fluid.

Intraoperative 4-Dimensional Microscope-Integrated Optical Coherence Tomography–Guided 27-Gauge Transvitreal Choroidal Biopsy for Choroidal Melanoma

Purpose We describe two cases of intraoperative 4D microscope–integrated swept source optical coherence tomography (4D MIOCT) guided 27-gauge transvitreal retinochoroidal biopsy for choroidal melanoma. Methods Two 68-year-old females with choroidal melanomas underwent a transvitreal 27-gauge vitrectomy assisted chorioretinal biopsy for histologic and cytogenetic testing during I-125 radioactive episcleral plaque placement. A 4D (volumetric imaging through time) MIOCT device was used to simultaneously enable OCT image acquisition with surgical maneuvers during entry of and engagement of the vitreous cutter in the choroidal lesion. Results 4D MIOCT permitted real-time visualization of the choroidal tumor for selection of biopsy site in an area of adequate thickness and free of subretinal fluid, relatively perpendicular entry of the vitrectomy probe into the choroidal lesion, confirmation of adequate penetration depth prior to and during engagement of the vitreous cutter, and absence of subretinal fluid surrounding the retinotomy following removal of the probe. In both cases an adequate sample for histological and cytogenetic testing was obtained and no tamponade was required. Conclusion Intraoperative 4D MIOCT imaging permits real-time visualization of vitreous cutter penetration and depth into the choroidal melanoma during a transvitreal choroidal biopsy.

Development of cooperative robot-assistant surgery system for vitreoretinal microsurgery and its feasibility test in an animal model

Background Robotic systems are increasingly utilized in numerous disciplines including ophthalmology.Several reports showed potential benefits of robotic-assisted surgery, such as increased precision and dexterity, elimination of tremor, task automation and shortening of learning curve.However, there is still no relative report in China. Objective The present study was to develop a novel robotic-assisted vitreoretinal microsurgery system and assess its overall capacities. Methods A robotic-assisted vitreous and retinal microsurgery system was cooperatively built by Eye Hospital of Wenzhou Medical University and Beijing University of Aeronautics.This platform has two mechanical arms, end-effector of each can grip common instruments such as vitrectomy cutter, illumination probe, laser probe, 23-gauge intraocular forceps.The intraocular surgical tasks were performed assisted by surgical robot on 15 fresh in vitro porcine eyes by three interns to test the feasibility of performing pars plana vitrectomy (PPV) and posterior vitreous detachment (PVD). Vitrectomy steps consisted of preparing three 23-gauge scleral incisions, inserting vitreous cutter towards vitreous and retina via the incisions, and using vitreous cutter to induce and remove a PVD assisted with triamcinolone.The duration and the successful completion of the task with or without complications or involuntary events was assessed. Results PPV and PVD procedures were successfully finished on 15 porcine eyes, and no noted deformation of eyeballs during surgery and no iatrogenic complication such as retinal tear or retinal detachment occurred after operations, with the successful rate 100%.The mean duration of surgery was (12.76±3.44) minutes among the 15 eyeballs and the mean duration for each operator was (13.67±4.23), (10.83±2.30) and (13.77±1.91) minutes, respectively. Conclusions Robotic-assisted vitreoretinal microsurgery system is varified to have good stability and accuracy in intraocular surgery, and the robotic surgical system may be technically feasible to preform human manual PPV and PVD procedures. Key words: Robotic surgical procedures; Robotics/instrumentation; Surgery, computer-assisted/methods; Vitrectomy/methods; Feasibility studies; Swine

Neurocysticercosis - A Window to Intraocular Involvement.

