Evaluation of a novel treatment, selenium disulfide, in killing Demodex folliculorum in vitro.

OBJECTIVE: To evaluate the effectiveness of varying concentrations of selenium sulfide, an active ingredient in antidandruff shampoo, in killing Demodex folliculorum. METHODS: Sixty-five eyelashes with live Demodex from 29 patients seen at the Nassau University Medical Center (17 patients) and Ophthalmic Consultants of Long Island (12 patients) were observed under light microscopy for 90 minutes in 0.1%, 0.5%, 1.0%, and 4% selenium sulfide with either carboxymethyl cellulose (CMC) solution or petroleum jelly ointment (Vaseline, Unilever, London) as excipients. Positive and negative controls also were evaluated as separate solutions of CMC, petroleum jelly, basic saline solution, 50% tea tree oil, and 100% tea tree oil. The number of Demodex deaths and time of death were recorded. RESULTS: Demodex deaths in the selenium sulfide reagents were observed in the 4% selenium sulfide solution with CMC (36.4% kill rate, 4 of 11 Demodex, average time of death 17.5 minutes, p = 0.038) and 4% selenium sulfide with petroleum jelly ointment (12.5% kill rate, 1 of 8 Demodex, time of death 75 minutes, p = 0.351). No Demodex deaths were witnessed in the other selenium sulfide treatment groups. All Demodex died in the 50% and 100% tea tree oil positive control group. CONCLUSIONS: Selenium sulfide has shown efficacy in killing Demodex at a 4% concentration with the CMC solution and mild activity with 4% petroleum jelly. More research on selenium sulfide solutions at higher concentrations is indicated.

Optimizing Tip Diameter in Phacoemulsification of Varying Lens Sizes: An in vitro Study.

PURPOSE: We assessed the effect of two lens cube sizes, three tip sizes, and two ultrasound (US) approaches on phacoemulsification efficiency and chatter. METHODS: After porcine lens nuclei were soaked in formalin, we divided them into cubes measuring 2.0 mm or 3.0 mm. We collected efficiency and chatter data for 30-degree bent 19 G, 20 G, and 21 G tips with a continuous torsional US system; and for straight 19 G, 20 G, and 21 G tips with a micropulse longitudinal US system. RESULTS: The average time needed for removal was always higher for the 3.0 mm lens cube than for the 2.0 mm lens cube. Statistically significant differences were observed between the 19 G and 21 G tips with micropulse longitudinal US using a 2.0 mm cube and a 3.0 mm cube, and with continuous transversal US using a 2.0 mm lens cube and a 3.0 mm cube. We did not observe significant differences between 19 G and 20 G tips with either cube size in either US system. However, we noted identical trends for both cube sizes with both US approaches; 19 G tips performed better than 20 G and 21 G tips. CONCLUSION: Regardless of the lens size, 19 G needles were the most efficient, and had both the fewest outliers and the smallest standard deviations.

'S' means stop! Critical examination of capsular tension ring movements with Miyake-Apple video analysis.

PURPOSE: To examine capsular tension ring (CTR) implantation to establish whether there are predictable movements of the CTR during deployment, indicating complicated vs uneventful implantation. SETTING: Intermountain Ocular Research Center, John A. Moran Eye Center, University of Utah, Salt Lake City, Utah. DESIGN: Experimental study. METHODS: Nine cadaver eyes were prepared using standard Miyake-Apple protocol with digital video recording. A 4 o'clock-hour zonular dialysis was created, followed by a capsulorhexis and hydrodissection. In 4 eyes, a suture-guided CTR (SGCTR) injector and 8-0 nylon suture through the leading eyelet served as a visible tracer for the CTR. In 5 eyes, a standard CTR was used. The movements of the CTR during implantation were observed. RESULTS: In all eyes, SGCTR and CTR movements were predictable during implantation. All CTRs displayed cardinal movements within the injector, initially adjacent to the side of the inner diameter of the CTR. As the CTR made contact with lens or capsule, it shifted first to the center and then to the opposite side of the injector lumen. The appearance of an S-curve in the surgeon's view coincided with an obstruction of the leading eyelet and stress on the zonular fibers, as viewed with Miyake-Apple analysis. CONCLUSIONS: Traumatic CTR implantation might be avoided by understanding the characteristics of uneventful insertion vs an insertion complicated by entrapment or entanglement of the CTR. By recognizing the abnormal movements of the CTR associated with an obstruction, a surgeon might avoid iatrogenic complications.

Capsular tension ring explant complication rate comparison using Miyake-Apple video analysis.

