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Biomedical subjects

Randall J Olson

Publications and source records attributed to Randall J Olson.

12 recordsLinked to original sources
PubMed2003

Cataract treatment in the beginning of the 21st century.

PURPOSE: To describe the principles upon which present day cataract treatment success resides. DESIGN: Literature review and collective experience of the authors. RESULTS: Surgical removal remains the standard treatment for cataract now and in the foreseeable future. Ultrasound cataract removal with a foldable "in-the-bag" intraocular lens with a truncated edge treated for dysphotopsia best correlates with core treatment principles, as we now understand them. Improving refractive results is an important trend. The worldwide burden of this problem is immense. CONCLUSIONS: While results for treatment of cataracts are excellent today, improvements in safety and refraction precision are needed. Other approaches are desperately needed to stem the worldwide tide of cataract related ocular dysfunction.

Cataract↗
PubMed2003

A clinical comparison of single-piece and three-piece truncated hydrophobic acrylic intraocular lenses.

PURPOSE: To determine the clinical differences between three-piece (3P) and single-piece (SP) truncated hydrophobic acrylic intraocular lenses (IOL). DESIGN: Retrospective cohort clinical study. METHODS: The setting was an academic clinical practice. The patient population consisted of subjects without confounding comorbidity that could effect central vision with at least 1-year follow-up after uncomplicated surgical placement of 3P or SP IOLs in the capsular bag and at least 20/25 best-corrected postoperative vision documented. Observation procedures were as follows: logarithm of the minimal angle of resolution (LogMAR) visual acuity (uncorrected and best corrected), digital retroillumination photographs to ascertain posterior capsular opacification (PCO), anterior capsular opacification (ACO), IOL centration, and refractive stability by comparing this refraction with the early postoperative refraction. Patients completed a dysphotopsia questionnaire. Main outcome measures were as follows: LogMAR visual acuity (uncorrected and best corrected), PCO, ACO, IOL centration, refractive stability, and dysphotopsia outcomes comparing 3P and SP. RESULTS: Seventy-five patients were enrolled (36 3P and 39 SP). Corrected and uncorrected visual acuity, refractive stability, and IOL centration were similar. Single piece truncated hydrophobic acrylic intraocular lenses had more PCO (P =.013), less ACO (P =.001), less central flash looking at a peripheral light (P =.044), and less unwanted images to the side of a light source (P =.025) . CONCLUSIONS: Although similar in centration and refractive stability, SP has more PCO, less ACO, and less dysphotopsia than 3P.

Acrylic Resins↗
PubMed2003

Efficacy and wound-temperature gradient of whitestar phacoemulsification through a 1.2 mm incision.

PURPOSE: To evaluate the efficacy and wound-temperature gradients of WhiteStar micropulse technology using bimanual phacoemulsification without an irrigation sleeve through a 1.2 mm incision. SETTING: Island Eye Surgicenter, Carle Place, New York, USA. METHODS: Ten patients had bimanual phacoemulsification using micropulse technology without an irrigation sleeve through a 1.2 mm clear corneal incision. A thermocouple consisting of a 30-gauge copper wire was inserted into clear cornea directly adjacent to the wound to digitally record temperature gradients at the wound. Endothelial cell counts were evaluated preoperatively and postoperatively in all patients. RESULTS: All 10 patients maintained corneal clarity with no sign of thermal damage to the wound. The maximum corneal wound temperatures during phacoemulsification ranged from 24 degrees C to 34 degrees C, well below the temperature of collagen shrinkage. The endothelial cell loss at 3 months was 7%. CONCLUSIONS: Because of the decreased thermal effect with WhiteStar technology, an irrigation sleeve over the phacoemulsification needle is superfluous. As a result, bimanual phacoemulsification can be safely performed through a 1.2 mm incision.

Body Temperature↗
PubMed2003

White Star technology.

White Star micropulse technology is a software modification that allows extremely short bursts of ultrasound energy. Studies have shown that this decreases wound heat build-up with the retained efficiency of continuous ultrasound. Decreased energy utilization with improved corneal function and improved nuclear fragment followability appear to be additional benefits.

