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At least 775 records · Page 43Linked to original sources
PubMed2006

Intraocular pressure during phacoemulsification.

PURPOSE: To assess changes in intraocular pressure (IOP) during standard coaxial or bimanual microincision phacoemulsification. SETTING: Oregon Eye Center, Eugene, Oregon, USA. METHODS: Bimanual microincision phacoemulsification (microphaco) was performed in 3 cadaver eyes, and standard coaxial phacoemulsification was performed in 1 cadaver eye. A pressure transducer placed in the vitreous cavity recorded IOP at 100 readings per second. The phacoemulsification procedure was broken down into 8 stages, and mean IOP was calculated across each stage. Intraocular pressure was measured during bimanual microphaco through 2 different incision sizes and with and without the Cruise Control (Staar Surgical) connected to the aspiration line. RESULTS: Intraocular pressure exceeded 60 mm Hg (retinal perfusion pressure) during both standard coaxial and bimanual microphaco procedures. The highest IOP occurred during hydrodissection, ophthalmic viscosurgical device injection, and intraocular lens insertion. For the 8 stages of the phacoemulsification procedure delineated in this study, IOP was lower for at least 1 of the bimanual microphaco eyes compared with the standard coaxial phaco eye in 4 of the stages (hydro steps, nuclear disassembly, irritation/aspiration, anterior chamber reformation). CONCLUSION: There was no consistent difference in IOP between the bimanual microphaco eyes and the eye that had standard coaxial phacoemulsification. Bimanual microincision phacoemulsification appears to be as safe as standard small incision phacoemulsification with regard to IOP.

Anterior Chamber↗
PubMed2006

Quantitative thermographic analysis of viscoelastic substances in an experimental study in rabbits.

PURPOSE: To measure the temperature parameters on the corneal surface during the delivery of standardized ultrasound energy assisted with ophthalmic viscosurgical devices (OVDs) or different temperatures of irrigating solutions in an experimental animal model. SETTING: Department of Ophthalmology and Visual Rehabilitation, Medical University of Lodz, and Central Institute for Labor Protection, National Research Institute, Warsaw, Poland. METHODS: Thirty rabbits (60 eyes) were randomly divided into 6 groups in which different OVD or balanced salt solutions (BSS) were used: group 1: Viscoat (sodium hyaluronate 3%-chondroitin sulfate); group 2: Provisc (sodium hyaluronate 1%); group 3: soft-shell technique; group 4: Celoftal (hydroxypropyl methylcellulose 2%); group 5: BSS 22 degrees C; and group 6: BSS 4 degrees C. After the nucleus and lens cortex were removed, the anterior chamber was filled with OVD or BSS and a phaco tip was introduced into the pupillary plane and switched on. The same phaco tip parameters were used in all groups. For thermographic measurements (ie, maximal temperature [MT], dynamic rise in temperature [DRT], and time when the maximal level of temperature [TMLT] was achieved), a thermocamera was used. RESULTS: Mean preoperative temperature on the rabbit corneal surface was 22.76 degrees C +/- 1.48 degrees C (SD). Working with a phaco tip increased the temperature in each group. A significantly higher MT was observed in group 5 (27.85 degrees C +/- 0.52 degrees C), followed by group 2 (27.75 degrees C +/- 0.54 degrees C), group 3 (27.74 degrees C +/- 0.46 degrees C), and group 4 (27.25 degrees C +/- 0.60 degrees C), than in group 6 (26.81 degrees C +/- 0.34 degrees C) and group 1 (26.52 degrees C +/- 0.48 degrees C) (P<.05). Significantly higher values of DRT and shorter TMLT values were observed in group 5 (1.16 degrees C/s +/- 0.42 degrees C/s, 4 seconds) and group 6 (0.91 degrees C/s +/- 0.13 degrees C/s, 5 seconds) than in groups 2, 3, 1, and 4 (0.09 degrees C/s +/- 0.07 degrees C/s, 30 seconds; 0.08 degrees C/s +/- 0.04 degrees C/s, 40 seconds; 0.07 degrees C/s +/- 0.03 degrees C/s, 45 seconds; 0.06 degrees C/s +/- 0.02 degrees C/s, 50 seconds, respectively) (P<.0001). CONCLUSIONS: Currently used OVDs potentially offer different levels of protection against the increase in temperature that occurs during phacoemulsification. Therefore, the surgeon should consider this aspect when choosing an OVD, particularly in difficult cases (ie, hard nucleus, shallow anterior chamber, endothelial abnormalities).

Animals↗
PubMed2006

Visual outcomes after accommodating intraocular lens implantation.