PURPOSE: To compare the complication rate and time required to explant standard capsular tension rings (CTRs) vs suture-guided CTRs (SGCTRs). SETTING: Intermountain Ocular Research Center, John A. Moran Eye Center, University of Utah, Salt Lake City, Utah. DESIGN: Experimental study. METHODS: Eight cadaver eyes were prepared using standard Miyake-Apple protocol with digital video recording. A 4 clock-hour zonular dialysis was created, followed by a capsulorhexis, hydrodissection, and CTR (n = 4) or SGCTR (n = 4) implantation. With the CTR hidden from view by the overlying iris, ophthalmic surgical instruments were used to remove the CTRs. Time required to remove the CTR and any complications were recorded. A limit of 180 seconds was imposed to determine inability to remove the CTR. RESULTS: In the standard CTR group (n = 4), removal was associated with high rates of complication (100%). Complications included capsular tears (n = 2), dialysis extension (n = 1), and inadvertent intracapsular cataract extraction (n = 1). The SGCTR group had no complications associated with removal (n = 4). Time required to explant a CTR was significantly reduced from 164.5 seconds with standard CTRs to 6.9 seconds with SGCTRs (P = .001). CONCLUSIONS: Attempts to remove a standard CTR from the capsular bag was met with a high complication rate. The addition of suture to the leading eyelet of the CTR prior to implantation significantly reduced the time and effort required to remove the CTR and was associated with a significant reduction in complication rates.

Evaluation of the capsular safety of a new hybrid phacoemulsification tip in a cadaver eye model.

PURPOSE: To evaluate the use of a new hybrid phacoemulsification tip made with a high strength polymer overmold designed to prevent posterior capsule rupture (PCR) compared with a metal tip. SETTING: John A. Moran Eye Center, University of Utah, USA. DESIGN: Experimental study. METHODS: This ex vivo crossover study compared a new phacoemulsification tip to a metal tip. After a preliminary experiment applying the tips to the posterior capsule with the bevel down, 10 phakic cadaver eyes were prepared using the Miyake-Apple technique, after which each tip was tested in a series. After lensectomy, the posterior capsule was subjected to direct contact from the tip with the bevel up. The vacuum limit was set to 150 mm Hg, and the aspiration flow rate to 30 cc/min, after which the torsional power was increased by increments of 5% up to a maximum amplitude of 60%. The primary endpoint was the torsional power required to produce PCR. RESULTS: Vacuum alone did not cause PCR with either tip. All tests showed that a higher torsional power was required for PCR with the hybrid tip. With the bevel directed upward, the hybrid tip required higher torsional power before PCR than the metal tip (55% ± 10.0% [SD] versus 15% ± 4.1%, respectively) (P value < .001). This indicates that there is a lower likelihood for PCR with the hybrid tip. CONCLUSION: The hybrid tip used in this study can be an effective means of preventing surgical complications such as PCR. This tip would be useful for experienced surgeons as well as for those who are in training.

Impact of torsional micropulse on phacoemulsification efficiency and chatter.

OBJECTIVE: Evaluate the effect of increasing ultrasound (US) power on chatter events and efficiency under both continuous and micropulse torsional US to reduce total cataract extraction times. DESIGN: In vitro laboratory study. METHODS: Porcine lens nuclei were incubated in formalin for 2 hours and then cut into 2-mm cubes. Phacoemulsification was performed using the Centurion Vision System and Infiniti OZil handpiece with the balanced tip. Both US modalities were studied at 60%, 80%, and 100% power. Micropulse rate was 83 pulses per second with 50% on time. Each combination comprised 20 runs. Efficiency was considered as the total time for a cube to be emulsified; chatter was the number of times the lens fragment bounced off the tip. RESULTS: There was significant decrease in efficiency when power was increased from 60% to 100% (1.33-1.97 s; p < 0.001) under micropulse US and significant increase in chatter when power was further increased to 100% from 60% (0.15-0.94 s; p < 0.001). There was no significant efficiency change with increased power under continuous US. Comparing the phacoemulsification efficiency between continuous and micropulse US, we found no significant difference at 60% and 80% power; at 100% power, continuous was significantly more efficient than micropulse (1.48 and 1.97 s, respectively; p = 0.001). CONCLUSIONS: Increasing power above 60% decreased efficiency under torsional micropulse US. We believe that this was due to the chatter increase observed with increasing US power. Torsional continuous US was significantly more efficient than micropulse US at 100% power.

Optimization of the Oertli CataRhex 3® phacoemulsification machine.