Hot Temperature↗
PubMed2002

Accuracy and reproducibility of biometry using partial coherence interferometry.

PURPOSE: To determine whether partial coherence interferometry is comparable to standard contact ultrasonic biometry in accuracy, reproducibility, and ease of use. SETTING: Academic university practice. METHODS: In this prospective study, simultaneous biometry was performed in 91 consecutive patients (111 eyes) using partial coherence interferometry (IOLMaster, Zeiss Humphrey Systems) and ultrasonic biometry (I(3), Innovative Imaging, Inc.). The differences between the predicted spherical equivalent in diopters (D) and the actual results with both techniques were compared. RESULTS: The IOLMaster was significantly better in the mean absolute error (0.533 D +/- 0.589 [SD] versus 0.757 +/- 0.723 D; P = .012) and the percentage of eyes within +/-0.5 D (61.2% versus 42.3%; P = .003) and +/-1.0 D (87.4% versus 77.5%; P =.05) of the predicted refraction. CONCLUSION: The IOLMaster was more accurate and reproducible than the contact ultrasonographic technique.

Biometry↗
PubMed2002

In vitro comparison of glistening formation among hydrophobic acrylic intraocular lenses(1).

PURPOSE: To compare glistening formation induced by temperature stressing in vitro among hydrophobic acrylic intraocular lenses (IOLs) available in the United States. SETTING: John A. Moran Eye Center, University of Utah, Salt Lake City, Utah, USA. METHODS: Wagon Wheel (WW) packaged 1-piece AcrySof IOLs (Alcon), WW-packaged 3-piece AcrySof IOLs, and Sensar IOLs (Allergan Medical Optics) were analyzed in vitro for 5 consecutive days. Ten IOLs of each type were inserted into viewing chambers filled with balanced salt solution, maintained at 37 degrees C, and evaluated every 24 hours at 37 degrees C and then, after a 2-hour cooling, at room temperature. The IOLs were examined by slitlamp to quantify glistenings and by digital photography to determine glistening size. RESULTS: The glistening quantity was minimal and did not differ among IOL types at 37 degrees C. The glistenings were smallest in the 1-piece AcrySof IOLs (P <.001): 6.3 microm versus 11.5 microm in the Sensar and 13.4 microm in the 3-piece AcrySof. Upon cooling, the glistening quantity increased dramatically in the 1-piece AcrySof IOLs (P <.008) and was the highest among the IOL types at room temperature (P <.001). The mean glistening size was 7.7 microm. The 3-piece AcrySof IOLs showed a significant decrease in slitlamp-countable glistenings but acquired a dense haze seen as minute glistenings (4.0 microm) at x80 magnification. The glistening quantity in the Sensar IOLs was fairly stable upon cooling; a statistical increase was seen on the last day (P =.007). Cooling nearly doubled the size of the Sensar glistenings, which were the largest at room temperature, 21.7 microm (P <.001). CONCLUSIONS: Glistening quantity varied among hydrophobic acrylic IOLs and was temperature dependent. Sensar IOLs were more stable than the 2 other IOL types. The glistening phenomenon must be studied further to eliminate the problem.

Acrylic Resins↗
PubMed2002

Microphacoemulsification with WhiteStar. A wound-temperature study.

