Evaluation of a new method of irrigation and aspiration for removal of ophthalmic viscoelastic device during cataract surgery in a porcine model.

BACKGROUND: To determine if a method for irrigation and aspiration (I/A) during cataract surgery provides effective removal of ophthalmic viscoelastic device (OVD). METHODS: Japanese porcine eyes were used to evaluate I/A performance with Technique 1 (the I/A tip placed on the center of the anterior surface of the IOL), Technique 2 (the I/A tip alternately pressed near the edge of the IOL optic anterior surface on one side and then the other to tilt the IOL back and forth), and Technique 3 (the I/A tip inserted behind the IOL optic, between it and the posterior capsule). Techniques 1 and 2 were compared using the Miyake-Apple posterior view video technique to visualize the flow of irrigation fluid containing triamcinolone acetonide particles behind the IOL. To check the efficacy of OVD removal from behind the IOL for of all three I/A techniques, OVD with fluorescein beads were inserted inside the lens capsule before implantation of the IOL. After each I/A technique, eyes were prepared for Miyake-Apple viewing and pictures of the lens capsule were taken using fluorescent microscopy. Residual fluorescein beads in the capsular bag were analyzed. RESULTS: Technique 1 resulted in a straight flow of fluid behind the IOL, while Technique 2 resulted in a vortex flow. The average amount of OVD retained inside the capsule after using Technique 2 or 3 was significantly lower than after using Technique 1 (p <0.0001). CONCLUSIONS: Technique 2 proved to remove more effectively fluorescein bead-labelled OVD under the IOL than Technique 1.

Ocular penetration and efficacy of levofloxacin using different drug-delivery techniques for the prevention of endophthalmitis in rabbit eyes with posterior capsule rupture.

PURPOSE: To evaluate the effects of different drug-delivery techniques for levofloxacin (LVFX) in ocular penetration and the prevention of endophthalmitis using an aphakic rabbit model with posterior capsule rupture (PCR). METHODS: LVFX was administered to aphakic rabbit eyes with or without PCR using eye drops (EDs), subconjunctival injection (SCI), or intracameral (IC) injection. The concentration of the drug in the vitreous and aqueous humors was estimated at 2 h after injection. In another study, aphakic rabbit eyes with PCR were inoculated with Enterococcus faecalis, immediately followed by 0.5% LVFX ED, 0.5% moxifloxacin (MFLX) ED, LVFX IC (500 µg/0.1 mL), or IC saline. EDs were administered 0, 3, and 6 h after surgery. Changes on electroretinography (ERG) and intraocular bacterial growth were determined sequentially until 48 h after inoculation. RESULTS: The concentrations of LVFX at 2 h after IC were higher in the aqueous humor and the vitreous cavity of eyes with or without PCR, compared with EDs or SCI. Eyes treated with LVFX ED, MFLX ED, or IC saline showed a significantly greater reduction in b-wave amplitude on ERG at 48 h compared with eyes treated with LVFX IC. The number of bacteria recovered from the vitreous humor in eyes treated with IC LVFX at 48 h was significantly less than from eyes that received other treatments. CONCLUSION: The LVFX IC was effective at suppressing endophthalmitis caused by E. faecalis in eyes with a PCR.

New side-view imaging technique for observing posterior chamber structures during cataract surgery in porcine eyes.