To analyse the clinical characteristics of intraocular cysticercosis and the association of neurocysticercosis with intraocular involvement in these patients Materials and methods: Retrospective case series of records of patients managed at a Tertiary Care Hospital in South India. Case records of patients managed at a Tertiary Care Hospital in South India over two years (October 2012 - October 2014) were reviewed and cases reported with intraocular cysticercosis were included in the study and results analyzed. Five (5) patients of intraocular cysticercosis were diagnosed in a two year period at our centre, 60% being bilateral. Eight (8) eyes of five (5) patients had intraocular cysts documented by clinical examination and B mode ultrasonography (75% eyes with active cysts, 25% eyes inactive) .Visual acuity at presentation of eyes with active cysts ranged from perception of light to counting finger 4m. The 75% eyes had tractional retinal detachment at presentation. Neurocysticercosis was documented in 80% of the cases oncomputed tomography / magnetic resonance imaging . Six (6) eyes with active cysts underwent parsplanavitrectomy with cyst removal using vitreous cutter with concurrent management of tractional retinal detachment in five (5) eyes. Postoperative visual recovery was poor in eyes with associated tractional retinal detachment while good anatomical outcome was achieved in all six (6) cases. Intraocular cysticercosis can be associated with cysts in other areas. High number of patients with neurocysticercosis (80%) in those with intraocular cysticercosis in our study may indicate positive association between the two which needs further investigation.

Comparison of microbiology and visual outcomes of patients undergoing small-gauge and 20-gauge vitrectomy for endophthalmitis.

BackgroundThe role of pars plana vitrectomy (PPV) for endophthalmitis has evolved over recent decades but the literature is lacking on comparisons between small-gauge and 20-gauge vitrectomy.ObjectiveTo evaluate evolving etiological and microbiological trends in patients undergoing vitrectomy for endophthalmitis and to compare culture-positive rates and visual outcomes between small-gauge (23- and 25-gauge) and 20-gauge instrumentation during vitrectomy for endophthalmitis.MethodsTen-year retrospective comparative case series and prospective laboratory in vitro testing. Tertiary care academic referral center. Patients who underwent PPV for endophthalmitis between 2003 and 2013. Vitreous biopsies were obtained in all cases. The effect of vitrectomy gauge (20-, 23-, and 25-gauge) and vitreous cutting rate (1,500 and 5,000 cuts per minute) on the viability of bacterial culture was evaluated in an in vitro prospective laboratory investigation.Main outcome measuresComparison of etiology, microbiology culture-positive rates, and visual outcomes between small-gauge and 20-gauge instrumentation in patients undergoing PPV for infectious endophthalmitis.ResultsA total of 61 cases of vitrectomy for endophthalmitis were identified over a 10-year period; of these, 34 were treated with small-gauge (23- and 25-gauge) vitrectomy and 27 were treated with 20-gauge vitrectomy. In the small-gauge group, 12 cases (35.3%) yielded culture-positive results versus 20 cases (74.1%) with culture positivity in the 20-gauge cohort (P=0.002). The most common cause of endophthalmitis was cataract surgery and the most frequently identified organism was coagulase-negative Staphylococci in both groups. There was no significant difference in mean postoperative visual acuities between groups (P=0.33). Etiological trends indicate an increase in endophthalmitis due to intravitreal injection in the small-gauge group (n=9) compared to the 20-gauge group (n=3) (P=0.001). In vitro laboratory testing revealed no significant difference in rates of culture growth for different vitrectomy gauge sizes or vitreous cutting speeds.Conclusion and relevanceSmall-gauge vitrectomy for endophthalmitis yields final visual outcomes comparable to 20-gauge instrumentation. A significant difference in culture-positive rates was observed between small-gauge and 20-gauge instrumentation for vitrectomy in endophthalmitis; however, laboratory testing indicates this is not related to either vitreous gauge size or cutter speed. Intravitreal injections are emerging as a common etiology of vitrectomy for endophthalmitis.

Two-Dimensional Cutting (TDC) Vitrectome: In Vitro Flow Assessment and Prospective Clinical Study Evaluating Core Vitrectomy Efficiency versus Standard Vitrectome.

Purpose. To evaluate comparative aspiration flow performance and also vitrectomy operating time efficiency using a double-cutting open port vitreous cutting system incorporated in a two-dimensional cutting (TDC, DORC International) vitrectome design versus standard vitreous cutter. Methods. In vitro investigations compared aspiration flow rates in artificial vitreous humor at varying cutter speeds and vacuum levels using a TDC vitrectome and a standard vitrectome across different aspiration pump systems. A prospective single-centre clinical study evaluated duration of core vitrectomy in 80 patients with macular pucker undergoing 25-gauge or 27-gauge vitrectomy using either a TDC vitrectome at 16,000 cuts per minute (cpm) or standard single-cut vitrectome, combined with a Valve Timing intelligence (VTi) pump system (EVA, DORC International). Results. Aspiration flow rates remained constant independent of TDC vitrectome cut rate, while flow rates decreased linearly at higher cutter speeds using a classic single-blade vitrectome. Mean duration of core vitrectomy surgeries using a TDC vitreous cutter system was significantly (p < 0.001) shorter than the mean duration of core vitrectomy procedures using a single-cut vitrectome of the same diameter (reduction range, 34%–50%). Conclusion. Vitrectomy surgery performed using a TDC vitrectome was faster than core vitrectomy utilizing a standard single-action vitrectome at similar cut speeds.