PURPOSE: The aim of this study was to determine optimal bottle height, vacuum, aspiration rate, and power settings of the Oertli CataRhex 3® phacoemulsification machine. METHODS: Porcine lens nuclei were hardened with formalin and cut into 2.0 mm cubes. Lens cubes were emulsified using the easyTip® 2.2 mm at 30°. Fragment removal time (efficiency) and fragment bounces off the tip (chatter) were measured. Settings tested included bottle height of 60, 80, 100 and 120 cm; aspiration rate of 40, 45, and 50 mL/min; vacuum of 400, 500, and 600 mmHg; and power of 50, 60, 70, 80, 90, and 100%. RESULTS: Efficiency and chatter increased in a linear fashion with increasing vacuum to 600 mmHg (P=0.017, P=0.046, respectively). The most efficient aspiration rate was 50 mL/min, although this finding lacked statistical significance (P=0.66). Increasing power increased efficiency up to 80% without increasing chatter (P=0.042, P=0.71, respectively). Compared to all other power settings, chatter was increased at 100% (P=0.014). CONCLUSION: The most efficient machine settings were vacuum at 600 mmHg, aspiration rate at 50 mL/min, and power at 80%.

The effect of increasing power when grooving using phacoemulsification.

PURPOSE: To determine optimal power settings on the Centurion Vision System during the grooving step in cataract surgery. METHODS: Intact porcine lenses hardened by formalin and placed in a chamber designed to simulate the anterior chamber of the eye were used to test longitudinal power at 40%, 70%, and 100% and torsional power at 0%. Flow rate was set at 40 mL/min. Vacuum was set at 400 mmHg, intraocular pressure was set at 50 mmHg, and a balanced phacoemulsification tip with a 20 degree tip and a 30 degree bevel was used. Efficiency (time to groove the lens in half) was determined. RESULTS: Increasing longitudinal power from 40% to 70% increased efficiency by 28% (P<0.05), and by 32% (P<0.05) when increasing longitudinal power from 40% to 100%. There was no statistically significant increase in efficiency from 70% to 100%. CONCLUSION: For the tested variables, a longitudinal power of 70% was determined to be most efficient during the grooving step of cataract surgery for equivalent 3-4+ nuclei. Further increases in power demonstrated no statistically significant improvement in efficiency.

Determining optimal ultrasound percent on time with long-pulse torsional phacoemulsification.

OBJECTIVE: To evaluate the optimum percent on time for the most efficient lens fragment removal using long-pulse torsional ultrasound (US). DESIGN: In vitro laboratory study. METHODS: Porcine lens nuclei were incubated in formalin for 2 hours and then cut into 2 mm cubes. Phacoemulsification was performed using the Centurion® Vision System and Infiniti OZil handpiece with the balanced tip. Vacuum was set at 500 mm Hg, aspiration rate at 50 mL/min, and intraocular pressure (IOP) at 50 mm Hg. Pulse rate was 26 pulses/second. Studied parameters were percent power: 60%, 80%, and 100%, and percent on times: 50%, 60%, 70%, and 80%. Efficiency was the total time for a cube to be emulsified. Chatter was the number of times the lens fragment bounced off the tip. RESULTS: There was no significant difference in efficiency between 50%, 60%, and 70 % on-time settings (p = 0.17 and 0.08, respectively); however, there was significant increase in efficiency when the on time was increased from 70% to 80% (p = 0.03). Increasing power from 60% to 100% showed a statistically significant efficiency increase (p = 0.001). There was no significant change in chatter with increasing on time; however, there was a statistically significant increase in chatter with every power level increase. CONCLUSION: Increasing on-time percent does not improve efficiency under torsional long-pulse US. There is no significant change in chatter with increasing on-time percent. Increasing power increases efficiency despite chatter increase. Long-pulse US does not appear to influence torsional action in a clinically meaningful way.

In vivo evaluation of a new hydrophobic acrylic intraocular lens in the rabbit model.

PURPOSE: To evaluate the uveal and capsular biocompatibility as well as positioning stability of a new hydrophobic acrylic intraocular lens (IOL) in vivo in the rabbit model and compare it with a commercially available IOL. SETTING: John A Moran Eye Center, University of Utah, Salt Lake City, Utah, USA. DESIGN: Experimental study. METHODS: Fifteen New Zealand rabbits had the new test IOL (Clareon CNA0T0) implanted in one eye and a control IOL (Acrysof SN60WF) implanted in the contralateral eye. The test IOL is manufactured from a new hydrophobic acrylic material incorporating ultraviolet blocker and blue light filter. Its design is based on the control IOL's platform. The rabbits were followed up with weekly slitlamp evaluations, which assessed inflammatory reactions as well as capsular bag opacification. Anterior chamber depth was measured at 1 and 4 weeks post-implantation (high-frequency ultrasound). After 4 weeks, the rabbits were killed humanely and the eyes were enucleated. The anterior segment was evaluated from the posterior or Miyake-Apple view, and was then processed for complete histopathology. RESULTS: There were no statistically significant differences between test and control eyes in terms of postoperative inflammation and capsular biocompatibility, including posterior capsule opacification (P = .34, paired t test), and anterior capsule opacification (P = .53, paired t test), as observed during clinical and pathological evaluation. In vivo axial positioning for the test IOL was comparable to the control IOL and stable over time (P = .531 versus P = .788). CONCLUSIONS: The new IOL showed biocompatibility and stability comparable to the control IOL.