PURPOSE: To evaluate and compare the visual outcomes and accommodative amplitude in cataract patients after implantation of the Crystalens intraocular lens (IOL) (Eyeonics) versus standard monofocal IOLs. SETTING: Ten clinics in a nationwide multicenter study in the United States. METHODS: A multicenter comparative interventional case series with masked randomized postoperative examination of 224 eyes of 112 patients was performed by a single observer. Patients were divided into 2 groups (56 patients; 112 eyes each) depending on which IOL was implanted (Crystalens or monofocal). Accommodation was measured using 1 objective (dynamic retinoscopy) and 2 subjective methods (defocus and near point of accommodation). Visual acuity measurements were performed under the same conditions with standard visual acuity charts. RESULTS: Uncorrected monocular near vision was significantly better in the Crystalens group than in the standard monofocal group, with 101 of 112 eyes (90%) and 17 of 112 (15%), respectfully, reading J3 or better postoperatively. All 56 Crystalens patients had a binocular uncorrected near visual acuity of J3 or better compared with 16 of 56 (29%) standard monofocal patients. The mean postoperative monocular (0.85 +/- 0.30 [SD] versus 0.70 +/- 0.19, P<.01) and binocular (1.16 +/- 0.17 versus 1.01 +/- 0.14, P<.01) distance uncorrected visual acuities were also better in the Crystalens group than in the control group. All patients in the study achieved a corrected distance visual acuity of 20/20 or better. Measures of accommodation were significantly higher in Crystalens patients than in the monofocal IOL patients (dynamic retinoscopy 2.42 +/- 0.39 diopters [D] versus 0.91 +/- 0.24 D, P<.01; monocular defocus 1.74 +/- 0.48 D versus 0.75 +/- 0.25 D, P<.01; monocular near point of accommodation 9.5 +/- 3.1 inches versus 34.7 +/- 9.8 inches, P<.01). Perceived accommodation (5.79 D) was significantly greater than the measured accommodation (1.96 to 2.42 D) in Crystalens patients (paired t test, P<.01). CONCLUSIONS: The Crystalens IOL provided better uncorrected near and distance visual outcomes than standard monofocal IOLs in all analyses performed. Patients perceived a greater accommodation than measured. Understanding why this occurred could lead to valuable advances in accommodating IOL technology.

Accommodation, Ocular↗
PubMed2006

Iris fixation of foldable intraocular lenses for ectopia lentis in children.

PURPOSE: To describe a technique for iris fixation of acrylic intraocular lenses (IOLs) in ectopia lentis and evaluate the medium-term anatomical and functional results in children. SETTING: Pediatric Ophthalmology Department, Fondation Rothschild, Paris, France. METHODS: This retrospective study included 17 eyes of 9 children. The technique consisted of lens ablation, leaving in place the capsule in the zone of nonruptured zonule, and an IOL placement in the remaining sulcus with 2 iris sutures. The age of patients, postoperative complications, follow-up, anatomical results, final refraction, and visual acuity were noted. RESULTS: Median age was 4.8 years. One case of postoperative hyphema and 1 case of aseptic endophthalmitis occurred and resolved after treatment. The anatomical outcome was favorable in all cases, with centered IOLs and round pupils. Mean follow-up was 16.3 months. Mean final refraction was +0.18 diopter, and mean final best corrected visual acuity was 20/32 (range 20/50 to 20/20). CONCLUSIONS: The results suggest that iris fixation of foldable IOLs for ectopia lentis in children can lead to good anatomical and functional results. The use of the remaining part of the sulcus is helpful in reaching correct positioning of the IOL. The complication rate is similar to that with other techniques described in the literature, whereas the small incision and the absence of transscleral sutures could simplify the short-term and long-term evolution.

Capsulorhexis↗
PubMed2006

Bimanual microphaco for posterior polar cataracts.

We describe a technique in which bimanual microphacoemulsification technique through 2, 1.4 mm incisions is performed for posterior polar cataract extraction. The low-infusion and low-vacuum system provides good anterior chamber stability and followability. The irrigation and aspiration handpieces are interchangeable, enabling removal of the lens fragments without hydrodissection or nucleus rotation. Only 1 (12.5%) of the 8 cases presented here was complicated by posterior capsule rupture. This occurred after epinucleus removal without any vitreous disturbance. The bimanual microphacoemulsification technique appears to minimize the risk for complications, allowing posterior polar cataract extraction to be performed more safely.

Adult↗
PubMed2004

Comparison of various pupil dilatation methods for phacoemulsification in eyes with a small pupil secondary to pseudoexfoliation.