BACKGROUND: To develop a side-view imaging technique for observing the dynamic behavior of posterior chamber structures (PCSs) in porcine eyes which mimics closed-eye cataract surgery in humans. METHODS: Enucleated porcine eyes were placed into liquid nitrogen for 5 seconds and immediately bisected at about a 45-degree angle to the equatorial plane. The anterior portion was attached firmly to a glass slide with superglue and sprinkled with wheat flour. Phacoemulsification and aspiration (PEA) was performed as in humans on 10 consecutive porcine eyes. The movements of the PCSs were monitored through the glass slide with a high-resolution video camera set below the cut surface of the eye. The intraocular pressure (IOP) was monitored during the surgery. The highest IOP, operation time, and volume of irrigation fluid of 10 whole eyes were compared to that obtained from the bisected eyes glued to a glass slide. In a second set of experiments, the strength of the seal between the bisected eye and the glass slide was tested in three sets of eyes: 1) frozen eye fixed with superglue with wheat flour for 3 min; 2) frozen eye fixed with superglue for 3 min; and 3) non-frozen eye fixed with superglue for 30 min. The highest IOP that led to a disruption of the seal was compared among the three groups. RESULTS: PEA was successfully performed on 9 of 10 (90%) eyes with the movements of the PCSs clearly observed. The average maximum intraocular pressure of the 9 bisected eyes was 55.8 ± 4.7 mmHg and that for the 10 unbisected eyes was 55.3 ± 5.0 mmHg (P = 0.650). The frozen eye fixed with superglue in combination with wheat flour (Group 1) had the strongest sealing strength with an average IOP at the breaking point of 117.3 ± 36.2 mmHg. CONCLUSIONS: Our side-view imaging technique can be used to evaluate the changes of the PCSs during intraocular surgery and for surgical training of new residents.

Moxifloxacin as postoperative prophylaxis for Enterococcus faecalis-induced endophthalmitis after cataract surgery in aphakic rabbits.

PURPOSE: The development of endophthalmitis after cataract surgery often results in significant vision loss. Inhibition of bacterial proliferation in the anterior chamber using antibiotic eye drops is important to prevent endophthalmitis after cataract surgery. We aimed to determine the sensitivity of fluoroquinolones against Enterococcus faecalis ocular isolates and the efficacy of fluoroquinolones to prevent E. faecalis-induced endophthalmitis in aphakic rabbits. METHODS: The minimum inhibitory concentrations (MICs) of moxifloxacin (MFLX) and levofloxacin (LVFX) used in ophthalmic solutions for 13 E. faecalis isolates obtained from the conjunctival sac or endophthalmitis cases were determined. Eye drops containing MFLX (0.5%), LVFX (0.5%), or saline were administered to aphakic rabbits with endophthalmitis induced by E. faecalis. The eye drops were administered immediately after lensectomy and at 3 and 6 h after cataract surgery (early instillation group) or immediately after lensectomy and at 12 and 15 h after cataract surgery (delayed instillation group). Bacterial growth, electroretinography (ERG), and slit-lamp examination (SLE) were determined throughout the course of infection. RESULTS: In vitro susceptibility testing revealed that the MICs of MFLX for E. faecalis isolates were lower than those of LVFX. In the early ocular instillation groups, MFLX significantly improved SLE scores, ERG, and viable bacterial counts compared with LVFX and saline (all, P<0.05). There were no significant differences in any parameter between MFLX and saline in the delayed ocular instillation groups. CONCLUSIONS: Early ocular instillation of MFLX delays retinal damage compared with LVFX when used to treat E. faecalis-induced endophthalmitis after cataract surgery.

Influence of elevated intraocular pressure on the posterior chamber-anterior hyaloid membrane barrier during cataract operations.