Efficacy of Higher Cutting Rates during Microincision Vitrectomy for Proliferative Diabetic Retinopathy

To compare the outcomes of 25-G vitrectomy using a vitreous cutter with a higher cutting rate to that of conventional 25-G vitrectomy with a lower cutting rate on eyes with severe proliferative diabetic retinopathy (PDR). The medical records of 393 eyes of 326 patients with severe PDR were reviewed. A higher cutting rate dual-pneumatic 25-G vitrectomy probe (5,000 cuts/min, Constellation) was used on 219 eyes (group C) and a conventional 25-G pneumatic vitrectomy probe with lower cutting rate was used on 174 eyes (2,500 or 1,500 cuts/min, Acurrus) (group A). The visual and anatomical outcomes and the incidences of intraoperative and postoperative complications were compared. The incidence of combined cataract surgery was significantly higher in group C (p&lt;0.001). The number of eyes in which scissors were used was significantly lower in group C (p&lt;0.001), and the use of perfluorocarbon liquid was higher in group C (p = 0.015). The incidence of intraoperative iatrogenic tears, postoperative retinal detachments, and neovascular glaucoma was not significantly different between the 2 groups, but the incidence of postoperative vitreous hemorrhage was significantly lower in group C eyes (p&lt;0.001). Preoperative and postoperative vision were not significantly different between the 2 groups. The higher vitreous cutting rates during 25-G vitrectomy make it easier to dissect fibrovascular membranes with only the vitreous cutter, and achieved equivalent anatomical and visual outcomes after 25-G vitrectomy for PDR.

How far is observation allowed in patients with ectopia lentis?

Surgical timing for ectopia lentis has not been well described until now. The purpose of this study is to find a benchmark as to how far observation would be allowed in children with ectopia lentis when they and their families are reluctant to go through surgery. Retrospective review was made on 15 consecutive patients (14 children and one adult) with ectopia lentis in both eyes, seen at a referral-based institution in 5 years from April 2008 to March 2013, to survey the reasons for continuing observation or deciding surgical intervention. The diagnoses were Marfan syndrome in six patients, familial ectopia lentis in six, and sporadic ectopia lentis in three. Observation was continued in nine patients with the age at the final visit, ranging from 4 to 17 (median 9) years, because six children had good visual acuity at both near and distant viewing with glasses, and three children had visual acuity of 0.4 at near viewing despites poor visual acuity at distant viewing with glasses. In contrast, lensectomy was determined in six patients (5 children and one adult) with the age at surgery, ranging from 4 to 36 (median 9) years, and the age at the final visit, ranging from 7 to 42 (median 11) years, mainly because of poor visual acuity at near and distant viewing. More specific causes for surgeries in five children were the optical axis to become aphakic due to the progression of ectopia in the course in two children, lens dislocation to the anterior chamber after blunt eye injury in one child, and difficulty in studying at school classes in two children. One adult patient developed cataract in ectopic lenses. Lensectomy, combined with anterior vitrectomy, was done from two limbal side ports with a 25-gauge infusion cannula and vitreous cutter. Two patients at the age of 16 and 36 years, additionally, underwent intraocular lens-suturing in both eyes. In conclusions, observation was continued in children with ectopia lentis who had good visual acuity at near viewing. The visual acuity at near viewing, 0.4 or better, would give a benchmark for continuing observation in children with ectopia lentis.