PURPOSE: To compare 4 methods for intraoperative pupil dilatation in eyes with pseudoexfoliation syndrome and insufficient pupil size during phacoemulsification. DESIGN: Prospective, randomized, comparative, interventional case series. PARTICIPANTS: Forty eyes of 40 patients with pseudoexfoliation and maximally dilated pupil size smaller than 3.5 mm. INTERVENTION: Mechanical pupil dilatation with iris-retractor hooks (group I), polymethyl methacrylate (PMMA) pupil dilator-ring (Morcher, Stuttgart, Germany) (group II), Beehler pupil dilator (group III), and bimanual stretching (group IV). MAIN OUTCOME MEASURES: Performance (pupil size achieved), complications, and added surgical time. RESULTS: The mean pupil sizes achieved with the PMMA pupil-dilator ring, Beehler pupil dilator, and bimanual stretching were 5.9+/-0.6 mm, 5.5+/-0.8 mm, and 4.9+/-0.7 mm, respectively. A square-shaped pupil was achieved with iris-retractor hooks, and the mean size of the largest circle that can fit in this square was 5.6+/-0.6 mm. There were no statistically significant differences in the postdilatation pupil sizes between the 4 study groups (P>0.05). Apart from self-limited intraoperative hemorrhage from pupil margin, iris sphincter rupture was the only observed complication related to mechanical pupil dilatation. This occurred in 4 eyes in groups I and III, 3 eyes in group IV, and 1 eye in group II (P>0.05). The mean added surgical time for placement of iris-retractor hooks and for implantation of a PMMA pupil-dilator ring was 297+/-51 and 176+/-54 seconds, respectively. The additional time required for pupil dilatation with the Beehler pupil dilator and bimanual stretching was 65+/-8 and 55+/-10 seconds, respectively. The time needed for pupil dilatation in groups I and II is significantly longer than that in groups III and IV (P<0.001). CONCLUSIONS: All 4 methods used in this study were effective procedures for the mechanical dilatation of small pupils secondary to pseudoexfoliation syndrome. Iris-retractor hooks and the PMMA pupil-dilator ring are the most time-consuming techniques but have the advantage of a stable pupil size throughout the surgery. The PMMA pupil-dilator ring causes the least iris trauma. The Beehler pupil dilator and bimanual stretching technique were the least time-consuming methods for mechanical pupil dilatation.

Aged↗
PubMed2005

Stimulus-driven versus pilocarpine-induced biometric changes in pseudophakic eyes.

PURPOSE: Most trials that study the lens movement of accommodative intraocular lens (IOLs) use pilocarpine to stimulate ciliary muscle contraction. The aim of this study is to assess in vivo whether a more physiologic, stimulus-driven accommodation is comparable to pilocarpine-induced IOL movement. DESIGN: Controlled patient- and examiner-masked clinical trial. PARTICIPANTS: The study population included 38 eyes with accommodative IOL implants (1CU) and a control group of 28 eyes with conventional open-loop IOLs. METHODS: A high-precision biometry technique, partial coherence interferometry, was used to measure IOL position. Anterior chamber depth was measured during physiologic (near point) and pharmacological (pilocarpine 2%) stimulation. In a subgroup of 14 1CU eyes, IOL position was determined repeatedly within 90 minutes after pilocarpine administration. A different subgroup was investigated as to the effect of cyclopentolate on IOL position. Best-corrected distance visual acuity (VA), best-corrected near VA, and distance-corrected near VA (DCNVA) were assessed using logarithm of the minimum angle of resolution charts. MAIN OUTCOME MEASURES: Anterior chamber depth change under pilocarpine and near-point-driven accommodation. RESULTS: Near-point accommodation did not induce movement of either the accommodating 1CU or the control IOLs. Pilocarpine induced a 201+/-0.137-mm anterior movement of the 1CU IOL (P<0.001), compared with no movement within the control IOL groups (P>0.05). There was no significant (P>0.05) difference in DCNVA between the accommodative and open-loop IOLs. No correlation between near point- or pilocarpine-stimulated IOL movement and DCNVA was found. Concerning the time course of movement after pilocarpine administration, most of the 1CU IOLs showed some movement 30 minutes after application. Cyclopentolate-induced ciliary muscle relaxation caused a posterior IOL movement, as compared with the relaxed state, when focusing on a distant target. CONCLUSION: Pilocarpine-induced ciliary muscle contraction seems to overestimate IOL movement relative to a monocular near-driven stimulus. Therefore, concerning IOL movement, pilocarpine may act as a superstimulus and may not adequately simulate daily life performance of accommodative IOLs. However, it may be helpful to evaluate the maximum potential of an accommodating IOL.

Accommodation, Ocular↗