OBJECTIVE: To investigate the influence of elevated intraocular pressure on the posterior chamber-anterior hyaloid membrane (PC-AHM) barrier during cataract operations in ex vivo porcine eyes. METHODS: A pressure transducer was connected to porcine eye anterior chambers (ACs). In experiment 1, ACs were perfused for 20 seconds with balanced salt solution containing 1.0-µm fluorescein beads (10 eyes per bottle height: 45, 85, 145, and 285 cm). In experiment 2, 5 ophthalmic viscosurgical devices with different molecular weights and sodium hyaluronate concentrations were infused into the ACs (20 eyes per ophthalmic viscosurgical device). After continuous curvilinear capsulorrhexis, hydrodissection was performed. After both experiments, PC-AHM barrier staining was evaluated through the Miyake-Apple view. RESULTS: Types of fluorescein staining patterns were classified as AC, zonule of Zinn, AHM, AHM tear, and ruptured capsule. In experiment 1, plateau intraocular pressure and staining type were positively correlated (Spearman rank correlation; r = 0.703, P < .001). In experiment 2, mean peak intraocular pressure was significantly greater in the ruptured capsule-type eyes than in the AC-, zonule of Zinn-, AHM (P < .001), or AHM-tear-(P = .02) type eyes, as well as in the AHM- and AHM-tear-type eyes compared with the AC and zonule of Zinn type eyes (P < .001). Intraocular pressure was significantly higher in eyes infused with ophthalmic viscosurgical devices with a higher molecular weight or sodium hyaluronate concentration (P < .05). CONCLUSIONS: Stress on the PC-AHM barrier increases as intraocular pressure increases. Ophthalmic viscosurgical devices with a higher molecular weight or sodium hyaluronate concentration might induce increased IOP during cataract operations. CLINICAL RELEVANCE: To maintain normal PC-AHM barrier function, excessive intraocular pressure should be avoided during cataract operations.

[The effectiveness of intravitreal administration of bevacizumab for choroidal neovascularization in retinal angioid streaks].

PURPOSE: To investigate the effectiveness of intravitreal administration of bevacizumab (IVB) for choroidal neovascularization (CNV) in retinal angioid streaks (AS). SUBJECTS AND METHODS: Five eyes of four subjects with CNV in AS were observed for an average followup period of 12 months. The average greatest linear diameter (GLD) of the AS was 4315 microm before treatment. IVB (1.0 mg or 1.25 mg) was performed a total of two times at eight week intervals, and additional bevacizumab was administered whenever exudative changes occurred. RESULTS: Visual acuity improved in one eye (20%), was maintained in two eyes (40%), and worsened in two eyes (40%). Recurrence of CNV was observed in two eyes (40%). Before treatment, the GLD was 2439, 2844, and 3654 microm in the three eyes in which visual acuity was maintained, and 5803 and 6837 microm in the two eyes with worsened visual acuity. Recurrence of CNV was observed in the two eyes with worsened visual acuity. CONCLUSION: Short-term CNV fibrosis and maintenance of visual acuity were achieved with IVB in cases in which the GLD was less than 3500 microm.

Disruption of the posterior chamber-anterior hyaloid membrane barrier during phacoemulsification and aspiration as revealed by contrast-enhanced magnetic resonance imaging.

OBJECTIVE: To determine the effect of phacoemulsification and aspiration (PEA) in different surgical settings on the posterior chamber-anterior hyaloid membrane (AHM) barrier. METHODS: Eighty enucleated porcine eyes divided into 8 groups underwent lens extraction at a bottle height of 35 or 95 cm by 1 of the following 4 procedures: standard PEA, standard PEA without hydrodissection (sPEA-), sPEA- including 5 minutes of irrigation of the anterior chamber, and sPEA- including 20 cycles of deflation (5 seconds each cycle) and inflation (10 seconds each cycle) of the anterior chamber. Distribution of gadopentetate dimeglumine (gadolinium-diethylenetriamine pentaacetic acid [Gd-DTPA]) in the irrigating fluid was assessed by magnetic resonance imaging (MRI). RESULTS: The most common MRI pattern was the posterior chamber type, where Gd-DTPA was localized in the anterior and posterior chambers, followed by AHM detachment, in which Gd-DTPA was evident beneath the posterior lens capsule. The least common was AHM tear, in which Gd-DTPA entered the vitreous cavity through a tear in the AHM. Logistic regression analysis revealed prolonged irrigation (P< .001) and deflation/inflation of the anterior chamber (P< .001) as risk factors for AHM detachment and hydrodissection (P= .04) as a risk factor for AHM tear. CONCLUSION: Changes in intraocular pressure can disrupt the posterior chamber-AHM barrier during PEA. CLINICAL RELEVANCE: Cataract surgeons should reexamine their surgical settings to avoid unnecessary stress on the eye.