Myopia Research Today is a free monthly online journal that collates and summarizes the latest research about Myopia, including details on treatment, prevention, causes, correction.

Predictive factor analysis for successful performance of iris recognition-assisted dynamic rotational eye tracking during laser in situ keratomileusis.

Prakash G, Ashok Kumar D, Agarwal A, Jacob S, Sarvanan Y, Agarwal A

Dr Agarwal's Eye Hospital and Eye Research Centre, 19 Cathedral Road, Chennai, India.

PURPOSE: To analyze the predictive factors associated with success of iris recognition and dynamic rotational eye tracking on a laser in situ keratomileusis (LASIK) platform with active assessment and correction of intraoperative cyclotorsion. DESIGN: Interventional case series. METHODS: Two hundred seventy-five eyes of 142 consecutive candidates underwent LASIK with attempted iris recognition and dynamic rotational tracking on the Technolas 217z100 platform (Techolas Perfect Vision, St Louis, Missouri, USA) at a tertiary care ophthalmic hospital. The main outcome measures were age, gender, flap creation method (femtosecond, microkeratome, epi-LASIK), success of static rotational tracking, ablation algorithm, pulses, and depth; preablation and intraablation rotational activity were analyzed and evaluated using regression models. RESULTS: Preablation static iris recognition was successful in 247 eyes, without difference in flap creation methods (P = .6). Age (partial correlation, -0.16; P = .014), amount of pulses (partial correlation, 0.39; P = 1.6 x 10(-8)), and gender (P = .02) were significant predictive factors for the amount of intraoperative cyclodeviation. Tracking difficulties leading to linking the ablation with a new intraoperatively acquired iris image were more with femtosecond-assisted flaps (P = 2.8 x 10(-7)) and the amount of intraoperative cyclotorsion (P = .02). However, the number of cases having nonresolvable failure of intraoperative rotational tracking was similar in the 3 flap creation methods (P = .22). CONCLUSIONS: Intraoperative cyclotorsional activity depends on the age, gender, and duration of ablation (pulses delivered). Femtosecond flaps do not seem to have a disadvantage over microkeratome flaps as far as iris recognition and success of intraoperative dynamic rotational tracking is concerned.

Published 27 January 2010 in Am J Ophthalmol, 149(2): 229-237.e2.
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Articles on Myopia published 27 January 2010:

Surgical procedure for correcting globe dislocation in highly myopic strabismus.   Am J Ophthalmol, 149(2): 341-346.e2.

PURPOSE: To design a surgical procedure for correcting globe dislocation in strabismus in high myopia (highly myopic strabismus). DESIGN: Prospective, interventional case series. METHODS: We examined 36 eyes of 21 patients with highly myopic strabismus and 27 eyes of 27 healthy volunteers as controls at Osaka City General Hospital between 2000 and 2006. Anatomic relationships between the muscle cone and globe were analyzed using magnetic resonance imaging. Ranges of globe movement and angles of ... [Abstract] [Full-text]

Height, stunting, and refractive error among rural Chinese schoolchildren: the See Well to Learn Well project.   Am J Ophthalmol, 149(2): 347-353.e1.

PURPOSE: To evaluate the hypothesis that changes in nutritional status could be partly responsible for observed increases in myopia prevalence among Chinese children. DESIGN: Cross-sectional cohort study. METHODS: Rural Chinese secondary school children participating in a study of interventions to promote spectacle use were randomly sampled (20% of children with uncorrected vision >6/12 bilaterally, and 100% of remaining children) and underwent cycloplegic refraction with subjective ... [Abstract] [Full-text]

Two-year visual results for older Asian women treated with photodynamic therapy or bevacizumab for myopic choroidal neovascularization.   Am J Ophthalmol, 149(1): 140-6.

PURPOSE: To compare the long-term visual and anatomic outcome of treatment with photodynamic therapy (PDT) or intravitreal bevacizumab (IVB; Avastin; Genentech Inc, South San Francisco, California, USA) for choroidal neovascularization attributable to pathologic myopia (mCNV). DESIGN: An open-label, interventional case series. METHODS: SETTING: Multi-institutional. PATIENTS: Thirty-one eyes of Japanese women who received either PDT or IVB for mCNV. Inclusion criteria were age 50 years or older, ... [Abstract] [Full-text]

Articles on Myopia published 19 January 2010:

Adaptive gait changes due to spectacle magnification and dioptric blur in older people.   Invest Ophthalmol Vis Sci, 51(2): 718-22.

PURPOSE: A recent study suggested that updated spectacles could increase fall rate in frail older people. The authors hypothesized that the increased risk may be due to changes in spectacle magnification. The present study was conducted to assess the effects of spectacle magnification on step negotiation. METHODS: Adaptive gait and visual function were measured in 10 older adults (mean age, 77.1 +/- 4.3 years) with the participants' optimal refractive correction and when blurred with +1.00, ... [Abstract] [Full-text]

Enhanced contrast sensitivity confirms active compensation in blur adaptation.   Invest Ophthalmol Vis Sci, 51(2): 1242-6.

PURPOSE: To determine the effects of defocus-induced blur adaptation on human contrast sensitivity (CS) function. METHODS: Defocused (+2 D) CS was measured for spatial frequencies between 0.5 and 12 cycles per degree (cpd) before and after adaptation to +2 D blur in six subjects with normal vision. During the 30-minute adaptation period with +2 D lens, subjects were exposed to a succession of static calibrated natural images that were also used to "top-up" adaptation between ... [Abstract] [Full-text]

Parameters associated with the different astigmatism axis orientations.   Invest Ophthalmol Vis Sci, 51(2): 723-30.

PURPOSE: To evaluate parameters associated with astigmatism axis orientation. METHODS: A retrospective population-based study was conducted on 67,899 (53% males) Israeli Defense Force conscripts aged 16 to 22 years with >or=0.25 D of astigmatism, using prerecruitment examination and demographic data that included a validated general intelligence score. Refractive errors were classified by the cylinder axis with the least deviation from emmetropia (LDE), a scheme intended to avoid confounding ... [Abstract] [Full-text]

Model to predict endothelial cell loss after iris-fixated phakic intraocular lens implantation.   Invest Ophthalmol Vis Sci, 51(2): 811-5.

PURPOSE: To describe a model predicting endothelial cell (EC) loss after iris-fixated phakic intraocular lens (pIOL) implantation, taking distance from the edge of the pIOL to the endothelium into account. METHODS: This prospective observational study monitored long-term EC changes in 306 eyes after pIOL implantation. EC density (ECD) was determined before surgery, 6 months after surgery, and then annually up to 8 years after surgery. Mean follow-up was 31.7 +/- 25.7 months. All eyes underwent ... [Abstract] [Full-text]

Increased 24-hour variation of human intraocular pressure with short axial length.   Invest Ophthalmol Vis Sci, 51(2): 933-7.

PURPOSE: To characterize 24-hour variation of intraocular pressure (IOP) in healthy young adults based on the axial length of the eye. METHODS: Twenty-four-hour IOP data were collected from nine healthy young adults with hyperopia, age range 18 to 25 years, in a sleep laboratory. Every 2 hours, measurements of IOP were taken in the participants after 5 minutes in the supine position and 5 minutes in the sitting position during the 16-hour diurnal/wake period as well when supine in bed during ... [Abstract] [Full-text]

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