PURPOSE: To verify the temperature-induction effect of bimanual ultrasound-based phacoemulsification through 2 stab incisions with a bare aspiration needle and new proprietary technology. SETTING: In vitro laboratory. METHODS: The Sovereign phacoemulsification unit and the WhiteStar system (Allergan) were used in conjunction with the Olson irrigating chopper (ASICO) and a 19-gauge bare phaco needle in 2 human cadaver eye-bank eyes at 100% power unoccluded, 100% power with aspiration completely occluded, and 100% power with aspiration and flow completely occluded. Temperature data were monitored throughout the experiment. Any sign of a wound burn, defined as temperature exceeding 45 degrees C, whitening around the wound, or wound contraction, was the end point. RESULTS: At 100% continuous phacoemulsification power, the temperature did not rise above 27.3 degrees C. When the aspiration line was totally occluded at 100% continuous power, the temperature did not rise above 32.5 degrees C. When flow into the eye and aspiration were completely occluded at 100% power, a wound change and temperature of 45 degrees C occurred in 45 seconds in the first eye and in 29 seconds in the second eye. CONCLUSIONS: Using the Sovereign phacoemulsification unit with the WhiteStar system during 2-stab-incision bimanual microphacoemulsification with a bare 19-gauge aspiration needle in human cadaver eyes, a wound burn could not be produced at the highest energy settings unless all flow into the eye and all aspiration were occluded. These settings were well beyond clinically applicable conditions and provide evidence that microphacoemulsification can be performed safely with the WhiteStar system.

Anterior Eye Segment↗
PubMed2002

Bimanual phacoemulsification through 2 stab incisions. A wound-temperature study.

PURPOSE: To determine the thermal parameters of bimanual ultrasound-based phacoemulsification through 2 stab incisions with a bare aspiration needle. SETTING: In vitro laboratory. METHODS: The Sovereign phacoemulsification unit (Allergan) was used in 3 modes in conjunction with the Olson irrigating chopper (ASICO) in 6 fresh human cadaver eye-bank eyes to determine the temperature at which a wound burn would occur. A wound burn was defined as temperature exceeding 45 degrees C, whitening around the wound, or wound contraction. RESULTS: One hundred percent ultrasound power was required to create a wound burn in the unoccluded mode in continuous ultrasound and the burst mode. The time to create the wound burn was 160 and 180 seconds in 2 eyes in continuous ultrasound and 42 and 50 seconds in 2 eyes in the burst mode; it was 58 and 70 seconds in continuous ultrasound with complete occlusion and required 80% power. CONCLUSIONS: The energy necessary to obtain a wound burn during 2-incision bimanual ultrasound-based phacoemulsification with a bare aspiration needle in human cadaver eyes was extremely high. The parameters necessary to create a wound burn in each modality occurred well beyond normal clinical settings and provide evidence that 2-stab ultrasound-based lens extraction can be performed safely with the Sovereign machine.

Anterior Eye Segment↗
PubMed2002

Three-year clinical comparison of 3-piece AcrySof and SI-40 silicone intraocular lenses.

PURPOSE: To compare the 3-year performance of the 3-piece AcrySof (Alcon) and the SI-40 silicone (Allergan) intraocular lenses (IOLs). SETTING: John A. Moran Eye Center, University of Utah, Salt Lake City, Utah, USA. METHODS: In this retrospective study, patients with no complications and at least a 3-year follow-up after IOL implantation were examined for signs of inflammation, visual function, posterior capsule opacification (PCO), and satisfaction. RESULTS: One hundred eleven patients were enrolled with equivalent visual acuity, inflammation, and PCO parameters. The AcrySof eyes had less anterior capsule opacification and more intralenticular inclusions than the other group. Complete anterior capsule overlap was associated with decreased PCO, and significantly more SI-40 eyes had complete anterior capsule overlap. CONCLUSIONS: The second-generation silicone IOL was equivalent to the 3-piece AcrySof in patient satisfaction, visual function, inflammation, and PCO. The amount of anterior capsule overlap on the IOL may help to explain the study differences.

Acrylic Resins↗
PubMed2002

Survey of intraocular lens material and design.

Modern cataract surgery is constantly evolving and improving in terms of lens material and design. Researchers and physicians strive to obtain better refractive correction with smaller wound size and minimizing host cell response to limit the proliferation of lens epithelial cells leading to opacification of the lens capsule. Intraocular lens material varies in water content, refractive index, and tensile strength. Intraocular lens design has undergone revisions to prohibit lens epithelial cell migration and reflection of internal and external light. The evolution of intraocular lens and extracapsular cataract surgery has lead to faster postoperative recovery and better visual outcomes.

Acrylic Resins↗