Background:We objectively assessed the optical quality and intraocular scattering by means of parameters provided by a clinical double-pass system in healthy young subjects and thereby we obtained new reference data for clinical diagnosis. We calculated normal values of neural contrast sensitivity function (nCSF) from the measured modulation transfer function (MTF) and the contrast sensitivity function (CSF). Methods: Eligible subjects were healthy adults aged from 18 to 30 years with a logMAR visual acuity (VA) of 0.0 or better and normal values of CSF. Optical quality measurements for a 4.0 mm pupil were performed using the Optical Quality Analysis System (OQAS) based on the double-pass technique. The following parameters were analysed: the modulation transfer function cutoff frequency (MTF cutoff), the Strehl 2D ratio, the OQAS values (OV) at 100, 20 and nine per cent contrasts and the objective scatter index (OSI). Results: A total of 178 volunteers responded to the call, of whom 181 eyes were finally part of the study taking into account the criteria for inclusion. The values for the optical quality parameters were: 44.54 Ϯ 7.14 cpd (MTFcutoff), 0.27 Ϯ 0.06 (Strehl 2D ratio), 1.48 Ϯ 0.24 (OV100%), 1.58 Ϯ 0.32 (OV20%), 1.64 Ϯ 0.39 (OV9%), and 0.38 Ϯ 0.19 (OSI). The nCSF calculated was 1.76 Ϯ 0.21 (3 cpd), 2.13 Ϯ 0.23 (6 cpd), 2.01 Ϯ 0.28 (12 cpd) and 1.86 Ϯ 0.33 (18 cpd). Conclusion:The normal values provided can be a useful tool for discriminating healthy eyes from early abnormal ones in which the optical quality or sensory function is impaired.

CONCLUSIONS:The results of the study showed that OSI is a useful parameter for evaluating large amounts of intraocular scattering that can be used, in combination with other conventional procedures, as a valuable tool in the clinical practice to objectively grade cataracts.

Verisyse and Veriflex phakic IOL implantation and LASIK are both safe and effective in correcting moderate to high myopia, but they involve different processes of optical quality recovery. One day after surgery, the Verisyse IOL implantation significantly reduced the eye's optical quality, mainly due to the larger incision required and the higher number of sutures used. This reduction was not as remarkable with the other two techniques. However, 1 month after surgery, patients with IOL implants recovered more optical quality than LASIK patients.

Background We assessed the effects of aging on visual function and optical quality in a healthy adult population and provide reference values for different age ranges. Methods We conducted a prospective study with 198 healthy volunteers from 31 to 70 years of age. The visual acuity (VA) and contrast sensitivity (CS) at 3, 6, 12 and 18 cycles per degree (cpd) frequencies were assessed, together with values of optical quality and intraocular scattering obtained with a double‐pass system (Optical Quality Analysis System – OQAS), specifically the modulation transfer function cutoff frequency (MTFcutoff), the Strehl ratio, the OQAS values (OV) at contrasts of 100, 20 and nine per cent and the objective scatter index (OSI). We studied the change of these variables with age and obtained standard values for optical quality and intraocular scattering parameters for four age groups: 31 to 40, 41 to 50, 51 to 60 and 61 to 70 years. Results We found significant correlations between age and all variables analysed and significant differences among the age groups considered except for CS (3 cpd) (p = 0.067). Ageing particularly affected low‐contrast parameters, such as the OV nine per cent and the OSI, which decreased to 37 and 50 per cent of their original values, respectively. The OSI was found to provide high sensitivity and specificity values, when healthy and caratactous eyes were considered. The results suggest that optical deficits are compensated until 50 years of age with sensory and perceptual factors, as smaller changes were found for visual function than for objective measurements of optical quality and intraocular scattering. Conclusions Measures of optical quality assessed by subjective psychophysical and objective techniques varied differently with age. Values obtained for each age group can be used to determine normal limits of optical quality and intraocular scattering for diagnosis of ocular conditions.

Retinal image quality was similarly reduced with PRK and LASIK, with no significant differences between the 2 methods. Some PRK patients had a residual refractive error that might have been related to corneal-wound healing still present 3 months postoperatively.