Effect of high vacuum and aspiration on phacoemulsification efficiency and chatter using a transversal ultrasound machine.

PURPOSE: To examine the role of high vacuum and aspiration settings on efficiency using a transversal ultrasound (US) machine. SETTING: John A. Moran Eye Center Laboratory, University of Utah, Salt Lake City, Utah, USA. DESIGN: Experimental study. METHODS: Porcine lens nuclei were incubated in formalin for 2 hours and then cut into 2.0 mm cubes. Phacoemulsification was performed using the Whitestar Signature machine. Settings were bottle height 50 cm, on-time 6 milliseconds, and off-time 6 milliseconds. One hundred percent power was used for all 240 runs. Tested parameters were aspiration of 50 mL/min and 60 mL/min and vacuum of 500, mm Hg, 600 mm Hg, and 650 mm Hg. RESULTS: With continuous US, increasing aspiration from 50 mL/min to 60 mL/min significantly increased efficiency (23%). Increasing vacuum from 500 mm Hg to 650 mm Hg and from 600 mm Hg to 650 mm Hg significantly increased efficiency (20.2% and 13.6%, respectively). Higher vacuum and aspiration parameters did not influence the incidence of chatter events. In the micropulse US group, there was no significant efficiency increase with increasing vacuum or aspiration levels. There was a significant efficiency increase of continuous over micropulse US at an aspiration setting of 60 mL/min and vacuum settings of 600 mm Hg and 650 mm Hg. CONCLUSIONS: As aspiration and vacuum increased, efficiency increased under continuous transverse US. No significant efficiency improvement occurred at high aspiration and vacuum settings under micropulse US. At 60 mL/min aspiration and more than 600 mm Hg vacuum, continuous power was significantly more efficient than micropulse transverse US.

Effect of increasing flow when grooving during phacoemulsification.

PURPOSE: To determine optimum flow settings on the Centurion Vision System during the grooving step in cataract surgery. SETTING: John A. Moran Eye Center Laboratory, University of Utah, Salt Lake City, Utah, USA. DESIGN: Experimental study. METHODS: Intact porcine lenses hardened by formalin and placed in a chamber designed to simulate the anterior chamber of the eye were used to test flow rate settings at 20 mL/min, 40 mL/min, and 60 mL/min. Vacuum was set at 400 mm Hg, longitudinal power at 80%, torsional power at 80%, and intraocular pressure at 50 mm Hg. A balanced phaco tip with a 20-degree tip and a 30-degree bevel was used. Efficiency (time to groove the lens in half) was determined. RESULTS: Increasing flow from 20 to 40 mL/min during grooving increased efficiency by 17% (P = .05), with no significant improvement shown at 60 mL/min. CONCLUSIONS: A flow rate of 40 mL/min was determined to be most efficient during the grooving step of cataract surgery. Further increases in flow rate showed no statistically significant improvement in efficiency, and with only 17% improvement flow rates less than 40 mL/min might be almost as efficient and might be safer.

Rapid neuroadaptation to surgically-induced aniseikonia in a 17-year-old patient with high preoperative anisometropia: A case report.

PURPOSE: To report a case of rapid neuroadaptation to surgically-induced aniseikonia in a 17-year-old with preoperative anisometropia of 9.5 D. OBSERVATIONS: A 17-year-old female with a history of retinopathy of prematurity (ROP) and progressive high myopia with resulting anisometropia secondary to conventional laser photocoagulation in her right eye was found to have diplopia after undergoing cataract surgery in that eye. Other etiologies of diplopia were ruled out and reversal of anisometropia remained the only viable diagnosis. Her diplopia fully resolved without intervention within one month of the surgery. CONCLUSION AND IMPORTANCE: In cases of neuroadaptation to long standing anisometropia, even if that anisometropia develops in infancy, abrupt reversal following surgery can be surprisingly well tolerated.