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Corrections in highly aberrated eyes
Published in Pablo Artal, Handbook of Visual Optics, 2017
Jason D. Marsack, Raymond A. Applegate
In addition to the subjective process described earlier, clinicians currently have at their disposal objective methods to determine the sphero-cylindrical error of the eye. These instruments as a class are called autorefractors and utilize some objective optical metric to determine the eye’s sphero-cylindrical correction. However, unlike the subjective method, the quality of vision is not assessed by the patient in this method. For this reason, objective refractions are typically used as a starting point for the subjective refraction process in the clinic. This is logical due to the fact that the patient’s perceived quality is, in the end, the ultimate assessment of the quality of the correction.
Impact of Lens Material on Objective Refraction in Eyes with Trifocal Diffractive Intraocular Lenses
Published in Current Eye Research, 2022
Nuria Garzón, Francisco Poyales, María García-Montero, Fidel Vega, María Sagrario Millán, César Albarrán-Diego
Subjective or manifest refraction (Rx) is still considered as the Gold Standard method to determine the eye’s refractive status after cataract surgery, and for prescribing eyeglasses.19 Subjective refraction can be measured without a reliable objective refraction value as a starting point, but the procedure will be more time-consuming, increasing both the patient’s fatigue and the probability of inaccuracies in the obtained value.20 The techniques for ObjRx measurement include AR, keratometry, aberrometry and retinoscopy. In the general population, retinoscopy is superior to AR as starting point to non-cycloplegic Rx,21 but retinoscopy needs experienced clinicians. In pseudophakic eyes, with no accommodation, AR can be a good starting point for Rx19,22 since it requires less training than retinoscopy.
Validation of an Objective Method for the Qualitative and Quantitative Assessment of Binocular Accommodative Facility
Published in Current Eye Research, 2020
Jesús Vera, Beatríz Redondo, Rubén Molina, George-Alex Koulieris, Raimundo Jiménez
Four sessions in different days were conducted for this study. Participants received written information about the study and were informed about their right to leave the experiment at any time. All experimental sessions were scheduled at the same time of the day (±1 h), and separated by a minimum of 24 h and a maximum of 72 h. In the first visit, both a biomicroscopy and a direct ophthalmoscopy examination were performed in order to detect any ocular disease. An auto Ref/Keratometer in static mode (WAM-5500, Grand Seiko Co. Ltd., Hiroshima, Japan) was used to obtain the objective baseline refractive value, with these measurements being used to calculate the magnitude of accommodation (see below), and keratometry. Three readings were taken in each eye and averaged. Then, a monocular and binocular subjective refraction using an endpoint criterion of maximum plus consistent with best vision was performed. At this point, soft contact lenses (SCLs) were ordered to the manufacturer (Servilens Fit & Covers Company, Granada, Spain) based on the refractive and keratometric assessment and adjusted for the vertex distance of each individual. Disposable HEMA and Ocufilcon D (55% water content) soft contact lenses were used. When a lower 0.75D astigmatism was found, soft contact lenses with appropriate spherical equivalent were selected and toric soft contact lenses were used to compensate astigmatism ≥0.75D. For screening purposes, we also measured the accommodative response at 20 cm with the WAM-5500, since lags of accommodation greater than 1.55 D at this distance were considered as exclusion criteria.
Vergence Profile and Prevalance of Non-Strabismic Vergence Anomalies Among School Children in Abia State, Nigeria
Published in Ophthalmic Epidemiology, 2019
Uchenna C. Atowa, Samuel O. Wajuihian, Rekha Hansraj
Refraction was performed on all children irrespective of their visual acuity. Objective refraction was carried out using the Topcon RM-8000B (Topcon Corporation, Tokyo, Japan) autorefractometer in three repeated measures. The average of the readings was then refined subjectively to best comfortable visual acuity achievable with maximum plus and minimum minus lenses. Cycloplegia was not applied as this would have disrupted the evaluation of accommodation, which was also investigated in this study. However, the plus lens (+2.00 DS) test was conducted on all subjects to rule out latent hyperopia. Following the subjective refraction, the binocular vision system was evaluated.