The changes in physical properties of silicone oil after intraocular tamponade

Objective To observe the changes in physical properties of silicone oil after intraocular tamponade. Methods The silicone oil was removed from 99 patients (99 eyes) of primary retinal detachment with 23G vitreous cutter system. The upper silicone oil was collected after put the vitrectomy samples at room temperature for 3 days. According to the time of intraocular tamponade, the silicone oil samples were divide into six groups including group A (1 month, 12 samples), group B (2 months, 15 samples), group C (3 months, 25 samples), group D (6 months, 22 samples), group E (1 - 2 years, 13 samples) and group F (above 2 years, 12 sample). Fresh unused silicone oil was set as blank control group. Then the emulsion particles, kinematic viscosity, surface tension, density, transmittance and refractive index were measured. Results The difference between group A - F and the control was statistical significant (P 0.05). The number of silicone oil emulsion particles has no statistical difference between group A and the control (P>0.05), but was significantly different between group B - F (P 0.05), but was significantly different between group C - F (P 0.05), but is significantly different between group E and F (P 0.05), but was significantly different between group E and F (P 0.05). Conclusions The physical properties of silicone oil will change during the intraocular tamponade. The emulsion particles number will increase and the transmittance will decrease after 2 months, the kinematic viscosity of silicone oil will decrease significantly after 3 months, and the density and surface tension will change significantly after 1 year of tamponade. Key words: Silicone oils/therapeutic use; Silicone oils/ adverse effects

Instantaneous flow rate of vitreous cutter probes.

We report on instantaneous volumetric flow rate of vitreous cutters measured by means of particle image velocimetry (PIV). In an in vitro experimental study, vitreous cutters mounting a regular blade (RB) or modified Twedge blade (TB) engineered for higher flow were connected to a console machine equipped with a double peristaltic and Venturi pump, and immersed in balanced salt solution (BSS). Instantaneous flow was measured on aspiration tubing sections proximal to the cutter hand piece. Measures settings were as follows: (1) regular functioning at 3000 and 6000 cuts per minute (cpm) with 300 mm Hg aspiration with both pumps, (2) aspiration tubing clamped proximal to pump cassette, and (3) aspiration tubing clamped proximal to hand piece, and (4) flow fluctuation as a function of cut rate also was calculated. For main outcome measures, instantaneous volumetric flow rate in mL/min and flow fluctuation measured as the standard deviation of flow rate were measured. Regular functioning shows sinusoidal flow oscillating at cut rate frequency, with amplitude between ±50 mL/min at 3000 cpm and ±35 mL/min at 6000 cpm. The TB always determined a bimodal wave and neither blade nor pump type influenced the sinusoidal pattern of flow. Clamping aspiration tubing zeroes flow, but does not influence fluctuation frequency or amplitude. Clamping at the hand piece determined a significantly higher oscillation. Oscillation amplitude retain a typical resonance pattern with significant changes in function of cut rate and resonance occurs at approximately 4000 cpm. Cutter blade action determines instantaneous flow rate fluctuation that interferes significantly with cutter suction and hampers a steady suction through cutter port. In a surgical scenario, this translates into a higher risk of inadvertent retinal entrapment and lower predictability of cutter behavior, especially at frequency approaching resonance.

Introducing new vitreous cutter blade shapes: a fluid dynamics study.

To assess the efficacy of novel vitreous cutter blades compared with the regular guillotine by means of particle image velocimetry. Tested blades included a regular blade (RB) and newer designs where a circular (hole blade [HB]) or a slit aperture (slit blade [SB]) had been opened proximal to the cutting edge. Twenty-three-gauge probes were immersed in BSS or egg albumen, and high-speed video (1,000 frames per second) was recorded. Duty cycle, flow rate, and acceleration generated by Venturi and peristaltic pumps were measured under cutter settings simulating "low-speed" vitrectomy (1600 cuts per minute, 200 mmHg vacuum) and "high speed" vitrectomy (3000 cuts per minute, 300 mmHg vacuum). The SB and HB had a significantly more favorable duty cycle than that of the RB (P < 0.01) and higher BSS flow rate regardless of the aspiration. The SB flow rate in albumen was significantly higher than that of the HB and RB only over 1,000 cuts per minute using a peristaltic pump and at any cut rate with Venturi pump (P < 0.001). The SB also yielded the lowest fluid acceleration than both the HB and SB (P < 0.001 in all cases). The HB and SB proved to be significantly more efficient than the RB, with better duty cycle and higher flow rate. The SB generated significantly less fluid acceleration than any other tested blade, regardless of the fluid viscosity and pump technology. The SB design is significantly more efficient and possibly safer than both HB and RB.