Cortical visual impairment: new directions. (65/129)

 (+info)

Characteristics of low-vision rehabilitation services in the United States. (66/129)

 (+info)

An evaluation of the Bausch & Lomb Zywave aberrometer. (67/129)

PURPOSE: The Bausch & Lomb Zywave uses Shack-Hartmann aberrometry to determine wavefront aberrations of the human eye and provide an estimate of refractive error. We investigated the effect of pupil size on the repeatability and validity of refractive errors estimated by the Zywave and the repeatability of higher-order aberrations. METHODS: Twenty-three subjects were measured with the Zywave under natural and cycloplegic conditions on two occasions separated by at least one week. Refractive error was also measured using a Nidek ARK-700A autorefractor. At one visit, a cycloplegic subjective refraction was performed. Measured ocular wavefront aberrations were expressed as the polynomial coefficients from a least-squares fitted fifth-order Zernike polynomial expansion over three, five and seven millimetre diameters. Repeatability and validity were evaluated by calculating the difference between pairs of refractive estimates or Zernike terms, determining the mean and standard deviation of these differences and calculating the 95% limits of agreement (LoA = mean +/-1.96 x SD). RESULTS: The repeatability of refractive error estimated by the Zywave was better than that of the Nidek autorefractor for both manifest and cycloplegic conditions. Manipulating the pupil size on the Zywave from three to seven millimetres changed the mean cycloplegic spherical equivalent from -1.91 D to -2.60 D, a shift that was negatively correlated with spherical aberration. As expected, the magnitude of the Zernike coefficients increased with increasing pupil diameter, as did their corresponding 95% LoA. The 95% LoA decreased for higher-order terms but the magnitude of the terms and the variation between subjects also decreased with increasing order. To compensate for these factors,the ratio of the SD between sessions to the SD across subjects was calculated. The ratios were lowest for second-order terms (less than 0.08 for 7.0 mm pupil), intermediate for the C4,0 spherical aberration term (0.14) and third-order terms (approximately 0.25) but approached and exceeded 1.0 for many fourth- and fifth-order terms. CONCLUSIONS: The Zywave provides valid and repeatable estimates of refractive error. We attribute the myopic shift for larger pupils to the eye's spherical aberration. The repeatability of the Zernike terms measured with the Zywave was acceptable for the second-order and spherical aberration terms but for other higher-order terms, the variation between sessions may exceed the variation between subjects indicating unacceptable repeatability. This may have important ramifications for wavefront-guided LASIK.  (+info)

Refractive error changes in children with intermittent exotropia under overminus lens therapy. (68/129)

 (+info)

Effect of examiner experience and technique on the alternate cover test. (69/129)

 (+info)

Changes in dynamics of accommodation after accommodative facility training in myopes and emmetropes. (70/129)

 (+info)

Efficiency of referral for suspected glaucoma. (71/129)

OBJECTIVE: To examine the efficiency of referral for suspected glaucoma to general practitioners and consultants by optometrists. DESIGN: A prospective survey covering 5% of all sight tests performed by optometrists in England and Wales over six months, with analysis of referred patients. SETTING: 241 optometrists' practices in areas representative of England and Wales in socioeconomic terms. SUBJECTS: Of 275,600 people attending for a sight test, 1505 were referred with suspected glaucoma (0.9% of those aged over 4%). Outcomes were recorded for 1228 patients, 1103 (90%) of whom attended for examination by a consultant ophthalmologist (8% on a private basis). The analysis was confined to the 704 cases in which the information on diagnosis was received directly from a consultant or general practitioner. MAIN OUTCOME MEASURES: Diagnoses reported by consultant ophthalmologists. Waiting times before an appointment for examination by a consultant ophthalmologist. RESULTS: Glaucoma was confirmed in 283 of the 704 referred patients, and another 222 patients were considered to require further monitoring. In all, 112 (41%) of 275 confirmed cases of glaucoma were in patients with intraocular pressures greater than or equal to 30 mm Hg. At all levels of intraocular pressure the accuracy of referral was greater when the optometrist also recorded the presence of suspicious optic discs or loss of visual field, or both; but only 331 (47%) out of the 704 referred patients had been tested with a field screener. The median waiting time for an NHS clinic appointment was nine weeks. Almost a 10th of confirmed cases of glaucoma were in people in a high risk category for glaucoma who had to wait at least 14 weeks for an appointment. CONCLUSIONS: Closer cooperation, especially at the local level, among consultants, general practitioners, and optometrists is needed to improve testing and referral for suspected glaucoma. Optometrists should be encouraged to perform all the three main tests--ophthalmoscopy, tonometry, and perimetry--in patients before referral and to report precisely on reasons for referral to help prioritisation. The optometrist's referral letter to the general practitioner should always be passed on to the consultant. Similarly, the diagnosis should always be reported back to the optometrist.  (+info)

Accommodation in mild traumatic brain injury. (72/129)

Accommodative dysfunction in individuals with mild traumatic brain injury (mTBI) can have a negative impact on quality of life, functional abilities, and rehabilitative progress. In this study, we used a range of dynamic and static objective laboratory and clinical measurements of accommodation to assess 12 adult patients (ages 18-40 years) with mTBI. The results were compared with either 10 control subjects with no visual impairment or normative literature values where available. Regarding the dynamic parameters, responses in those with mTBI were slowed and exhibited fatigue effects. With respect to static parameters, reduced accommodative amplitude and abnormal accommodative interactions were found in those with mTBI. These results provide further evidence for the substantial impact of mTBI on accommodative function. These findings suggest that a range of accommodative tests should be included in the comprehensive vision examination of individuals with mTBI.  (+info)